Innovations for cost-effective and eco-friendly solutions to combat chemotherapy-induced alopecia: a narrative systematic review.

Introduction
Chemotherapy-induced alopecia (CIA) is one of the most visible and distressing side effects of cancer treatment, often impacting patients’ self-esteem, sense of identity, and overall quality of life [1]. While scalp cooling has emerged as an effective intervention for reducing hair loss during chemotherapy [2–6], its accessibility remains limited due to high costs, logistical challenges, and environmental concerns [7]. For many low-income patients, especially in resource-limited settings, access to scalp cooling is hindered by these factors, despite its potential to alleviate some of the emotional burden associated with cancer treatment.
Patients with breast cancer, lymphoma, leukemia, ovarian cancer, and paediatric cancers are particularly affected by CIA [5, 7–11], with those undergoing chemotherapy regimens that include specific drug classes being more prone to hair loss. Breast cancer patients, especially those treated with taxanes (e.g., paclitaxel, docetaxel) [5, 6, 12, 13] and anthracyclines (e.g., doxorubicin) [14, 15], often experience significant hair loss, which can deeply affect their emotional well-being. Similarly, lymphoma and leukemia patients receiving alkylating agents (e.g., cyclophosphamide) and anthracyclines (e.g., daunorubicin) also experience high levels of alopecia [7, 9–11]. This side effect is particularly pronounced in pediatric patients, who may already face additional psychological challenges due to cancer treatment. Ovarian cancer patients treated with platinum compounds (e.g., cisplatin) and taxanes also experience moderate to high hair loss, as do lung cancer patients on platinum-based chemotherapy (e.g., cisplatin, carboplatin), although the severity can vary based on treatment regimens [10, 16].
The average total cost for scalp cooling treatment in the USA is approximately USD 1500 to 3000 per patient, depending on the number of chemotherapy cycles required [17]. In Asia, scalp cooling is usually billed per session where the cost varies by provider and location. For example, the National University Cancer Institute of Singapore (NCIS) offers scalp cooling for chemotherapy patients at affiliated hospitals with charges ranging from SGD 200 to 400 (~ USD 150 to 300) [18]. In Malaysia, costs generally fall between MYR 600 and 1000 per session (~ USD 135 to 225), with private hospitals such as Pantai Hospital in Kuala Lumpur and the National Cancer Society of Malaysia offering this treatment [19]. However, accessibility is often restricted due to the lack of insurance coverage, further limiting accessibility for many patients.
Notably, no scientific studies have specifically addressed the pricing structure or affordability of scalp cooling, particularly in low- and middle-income countries. This gap highlights the critical need for research into the economic feasibility and broader accessibility of scalp cooling treatments, especially for low-income cancer patients in resource-limited settings. Since scalp cooling is typically charged per session, it can quickly become a significant financial burden, particularly for patients undergoing prolonged chemotherapy regimens. This fee structure can accumulate rapidly, rendering the treatment inaccessible for individuals with limited financial resources. As such, there is an urgent need for more affordable and sustainable alternatives to ensure that cancer patients from all socioeconomic backgrounds can benefit from scalp cooling to mitigate chemotherapy-induced alopecia (CIA). Addressing these financial barriers is crucial to promoting equity in cancer care and ensuring that hair-preserving interventions are accessible to all patients, regardless of their financial means.
Recent advancements in scalp cooling technology have sparked interest in developing more affordable, sustainable, and user-friendly solutions. Innovations in materials, cooling mechanisms, and device design are making scalp cooling more cost-effective and eco-friendly, broadening its potential reach. These technological advances aim to lower the barriers that prevent economically disadvantaged patients from benefiting from this hair-preserving intervention.
This review examines the latest developments in scalp cooling technologies and explores their alignment with three core goals: affordability, sustainability, and inclusivity, with an emphasis on planetary health. By evaluating both current and emerging solutions, we aim to provide a comprehensive overview of the progress made in making scalp cooling accessible to a broader population. In doing so, we highlight the importance of equitable healthcare solutions that not only prioritize efficacy but also economic feasibility, environmental responsibility, and the impact on planetary health. These factors are essential to ensure that cancer care is sustainable, inclusive, and mindful of the broader environmental context, paving the way for more equitable and eco-friendly cancer treatments for all patients.

Methods
This narrative systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020) guidelines. It synthesizes current literature on scalp cooling technologies, emphasizing innovations that enhance cost-effectiveness, sustainability, and accessibility for low-income cancer patients. Relevant peer-reviewed articles, clinical trial reports, industry publications, and case studies published between January 2014 and December 2024 were identified through a comprehensive search strategy. The primary databases searched included PubMed, Scopus, Web of Science, ScienceDirect, and Google Scholar, and the process was complemented by manual searches of reference lists from key articles to ensure complete coverage. The final search was completed on 31 January 2025.
The search strategy used a combination of keywords and Boolean operators, including “scalp cooling,” “cold cap,” “chemotherapy-induced alopecia,” “hair preservation,” “low-cost,” “affordable,” “sustainable,” “eco-friendly,” and “inclusive cancer care.” Studies were selected based on their relevance to three main aspects: innovations in cost-effective scalp cooling, environmentally friendly materials and device designs, and initiatives that improve accessibility for economically disadvantaged populations. Eligible studies included experimental, quasi-experimental, observational, and qualitative designs that reported on device performance, cost, feasibility, or user experience. Publications that were not in English, conference abstracts without full texts, editorials, commentaries, and studies unrelated to chemotherapy or hair preservation were excluded.
All search results were imported into Mendeley Reference Manager for citation management. Duplicate records identified across databases were automatically removed and then manually verified for accuracy. Title and abstract screening were conducted independently by two reviewers to identify potentially relevant studies. Full-text assessments were then carried out to confirm inclusion based on the predefined criteria. Any discrepancies between reviewers were resolved through discussion or consultation with a third reviewer. Figure 1 illustrates the PRISMA flow diagram, which summarizes the process of identification, screening, eligibility assessment, and final inclusion of studies in this review.
Data extraction was conducted using a standardized form designed to ensure consistency and completeness. Information extracted from each study included the type of scalp cooling device, cooling mechanism, energy consumption, materials used, cost and maintenance requirements, patient comfort and satisfaction, and logistical or operational considerations. Data extraction was performed independently by two reviewers and cross-checked for accuracy. Quantitative data were summarized descriptively, while qualitative findings were synthesized narratively to identify overarching themes, patterns, and technological trends.
The methodological quality and risk of bias of the included studies were assessed using appropriate tools depending on study design. The Cochrane Risk of Bias tool (RoB 2) was applied to randomized controlled trials, the ROBINS-I tool was used for non-randomized studies, and the Joanna Briggs Institute (JBI) Critical Appraisal Checklist was used for qualitative studies. Quality assessments were conducted independently by two reviewers, and disagreements were resolved through consensus.
Both quantitative and qualitative analyses were then integrated to provide a comprehensive understanding of how current scalp cooling technologies align with the goals of affordability, sustainability, and inclusivity in cancer care. The analysis sought to highlight practical and scalable innovations, identify limitations in existing approaches, and offer insights into potential directions for future research and technological development in this field.

Results
This review identified key advancements in scalp cooling technologies that address three central objectives: (1) cost-effectiveness, (2) environmental sustainability, and (3) accessibility for low-income cancer patients. Fifty-two studies published between 2014 and 2024 contributed clinical, engineering, and implementation evidence that informs these themes.

Cost-effectiveness of cooling technologies
A range of low-cost scalp cooling devices now provides more affordable alternatives to machine-based systems, which are often too costly for many patients. These options include manually operated cooling caps that do not require expensive cooling machines. Studies show these alternatives can effectively reduce hair loss, although they may trade off some comfort and consistency. Some designs allow patients to control cooling intensity, reducing production costs while maintaining hair preservation benefits. Cost analyses indicate these devices can cut costs by up to 50% compared to automated systems, making them more accessible to low-income patients [20].
Recent innovations are making scalp cooling more inclusive, with caps that use frozen or chilled gel packs and simpler manual controls that require no electronic components. These designs offer practical, adaptable solutions for patients, particularly in low-resource settings, and allow healthcare providers to expand hair-preserving options to more patients, promoting equity in cancer care. Manual cooling methods, while not FDA-regulated, eliminate the need for costly machines by using pre-cooled materials to maintain temperatures during chemotherapy sessions. Although these methods may require periodic re-cooling or cap replacement to maintain effectiveness, they present a more affordable option for patients with financial limitations.

Gel-based cooling caps
Gel-based cooling caps are among the most affordable alternatives to traditional machine-operated cooling systems. These caps use specially formulated cooling gels that maintain low temperatures for prolonged periods, typically by pre-freezing the caps before use. Studies show that gel-based caps can be effective in reducing chemotherapy-induced alopecia, although their efficacy can vary depending on the gel composition and cooling duration. Chemo Cold Cap has been shown to retain cooling properties for approximately 1–2 h before needing replacement with a re-cooled cap [21]. However, these caps may require multiple cap changes during a chemotherapy session to maintain a consistent cooling effect, presenting logistical challenges in settings without easy access to freezing facilities [22].

Cryogel caps
Cryogel caps are an adaptation of gel caps, using a combination of gel and polymer technology to enhance cooling duration. Cryogels offer more consistent cooling temperatures over extended periods compared to standard gel caps. Standard gel caps generally maintain effective cooling for approximately 1–2 h before requiring replacement [21, 22]. In comparison, cryogel caps provide a longer and more stable cooling duration of around 2–3 h, attributable to their enhanced polymer–gel matrix, which slows heat absorption and prolongs temperature stability [23, 24]. This extended cooling period reduces the number of cap changes needed during chemotherapy sessions and may improve patient comfort and workflow efficiency. Research has demonstrated that cryogel caps can offer more comfortable and reliable cooling, while still being cost-effective, as they do not require a continuous connection to a cooling machine [23]. Some cryogel cap models are designed to be reused with minimal wear and tear, which can reduce the long-term cost for both patients and healthcare facilities, making them suitable for low-income patients or clinics with budget constraints [24].

Dry ice-powered caps
Dry ice-powered cooling caps offer a unique solution for areas without access to reliable electricity or freezing facilities. These caps are activated by placing dry ice in an insulated cap compartment, where it maintains a steady cooling effect. A study conducted in rural health facilities found dry ice-powered caps effective for patients who otherwise had no access to automated scalp cooling methods [25]. However, handling and accessibility of dry ice pose potential safety and logistical challenges, especially in regions where dry ice is not readily available or affordable. Despite these limitations, dry ice-powered cooling caps have been used as a low-cost, practical option in some developing countries where alternative resources are scarce [26].

Modular passive cooling caps
Modular passive cooling caps are designed with customizable sections that patients can pre-freeze and assemble based on their specific needs. These caps often feature individual gel or phase-change material (PCM) inserts that can be frozen separately and placed in strategic areas of the cap to enhance comfort and coverage. Modular cooling caps allowed patients to adapt cooling to areas most prone to alopecia, potentially increasing comfort and reducing material use [27]. This design also allows parts of the cap to be reused, reducing the need for full replacement, which helps lower costs. PCM inserts used in these caps are known to maintain consistent temperatures longer than standard gel inserts, though they are often more expensive upfront, suggesting a balance between initial cost and long-term savings [28].

Silicone-based caps
Silicone-based cooling caps offer durability and reusability, making them a cost-effective option over time. These caps are typically made from medical-grade silicone filled with a cooling gel, which is both durable and effective in maintaining low temperatures. Because of their durable material, these caps can be repeatedly sterilized and reused in clinical settings, significantly reducing the per-use cost for healthcare providers. A comparative study found silicone-based cooling caps to have a similar efficacy rate to standard machine-based cooling systems when regularly chilled, with the added benefit of long-term cost savings [29]. Silicone caps are also relatively lightweight and comfortable, improving patient adherence and satisfaction with scalp cooling [30].

DIY cold caps
Do-it yourself (DIY) cold caps offer a cost-effective alternative to machine-operated scalp cooling systems and an accessible substitute for wigs, especially in resource-limited settings. These caps enable patients to assemble and freeze components themselves, reducing dependence on expensive equipment. However, they lack consistent, regulated cooling, which can reduce their effectiveness in preventing hair loss during chemotherapy. DIY caps often need frequent re-cooling, which may disrupt sessions and pose challenges without access to freezing facilities. Additionally, uneven coverage can lead to inconsistent cooling across the scalp, and the lack of ergonomic design may cause discomfort [31]. Despite these limitations, DIY caps remain a flexible, viable option for patients and healthcare providers, meeting unique needs in settings with low resources and limited access to automated scalp cooling.

Practical requirements and safety considerations
Many low-cost and manual scalp cooling options require the assistance of a trained scalp cooling nurse to properly fit, secure, and rotate caps during chemotherapy sessions. This support role is essential for ensuring tight contact between the cap and scalp, maintaining effective cooling, and performing timely cap changes. However, the need for trained personnel introduces an additional resource requirement, which may limit feasibility for patients without dedicated support or for clinics with staffing constraints. In community or home-based settings, trained personnel, typically caregivers or family members, can help enhance the overall effectiveness of these cooling methods. Safety considerations are also important, particularly for DIY or frozen caps. Improperly chilled caps, such as those below recommended temperatures, carry a risk of hypothermia, frostbite, or thermal skin injury if applied directly to the scalp without adequate insulation. Unlike machine-regulated systems, manual caps lack consistent temperature control, making careful monitoring essential. Studies caution that users must follow safe handling guidelines, ensure caps are not frozen to excessively low temperatures, and apply appropriate protective layers to reduce risk while maintaining cooling efficacy [31].
Across these innovations, quantitative comparisons highlight clear differences in cooling performance and cost benefits. Cryogel caps maintain stable temperatures for 2–3 h and demonstrate 45–60% hair retention [23, 24], reducing the need for frequent cap changes during chemotherapy. Phase-change material (PCM) caps offer the longest uninterrupted cooling at 3–4 h, while using 30–40% less energy than automated systems [35], and early trials report 40–55% hair retention [28]. Silicone-based caps, valued for durability and repeated sterilization, achieve 50–70% hair retention [29, 30], comparable to machine-based scalp cooling, and provide an estimated 20–35% overall cost reduction for clinics through long-term reuse [29]. These quantitative differences in cooling duration, efficacy, and cost savings enhance the comparative understanding of emerging scalp cooling technologies.
Among the manual scalp cooling options, cryogel caps stand out as a superior choice for innovation. They offer consistent, long-lasting cooling without the need for frequent re-cooling, enhancing patient comfort and minimizing treatment interruptions. The combination of gel and polymer technology provides steadier cooling temperatures, reducing discomfort and improving hair preservation more effectively than other cooling cap technologies. Cryogel caps also excel in usability and practicality, especially in low-resource settings where access to reliable freezing facilities may be limited. They present a promising foundation for further development, focusing on comfort, reusability, and extended cooling duration, all without a significant cost increase. Table 1 outlines the cost-effectiveness of various cooling technologies.

Eco-friendly innovations in scalp cooling materials
Cooling caps made from biodegradable or recyclable materials are gaining prominence for reducing waste and minimizing environmental impact in high-use clinical settings. Energy-efficient cooling units that consume less electricity while maintaining consistent temperatures have emerged as a cost-saving innovation over time. Additionally, solar-powered cooling systems hold promise for improving access in remote or resource-limited areas with unreliable electricity. Future research should ensure these sustainable solutions remain effective in preventing chemotherapy-induced alopecia (CIA) while offering eco-friendly alternatives. By integrating sustainable materials and energy-efficient designs, scalp cooling technologies can address environmental concerns and reduce costs, making them viable for broader clinical adoption, particularly in low-resource settings. These innovations align with global efforts to achieve equitable and environmentally responsible healthcare.

Biodegradable and recyclable cooling caps
Biodegradable and recyclable materials are being adopted as sustainable alternatives to traditional synthetic polymers, which significantly contribute to medical waste. Biodegradable options, such as polylactic acid (PLA), are often plant-based and capable of decomposing under controlled conditions. Research demonstrates that PLA-based cooling caps deliver performance comparable to synthetic alternatives, maintaining effective cooling durations and consistent temperatures while reducing environmental impact. This makes them an environmentally responsible choice, particularly in high-turnover clinical environments [32]. Meanwhile, recyclable materials like thermoplastic polyurethane (TPU) and silicone are also gaining popularity due to their durability and reusability. These materials can endure repeated use and sterilization, extending their lifespan and minimizing waste per use. TPU has shown resilience without significant temperature degradation, making it a practical option for healthcare providers focused on sustainability [33]. Clinical trials with recyclable caps have reported positive outcomes in terms of durability, patient comfort, and waste reduction, further supporting their potential for widespread use in sustainable medical practices [34].

Phase Change Materials (PCMs) for energy-efficient cooling
Phase change materials (PCMs) are widely used in energy-efficient cooling technologies due to their ability to store and release large amounts of thermal energy at specific temperatures. PCMs absorb heat when they melt and release it when they solidify, maintaining a consistent cooling temperature for prolonged periods. This characteristic reduces the need for active cooling devices and lowers overall energy consumption [35]. PCM-based cooling caps could achieve consistent cooling effects comparable to machine-operated systems but with significantly reduced energy demands. This technology is recognized as a sustainable option for scalp cooling, especially in off-grid or energy-scarce environments.

Solar-powered cooling devices
Solar-powered cooling devices represent a promising solution for delivering sustainable scalp cooling in remote or low-resource regions. These devices are equipped with small solar panels that power the cooling mechanism, either directly or by charging a battery that operates the cooling cap. Solar power eliminates reliance on conventional electricity, making these systems both environmentally friendly and suitable for areas with limited electrical infrastructure. Solar-powered cooling caps have demonstrated efficacy in rural oncology clinics, where traditional cooling methods are often impractical due to lack of reliable power [36]. Solar energy not only decreased reliance on external power sources but also provided a sustainable, continuous power supply that allowed for consistent cooling throughout chemotherapy sessions. Although still in developmental stages, solar-powered cooling devices offer great potential for reducing environmental impact while expanding access to sustainable cooling options.
Solar-powered cooling systems do not require the device to be used outdoors. Only the solar panels are placed outside, while the cooling unit functions indoors. In healthcare settings, solar power is typically used in two ways: (i) PV panels charging a battery that runs a compressor or thermoelectric cooler, or (ii) PV panels driving cooling during the day while excess cold is stored in ice or phase-change materials (PCM) for later use. Thermal storage helps reduce battery needs and keeps temperatures stable. These approaches are already used in vaccine and medical refrigeration and offer a practical pathway for off-grid scalp cooling when paired with PCM or battery support [36, 49]. Continued development should focus on ensuring adequate cooling time for chemotherapy sessions and safe temperature control.

Reusable gel-based caps with reduced plastic content
Many newer gel-based cooling caps are designed to reduce plastic content by incorporating natural, eco-friendly fibers in the cap structure. By replacing synthetic outer layers with materials like organic cotton or biodegradable polyester, these caps maintain effectiveness while reducing their environmental footprint. A study on reusable gel caps by Tanaka et al. [37] demonstrated that using biodegradable polyester reduced overall plastic use without impacting the cap’s cooling properties or durability. Additionally, these caps can be reused multiple times, significantly decreasing the waste generated in clinical settings. Reusable caps also minimize single-use waste by allowing for sterilization and multiple applications. For example, cooling caps with gel inserts that can be replaced or re-chilled rather than discarded have shown effectiveness in clinical studies, extending the cap’s lifespan and reducing the need for disposal after each session [38]. This reusability, combined with the reduced plastic content, makes them a cost-effective and sustainable solution for clinics looking to reduce environmental waste.
Among the four cooling materials, biodegradable and recyclable cooling caps stand out as the most practical and sustainable option. They offer a strong balance of environmental responsibility, clinical effectiveness, and cost-efficiency. Materials like PLA, TPU, and silicone provide durability, reusability, and consistent cooling performance while significantly reducing medical waste. Although phase change materials and solar-powered devices show promise, particularly in low-resource or off-grid settings, they are still in developmental stages and lack widespread implementation. Reusable gel-based caps also contribute to sustainability but offer less durability compared to recyclable alternatives. Overall, biodegradable and recyclable caps are the most viable choice for scalable, eco-friendly scalp cooling. Table 2 outlines the eco-friendly innovations in scalp cooling materials.

Accessibility initiatives for underserved populations
To improve the accessibility of scalp cooling for low-income patients, various community-supported initiatives and funding programs have emerged. Patient assistance programs, funded by non-profits and healthcare organizations, offer subsidies or loans to cover the costs of scalp cooling devices. Additionally, hospital-led initiatives in low-income regions have started pilot programs offering free or low-cost cooling caps to eligible patients. These initiatives have shown a significant positive impact, with surveys indicating high patient satisfaction and reduced distress related to hair loss. To improve the accessibility of scalp cooling, recent initiatives have demonstrated measurable progress, particularly for low-income patients. Non-profit organizations in the USA and Europe have collectively supported over 3500 patients through subsidy and loan-based programs, with reported patient satisfaction ranging from 78–90% [39–41]. Hospital-led initiatives in Australia and South Korea have further expanded access by integrating subsidized scalp cooling into routine breast cancer care, with an estimated 25–40% of oncology units now offering reduced-cost or free cooling services [42–45]. In low-resource settings, pilot programs in rural Kenyan clinics have shown promising feasibility, enabling 60–120 patients annually to access PCM- or gel-based cooling caps that would otherwise be unavailable [46]. Additionally, community-based initiatives report that 70–85% of participants experienced reduced distress related to chemotherapy-induced alopecia after receiving subsidized scalp cooling support [47, 48]. Together, these numeric indicators underscore the growing global commitment to improving equitable access to scalp cooling across diverse healthcare systems. Educational outreach efforts aimed at patients and healthcare providers are also contributing to greater awareness and acceptance of scalp cooling, particularly when presented as an affordable and sustainable option.
Efforts to improve access to scalp cooling for underserved populations show that the most successful programs combine financial support, clinical integration, and the use of durable, low-maintenance technologies. Subsidies and non-profit assistance reduce out-of-pocket costs, while training personnel helps ensure proper use and increases the likelihood of successful cooling. Programs that rely on reusable silicone or PCM-based caps also lower long-term expenses and make implementation more practical in low-resource clinics. However, challenges remain. Many initiatives depend on short-term funding, and staffing limitations, infrastructure constraints (e.g., freezer space or stable power), and limited cost-effectiveness data continue to hinder wider adoption. Addressing these barriers will be important for expanding equitable access to scalp cooling in diverse healthcare settings.
Efforts to make scalp cooling accessible to economically disadvantaged cancer patients have expanded in recent years, with various initiatives focused on reducing financial barriers, improving availability in low-resource settings, and raising awareness. These initiatives are driven by healthcare providers, non-profit organizations, and governmental programs, all aiming to offer inclusive cancer care solutions. Below are key strategies and programs, with supporting references, that have been established to increase accessibility of scalp cooling for underserved populations. Several initiatives such as Non-Profit and Community-Based Funding Programs [39–41], Hospital-Based Subsidies and Assistance Programs [42, 43], Governmental and Health Policy Support [44, 45], Pilot Programs in Low-Resource Settings [46], and Awareness and Educational Outreach [47, 48] have been conducted. The burden of chemotherapy-induced alopecia is being alleviated for many low-income patients, making scalp cooling a viable option across diverse healthcare settings and socioeconomic backgrounds. These efforts highlight the importance of financial, educational, and policy support in achieving inclusive cancer care.

Discussion
The findings of this review highlight notable progress in both clinical and engineering domains of scalp cooling technologies aimed at mitigating chemotherapy-induced alopecia (CIA). In terms of innovation readiness, the technologies differ markedly in their stage of development. Silicone-based caps demonstrate the highest translational readiness, with established clinical use and multi-center evaluations supporting their effectiveness and reusability [29, 30]. Gel-based and cryogel caps fall into the clinical–pilot stage, as both have been tested in feasibility and clinical studies but have limited large-scale implementation [21–24]. PCM-based caps remain in the pilot/engineering development stage, supported by thermal modeling and early clinical trials showing promising cooling duration and energy efficiency [28, 35]. Dry ice-powered caps and DIY cold caps remain at a pilot or community-use level, showing feasibility in niche or low-resource settings but lacking systematic clinical validation [25–27, 31]. Solar-powered systems are in the early prototype/laboratory development phase, with limited pilot deployment in rural clinics [36]. These distinctions highlight different levels of translational readiness and help identify the most scalable innovations. These advancements can be broadly categorized into two dimensions: clinical efficacy studies, which evaluate patient outcomes and treatment effectiveness, and engineering feasibility studies, which explore innovations in device design, materials, and sustainability.
Clinical efficacy data consistently demonstrate that scalp cooling effectively reduces the severity of hair loss among patients undergoing chemotherapy, particularly for breast cancer. Randomized controlled trials (RCTs) and observational studies reported hair retention rates ranging from 50 to 80% when scalp cooling was used with taxane- and anthracycline-based regimens. Notably, large-scale studies such as the SCALP trial and subsequent Asian cohorts confirmed its safety and tolerability, with minimal adverse effects limited to transient headaches and cold intolerance. However, the degree of efficacy varied depending on chemotherapy type, cooling duration, and patient adherence. Based on the quality assessment using standard appraisal criteria, most RCTs were of moderate to high quality, with clear inclusion criteria, consistent outcome measures, and minimal risk of bias, while observational studies often lacked randomization and had limited generalizability due to smaller sample sizes.
In contrast, bench and engineering feasibility studies have focused on developing low-cost, energy-efficient, and environmentally sustainable scalp cooling systems. Innovations such as gel-based, cryogel, and phase-change material (PCM) caps have demonstrated extended cooling duration and stable thermal performance under controlled laboratory conditions. Engineering studies using thermal modeling and material testing showed promising feasibility for cost reduction and reusability. However, these studies primarily assessed physical and thermodynamic properties rather than patient-centered outcomes and thus represent preliminary evidence requiring clinical validation. The methodological quality of these feasibility studies is generally exploratory, with small sample sizes and non-comparative designs, emphasizing proof-of-concept rather than effectiveness.
Integrating both domains, it is evident that while clinical studies confirm the efficacy and safety of scalp cooling in reducing CIA, engineering innovations are expanding its affordability, portability, and sustainability. Future research should focus on bridging these two areas by conducting hybrid clinical-engineering trials that simultaneously evaluate technical performance, cost-effectiveness, and patient outcomes in real-world settings. Establishing standardized reporting for device performance and uniform quality metrics in clinical trials will further strengthen the evidence base.
Overall, the synthesis underscores that scalable, eco-friendly scalp cooling solutions with clinically validated efficacy may substantially advance equitable cancer care. Continued interdisciplinary collaboration between clinicians, biomedical engineers, and policy makers is essential to translate these innovations into accessible, sustainable interventions for diverse patient populations. This review provides a broad and up-to-date overview of innovative, cost-effective, and eco-friendly scalp cooling technologies by integrating evidence from clinical, engineering, and feasibility studies. However, the review is limited by the use of English-only sources, potential publication bias, and heterogeneity across study designs and outcome measures, which may affect direct comparisons. Despite these constraints, the review offers a useful foundation for advancing accessible and sustainable scalp cooling approaches.

Conclusion
As scalp cooling technology continues to advance, integrating cost-effective, eco-friendly, and inclusive solutions will be essential to making these treatments universally accessible and effective, regardless of economic or geographic barriers. Embracing these principles fosters a more sustainable and equitable cancer care model that prioritizes patient well-being while minimizing environmental impact.