The Diagnostic and Prognostic Potential of Serum Taurine and PUMA in Staging Colorectal Cancer Patients.

[INTRODUCTION] Ranked as the third most diagnosed cancer globally, colorectal cancer (CRC) is the seventh most prevalent cancer in Egypt. This study aimed to assess the levels of taurine (Tau), carcinoembryonic antigen (CEA), and p53 upregulated modulator of apoptosis (PUMA) in CRC patients.

[METHODS] We conducted a pilot study involving 70 patients with CRC. Serum Tau was measured using ELISA, CEA was evaluated by immunohistochemistry (IHC), and PUMA expression was assessed using quantitative real-time PCR (qPCR). All measurements were taken before surgery, one week after surgery, and one month later.

[RESULTS] Tau levels were significantly lower in adenocarcinoma groups (G1, G2, and G3) and in the malignant metastatic group compared with the control and inflammatory groups (p < 0.001). Tau levels increased in G1, G2, and G3 patients one week and one month after surgery. PUMA expression after surgery was higher than before surgery in G1, G2, and G3 adenocarcinoma groups, while it was absent in the metastatic group. The specificity of the Tau test before surgery, one week after, and one month after was 53.33%, 76.92%, and 46.67%, respectively. The specificity of the PUMA test was 76.92% before surgery and 71.43% after surgery. CEA levels were significantly higher in adenocarcinoma (G1 and G2) compared with control and inflammatory groups, whereas CEA staining intensity was significantly decreased in adenocarcinoma (G1 and G2) compared with these groups (p < 0.001).

[DISCUSSION] PUMA expression tends to be lower in advanced CRC stages and increases after surgery, supporting its potential role in tumor suppression and prognosis. Taurine shows variable levels among CRC patients and may aid in non-invasive cancer staging; its lower serum levels are associated with more advanced disease, and levels rise following surgical removal of the tumor.

[CONCLUSION] This study highlights PUMA as a potential prognostic indicator for CRC. Tau levels may also hold diagnostic value and could contribute to the development of non-invasive screening methods for early CRC detection, particularly within the Egyptian population, which remains underrepresented in current research.