Is Surgery Necessary for Stage IVB Gastric Cancer Showing Clinical Complete Response to Chemotherapy or Systemic Cancer Therapy?

[BACKGROUND] For stage IVB gastric cancer, recently, systemic cancer therapy (including cytotoxic chemotherapy, immune checkpoint inhibitors, and molecular targeted agents) is the standard treatment based on biomarker testing. If these treatments are successful and the tumor becomes resectable, conversion surgery may be considered, though its significance remains unclear. In cases showing clinical complete response (cCR), the necessity of surgery is further debated.

[METHODS] This retrospective single-center study included patients with cStage IVB gastric cancer who received chemotherapy or systemic cancer therapy, regardless of undergoing conversion surgery, between 2013 and 2023. Patients were stratified by objective tumor response on imaging (cCR or others). Those achieving cCR were further divided into two groups: non-OP (follow-up without surgery) and OP (underwent conversion surgery) for survival comparison.

[RESULTS] Among 1591 patients treated with systemic chemotherapy, 51 (3.2%) achieved cCR (33 non-OP; 18 OP). In the cCR cohort, the median follow-up was 57 months. The 3-year overall survival (OS) was 97% in the non-OP group and 86% in the OP group (P = 0.44), respectively. Among the entire population, conversion surgery was performed in 121 patients (7.6%), in whom pathological CR (pCR) was seen in 17 (14%). This included 10 patients with cCR and seven without cCR. Three-year OS of pCR patients was 93%.

[CONCLUSIONS] The results suggested the potential for long-term survival without surgery in patients showing cCR. However, further investigation is needed regarding accurate methods to assess tumor disappearance.