Oba K., Teramukai S., Kobayashi M., Matsui T., Kodera Y., Sakamoto J. Efficacy of adjuvant immunochemotherapy with polysaccharide K for patients with curative resections of gastric cancer. Cancer Immunol Immunother. 2007 Jun;56(6):905–911. (Epub 2006 Nov 15.)
Rationale
Gastric cancer was the other major indication for adjuvant PSK in Japan. Eight randomized trials existed; this meta-analysis quantified the pooled survival effect for the first time.
Methods
A meta-analysis of 8 randomized controlled trials with central randomization, n=8009 patients after curative gastric-cancer resection, comparing chemotherapy + PSK versus chemotherapy alone, with overall survival as the endpoint.
Results
Pooled hazard ratio for overall survival 0.88 (95% CI 0.79–0.98; P=0.018) — a 12% relative mortality reduction — without significant heterogeneity across trials (χ²(8)=11.7; P=0.16).
Conclusions
Adjuvant PSK improves overall survival after curative gastric-cancer surgery by a statistically solid if modest margin — consistent with, though smaller than, the colorectal signal.
Worth noting
n=8009 is large, central randomization is rigorous, and the effect is modest (HR 0.88) rather than dramatic — the honest shape of adjunctive therapy. Same caveats as the colorectal meta: Japanese standardized PSK added to chemotherapy of its era; not transferable to supplements or to non-surgical disease.