[Effectiveness of precautionary chemotherapy in gastric cancer]

Gastric cancer is a very aggressive disease. Surgery is the treatment of choice, with less than 30% 5-year survival for patients with complete resection. Although the incidence of gastric cancer in Western countries has declined progressively in recent decades, the prognosis of the disease has not changed in the last 30 years, with 5-year global survival rates between 7 and 15%. The achievement of an increase in the rate of cure would be therefore an important goal, but the efficacy of adjuvant chemotherapy in this disease is still controversial. The aim of this overview is to document that postoperative chemotherapy may be effective in patients operated with curative intent for gastric cancer. We reviewed the results of randomized trials comparing adjuvant chemotherapy versus surgery alone, divided into those performed in the West and those performed in Asia, and according to publication period. We also reported the preliminary results of an intergroup randomized study of postoperative chemoradiation versus follow-up. Then, we summarized and discussed the results of the 3 meta-analyses, published respectively in 1993, 1999, and 2000, that evaluated the combined results from the over mentioned trials. Singular studies reported conflicting results and failed to show a clear indication for chemotherapy, but they were open to criticisms, due to methodological and therapeutical limitations. The meta-analysis published by Hermans showed a non-significant trend in favor of adjuvant treatment. This analysis was later criticized, and, in response, the author published an update in 1994 in which he recalculated a significant odds ratio. Meta-analyses by Earle and Mari indicated that postoperative chemotherapy produces a small survival benefit in patients with curatively resected gastric carcinoma. Subgroup analyses produced some interesting findings. There was a partial evidence of better results with chemotherapy regimens containing anthracyclines, but it is possible that the results of the ongoing trials testing regimens including cisplatin will add more reliable information about the new regimens. Studies with longer follow-up maintained a trend towards benefit from adjuvant therapy, indicating that long-term survival may be afforded by treatment, as opposed to simply delaying relapse. Finally, there was a trend towards a larger magnitude of the effect when analyses were restricted to trials which included higher risk patients. In conclusion, the results of the 3 meta-analyses suggest that adjuvant chemotherapy may be effective. However, other studies to confirm an effective treatment and to find new therapeutic combination or strategies in the field of adjuvant therapy for gastric carcinoma are warranted.