Adjuvant chemotherapy for gastric cancer: current evidence and future challenges

Gastric cancer still represents one of the major causes of cancer mortality worldwide. Patients survival is mainly related to stage, with a high proportion of patients with metastatic disease at presentation. Thus, the cure rate largely depend upon surgical resection. Despite the additional, albeit small, benefit of adjuvant chemotherapy has been clearly demonstrated, no general consensus has been reached on the best treatment option. Moreover, the narrow therapeutic index of adjuvant chemotherapy (i.e., limited survival benefit with considerable toxicity) requires a careful assessment of expected risks and benefits for individual patients. Treatment choices vary widely based on the different geographic areas, with chemotherapy alone more often preferred in Europe or Asia and chemoradiotherapy in the United States. In the present review we discuss the current evidence and future challenges regarding adjuvant chemotherapy in curatively resected gastric cancer with particular emphasis on the recently completed landmark studies and meta-analyses. The most recent patient-level meta-analysis demonstrated the benefit of adjuvant chemotherapy over curative surgery; the same Authors also showed that disease-free survival may be used as a surrogate end-point for overall survival. We finally discuss future research issues such as the need of economic evaluations, development of prognostic or predictive biomarkers, and the unmet clinical need of trials comparing perioperative chemotherapy with adjuvant treatment.