A prospective observational study on the optimal maintenance strategy in HER2-positive advanced gastric cancer treated with trastuzumab-based therapy.

Mono-chemo-agent combined with trastuzumab showed an advantage of absolute value and hazard ratio on OS, in addition to ICER of PFS for patients who benefit from the initial six cycles of trastuzumab-based first line therapy, especially in patients with certain clinical or treatment-related characterisitics. A large sample randomized trial is warranted.