An observational study of patients with HER2-positive metastatic gastric cancer treated with trastuzumab: Single center experience.

Abstract

e15500 Background: In this study, during a 54-month follow-up period, we presented clinicopathological features and survival results of patients treated with trastuzumab. Methods: We retrospectively analyzed the efficacy of trastuzumab-based chemotherapy in 21 patients with HER2-positive gastric cancer between January 2012 and July 2016. Results: Eighteen (86%) patients were male with a median age of 61 (34-80) years. One of the patients was stage 2, 2 were stage 3 and 18 were stage 4, at the time of diagnosis. From 21 tumours, 11 (52%) were located in the cardia, 5 (23%) in the antrum and 5 (23%) in the corpus. In the histopathological examination, 18 (86%) cases were adenocarcinoma and 3 (14%) were signet-ring cell. Seven of the patients with metastatic disease were operated (total/subtotal gastrectomi). The most common metastatic sites were liver (%86), lung(%33), distant lymph node(%23), and periton(%14). Trastuzumab was administered in combination with chemotherapy as first-line treatment and beyond progression as a secondline, and third-line treatment in 18, 2, and 1 patients, respectively. When tumour response was assessed after three cycles of chemotherapy, one complete response (5%),4 partial response (19%),12 stabil disease (57%) were observed, and 4 (19%) patients had progressive disease. Clinical benefit rate was 81%. The maintenance treatment of trastuzumab was applied to 10 patients (47%). At a median follow-up of 17.8 (5-38) months, median progression-free survival was 12.8 months (3-31) and overall survival 18.6 months (3-91). Conclusions: Proximal gastric carcinomas with intestinal phenotype are found to have a higher expression of HER2-gene (range 8-34%) than distal diffuse gastric carcinomas (range 1-7%). The present results are similar to those of the ToGA study in terms of overall survival and response rate.