Patients with distal intestinal gastric cancer have superior outcome with addition of taxanes to combination chemotherapy, while proximal intestinal and diffuse gastric cancers do not: does biology and location predict chemotherapy benefit?

Gastric cancer, with one million new cases observed annually, and its dismal prognosis, is one of the leading causes of cancer-related mortalities. Systemic chemotherapy is the main treatment modality in advanced gastric cancer patients. We aim to evaluate the predictive role of tumor localization and histopathology on choosing three or two-drug combination regimens. Consecutive 110 metastatic gastric adenocarcinoma patients who were admitted to the Baskent University Department of Medical Oncology and the Van Research and Training Hospital were included in the study. Data of patients were analyzed retrospectively. Median age of patients was 58 years (range 30-80). Proximal intestinal, distal intestinal, and diffuse gastric cancers were found in 35 (32 %), 64 (58 %), and 11 (10 %) patients, respectively. 5-fluoracil and platinum (PF) and PFtax were administered to 47 (43 %) and 63 (57 %) patients, respectively. Median progression-free survival (PFS) was 4.0 (95 % CI 2.5-5.6) and 7.4 months (95 % CI 6.0-8.7) for PF and PFtax groups, (p = 0.034). When we used tumor localization as strata in the PFS survival curve, PFtax produced significantly higher PFS rates only in distal intestinal-type gastric cancer, compared with PF (p = 0.03). Median overall survival (OS) was 9.0 (95 % CI 5.2-12.3) and 17.3 months (95 % CI 7.8-27) for PF and PFtax groups, (p = 0.010). When we used tumor localization as strata in the OS survival curve, PFtax produced significantly higher OS rates only in distal intestinal-type gastric cancer compared with PF (p = 0.015). Pathology and tumor location in gastric cancers may affect the outcome, the addition of taxanes as a third drug may significantly increase PFS and OS rate purely in distal intestinal-type gastric cancer but not in patients with proximal and diffuse-type gastric cancers.