Gemcitabine plus S-1 versus cetuximab as a third-line therapy in metastatic colorectal cancer: an observational trial

Background and aim: After failure of oxaliplatin, irinotecan, and 5-fluorouracil (5-FU), there is no effective and low-cost therapy for metastatic colorectal cancer (mCRC). The purpose of this study was to assess the efficacy and safety of gemcitabine plus S-1 (GS) versus cetuximab as a third-line chemotherapy for mCRC patients.

Methods: Patients with previous failure of oxaliplatin, 5-FU, and irinotecan chemotherapy were included. The patients received GS or cetuximab until disease progression or intolerable toxicity occurred. The regimen that was selected by the patient depended on their economic ability.

Results: In all, 38 patients were enrolled between October 2009 and October 2012, and the patients were divided into 2 groups of 19 patients each. The median overall survival (OS) was 10 months for the GS group and 6.9 months for the cetuximab group (P = 0.047). The median progression-free survival (PFS) was 79 days and 78 days (P = 0.344), respectively. The disease control rate (DCR) was 42.11% and 47.37%, respectively (P = 0.985). The overall response rate was 0% and 10.52%, respectively (P = 0.169). Adverse events related to chemotherapy were mild to moderate. Only grade 3-4 neutropenia was found in the GS group at a rate of 21.1%. In the cetuximab group, the rash incidence rate was 89.6%, with 1 patient reaching grade 3.

Conclusions: GS has benefits in OS compared with cetuximab, and is a promising and safe regimen as a third-line chemotherapy for oxaliplatin- and irinotecan-refractory mCRC with good performance status for mCRC patients.