Clinical outcome for continuous versus intermittent chemotherapy for unresectable metastatic colorectal cancer: Comparative analysis after first-line therapy.

Abstract

825 Background: Colorectal cancer (CRC) is the third most common and second most lethal cancer in the U.S, with almost 50% of patients developing metastatic disease. Although survival of metastatic CRC (mCRC) has improved significantly, current treatment strategies are associated with many adverse effects. With no prospect of cure, goals of treatment should consider both quantity and quality of life. Interruption of chemotherapy after induction can represent a means to achieve this balance. Methods: The primary objective of this meta-analysis is to assess the effect of continuation vs interruption of systemic therapy in terms of survival in patients with unresectable mCRC after first line treatment. Among 15 prospective studies published from 2009-2017, 9 qualified for inclusion. Random-effect model was used for pooled effects within two main categories: continuous chemotherapy vs chemotherapy-free interval after first line induction. Studies with maintenance fluoropyrimidine and/or bevacizumab were excluded. Primary endpoint was median progression free survival (PFS) and secondary endpoint was median overall survival (OS). z statistics were used for comparing subgroups. All statistical tests were two-sided. P values < 0.05 were considered significant. Results: 1366 patients (55% males) were included in the final analysis. Induction treatment was 5-FU or capecitabine-based chemotherapy with either oxaliplatin or irinotecan with or without bevacizumab. After stratifying for induction status, there was no statistically significant difference in median PFS between continuous vs chemotherapy free interval [Median PFS 4.74-month (95% CI 3.87-5.61) vs 3.52 month (95% CI 2.97-4.07), z-test adjusted p value 0.1383]. No significant difference in median OS between both groups [Median OS 16.95-month (95% CI 15.40-18.50) vs 18.35 month (95% CI 15.17-21.54)]. Conclusions: In mCRC patients, the superiority of continuous chemotherapy was not demonstrated. Further studies should shed light on patient and tumor characteristics most likely to benefit from continuous chemotherapy to limit delivery of cytotoxic therapy to this subset of patients.