The survival benefit of increasing the number of active drugs for metastatic colorectal cancer: A multicenter retrospective study

BACKGROUND: The development of chemotherapy and treatment strategies for metastatic colorectal cancer (mCRC) have provided patients with significant survival benefits. Currently, molecular targeting agents and late‐line treatment with regorafenib and trifluridine/tipiracil (FTD/TPI) are available. However, the impact of this increase in drug availability on overall survival (OS) in mCRC remains a clinical question. METHODS: We retrospectively collected data on consecutive mCRC patients who were treated at three institutions in Japan. We divided the patients into three cohorts: patients who initiated first‐line treatment from Jan 2005 to Dec 2006 (cohort A: only cytotoxic drugs available), Jan 2007 to Dec 2011 (cohort B: molecular targeting drugs available), and Jan 2012 to Sep 2016 (cohort C: late‐line treatment available). RESULTS: A total of 1409 consecutive patients were analyzed. The median survival time (MST) in cohorts A, B, and C was 18.6, 25.4, and 26.4 months, respectively. The hazard ratio (HR) for cohort B versus A was 0.81 (95% CI 0.68–0.97), for cohort C versus A was 0.74 (95% CI 0.61–0.89), and for cohort C versus B was 0.92 (0.81–1.03). The median number of administered drugs (range) was 3 (1–5) in cohort A, 4 (1–7) in cohort B, and 4 (1–7) in cohort C. The increase in drug availability extended the MST from 15.5 months in patients treated with ≤3 drugs to 36.0–37.3 months in patients treated with six to seven drugs. CONCLUSION: The development of chemotherapy including late‐line treatments could improve the prognosis of mCRC patients.