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.