Primary tumor location and survival among metastatic colorectal cancer patients treated with systemic chemotherapy and biologic therapies: Retrospective analysis.

BACKGROUND

Metastatic colorectal cancer (mCRC) is a genetically heterogeneous disease and different ethnicities might result in different chemotherapy treatment responses. The aim of the study is to evaluate whether survival outcomes for mCRC patients treated with systemic chemotherapy (SC) and, with and without biologic therapies (BT) are different between left and right-sided tumors.

METHODS

A retrospective cohort study via the Ministry of National Guard- Health Affairs (MNG-HA) Cancer registry data was used to identify patients diagnosed with CRC between 2013 and 2016. Kaplan-Meier method and porosity score Cox proportional hazard models were used to assess survival for right and left-sided mCRC with and with BT.

RESULTS

There was a total of 549 CRC patients and 196 mCRC patients with mean age of 64 years and 57.65% were males. The median survival for the left-sided was higher than the right-sided mCRC tumors (P 0.03). mCRC patients treated with SC+BT were associated with decreased mortality only among patients with left-sided mCRC compared to right-sided mCRC (HR, 0.21; 95% CI, 0.05-0.92; P 0.03). mCRC with no primary-tumor resection and CS+TB left-sided mCRC was significantly associated with decreased mortality compared to right-sided mCRC (HR, 0.15; 95% CI, 0.03-0.72; P 0.02).

CONCLUSION

A significant decrease in mortality for the left-sided mCRC treated with SC + BT compared with the right-sided mCRC was observed. mCRC patients with unresectable metastases demonstrated survival benefits from left-sided SC + BT treatment. Randomized controlled trials are needed to determine the optimal treatment for mCRC patients.