Value of tumor size as a prognostic factor in metastatic colorectal cancer patients after chemotherapy: a population-based study.

To evaluate the relationship between tumor size and survival in metastatic colorectal cancer (mCRC) patients who received chemotherapy. SEER database was accessed for eligible patients. Multivariate Cox regression analysis was performed to compare the effect of tumor size on overall survival (OS) and CRC-specific survival (CCSS). Tumor size ≥5 cm was an independent risk factor for OS and CCSS in mCRC patients treated with chemotherapy. Tumor size <5 cm did not show a survival advantage in patients whose primary tumor site was rectosigmoid junction, while tumor size ≥5 cm was associated with poor OS and CCSS in left-and right-sided colorectal cancer. Tumor size ≥5 cm was associated with poor prognosis after receiving chemotherapy treatment and a risk factor for survival of mCRC.