The Impact of Primary Tumor Location in Synchronous Metastatic Colorectal Cancer: Differences in Metastatic Sites and Survival

Abstract

Purpose. We explored differences in survival between primary tumor locations, hereby focusing on the role of metastatic sites in synchronous metastatic colorectal cancer (mCRC). Methods. Data for patients diagnosed with synchronous mCRC between 1989 and 2014 were retrieved from the Netherlands Cancer registry. Relative survival and relative excess risks (RER) were analyzed by primary tumor location (right colon (RCC), left colon (LCC), and rectum). Metastatic sites were reported per primary tumor location. Survival was analyzed for metastatic sites combined and for single metastatic sites. Results. In total, 36,297 patients were included in this study. Metastatic sites differed significantly between primary tumor locations, with liver-only metastases in 43%, 54%, and 52% of RCC, LCC, and rectal cancer patients respectively (p \ 0.001). Peritoneal metastases were most prevalent in RCC patients (33%), and lung metastases were most prevalent in rectal cancer patients (28%). Regardless of the location of metastases, patients with RCC had a worse survival compared with LCC (RER 0.81, 95% CI 0.78-0.83) and rectal cancer (RER 0.73, 95% CI 0.71-0.76). The survival disadvantage for RCC remained present, even in cases with metastasectomy for liver-only disease (LCC: RER 0.66, 95% CI 0.57-0.76; rectal cancer: RER 0.84, 95% CI 0.66-1.06).Conclusions. This study showed significant differences in relative survival between primary tumor locations in synchronous mCRC, which can only be partially explained by distinct metastatic sites. Our findings support the concept that RCC, LCC and rectal cancer should be considered distinct entities in synchronous mCRC.

Informing metastatic colorectal cancer patients by quantifying multiple scenarios for survival time based on real‐life data

“…The superior survival for patients with left‐sided primary tumors compared to patients with right‐sided primary tumors is consistent with previous population based studies and clinical trials 52‐54 …”

“…The superior survival for patients with left-sided primary tumors compared to patients with right-sided primary tumors is consistent with previous population based studies and clinical trials. [52][53][54] The strength of our study is the use of a registry containing high- There are some limitations to our study. First, only data from patients with synchronous metastatic disease were available for our study.…”

A population‐based study on the prognostic impact of primary tumor sidedness in patients with peritoneal metastases from colon cancer

“…[10][11][12] Several studies have shown that primary tumor location also is a prognostic factor in patients with (metastatic) colon cancer. [13][14][15][16] Colon tumors can be divided into left-sided and right-sided tumors. Right-and left-sided primary tumors differ in embryological origin (mid-gut vs hind-gut), bacterial flora and tumor biology (ie, mutational status and microsatellite instability (MSI)).…”

Differences in management and outcome for colon and rectal carcinoma with synchronous liver metastases: a population‐based cohort study

“…Previous studies have reported an inferior outcome in right-sided colorectal tumours compared with left-sided tumours including rectal tumours [4,23,24], and this has been attributed to a more aggressive tumour biology and later diagnosis [23,25]. In this study, we chose to report on colon and rectal cancer separately because of the different clinical pathways.…”