Assessing Predictive Factors for Poor Survival Outcomes With Tumour Sidedness in Early-Stage Colon and Rectal Cancers

There is significant interest in identifying indicators to help predict patient outcomes, including tumour recurrence and survival from colorectal cancer (CRC). One such indicator is the primary tumour location. This study aimed to examine the prognostic implications of tumour location in patients undergoing surgery for early (Stages I and II) CRC, assessing its impact on metastatic behaviour and patient survival. The Cabrini Monash Colorectal Neoplasia Database includes complete data on all CRC patients at all Monash University-affiliated hospitals and was the basis for the binational database (https://bowelcanceraudit.com).

A database review was performed. Patients who underwent surgical resection for early-stage CRC (TNM Stage I or II) from 2010 to 2022 were reviewed. Oncological characteristics, overall survival and disease-free survival rates were examined.

One thousand, seven hundred three patients underwent surgical resection for early-stage CRC; of them, 49.8% were male. The tumour recurrence rate was 3.6%, 5.7% and 7.6% for right-sided, left-sided and rectal cancers, respectively (p = 0.013). While left-sided and rectal cancers were more likely to develop metastases to the lung (p < 0.001), there was no association between the site of the primary tumour and the location of recurrence in the liver (right-sided 2.5%, left-sided 2.7%, rectum 3.7%, p = 0.556), peritoneum (p = 0.423) or other sites (p = 0.387). Lung metastases originating from left-sided colorectal tumours (HR = 0.84, 95% CI: 0.25-2.84, p = 0.779) and rectal tumours (HR = 0.92, 95% CI: 0.26-3.26, p = 0.899) were not significantly associated with overall survival when compared to right-sided tumours.

This study demonstrates that overall recurrence rates during surveillance appear independent of tumour-sidedness in patients with early-stage CRC. Survival after disease recurrence is significantly worse in those with right-sided tumours, especially with a diagnosis of lung metastasis.