Whether the primary tumor is left- or right-sided should be considered when adjusting for treatment among patients with colon cancer regardless of disease stage, according to a study published in JAMA Oncology.1

Italian researchers led by Fausto Petrelli, MD, conducted a meta-analysis of 66 prospective and retrospective studies that included data on 1,437,846 patients. The goal was to compare overall survival between patients with left-sided and right-sided colon cancers, noting that the location of tumors has emerged as an important factor for prognosis.

The researchers evaluated for overall survival using prognostic data related to tumor location. The analysis found that patients with a primary tumor located on the left side had a significantly lower risk of death. This result was independent of factors such as stage, race, and number of participants in the included studies.

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The authors conclude that the side of colon cancer “should be considered when deciding treatment intensity in metastatic settings, and should represent a stratification factor for future adjuvant studies.”


  1. Petrelli F, Tomasello G, Borgonovo K, et al. Prognostic survival associated with left-sided vs right-sided colon cancer. JAMA Oncol. 2016 Oct 27. doi:10.1001/jamaoncol.2016.4227 [Epub ahead of print]