colon cancer

The location of a patient’s colon cancer may provide significant information about the condition and affect doctor’s recommendations. A new study shows that left side colon cancers have a significantly reduced risk of death and researchers believe colon cancer side should be considered in establishing prognosis


Colon cancer (CC) is one of the most common forms of cancer in both men and women. As our knowledge of the disease has grown, we have become more knowledgeable with regards to patient care. Depending on several patient factors, physicians can alter treatment plans to obtain better patient outcomes.

While current knowledge assists physicians with making decisions regarding treatment intensity, there is reason to believe further information is available. Localization of CC (originating on left or right side of colon) could significantly affect prognosis. Iron deficiency from blood loss is more prevalent in right sided CC, while changes in bowel habits are more common in left sided CC. The genes mutated causing the cancer are also different between the two sides. The location dependent differences in CC led researchers to investigate the predictive value of localization.

In their study published in JAMA Oncology, Petrelli et al. looked into the predictive value of CC localization. The researchers pooled data from studies reporting data on CC localization and patient survival information. In total, 66 studies and 1,437,846 patients’ data were used. Other information was also taken to prevent confounding such as age, race and type of study.

Researchers found strong support for utilizing CC localization information in determining patient prognosis. Left-sided colon cancers were significantly associated with a 19% reduction in risk of death, independent of all other factors including stage of cancer. Aside from biological differences, researchers believe the difference in risk of death can be attributed to different surgical techniques required and differing sensitivities to chemotherapy. The results shown in this study are supported by other studies with similar findings, though none previously had established an association independent of stage of cancer.

The findings of the study indicate that CC localization information should be considered in determining the course of treatment. Right-sided tumours may require more aggressive surgical procedures to achieve better patient outcomes. The study was limited by using study data rather than patient data, but this is not likely to have skewed the association significantly. Based on this data, the origin of CC should be considered when establishing patient prognosis in clinical settings.


Written By: Wesley Tin, BMSc

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