The side of origin of colon cancer has been associated with distinct genetic profiles and clinical presentations. Researchers have now shown that this impacts patients’ prognosis, with left-sided colon cancer associated with better survival rates than if the tumor developed on the right side.
The study, “Prognostic Survival Associated With Left-Sided vs Right-Sided Colon Cancer: A Systematic Review and Meta-analysis,” published in JAMA Oncology, shows the primary tumor location is an important prognostic factor in colon cancer patients given the distinct biological features found between left- and right-sided colon cancer.
However, the cancer’s side of origin is still not used as a prognostic parameter when it comes to deciding the best treatment approach for individual patients.
To determine the prognostic role of left- versus right-sided location of primary colon cancer, Fausto Petrelli, MD, of Italy’s ASST Bergamo Ovest and colleagues conducted a systematic review of the literature, looking for prospective and retrospective studies in which the side of colon cancer was noted and that reported data on overall survival. After an extensive search in several databases, they found 66 studies published from 1996 to 2015 that met the criteria.
The analysis, which included 1,437,846 patients followed for a median of 65 months, showed that primary colon tumors occurring on the left side were associated with an absolute 18 percent reduced risk of death. This result was independent of tumor stage, race, adjuvant chemotherapy, the year of the study, or the number of study participants.
The findings suggest that the side of the primary tumor is an important prognostic factor for patients with colon cancer, and should be considered when deciding the type of treatment a patient should receive.
“Based on these results, colon cancer side should be acknowledged as a criterion for establishing prognosis in all stages of disease. It should be considered when deciding treatment intensity in metastatic settings, and should represent a stratification factor for future adjuvant studies,” the researchers wrote.
Colom cancer is the third most common cancer in both men and women in the U.S., with the American Cancer Society estimating that 95,270 new cases will be diagnosed this year alone, and that 49,190 patients will die from the disease.