New research reveals that the specific location in the colon where colon cancer develops affects a patient’s odds for survival. Gastroenterologists describe colon cancers as left-sided or right sided. According to Dr. David Bernstein, chief hepatology at Northwell Health in Manhasset, N.Y., left-sided cancers are located closer to the anus and located in the rectum, sigmoid colon and descending colon. They are often characterized by bleeding or a partial obstruction, so patients tend to see a doctor sooner because they are experiencing symptoms.
Right-sided cancers are located in the first part of the colon where it joins with the small intestine. Typically, patients do not experience bleeding or an obstruction but are more likely to experience anemia. Also, right-sided cancers are more likely to metastasize to the liver. Because they are less likely to experience symptoms, right-sided cancers are often diagnosed in more advanced stages, which gives patients a worse prognosis than left-sided cancers.
To further understand the implication of right-sided versus left-sided colon cancer, Dr. Fausto Petrelli, of the ASST Bergamo Ovest, in Treviglio, Italy, reviewed information from 66 studies that involved over 1.4 million patients over the course of five years. Petrelli and his team found that patients with left-sided colon cancer were 20 percent less likely to die than patients who had tumors on the right side.
Interestingly, right and left-sided cancers were also genetically distinct, so the study authors believe that doctors should consider tumor location when deciding the type and intensity of treatment. One oncologist also suggested that this new information could influence whether patients want a sigmoidoscope or colonoscope for their colon screening. A sigmoidoscopy only examines the left side of the colon from the anus up to the left upper abdomen, whereas a colonoscopy is a complete exam of the entire colon. A colonoscopy can detect polyps and lesions that would not be visible with a sigmoidoscopy, making the colonoscopy the gold standard for colon screening. (Source: WebMD).