Risk factors for colorectal cancer (CRC) vary across different anatomical regions of the gastrointestinal tract, according to study results published in Gastroenterology.
Investigators collected data from the Nurses’ Health Studies 1 and 2, and the Health Professionals Follow-up Study for a total of 45,351 male and 178,016 female participants with a median age of 23 years. A total of 24 risk factors were recorded, as well as information on the 7 anatomical subsites of CRC.
The surveys included 3058 cases of CRC (cancers of the cecum n=474, ascending colon n=633, transverse colon n=250, descending colon n=221, sigmoid colon n=750, rectosigmoid junction n=202, and rectum n=528).
Some demographic parameters altered each patients’ likelihood of developing CRC. Age increased the likelihood in both the descending and sigmoid colon with a hazard ratio (HR) of 1.39 (P <.001) overall for distal colon cancer and for both rectosigmoid and the rectum with an overall HR of 1.36 (P <.001) for rectal cancer. Family history of cancer was positively correlated with the cecum and ascending and transverse colon with an overall HR of 1.65 (P <.001) for proximal colon cancer and in the sigmoid colon with an HR of 1.46 (P <.001). Endoscopic screening was negatively correlated with the distal colon (HR, 0.38; P <.001), rectal (HR, 0.51; P <.001), and ascending colon (HR, 0.71; P =.02) cancers.
Lifestyle choices that affected CRC included smoking, alcohol consumption, and dietary components. Smoking increased the likelihood of developing proximal colon (HR, 1.13; P <.001) and rectal (HR, 1.12; P =.009) cancers. Alcohol increased likelihood of developing cancer in the descending colon (HR, 1.37; P =.03). Diets high in processed red meat were positively correlated with CRC of the sigmoid colon (HR, 1.17; P =.04) and rectum (HR, 1.21; P =.04). Dietary components that significantly decreased likelihood of CRC of the rectum included whole grains (HR, 0.75; P <.001) and cereal fiber (HR, 0.60; P <.001).
A major limitation of this study is that the 3 surveys on which is based queried only health care professionals. As such, participants were likely younger, more likely to be Caucasians, and more likely to have a high socioeconomic status. Therefore, results may not reflect the general population.
The study authors concluded that the risk factor profiles differed across the gastrointestinal tract and that the 3 CRC types (i.e., proximal colon, distal colon, and rectum) are not sufficient for defining the regional variation in risk factors for CRC.
Disclosures: Some authors declared receiving consulting or funding from the pharmaceutical industry. A complete list of disclosures can be found in the original study.
Wang L, Lo C-H, He X, et al. Risk factor profiles differ for cancers of different regions of the colorectum. [available online April 1, 2020] Gastroenterology doi:10.1053/j.gastro.2020.03.054.