Colorectal Cancer Risk Factors Vary by GI Region

Colorectal cancer,medical anatomical illustration.
Risk factors for colorectal cancer (CRC) vary across different anatomical regions of the gastrointestinal tract, according to study results published in Gastroenterology.

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.

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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.

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Reference

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.