Link found between family history of colorectal polyps, risk for colorectal cancer
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Family history of colorectal polyps linked to a higher risk for colorectal cancer in a Swedish cohort, according to research published in BMJ.
“In contrast with the established increased risk associated with a family history of CRC, it remains unclear whether those with a family history of colorectal polyps have an increased risk of CRC. As a result, available screening recommendations are discrepant for individuals with a family history of polyps,” Mingyang Song, MBBs, ScD, department of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health, and colleagues wrote. “Given the higher prevalence of polyps than CRC associated with the increasing uptake of endoscopic screening, a better understanding about the influence of family history of polyps on CRC risk is critical to improve current screening recommendations.”
In a case control study, researchers analyzed 68,060 patients with CRC and 333,753 matched control patients to assess the risk for CRC in first-degree relatives of patients with precursor lesions (8.4% vs. 5.7%, respectively). According to study results, having a first-degree relative with a colorectal polyp correlated with a higher risk for CRC (OR = 1.4; 95% CI, 1.35-1.45). Further, there was a higher risk for CRC in patients with an increased number of first-degree relatives with colorectal polyps ( 2 relatives OR = 1.7; 95% CI, 1.52-1.9) as well as in patients with a decreased age at colorectal polyp diagnosis (< 50 years OR = 1.77; 95% CI, 1.57-1.99); researchers noted the strongest association between family history and CRC was early onset diagnoses before age 50 ( 2 relatives OR = 3.34; 95% CI, 2.05-5.43). Joint analysis yielded ORs of 1.79 (95% CI, 1.52-2.1), 1.7 (95% CI, 1.65-1.76) and 5 (95% CI, 3.77-6.63) for individuals with two or more first-degree relatives with colorectal polyps but no CRC, individuals with one first-degree relative with CRC but no colorectal polyps and individuals with two or more first-degree relatives with both, respectively.
“If additional studies reveal a link between a family history of polyps and the risk of colorectal cancer, it is something to take into account in the screening recommendations, especially for younger adults," Jonas F. Ludvigsson, MD, PhD, Orebro University Hospital and professor in the department of medical epidemiology and biostatistics at the Karolinska Institutet, said in a press release. "I really hope that this study can help doctors in Sweden and elsewhere identify patients at a higher risk of colorectal cancer."
Perspective
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Carol Burke, MD
CRC is one of the most common, yet most preventable cancers. It is known that both sessile serrated polyps and adenomatous polyps are the precursors to colorectal cancer. Strong data confirmed removing polyps by colonoscopy decreases the risk for colorectal cancer. Emerging data have confirmed that adenomas and serrated polyp detection is increasing, with detection rates being up to 60% and 9%, respectively.
Recent guidelines by the U.S. Preventive Services Task Force and the American College of Gastroenterology have joined the American Cancer Society in suggesting colorectal cancer screening be offered to individuals aged between 45 and 49 years. This is because of the increase in the incidence of colorectal cancer in individuals younger than 50 years. The reasons for young onset colorectal cancer are not confirmed but are likely due in part to obesity and lifestyle factors, such as lack of physical activity and poor dietary choices, to name a few. Established risk factors for colorectal cancer include a family history of colorectal polyps and colorectal cancer, particularly when numerous relatives are affected and when diagnosed at a young age.
The study by Song and colleagues confirms those findings but provides more granularity to which polyps contribute to the risk. Their case control study shows that all polyps, not just advanced adenomatous polyps and serrated polyps, contribute to the increased colorectal cancer risk in first-degree relatives. The practical point for gastroenterologists is that when your patient reports they have a first-degree relative with “polyps,” the histology does not seem to matter, and a colonoscopy is recommended.
The age to begin colonoscopy in individuals with a first-degree relative with polyps, according to the U.S. Multi-Society Task Force on Colorectal Cancer, is age 40 and at a frequency depending on the findings on the exam and the youngest age of relative who was affected with polyps.
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