Study: Distant Relatives of Individuals With Colon Cancer May Be at Risk

Immediate and second- and third-degree family members can benefit from colonoscopy screenings, new research results show.

Distant relatives of individuals with colorectal cancer may also be at risk for the disease, according to study results published in Cancer Epidemiology, led by investigators at the University of Buffalo and the University of Utah.

“Our study provides new insight into the magnitude of risk for more distant relatives of colorectal cancer cases, and in particular, for relatives of cases who were diagnosed before age 50,” Heather Ochs-Balcom, PhD, associate professor of epidemiology and environmental health at the University of Buffalo’s School of Public Health and Health Professions, said in a statement. “This work is important given the rising rates of early-onset colorectal cancer.”

Colonoscopy screening has been recommended for immediate relatives--parents, children, and siblings--with early onset colorectal cancer, before aged 50 years, but the study’s results suggest second-degree relatives, such as aunts uncles, and grandparents, or third-degree relatives, such as first cousins, great-grandparents, and grandchildren, may be at risk for the cancer as well.

Screening for distant relatives could also be beneficial.

Second-degree relatives are 3 times more likely to be diagnosed with colorectal cancer before the aged 50 years and third-degree relatives are 1.56 times more likely, while first-degree family members are 6 times more likely.

More than 1500 early-onset colon cancer cased in the Utah Cancer Registry were reviewed by the 2 universities. The results also showed that individuals are at 2.6-fold higher risk if they were first-degree relatives, 1.96 for second-degree relatives, and 1.3 for third-degree relatives.


Study: colon cancer risk extends to second- and third-degree relatives. EurekAlert. News release. September 13, 2021. September 14, 2021.