A new study has found that having second- or third-degree relatives with colorectal cancer increases a person’s risk of developing the disease.
Early colonoscopy screening is often recommended for first-degree relatives of someone diagnosed with early-onset (before age 50) colorectal cancer, cases of which have been increasing significantly over the past few decades. But the study suggests that early screening may be beneficial for second- and third-degree relatives as well.
The study reviewed more than 1500 early-onset colon cancer cases in the Utah Cancer Registry,found that first-degree relatives of someone diagnosed with early-onset colorectal cancer are 6 times more likely to be diagnosed with colorectal cancer before age 50, while second-degree relatives (aunts, grandparents etc) are 3 times likelier and third-degree relatives (first cousins etc) 1.56 times likelier.
“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,” said first author Heather Ochs-Balcom, associate professor of epidemiology and environmental health, UB School of Public Health and Health Professions. “This work is important given the rising rates of early-onset colorectal cancer.”
There was also 2.6-fold higher risk of colorectal cancer at any age if they have a first-degree relative with early-onset colon cancer. The risk is 1.96 and 1.3 times greater for second- and third-degree relatives, respectively. In addition, the risk for all degrees of relatives for early-onset colon cancer is higher than the risk for colon cancer at any age.
The findings, published in Cancer Epidemiology, suggest that early colonoscopy screening may be beneficial for second-degree relatives and possibly third-degree relatives, in addition to first-degree relatives of individuals diagnosed with colorectal cancer before age 50.
The researchers also point out that relatives may benefit from being more aware of their extended family history and sharing this information with their physician when making cancer-screening decisions.
Source: University at Buffalo
