How family history helps to prevent colorectal cancer

Martin (not his real name) is a colon cancer survivor. He was diagnosed with the condition in 2016 and have had persistent abdominal pains and constipation.

Luckily, the cancer had not spread to other parts of the body, so it was easier for doctors to effectively treat the condition through chemotherapy and radiotherapy.

"The cancer diagnosis came as a surprise to me since I was in my early 30s. In my mind, I had always assumed that the condition affects much older people," he says.

Martin's uncle died of the condition in his 70s. Since the cancer had not affected any members of his immediate family, he was not worried.

This assumption, which is common among many people, is misleading and could, therefore, be a major contributor to the increasing cases of the cancer in the country.

Colorectal cancer (also referred to as colon or rectal cancer) ranks high among the top five common cancers in the country, according to the 2020 Globocan Report released by the International Agency for Research on Cancer (IARC).

The disease usually affects the colon and rectum, which are parts of the large intestine. Its symptoms include blood in the stool, a change in bowel movements (diarrhoea, constipation or lump in the abdomen), unexplained weight loss and fatigue.

Even though the disease typically affects older people, health experts note that it can happen at any age and is increasingly affecting younger people due to sedentary lifestyles and unhealthy diets.

Most importantly, they caution that the disease may present itself much earlier in people with a family history of colon cancer infection, even among distant relatives as was the case with Martin.

Indeed, a new study published in the Cancer Epidemiology Journal indicates that having second- or third-degree relatives with colorectal cancer increases a person’s risk of developing the disease.

For a long time, health experts have recommended regular tests, beginning the age of 50 to effectively prevent the disease or catch it early enough.

An exemption is made for individuals with close (first-degree) relatives who have had the disease.

This group is supposed to begin screening much earlier, at 40 or ten years before the age that the immediate family member was diagnosed with cancer.

But based on the findings of this study, the researchers note the early screening should also encompass people with distant relatives (second-or third-degree) that have had the disease.

“We believe that it can be beneficial for them too, as they are also at risk of getting the cancer,” noted the researchers from the US-based University of Buffalo and the University of Utah who led the study.

First-degree relatives include parents, children and siblings. The second-degree relatives on the other hand include aunts, uncles, grandparents, grandchildren, nieces and nephews.

Examples of third-degree relatives include first cousins, great-grandparents and great-grandchildren.

During the study, the researchers reviewed more than 1,500 early-onset colon cancer cases in the Utah Cancer Registry, based in the US.

The findings of the study revealed that first-, second- and third-degree relatives of someone diagnosed with early-onset colorectal cancer are six times, three times and close to two (1.56) times more likely to be diagnosed with colorectal cancer before age 50 respectively.

“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. This work is important given the rising rates of early-onset colorectal cancer,” says Dr Heather Ochs-Balcom, the first author of the study from the University of Buffalo School of Public Health and Health Professions.

Aside from the early screening, lifestyle changes that can reduce the risk of colorectal cancer include healthy diets (comprising of a variety of fruits, vegetables and whole grains), no smoking, moderate consumption of alcohol (if at all), exercising for 30 minutes (at least five days a week) and maintaining a healthy weight.

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 screening decisions.