Colon cancer (colorectal cancer) often develops in people without a family history of the disease. However, a third of patients with this tumor have first-degree relatives (parents, siblings) who had it, according to the American Cancer Society. This can be caused not only by genes, but also by the influence of common environmental and lifestyle factors, such as diet.
If a person has had close relatives with colon cancer, they may be advised to start periodic colonoscopy for its prevention at an earlier age than most indicated (in the United States, it is usually prescribed from the age of 50).
Whether the risk of colon cancer is increased if it was diagnosed in more distant relatives – second and third degrees – was previously unknown. American scientists decided to clarify this risk. To do this, they analyzed the stories of 1,500 patients who diagnosed this tumor at a young age. They got the information from the Utah Cancer Database. Scientists pointed out that the uniqueness of the data obtained in Utah lies in the fact that it has created a digital genealogical database for the majority of the population.
Research has shown that the risk of colon cancer before age 50 is:
- six times higher than average in people whose first-degree relatives were sick with it;
- three times higher if he was with relatives of the second degree (aunts, uncles, grandfathers, grandmothers);
- 1.56 times higher in the case of cancer if third-degree relatives (cousins, great-grandparents and great-grandmothers) were ill with it.
Factors that can be influenced:
- Obesity and overweight.
- Low physical activity.
- Unhealthy diet (rich in red meat, meats, sugar).
- Lack of vitamin D.
- Alcohol consumption
Factors that cannot be influenced:
- Intestinal polyps or colorectal cancer in the past.
- Inflammatory bowel disease.
- Family history of the disease.
- Diabetes mellitus type 2.
- Some hereditary diseases.
Factors whose role is not precisely known:
- Night work.
- Any other cancer in the past.
They also found that the risk of colon cancer at any age was 2.6, 1.96 or 1.3 times higher if it was in first, second or third degree relatives, respectively. That is, the risk of early cancer is higher in these cases.
Scientists believe that people with a family history of colon cancer – not just those with close relatives – may need early screening for cancer with colonoscopy. The authors of the work emphasize the special role of knowledge of family history and the need to share its details with doctors.