A recent study describes the relationship between Family History of cancer and cancer risk for the same type or for a different type of cancer on a wide network of cases collected in Switzerland and Italy.
When someone is diagnosed with cancer, members of the family start periodical check-up, frightened by the idea that cancer could easily affect other relatives. Although approximately only the 7% of cancers are hereditary with known mutations that imprint the risk of cancer in the genes, scientists often refer to familial cancer. Indeed some type of tumors commonly spread in certain families. However, there are no other hereditary factors -other than gene mutations- known to drive the disease.
An interesting study published in the Journal “Annals of Oncology” by Turati et al. 1 last July tries to elucidate the relationship between Family History of cancer (FH) and cancer risk. The researchers provide a quantitative association of FH and risk of developing the same type or a different type of tumor in a cohort of 23000 individuals (11000 controls and 12000 cancer cases) collected in Switzerland and Italy between 1999 and 2009. They analyzed 13 cancer types (mouth and pharynx, nasopharynx, esophagus, stomach, colorectum, liver, pancreas, larynx, breast, womb, ovaries, prostate and kidneys) and incorporated several information, such as sociodemographic characteristics, lifestyle, dietary habits, and personal medical history.
In all cases, they found higher risk of developing cancer when a first degree relative had a history of the same type of cancer. Interestingly, the researchers found a plethora of associations between cancers of different origin: esophageal cancer and FH of oral and pharyngeal cancer, breast cancer and FH of colorectal and of hemolymphopoietic cancer, ovarian cancer and FH of breast cancer, prostate cancer and FH of bladder cancer. Some associations were stronger if analyzed in subjects before 60 years old (colorectal and FH of ovarian cancer and prostate cancer or endometrial cancer and FH of stomach cancer).
Some of these associations were already known. For example, subjects with BRCA1/2 mutations have increased risk of developing breast and ovarian cancer, as well as prostate, colon and pancreatic cancers. However, as they properly point out in their article, these mutations are associated with an increased risk, but “they are too rare to account for a substantial proportion of common cancers”. They may predispose to cancer, but other factors might concur in the development of a familial cancer. For instance, intrinsic factors, such as genetic polymorphisms occurring in the same family, or extrinsic factors, such as the environment and lifestyle habits, could affect the spread of cancer. Indeed, alcohol and tobacco are associated with increased risk of developing tumors. In some cases, cancer incidence was found higher in males than in women, in part due to a largest consumption of alcohol and tobacco among men in the past. These trends might change in the future. On one hand, women now consume as much alcohol and tobacco as men do, leading to a potential higher incidence of cancer in the female population. On the other hand, the anti-tobacco advertisements might have a positive effect and tobacco might be a limited issue in the future.
Family history of cancer has been studied for a long time, but lack of complete information limited rigorous epidemiological studies. The present study incorporates information about lifestyle and subjects’ characteristics for adjustment purposes which haven’t been considered previously, leading to better insights on how cancer can spread in some families. More analyses of this kind are needed in other population datasets to make a wide correlation between family history and risk of cancer.
We need to be aware that if cancer occurs in one member of a family, in some cases there might be either a genetic or an environmental factor that can predispose other members of the family. We need to know, to prevent it.
1. Turati, F. et al. Family history of cancer and the risk of cancer: a network of case-control studies. Ann Oncol, doi:mdt280 [pii] 10.1093/annonc/mdt280 (2013).