A family history of one type of cancer increases the risk not only of the same type of cancer but also of other types of cancer, according to the results of a study published in the Annals of Oncology.
The chance of an individual developing cancer depends on both genetic and non-genetic factors. A genetic factor is an inherited, unchangeable trait, while a non-genetic factor is a variable in a person’s environment, which can often be changed. A genetic predisposition means that a person may be at higher risk for a certain cancer if a family member has that type of cancer. Although family history of cancer is not a modifiable risk factor, researchers continue to explore the risks and develop a better understanding of familial risk in order to improve screening and prevention for the disease.
Research has long shown that the risk of many cancers is higher in people who have a family history of that cancer—but what about people who just have a family history of cancer in general? In other words, does type matter—or does a family history of cancer simply indicate an increased risk for any type of cancer?
To examine this question, researchers conducted a study examining a network of Italian and Swiss case–control studies on 13 cancer sites conducted between 1991 and 2009, that included more than 12,647 cancer patients identified at hospitals in Italy and Switzerland and 11,557 controls admitted to the same hospitals for other reasons. The researchers collected information regarding history of any cancer in first-degree relatives and age at diagnosis.
The results indicated that a family history of cancer at any site was associated with an increased risk of cancer at the same site. For example, a family history of breast cancer was associated with an increased risk of breast cancer. This was expected. What’s more, this link was stronger when the patient was under age 60.
However, the researchers also found significantly increased risks for other types of cancers depending on family history. For example:
- A family history of laryngeal cancer was linked with an increased risk of oral and pharyngeal cancer
- A family history of oral and pharyngeal cancer was linked to an increased risk of esophageal cancer
- A family history of colorectal cancer was linked to an increased risk of breast cancer
- A family history of breast cancer was linked to an increased risk of ovarian cancer
- A family history of bladder cancer was linked to an increased risk of prostate cancer
What’s more—the researchers noted that they couldn’t exclude the possibility that other associations exist, but simply didn’t emerge in the study. The data led the researchers to speculate that there may be “cancer syndromes” among family members and these syndromes might indicate that there are genetic factors that influence several cancer types.
The findings might help researchers identify genetic factors associated with certain cancers or “cancer syndromes” and as such, could help identify additional ways to improve screening for such cancers.
Turati F, Edefonti V, Bosetti C, et al. Family history of cancer and the risk of cancer: a network of case–control studies. Annals of Oncology. Published early online July 24, 2013. doi: 10.1093/annonc/mdt280