Family history of one kind of cancer increases the risk of the same and at other sites
The risk of many cancers is higher in persons with a family history of cancer at a corresponding site. However, there have been few studies that examined family history of cancer and discordant sites.
Eva Negri, ScD, of the Mario Negri Institute for Pharmacological Research in Milan, and colleagues examined the issue.
Researchers looked at participants in a network of case-control studies on 13 cancer sites, including prostate, breast and ovary conducted, between 1991 and 2009, that included 12,647 cancer patients identified at hospitals in Italy and the Canton of Vaud in Switzerland.
The studies also included 11,557 controls, who were patients, admitted to the same hospitals for reasons other than malignancy.
Cases and controls were interviewed during their hospital stay using a structured questionnaire, including information on sociodemographic characteristics, anthropometric measures, lifestyle habits (e.g. tobacco smoking and alcohol drinking), dietary habits, personal medical history, and, for women, menstrual and reproductive factors, use of oral contraceptives (OCs) and hormone replacement therapy (HRT).
Subjects were specifically asked for the number of siblings, and whether they, their parents, children, grandparents or spouses were ever affected by any form of cancer (excluding non-melanomatous skin cancer). For each relative with a history of cancer, the subject was asked to report the vital status at the time of interview, current age or the age at death, cancer site, and age at diagnosis.
The researchers found that for most cancer sites, the association with family history was stronger when the proband was affected under 60 years old.
The odds ratio for ovarian cancer, given a family history of the disease, was 20.1 when the participant was younger than 60 and 3.2 when she was 60 or older.
However, researchers also found significant increased risks for the following cancers; oral and pharyngeal cancer given a family history of laryngeal cancer, with an odds ratio of 3.3, esophageal cancer, given a family history of oral and pharyngeal cancer, where the odds ratio was 4.1, breast cancer, given a family history of colorectal cancer or hemolymphopoietic cancers, where the odds ratios were 1.5, and 1.7, respectively, ovarian cancer in the light of a family history of breast cancer, with an odds ratio of 2.3 and prostate cancer, given a first-degree relative with bladder cancer, where the odds ratio was 3.4.
The researchers note that some of the discordant site associations have not been consistently reported in the literature and may be chance finding. On the other hand researchers said they “cannot exclude” that some existing associations did not emerge in their analysis due to insufficient statistical power, particularly when the strength of the relation is modest, or the cancer(s) is rare.
In their conclusion the team writes “Our results point to several potential cancer syndromes that appear among close relatives and may indicate the presence of genetic factors influencing multiple cancer sites.”
These findings appear online in Annals of Oncology.