A new meta-analysis evaluated the link between breast cancer and prostate cancer risk to determine if breast cancer in first-degree relatives increased the risk of prostate cancer in men.
Prostate cancer is the second most commonly diagnosed cancer in men in most western countries. Prostate cancer has high morbidity and mortality making it the fifth leading cause of cancer deaths. Family studies have shown that some prostate cancers can be inherited genetically. In addition, studies show that certain genetic mutations that result in an increased risk of breast cancer may also be linked to an increased risk of prostate cancer in men.
The risk factors for prostate cancer
Although the cause of prostate cancer has not been fully determined yet, there are certain risk factors associated with the development of prostate cancer. Age, ethnicity, geography, genetic factors, and family history are some of the established risk factors. Unlike risk factors such as smoking that can be controlled, most risk factors for prostate cancer are not under an individual’s control.
The role of genetic mutations in the risk of prostate cancer
Prostate cancer is caused by changes in the DNA of a normal prostate cell. We know that our parents are the source of our DNA. Just as we inherit normal genetic makeup, there is a possibility of inheriting genetic mutations from our parents. Some genetic mutations, in fact, are passed on from generation to generation. Several inherited mutated genes have been linked to hereditary prostate cancer. However, prostate cancer can also be caused by mutations that are acquired during a person’s lifetime.
The link between breast cancer and prostate cancer risk
Several studies have shown that an increased risk of breast cancer development may result in an increased risk of prostate cancer in men. Mutations in genes BRCA1 and BRCA2 have long been associated with an increased risk of breast cancer. The researchers have recently found that men with certain mutations in BRCA1 and BRCA2 genes may have an increased risk of prostate cancer. However, the exact relationship between first-degree family history of breast cancer and prostate cancer risk is unclear.
New study evaluates the link between breast cancer and prostate cancer risk
Several analyses in the recent past have attempted to determine the correlation between the first-degree family history of female breast cancer and the risk of prostate cancer in men but the results have been inconclusive. Researchers from Sichuan University, China, recently conducted a systematic review with meta-analysis of all the past studies that investigated the link between family history of breast cancer and the risk of prostate cancer. The meta-analysis published in BMC Cancer included studies on the link between breast cancer and prostate cancer published between 1928 and December 18, 2018. These studies were based in America, Europe, and Asia. Of a total of 18 studies included in the meta-analysis, 13 studies reported a history of breast cancer in first-degree relatives, 11 studies in mothers only, and 10 studies in sisters only.
Breast cancer in first-degree relatives is significantly associated with prostate cancer
The results of the meta-analysis showed a significant link between history of breast cancer in first-degree relatives and the risk of prostate cancer. Subgroup analyses of the region showed that this link was found in America, Europe, and Asia. Furthermore, a family history of breast cancer in mothers only was associated with the incidence of prostate cancer but this association was seen only in America, and not in Europe and Asia. The researchers also observed that a family history of breast cancer in sisters only was associated with prostate cancer, while a history of breast cancer in daughters only was not associated with risk of prostate cancer.
The researchers also observed an increased risk of lethal prostate cancer in men with family history of female breast cancer in first degree relatives and in mothers only.
Can these findings help predict the risk of prostate cancer?
A family history of breast cancer is one of the most significant predictors of the risk of prostate cancer in men. Studies in the past have shown that men who have a family history of prostate cancer in first-degree relatives may have a two-fold increased risk of developing prostate cancer. Similarly, this meta-analysis showed a clear link between breast cancer and prostate cancer risk. The findings suggest that men with a family history of female breast cancer have a higher risk of developing prostate cancer.
Although the researchers are still not clear about the underlying mechanisms that are responsible for this link between breast cancer and prostate cancer, genetic alterations may play a role. These results imply that an analysis of family history of female breast cancer is an important determinant in evaluating the risk of prostate cancer in men.
This meta-analysis establishes the link between breast cancer and prostate cancer risk. The results showed an association between the family history of female breast cancer in first-degree relatives and risk of prostate cancer. The researchers indicate that further work is needed to understand the underlying mechanism that is responsible for this link between breast cancer and prostate cancer risk.
Written by Preeti Paul, M.Sc.
Reference: Zheng-Ju Ren et al., First-degree family history of breast cancer is associated with prostate cancer risk: a systematic review and meta-analysis. BMC Cancer 19, Article number: 871 (2019)
