Male pattern baldness: is there an association with bladder cancer?
Male pattern baldness (MPB, also referred to as androgenic alopecia) is a common cause of hair loss in men due to both genetic and hormonal factors. A polymorphism of the androgen receptor gene on the X chromosome has been found in nearly all men with MPB but is not alone sufficient to express the phenotype. The hormonal link with MPB has been the subject of extensive research. Early studies observed that castrated men did not developed MPB unless supplemented with testosterone. In line with this, DHT which is a more potent activator of the androgen receptor than testosterone has been implicated as having a important role in the development of MPB. Observational studies have found that individuals with androgen insensitivity syndrome or 5-reductase deficiency do not develop MPB. Likewise, it has been showed that the balding scalp possesses a higher concentration of DHT compared to the non-balding scalp. These findings are supported by the prescription and success of finasteride in reversing/slowing MPB.
A number of studies have demonstrated an association between MPB and prostate cancer risk which is possibly explained by the common pathophysiological (hormonal) mechanisms. This includes a report by Zhou et al which employed the PLCO database and found that frontal plus moderate vertex baldness at 45 years of age is associated with an increased risk of cancer. However, no studies have explored the link between MPB and BCa even though the results from pre-clinical studies and the observed relationship with finasteride suggest these two conditions could also share pathophysiological processes.
To determine whether male pattern baldness influences the incidence of bladder cancer
Niranjan Sathianathen, University of Minnesota
Stephanie Jarosek, University of Minnesota
Yunhua Fan, University of Minnesota