Men who start losing their hair at the age of 20 double their chances of developing prostate cancer in later life, a study has found.
Researchers suggest that an anti-baldness pill, finasteride, could be given to at-risk individuals as a preventative anti-cancer treatment.
Male hormones play a role both in male-pattern baldness and prostate cancer.
Finasteride, marketed as Propecia, prevents the conversion of testosterone to a form that promotes baldness.
Male pattern baldness, also known as androgenic alopecia, affects around half of all men in their lifetime.
Until now there has been conflicting evidence about links between balding and prostate cancer.
But the new French study found a specific association between hair loss at a young age and the risk of developing the disease.
Researchers compared 388 men being treated for prostate cancer with a “control group” of 281 healthy men.
They found that those with the disease were twice as likely as healthy individuals to have started losing their hair when they were 20.
Going bald at 30 or 40 had no effect on prostate cancer risk. Nor was there any association between early baldness and an early diagnosis of prostate cancer, or the pattern of hair loss and cancer development.
Study leader professor Philippe Giraud, from the Paris Descartes University, said: “At present there is no hard evidence to show any benefit from screening the general population for prostate cancer.
“We need a way of identifying those men who are at high risk of developing the disease and who could be targeted for screening and also considered for chemo-prevention using anti-androgenic drugs such as finasteride.
“Balding at the age of 20 may be one of these easily identifiable risk factors and more work needs to be done now to confirm this.”
The study participants with prostate cancer were aged 46 to 84.
Prof. Giraud’s team asked the men to indicate on four pictures any balding patterns they had at ages 20, 30 and 40. Those with prostate cancer were also asked to answer questions on their disease history.
The pictures showed four stages of hair loss: no balding, a receding hairline, a round bald patch, or a combination of both types of hair loss (stage IV).
Stage II to IV balding was associated with a doubling of cancer risk.
Kate Holmes, from The Prostate Cancer Charity, said: “This new research is an interesting addition to the growing body of evidence into whether two male conditions, pattern baldness and prostate cancer, can be linked together.”