March 19, 2010 -- Here's potentially good news for balding men, especially young balding men who may be distressed by their lack of locks.
''Men who have early-onset male pattern baldness, by age 30, were found to have a 29% reduction in the risk of developing prostate cancer," says study co-author Jonathan L. Wright, MD, an affiliate investigator at the Fred Hutchinson Cancer Research Center in Seattle and assistant professor of urology at the University of Washington School of Medicine in Seattle. The study is published online in Cancer Epidemiology.
''The longer you have the baldness, the more the protection," he tells WebMD.
The apparent protection was found, he says, for aggressive and less aggressive forms of prostate cancer.
In 2009, about 192,000 new cases of prostate cancer were expected to be diagnosed in the U.S., according to the American Cancer Society, with about 27,000 deaths expected. The prostate gland surrounds the neck of a man's bladder and urine-carrying tube, or urethra.
Male pattern baldness affects about 25% of men by age 30, 50% by age 50, and nearly 80% by age 70. Testosterone is converted to dihydrotestosterone or DHT, and baldness occurs when hair follicles become exposed to too much DHT.
Balding Men and Prostate Cancer Risk: Study Details
Wright and his colleagues evaluated 999 men, aged 35 to 74, diagnosed with prostate cancer between 2002 and 2005 in King County, Wash. They compared them to 942 men without prostate cancer, age-matched to the patients.
All of the men reported their hair pattern at age 30 -- little or no hair loss, loss at forehead only, loss at the top of head and forehead. The men diagnosed with prostate cancer also reported their hair loss pattern, if any, a year before their diagnosis. The men without a prostate cancer diagnosis reported their hair loss pattern a year before a reference date that corresponded with patients' various diagnosis dates.
The men also reported the use of any drugs that might interfere with male hormones, and the researchers took that into account.
Balding and Prostate Cancer Risk: Findings
Men with any significant hair loss at age 30 had a 29% reduced risk of prostate cancer, the researchers found.
Then Wright's team looked at a smaller subgroup -- men who were balding in their 30s at both the top of the head and the forehead -- and were over age 60 at the reference date.
In this subgroup, he found a risk reduction of 45%.
Balding and Lower Prostate Cancer Risk: Why?
Previous studies have found conflicting results when looking at the relationship between baldness and prostate cancer risk, Wright says. Some studies found an increased risk with baldness and others found no change in risk, regardless of hair patterns.
But his study, unlike others that looked only at baldness close to the diagnosis date, looks back decades.
Even so, he says, ''Our findings are a little bit counterintuitive."
He can't explain the finding linking baldness and a reduction in prostate cancer risk. ''It's not as simple as DHT and testosterone levels," he tells WebMD. "There is a very complex environment going on."
Genetic differences may help explain the link, he says. For instance, he says, a genetic variant in the male hormone receptor gene can affect cancer development and male pattern baldness.
They will look next at genetic data from the men to try and understand the link.
Balding and Lower Prostate Cancer Risk: Other Views
The new findings fly in the face of traditional thinking, says Leonard Lichtenfeld, MD, deputy chief medical officer of the American Cancer Society, who reviewed the findings for WebMD.
''The old thinking is, the balder you are, the higher your risk of prostate cancer," he says, and that link was thought to be associated with testosterone levels, with both baldness and prostate cancer thought to be sensitive to hormone levels.
''This study is saying just the opposite," Lichtenfeld says. ''This concept doesn't fit the concept of the way things should work." But, he says, ''you always have to be willing to look at new evidence."
He agrees with Wright that the relationship between hormone levels and baldness and prostate cancer is complicated. "It may have to do with other genetic changes that we don't fully understand at this time," he says.
The factors triggering male pattern baldness and prostate cancer may be the same process or may be different, Lichtenfeld says. "Testosterone and DHT may not be the whole story. More subtle genetic changes within the scalp and the prostate may actually explain these findings."
Another expert says more research is needed.
"I think it's going to take a lot of data to show an easy link between baldness and prostate cancer," says Peter Galier, MD, staff physician at Santa Monica-UCLA & Orthopaedic Hospital in Santa Monica, Calif., and associate professor of medicine at the University of California Los Angeles David Geffen School of Medicine.
Like other experts, he says there may be tissue-specific effects of hormones. It's known, he says, that men with high levels of DHT can lose their hair and also have enlarged [but not necessarily cancerous] prostates. ''If you lower DHT, he grows hair and the prostate shrinks."
But perhaps, Galier says, a man somehow has higher levels of DHT in the scalp than in the prostate, explaining the reduced risk found among bald men in Wright's study. More study is needed to replicate and clarify the link, he says.