This study of more than 500 black men found that those "who have baldness by age 30 are more likely to develop prostate cancer," said researcher Charnita Zeigler-Johnson, a research assistant professor at the University of Pennsylvania's Center for Clinical Epidemiology and Biostatistics, in Philadelphia.
Researchers have looked at baldness as a potential risk factor for prostate cancer for years, but studies to date have produced conflicting findings.
The new research is believed to be the first to focus only on blacks, Zeigler-Johnson said. Blacks in the United States get prostate cancer more often than other men and are more than twice as likely to die of the disease.
What the research found
For the study, published in the issue of Cancer Epidemiology, Biomarkers & Prevention, the researchers evaluated 318 men with prostate cancer and compared them to 219 men without the cancer. All were enrolled in the Study of Clinical Outcomes, Risk and Ethnicity between 1998 and 2010.
The men were asked about their hair loss, if any, at age 30. Options included: none, frontal (at the forehead or temples) and vertex (crown). They also supplied information on their medical history.
If the men reported baldness by 30, "their likelihood of developing prostate cancer was increased by about 70%, compared to men with no baldness at age 30," Zeigler-Johnson said.
While baldness of any type boosted risk, frontal baldness in younger men was most significant. "If they had frontal baldness at 30, men were 2.6 times more likely to be diagnosed with prostate cancer before age 60, compared to men at age 30 with no baldness," said Zeigler-Johnson.
For men diagnosed before age 60, frontal baldness was also strongly linked with more advanced and more aggressive cancers, she found.
Overall, 20% of those with cancer had baldness by age 30, but 13% of the group without cancer had baldness as well.
While the study found a link between early balding and prostate cancer, it didn't prove a cause-and-effect relationship. It does suggest a need for further study, however, experts noted.
This year, the American Cancer Society predicts about 238 000 new cases of prostate cancer will be diagnosed and that more than 29 000 men will die of the cancer.
Besides race, known risk factors for prostate cancer include older age and a family history of the disease.
Male hormones play a role
Zeigler-Johnson isn't sure how to explain the association between prostate cancer and baldness, but said male hormones might play a role. "Perhaps it is related to androgens, in particular to dihydrotestosterone [DHT], a metabolite of testosterone," she said.
"We know an increase in DHT increases prostate cancer occurrence and progression," she said. "But it is also related to thinning of the hair follicles." That thinning makes it difficult for hair to survive.
Dr Otis Brawley, chief medical officer of the American Cancer Society, said the study provides "more evidence of a link that has been talked about since the '70s."
The finding about balding in younger men is the newest information, he said.
Another expert, Dr Lionel Banez, a research investigator at Durham Veterans Affairs Medical Center in Durham, NC, said the new findings are important "because this is the largest cohort of purely African-American men published which examines the link between baldness and prostate cancer."
However, it is "quite premature" to use the findings to make any clinical recommendations about screening for the cancer, he said.
If other research confirms the link, Zeigler-Johnson said doctors might decide to follow and screen balding men more closely for prostate cancer.
One screening test for prostate cancer is the PSA (prostate-specific antigen) blood test, which measures normal and cancerous cells in the prostate gland. When PSA levels are high, it sometimes indicates cancer.
"We still do not know if prostate cancer screening saves lives," said Brawley. Currently, the American Cancer Society recommends informing men of average risk, without symptoms, of the known pitfalls (such as false "positive" results) and potential benefits (early detection) of prostate cancer screening beginning at age 50. They then can make a decision about screening.
To learn more about prostate cancer, visit the American Cancer Society.