Overall, 20 percent of those with cancer had baldness by age 30, but 13 percent 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.
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, N.C., 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.
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