"Men, as they get older, have a higher and higher rate of prostate cancer," said Dr. Ralph deVere White, a urological oncologist at the UC Davis Medical Center. "It is literally one of the risks of being an aging male."

Dr. Brian Naftulin, a urologist who is director of the Sutter Institute for Minimally Invasive Surgery in Sacramento, described prostate cancer as "the most common malignancy in men over age 65 other than skin cancer."

Brown was treated for a common type of skin cancer last year when he had a basal cell carcinoma growth removed from his nose. There is likely no medical connection between his being treated for skin cancer one year and prostate cancer the next, both Naftulin and deVere White said.

The fact that Brown's prostate cancer is localized means it hasn't spread to other parts of the body and is more likely to be cured, the doctors said.

Brown's office did not provide details on his treatment, saying only that the governor is undergoing "a short course of conventional radiotherapy."

Two types of radiation are most common for prostate cancer patients, Naftulin said. The first involves getting radiation beamed into the body five days a week during appointments that last less than 15 minutes, he said. The course of treatments would typically last up to eight weeks.

The second involves having radiation-filled pellets inserted into the body during a one-time outpatient procedure. The pellets stop giving off radiation after a few months, Naftulin said, but stay in the body permanently.

Either way, Brown is unlikely to experience significant side effects, the doctors said.

"He may have some fatigue, that's one of the more common side effects of the daily treatments. But in general, patients go to work and carry on their normal daily activities," Naftulin said. "There is no vomiting or nausea like there is with chemotherapy."

According to the National Cancer Institute, side effects depend on the type of radiation therapy and amount given.

"You're likely to become tired during external radiation therapy, especially in the later weeks of treatment," says a National Cancer Institute guide for patients. "Although getting enough rest is important, most people say they feel better when they exercise every day. Try to go for a short walk, do gentle stretches, or do yoga."

DeVere White, of UC Davis, said the governor's overall good health will help him overcome the disease.

"He has a treatment that has a 97 or 98 percent cure rate, which is outstanding. And this should not interfere with the governor doing his job or living his life in any way," he said.

Prostate cancer responds best to treatment when it is caught early, Naftulin said.

Steve Maviglio, a Democratic strategist, said Brown likely didn't mention his diagnoses before Wednesday only because he is a "private guy."

"He's healthier than most people half his age," Maviglio said. "I don't think it's going to affect him a bit."