When Tony Masraff was diagnosed with early stage prostate cancer seven years ago, his doctor advised surgery. But after doing some research, he decided the best option was no treatment at all.

Mr. Masraff wasn't giving up. Instead he opted for "watchful waiting," a little-understood option for men with prostate cancer, where the cancer is monitored with periodic tests rather than treated immediately. There's increasing evidence that watchful waiting is a safe option for 30 percent to 50 percent of men with newly diagnosed prostate cancer, but most of these men either aren't told about it or decide to pursue surgery or other aggressive treatment that leaves them impotent, incontinent or both.

Several cancer centers are now conducting research to determine which patients are the best candidates for watchful waiting. Last week University of Texas M.D. Anderson Cancer Center announced a watchful-waiting study of 650 men that will also try to find molecular markers to help better predict risk. This summer a multinational trial called START, supported in part by the U.S. and Canadian National Cancer Institutes, will start recruiting 2,100 men to evaluate watchful waiting compared with other treatments.

To be sure, prostate cancer is a potentially deadly disease. But in many men, the disease is slow-growing with little chance of ever causing problems. "A lot of patients harbor these small areas" of cancer that don't pose a threat, says Laurence Klotz, professor of surgery at the University of Toronto and principle investigator on the START study. Even so, many patients today "are treated as if they might have aggressive disease."

While one man in six will be diagnosed with prostate cancer in his lifetime, only about 1 in 34 men will die from the disease, according to the American Cancer Society. Although screening appears to be catching more cancers before they become deadly, it also is finding cancers that would have never caused harm. "We don't know to what extent we are over-treating patients," says Jeri Kim, associate professor in genitourinary oncology at M.D. Anderson. "But we are probably treating a lot of men who may not need it."

However, the strategy of watching cancer and waiting to see if it spreads also poses a psychological burden for men, who must walk around knowing they have untreated cancer. Doctors also have a hard time "leaving" cancer in a patient. But studies show prostate cancer causes anxiety for every man, whether or not he opts for watchful waiting or surgery.

Mr. Masraff said he was frustrated that several doctors never told him watchful waiting was an option for him, and says he prefers living with cancer than living with the aftereffects of treatment. "My quality of life is just too important," he says.

The biggest challenge is determining which patients are the best candidates for watchful waiting -- also called "active surveillance" or "expectant management." The strategy means that a man diagnosed with prostate cancer returns for regular PSA testing and additional biopsies. Depending on the case, the biopsies could be done every six to 12 months.

One concern is there isn't a consistent standard for what constitutes a "good risk" prostate cancer. Some doctors advise watchful waiting if the PSA score is under 10; others suggest a PSA below 4. A Gleason score, which measures how aggressive the cancer is, of 6 or lower is also used to determine risk. Whether a tumor can be felt in a rectal exam, a man's age and the number of positive biopsies all factor into the decision.

Another measure called prostate density, a combination of PSA score and prostate volume measured by ultrasound, is also used. It's important because sometimes a high PSA score is simply the result of an enlarged prostate and not necessarily an aggressive cancer.

Watchful waiting is typically advised for men over 60. Often, men under 60 are discouraged from watchful waiting because they have so many years left in their lifespan -- giving the cancer time to grow and cause harm.

Some patients who opt for watchful waiting will still end up needing treatment. This is recommended when PSA scores continue to rise or additional biopsies show the cancer was more aggressive than first thought. A PSA score that doubles in less than three years may signal a more aggressive cancer.

Watchful-waiting patients who end up needing treatment anyway haven't compromised their care, the Journal of the National Cancer Institute reported this month. Researchers at Johns Hopkins Medical School studied 38 patients who needed surgery after about two years of watchful waiting, compared with 150 similar patients who opted for surgery right away. There was no difference in noncurable cancer between the two groups.

"Most individuals are not comfortable with monitoring because the physicians and the patients are worried about losing the window of opportunity for a cure," says Ballantine Carter, professor of urology and oncology at Johns Hopkins. But if a careful selection process is used, "there is no reason for a man to rush into any treatment."

Last month the medical journal Urologic Oncology noted that among about 300 men considered candidates for watchful waiting and studied by the University of Toronto, 34 percent eventually needed treatment. But the remaining 66 percent of men who opted for watchful waiting remained stable and avoided radical treatment.

"It's a huge communication challenge to move beyond this widespread reaction to the word 'cancer,' " says Dr. Klotz. "We try to educate men that it doesn't always mean they have a serious disease."