Potency Status Before RT, Not Dose, Determines Post-RT Function

MIAMI BEACH--Potency status in prostate cancer patients beforeradiation therapy, not the radiation dose, is the main determinantof potency status afterwards, Adam P. Dicker, MD, said at the37th Annual Meeting of the American Society for Therapeutic Radiologyand Oncology (ASTRO).

The study, from Memorial Sloan-Kettering Cancer Center, showedthat prostate cancer patients who have difficulty maintainingan erection before radiation therapy are seven times as likelyto be impotent after radiation therapy as patients who are fullypotent prior to radiation treatment.

The researchers also found that the risk of impotency was highestin patients who had heart disease and patients who had undergoneneoadjuvant hormonal therapy before their radiation treatments.

Dr. Dicker and coworkers looked at the frequency of impotencyin 300 men who had been treated with 3D conformal radiation therapy(see related story on page 3 and illustration on page 1). Patientswere followed for up to 5 years.

"It has been widely established that prostate cancer patientshave essentially the same outcome in terms of survival and a declinein their PSA level whether they are treated with a radical prostatec-tomyor radiation therapy," Dr. Dicker said in an interview.

The Patient's Decision

He noted that "the patient's decision about which treatmenthe prefers to undergo thus depends on side effects, and the short-termand long-term effects of radiation therapy on potency in thesepatients had not been systematically assessed before our trial."

The higher doses of radiation used with the 3D conformal techniquedid not increase the risk of impotency in these patients, Dr.Dicker said. In fact, 84% of patients who were fully potent beforetherapy, had no previous heart attacks, and had not received hormonesremained potent 2 years after radiation therapy.

Only 54% of patients who had had a heart attack retained theirpotency 2 years after treatment, compared with 70% of patientswho had not had a heart attack. He added that it is importantto note that prostate cancer patients who have sustained a heartattack and have not undergone radiation therapy have a 16% to40% chance of becoming impotent.

The study also found that in men who were partially potent beforeirradiation, ie, their erectile function was inconsistent andhad already started to decline, the chances of being potent afterwardsare minimal. "By 3 years, the likelihood that these men willbe able to sustain an erection is virtually zero," Dr. Dickersaid.

Age, smoking, a history of hypertension, and the use of antihypertensivemedication had no impact on the development of impotency afterirradiation, suggesting that these factors should not be blamedfor post-treatment impotency in men who were potent prior to receivingradiation therapy.

Dr. Dicker emphasized that patients who have problems with potencyduring the first year or so after radiation therapy need not necessarilybe overly concerned that the problem will not reverse itself."We advise patients to wait at least 1½ to 2 years beforethey start going to the urologist for a comprehensive workup,since potency will return during that time period in 25% to 50%of cases," he said.

On the other hand, patients who are still impotent at 2 yearswill likely remain impotent and should be informed about possibletreatments for the problem.