New research could affect future treatment options for prostate cancer

Nov 8 2006

Two new studies on the treatment of prostate cancer could well affect future treatment options for patients.

The first study by Dr. Cliff Robinson, M.D., a radiation oncologist at Cleveland Clinic in Ohio, has found that patients treated with either radiation or surgery who use hormone therapy for longer than six months, do not survive any longer than patients who use the treatment for a shorter amount of time.

Robinson says many patients with high risk prostate cancer are treated with two or more years of hormone therapy based on studies performed over a decade ago, but his findings suggest that treating current patients with shorter-term hormone therapy may be equally effective, and also improve their quality of life because of fewer side effects.

The researchers also found that patients receiving longer than six months of hormone therapy were twice as likely to die than patients who use the treatment for a shorter amount of time, and the researchers are not sure why.

Dr. Robinson, says a number of factors could complicate the issue, and further investigation is needed before any conclusions can be drawn.

Androgen deprivation therapy is a hormone therapy used to treat prostate cancer by lowering the level of male hormones (androgens) to shrink or slow down the growth of prostate cancer.

It has been shown to dramatically slow advanced prostate cancer that has already spread to the lymph nodes or the bone, and improves survival when combined with radiation therapy in advanced prostate cancer that has not already spread.

Several side effects are common and vary significantly depending on the amount and length of time the hormone therapy is given.

They include reduced sexual desire, impotence, hot flashes, weakening of the bones, breast tenderness or breast growth, as well as other conditions.

The study reviewed 579 patients who were treated at the Cleveland Clinic with high risk prostate cancer from 1996 to 2003; the patients were divided into three groups, one that received no androgen deprivation therapy, one that had received six months or less of androgen deprivation therapy, and one that received more than six months of treatment.

This was done in order to determine if longer use of hormone therapy stopped cancer from growing and lengthened survival.

In the second study it was found that when prostate cancer patients were treated with intensity-modulated radiation therapy (IMRT) they suffered fewer long-term gastrointestinal side effects than those treated with another form of radiotherapy.

For this study researchers at Fox Chase Cancer Center in Philadelphia analyzed data on 489 men treated with IMRT and 928 men treated with the second type of radiation therapy, called three-dimensional conformal radiation therapy (3D CRT).

The researchers evaluated gastrointestinal side effects such as short-term diarrhea and longer-term bowel dysfunction, as well as genitourinary side effects such as urinary frequency, urgency, painful or difficult urination, or symptoms of urinary obstruction.

Study author Dr. Alexander Kirichenko says although there were no differences in the numbers of reports of acute gastrointestinal or genitourinary side effects for the two treatment modalities, there appear now to be more long-term gastrointestinal side effects in the men treated with 3D CRT.

The finding is particularly interesting because patients treated with IMRT receive higher radiation doses than those exposed to 3D CRT, but three years after treatment, gastrointestinal side effects were noted in 10.4 percent of patients treated with 3D CRT and in 6.3 percent of those treated with IMRT.

Both IMRT and 3D CRT enable doctors to precisely target cancer with multiple radiation beams, but IMRT allows doctors to control radiation dose intensity with far smaller radiation beams.

Both studies were presented at the annual meeting of the American Society for Therapeutic Radiology and Oncology in Philadelphia.