Post-Surgery Radiation of Some Benefit in Advanced Prostate CancerKey Words
Prostate cancer, radiation therapy. (Definitions of many terms related to cancer can be found in the Cancer.gov Dictionary.)
Summary
Prostate cancer that has spread beyond the affected gland is likely to come back after surgery. A new study shows that radiation treatment after surgery can reduce the risk of recurrence by about 50 percent. However, such treatment does not help patients live any longer and many experience difficult side effects from the radiation.
Source
Journal of the American Medical Association, November 15, 2006 (see the journal abstract).
(JAMA. 2006 Nov 15;296(19):2329-35)
Background
About 230,000 American men are diagnosed with prostate cancer each year. Roughly one third of these men choose to have surgery to remove the prostate gland and surrounding tissue, a procedure known as a radical prostatectomy.
Outcomes from radical prostatectomy are best when the disease is confined to the prostate gland. In about four out of 10 patients who opt for the surgery, however, doctors find that the tumor has spread beyond the prostate gland, although not into nearby lymph nodes. This condition, called pathologically advanced prostate cancer, poses a greater risk of recurrence.
For many years doctors have given such patients additional (adjuvant) treatment with radiation after surgery to reduce the risk of the cancer’s return. To date, however, no clinical trial has shown that adjuvant radiation treatment prevents prostate cancer from spreading to other organs or helps patients to live longer.
The Study
The 425 men who took part in this
phase III trial all had pathologically advanced prostate cancer and had had a radical prostatectomy. Their average age was 65. They enrolled in the study between 1988 and 1997. The men were randomly assigned either to receive radiation treatment or to be observed for disease progression. All the men were followed for a median of 10.6 years.
The study’s main goal was to determine how many patients died (whether from prostate cancer or any other cause) or developed tumors that spread to other organs (metastatic disease). Additional goals were to compare
- how many patients’ PSA levels began to increase - a rising PSA (prostate-specific antigen) level, called PSA relapse, is considered a sign of disease progression;
- how many patients had a disease recurrence other than PSA relapse;
- how many patients eventually needed hormonal therapy for disease progression; and
- patients’ overall survival.
The study’s principal investigator was Ian M. Thompson, Jr., M.D., of the University of Texas Health Science Center in San Antonio.
Results
In the radiation-treatment group, 35.5 percent of patients died or developed metastatic disease. This compared with 43.1 percent of those in the observation group. This difference was not statistically significant - that is, it could have occurred by chance.
The difference in overall survival between the two patient groups was also not statistically significant: 33.2 percent of patients died in the group receiving radiation treatment, compared with 39.3 percent in the observation group.
The researchers did find significant differences between the two groups on rates of PSA relapse, disease recurrence other than PSA relapse, and need for hormonal therapy.
PSA relapse was measured in a subgroup of 249 patients who were known to have undetectable PSA levels at the time they entered the study. Among those who received radiation treatment, 34.9 percent had a PSA relapse, compared with 64.0 percent of patients who were observed only.
A disease recurrence other than PSA relapse occurred in 39.3 percent of patients treated with radiation and in 52.6 percent of those who were observed. Ten percent of patients in the radiation group received hormonal therapy within five years compared with 21 percent of those in the observation group.
Complications from treatment were more common in the radiation group (23.8 percent) than in the observation group (11.9 percent). These complications included rectal inflammation and bleeding, difficulty passing urine due to narrowing of the urethra, and urinary incontinence.
Comments
The results offer guidance for doctors and patients who are weighing treatment options for pathologically advanced prostate cancer, say the authors. Arguments in favor of radiation therapy include the roughly 50 percent reduction in the risk of PSA relapse or disease recurrence. Arguments against radiation therapy must include the fact that it did not significantly reduce the occurrence of disease spreading to other organs, nor did it help patients to live any longer overall, although in both instances the trend favored the group that had been irradiated.
Since this study began in 1988, doctors have developed much better techniques for identifying before surgery men whose cancer is truly confined to the prostate gland, says Bhadrasain Vikram, M.D., of the National Cancer Institute’s Radiation Research Program.
“One hopes that with all of the information that is [now] available before the operation, very few men today will wake up to the news that their cancer was found to extend beyond the prostate,” adds Vikram. “For those that do, and their doctors, this study’s findings should be of help in deciding the best course of action.”
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