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ASTRO Patient Summary: Phase III Randomized Study of Adjuvant Radiation Therapy versus Observation in Patients with Pathologic T3 Prostate Cancer (SWOG 8794)

Carolyn Vachani, RN, MSN, AOCN
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: October 25, 2005

Phase III Randomized Study of Adjuvant Radiation Therapy versus Observation in Patients with Pathologic T3 Prostate Cancer (SWOG 8794)

This study looked at prostate cancer patients who were found to have "adverse pathologic features" (invasion beyond the prostate or positive surgical margins) after surgical removal of the prostate. There are two schools of thought with regard to this group: treat with radiation after surgery, or wait until a recurrence occurs to start radiation. Patients were assigned between 6/15/88 and 1/1/97 to immediate radiation versus observation following prostatectomy. To date, the radiation group has a significantly improved "biochemical disease free survival" (defined as PSA<0.4) at both 5 and 10 years (See the table above for results). A large number of patients ultimately received hormone ablation therapy, but this was delayed an average of 2.5 years in the radiation group. Overall survival was improved in the radiation group, but did not achieve statistical significance (the level at which the improvement didn't just happen by chance). As for side effects, there were more reported in the radiation group during treatment, but 2 years post- surgery, the groups had similar quality-of-life scores, so that it seems the side effects resolved over time. A second study (EORTC study 22911) has also confirmed these results. These results mean that radiation therapy immediately after surgery should be considered standard of care in patients with "adverse pathologic features".