The impact of radiotherapy on overall survival (OS) in men with locally advanced prostate cancer is unclear. The SPCG-7 trial, an open randomized phase III trial, recently showed a benefit to radiation therapy (RT) for locally advanced prostate cancer specific mortality.

The study reports that adding radiation therapy to androgen deprivation therapy (ADT; also known as hormone therapy) reduces the risk of dying from prostate cancer by 43% in men with locally advanced or high-risk prostate cancer compared to ADT alone.

?This study will challenge the prevailing dogma of only using hormone therapy for locally advanced prostate cancer,? said Padraig Warde, MBChB, deputy head of the radiation medicine program at the University of Toronto?s Princess Margaret Hospital. ?We found that men who received the combination lived longer, and were less likely to die of their prostate cancer than those who had only hormone therapy. These results suggest that adding radiation therapy to the treatment plan for these patients could become part of standard therapy and should be considered.?

Effects of radiation
Some physicians and clinical guidelines recommend radiation with ADT as a treatment option for locally advanced prostate cancer. But it has been unclear whether ADT alone was sufficient therapy for these patients, and whether the side effects of radiation could be avoided. ADT reduces the level of cancer-fueling male hormones in the body, and is standard therapy for men whose disease persists despite local treatment (radiation therapy or surgery).

Trial design
In this study, men with locally advanced or high-risk prostate cancer were randomly assigned to receive ADT alone (602 men) or ADT plus radiation (603 men).

Patients with T3/T4 (1057) or T2, PSA > 40 ?g/l (119) or T2 PSA > 20 ?g/l and Gleason ? 8 (25) and N0 /NX, M0 prostate adenocarcinoma were randomized to lifelong ADT (bilateral orchiectomy or LHRH agonist) with or without RT (65-69 Gy to prostate ? seminal vesicles with or without 45Gy to pelvic nodes). The primary endpoint was OS and secondary endpoints included disease specific survival (DSS), time to disease progression and quality of life.

After 7 years, 66% of men who had ADT alone were still alive, compared with 74% of those who had received ADT plus radiation. Among those in the ADT-only group, 26% died from their prostate cancer, versus 10% of those who received ADT plus radiation. Patients who received ADT plus radiation lived 6 months longer on average than those who received ADT alone. There was no increase in significant, long-term GI toxicity between treatment groups.

The researchers projected that fewer men (15%) who received ADT plus radiation would die from their prostate cancer over 10 years (10-year cumulative disease specific death rate) compared to 23% with ADT alone.

A new standard
The researchers concluded that the trial results indicate a substantial overall survival and disease specific survival benefit for the combined modality approach (ADT plus radiation) in the management of patients with locally advanced prostate cancer with no significant increase in late treatment toxicity. In view of this data, they conclude that combined modality therapy (ADT plus radiation) should be considered as the new standard treatment approach for these patients.

Oral Abstract Session: Genitourinary Cancer
Lead author: Padraig Warde, MBChB, Princess Margaret Hospital, University of Toronto, Toronto, Canada
Date: Sunday, June 6, 2010, 9:30-9:45 AM CDT
Location: E Hall D2
Abstract: CRA 4504
Title: Intergroup randomized phase III study of androgen deprivation therapy (ADT) + radiation therapy (RT) in locally advanced prostate cancer (CaP) (NCIC-CTG, SWOG, MRC-UK, INT: T94-0110; NCT00002633).
Authors: P. R. Warde, M. D. Mason, M. R. Sydes, M. K. Gospodarowicz, G. P. Swanson, P. Kirkbride, E. Kostashuk, J. Hetherington, K. Ding, W. Parulekar, NCIC CTG PR.3/ MRC PRO7/ SWOG JPR3 investigators.