SAN FRANCISCO—Whole-field radiotherapy improves progression-free survival in prostate cancer patients who have a 15% or greater risk of lymph node involvement, compared with prostate-only radiotherapy, according to a study presented at the 43rd Annual Meeting of the American Society for Therapeutic Radiology and Oncology (plenary 5).
The study also showed a progression-free survival advantage for whole-pelvic radiotherapy plus neoadjuvant hormone therapy, compared with whole-pelvic radiotherapy plus adjuvant hormone therapy (HT), noted Mack Roach III, MD, professor of radiation oncology, University of California, San Francisco. Dr. Roach reported the results on behalf of the RTOG 9413 study group.
Between April 1995 and June 1999, the RTOG 9413 researchers enrolled 1,323 men with biopsy-proven prostate cancer, pretreatment PSA values of less than 100 ng/mL, and a risk of lymph node involvement of at least 15%. The average age of the men was 70. Nearly 25% were black. Two thirds had bulky disease, one third had PSA of 30 ng/mL or higher, and more than 70% had Gleason scores between 7 and 10.
Patients were divided into four groups:
- The first arm was treated with neoadjuvant hormone therapy for 2 months, followed by 2 months of neoadjuvant hormone therapy combined with whole-pelvic radiotherapy.
- The second arm received neoadjuvant hormone therapy for 2 months, followed by 2 months of neoadjuvant hormone therapy combined with prostate-only radiotherapy.
- The third arm was treated with whole-pelvic radiotherapy for 2 months, followed by 4 months of adjuvant hormone therapy.
- The fourth arm was treated with prostate-only radiotherapy for 2 months, followed by 4 months of adjuvant hormone therapy.
Hormone therapy consisted of oral flutamide(Drug information on flutamide) (Eulexin) and either leuprolide (Lupron) or goseralin acetate depot (Zoladex). Whole-pelvic radiotherapy had a minimum field size of 16 cm by 16 cm, while prostate-only radiotherapy was limited to 11 cm by 11 cm.
Study Results
With a median follow-up of 59 months, 4-year progression-free survival was significantly higher in the patients treated with whole-pelvic radiotherapy and neoadjuvant hormone therapy: 61%, compared with 49% for whole-pelvic radiotherapy/adjuvant hormone therapy, 45% for prostate-only radiotherapy/neoadjuvant hormone therapy, and 47% for prostate-only radiotherapy/adjuvant hormone therapy (P = .005).
