LATE NORMAL TISSUE SEQUELAE IN THE SECOND DECADE AFTER HIGH DOSE RADIATION THERAPY WITH COMBINED PHOTONS AND CONFORMAL PROTONS FOR LOCALLY ADVANCED PROSTATE CANCER

Abstract

We determined the long-term normal tissue effects of 77.4 Gy. delivered to the prostate in patients with locally advanced prostate cancer. Between 1976 and 1992, 167 men with stages T3 to 4 prostate cancer were treated on protocol with 50.4 Gy. photons at 1.8 Gy. per fraction using a 4-field box arrangement, followed by a conformal perineal proton boost of 27 Gy. (cobalt Gy. equivalent) in 11 fractions. The chart was reviewed and 39 of the 42 surviving patients were interviewed. Median followup was 13.1 years (range 7 to 23). Normal tissue morbidity was recorded using Radiation Therapy Oncology Group criteria and the late effects normal tissue scale. The actuarial incidence of grade 2 or greater genitourinary morbidity was 59% at 15 years. However, these grade 2 or greater problems persisted to the time of the interview in only 7 of 39 cases. The actuarial incidence of grade 2 or greater hematuria was 21% at 5 years and 47% at 15. For grade 3 or greater hematuria the risk was 3% and 8% at 5 and 15 years, respectively. No patient required cystectomy but 1 required diversion for morbidity. Urethral stricture and urinary incontinence with pads needed developed in 4 and 3 men, respectively. This particular morbidity was strongly associated with previous or subsequent prostate surgery. The actuarial incidence of grade 2 or greater gastrointestinal morbidity was 13% at 5 and 15 years, while grade 1 rectal bleeding occurred in another 41%. High dose conformal radiation to the prostate is followed by a high rate of low grade rectal bleeding but a low rate of grade 2 or higher gastrointestinal morbidity. This rate is stable and does not increase beyond 5 years. Genitourinary morbidity continues to develop well into the second decade after treatment, although high grade morbidity is uncommon. These findings do not suggest that the modern trend toward high dose prostate treatment with conformal techniques will result in a high incidence of serious and permanent late sequelae but it appears that hematuria will be common.