Acute toxicity of three-dimensional conformal radiotherapy in prostate cancer patients eligible for implant monotherapy

Purpose: To assess the acute toxicity of three-dimensional conformal radiot herapy (3D-CRT) in prostate cancer patients eligible for implant monotherap y, Methods and Materials: Between December 1991 and June 1998, 198 prostate ca ncer patients were treated with 3D-CRT at the University of California Davi s Medical Center. Fifty-two of these patients had a prostate-specific antig en (PSA) level less than or equal to 10.0 ng/ml, Gleason score less than or equal to 6, and a 1997 AJCC clinical stage T1bN0-T2bN0. Eleven (21%) patie nts received radiotherapy to the prostate and seminal vesicles; the remaini ng patients were treated to the prostate only. The 3D-CRT treatment plannin g guidelines in Radiation Therapy Oncology Group (RTOG) 9406 were followed after 1994 (similar treatment planning was used before the protocol became available). Typically, 4 oblique and 2 lateral fields were treated, All pat ients were seen at least weekly while under treatment, 1 month postirradiat ion and then every 3 months, Total radiation doses ranged from 66.0-79.2 Gy , with a median dose of 73.8 Gy in 41 fractions over 8 weeks. Acute toxicit y is described according to the RTOG acute toxicity scoring system. Results: Overall, 3D-CRT was well-tolerated: 29% of patients experienced RT OG Grade 1 and 27% experienced Grade 2 acute lower gastrointestinal (GI) to xicity, Forty percent and 33% of patients experienced Grade 1 and 2 acute g enitourinary (GU) toxicity, respectively. As expected, more acute morbidity , especially GI, was observed with a Larger clinical target volume (prostat e and seminal vesicles versus prostate only; p = 0.05). Neoadjuvant hormona l therapy did not increase the incidence or severity of radiation-induced s ide effects. No acute toxicity greater than or equal to Grade 3, e.g., hour ly nocturia, gross hematuria, diarrhea requiring parenteral support, narcot ics for pain control, or catheterization for acute urinary retention, was o bserved. Conclusion: Although relatively high doses of radiation are delivered to pr ostate cancers with 3D-CRT compared with conventional radiotherapy, 3D-CRT is surprisingly well-tolerated. No patients in the cohort eligible for impl ant monotherapy experienced acute toxicity greater than or equal to Grade 3 . (C) 2000 Elsevier Science Inc.