Dose escalation for localized prostate cancer: substantial benefit observed with 3D conformal therapy.
OBJECTIVE
To determine the effect of radiation dose escalation on biochemical and/or disease failure in patients with localized prostate cancer treated with three-dimensional conformal radiotherapy (3D-CRT).


METHODS
Between May 1987 and December 2000, 1473 patients were assessed after treatment with 3D-CRT. The mean patient age was 70.4 +/- 6.8 years, 1316 patients had T1-T2 disease, and 1150 had Gleason score <or=7. The median pretreatment prostate-specific antigen (PSA) level was 8.9 ng/mL. The mean dose was 71.7 +/- 4.3 Gy (range 60.0-80.4). Failure was defined as the first event of any of the following: biochemical failure, local recurrence or metastasis, postirradiation hormonal therapy, or death from disease.


RESULTS
At a median follow-up of 35.2 months, 395 failures (26.8%) had occurred. Adjusting for dose as a continuous variable, the hazard ratio for failure was 2.03 (p < 0.0001) for 569 intermediate-risk patients (stage T1-T2 and Gleason score 7 or PSA 10-20 ng/mL) and 5.16 (p < 0.0001) for 456 high-risk patients (stage T3-T4 or PSA >20 ng/mL or Gleason score >or=8) compared with 448 low-risk patients (stage T1-T2 and Gleason score <or=6 and PSA <10 ng/mL). For intermediate-risk patients, each 1-Gy increment in total radiation dose was associated with a highly significant 8% reduction in the probability of failure (hazard ratio = 0.92, p = 0.005).


CONCLUSIONS
Dose escalation using 3D-CRT significantly reduces the risk of biochemical/disease failure among intermediate-risk prostate cancer patients.
Symon
Zvi
Z
Department of Radiation Oncology, University of Michigan, Ann Arbor 48109-0010, USA.
Griffith
Kent A
KA
McLaughlin
P William
PW
Sullivan
Molly
M
Sandler
Howard M
HM
D000368:Aged; D000704:Analysis of Variance; D000726:Androgen Antagonists; D017024:Chemotherapy, Adjuvant; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000097:blood / Q000517:prevention & control*; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*; D018570:Risk Assessment; D017211:Treatment Failure
D000726:Androgen Antagonists; D017430:Prostate-Specific Antigen