Effect of increasing radiation doses on local and distant failures in patients with localized prostate cancer.
OBJECTIVE
To study the effect of radiation dose on local failure (LF) and distant metastasis (DM) in prostate cancer patients treated with external beam radiotherapy.


METHODS
The study sample consisted of 919 Stage T1-T3N0M0 patients treated with radiotherapy alone. Three separate dose groups were analyzed: <72 Gy (n = 552, median dose, 68.4 Gy), > or =72 but <82 Gy (n = 215, median dose, 78 Gy), and > or =82 Gy (n = 152, median dose, 83 Gy). The median follow-up period for all patients and those receiving <72 Gy, > or =72 but <82 Gy, and > or =82 Gy was 97, 112, 94, and 65 months, respectively.


RESULTS
For all patients, the LF rate at 10 and 15 years was 6% and 13%, respectively. The 7-year LF rate stratified by dose group (<72 Gy, > or =72 but <82 Gy, and > or =82 Gy) was 6%, 2%, and 2%, respectively (p = 0.012). For all patients, the DM rate at 10 and 15 years was 10% and 17%, respectively. The 7-year DM rate stratified by dose group (<72 Gy, > or =72 but <82 Gy, and > or =82 Gy) was 9%, 6%, and 1%, respectively (p = 0.008). Multivariate analysis revealed T stage (p < 0.001), pretreatment prostate-specific antigen level (p = 0.001), Gleason score (p < 0.001), and dose (p = 0.018) to be independent predictors of DM. For all 919 patients, multivariate analysis revealed only Gleason score (p = 0.009) and dose (p = 0.004) to be independent predictors of LF.


CONCLUSIONS
Although the effect of increasing radiation doses has been documented mostly for biochemical failure rates, the results of our study have shown a clear association between greater radiation doses and lower LF and DM rates.
Kupelian
Patrick A
PA
Department of Radiation Oncology, M.D. Anderson Cancer Center Orlando, Orlando, FL 32806, USA. patrick.kupelian@orhs.org
Ciezki
Jay
J
Reddy
Chandana A
CA
Klein
Eric A
EA
Mahadevan
Arul
A
D000230:Adenocarcinoma / Q000097:blood / Q000532:radiotherapy* / Q000556:secondary; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018572:Disease-Free Survival; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; 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
D017430:Prostate-Specific Antigen