Conformal proton therapy for early-stage prostate cancer.
OBJECTIVE
To assess the effect of proton radiation on clinical and biochemical outcomes for early prostate cancer.


METHODS
Three hundred nineteen patients with T1-T2b prostate cancer and initial prostate-specific antigen (PSA) levels 15.0 ng/mL or less received conformal radiation doses of 74 to 75 cobalt gray equivalent with protons alone or combined with photons. No patient had pre- or post-treatment hormonal therapy until disease progression was documented. Patients were evaluated for biochemical disease-free survival, PSA nadir, and toxicity; the mean and median follow-up period was 43 months.


RESULTS
Overall 5-year clinical and biochemical disease-free survival rates were 97% and 88%, respectively. Initial PSA level, stage, and post-treatment PSA nadir were independent prognostic variables for biochemical disease-free survival: a PSA nadir 0.5 ng/mL or less was associated with a 5-year biochemical disease-free survival rate of 98%, versus 88% and 42% for nadirs 0.51 to 1.0 and greater than 1.0 ng/mL, respectively. No severe treatment-related morbidity was seen.


CONCLUSIONS
It appears that patients treated with conformal protons have 5-year biochemical disease-free survival rates comparable to those who undergo radical prostatectomy, and display no significant toxicity. A Phase III randomized dose-escalation trial is underway to define the optimum radiation dose for early-stage prostate cancer.
Slater
J D
JD
Department of Radiation Medicine, Loma Linda University Medical Center, California 92354, USA.
Rossi
C J
CJ
Yonemoto
L T
LT
Reyes-Molyneux
N J
NJ
Bush
D A
DA
Antoine
J E
JE
Miller
D W
DW
Teichman
S L
SL
Slater
J M
JM
D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000532:radiotherapy*
D017430:Prostate-Specific Antigen