Body mass index and prostate-specific antigen failure following brachytherapy for localized prostate cancer.
OBJECTIVE
Increasing body mass index (BMI) is associated with prostate-specific antigen (PSA) failure after radical prostatectomy and external beam radiation therapy (EBRT). We investigated whether BMI is associated with PSA failure in men treated with brachytherapy for clinically localized prostate cancer.


METHODS
Retrospective analyses were conducted on 374 patients undergoing brachytherapy for stage T1c-T2cNXM0 prostate cancer from 1996-2001. Forty-nine patients (13%) received supplemental EBRT and 131 (35%) received androgen deprivation therapy (ADT). Height and weight data were available for 353 (94%). Cox regression analyses were performed to evaluate the relationship between BMI and PSA failure (nadir + 2 ng/ml definition). Covariates included age, race, preimplantation PSA, Gleason score, T category, percent of prescription dose to 90% of the prostate, use of supplemental EBRT, and ADT.


RESULTS
Median age, PSA, and BMI were 66 years (range, 42-80 years), 5.7 ng/ml (range, 0.4-22.6 ng/ml), and 27.1 kg/m(2) (range, 18.2-53.6 kg/m(2)), respectively. After a median follow-up of 6.0 years (range, 3.0-10.2 years), there were 76 PSA recurrences. The BMI was not associated with PSA failure. Six-year PSA failure rates were 30.2% for men with BMI less than 25 kg/m(2), 19.5% for BMI of 25 or greater to less than 30 kg/m(2), and 14.4% for BMI of 30 kg/m(2) or greater (p = 0.19). Results were similar when BMI was analyzed as a continuous variable, using alternative definitions of PSA failure, and excluding patients treated with EBRT and/or ADT. In multivariate analyses, only baseline PSA was significantly associated with shorter time to PSA failure (adjusted hazard ratio, 1.12; 95% confidence interval, 1.05-1.20; p = 0.0006).


CONCLUSIONS
Unlike after surgery or EBRT, BMI is not associated with PSA failure in men treated with brachytherapy for prostate cancer. This raises the possibility that brachytherapy may be a preferred treatment strategy in obese patients.
Efstathiou
Jason A
JA
Department of Radiation Oncology, Massachusetts General Hospital, 100 Blossom Street, Boston, MA 02114, USA. jefstathiou@partners.org
Skowronski
Rafi Y
RY
Coen
John J
JJ
Grocela
Joseph A
JA
Hirsch
Ariel E
AE
Zietman
Anthony L
AL
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D000726:Androgen Antagonists / Q000627:therapeutic use; D015992:Body Mass Index; D001918:Brachytherapy; D003131:Combined Modality Therapy / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000097:blood* / Q000532:radiotherapy* / Q000601:surgery; D012044:Regression Analysis; D012189:Retrospective Studies; D017211:Treatment Failure
D000726:Androgen Antagonists; D017430:Prostate-Specific Antigen