Prostogram predicted brachytherapy outcomes are not universally accurate: an analysis based on the M. D. Anderson Cancer Center experience with (125)iodine brachytherapy.
OBJECTIVE
Many clinicians use Prostogram data to advise patients selecting prostate cancer therapy. We examined whether the Prostogram accurately predicted recurrence at 5 years in patients treated with (125)I brachytherapy at 1 tertiary cancer center.


METHODS
We retrospectively reviewed the records of 208 consecutive patients with prostate cancer treated with a permanent (125)I implant without neoadjuvant androgen deprivation therapy at 1 tertiary cancer center during 1998 to 2006. In each patient the Prostogram brachytherapy formula was used to calculate 5-year biochemical recurrence-free survival probability based on clinical stage, Gleason sum score, prostate specific antigen and the receipt or not of external beam radiotherapy. Recurrence was defined as clinical relapse, death from disease, posttreatment androgen deprivation therapy, secondary treatments administered before prostate specific antigen failure or biochemical recurrence based on the Kattan modification of the American Society for Therapeutic Radiology and Oncology definition of biochemical recurrence after external beam radiation therapy. Patients were divided into quartiles based on Prostogram predicted 5-year recurrence-free survival probability and mean probability was compared to the actual 5-year recurrence-free survival rate in each quartile. Harrell's concordance statistic was used to assess the predictive accuracy of the nomogram.


RESULTS
Actual 5-year biochemical recurrence-free survival rates were superior to Prostogram predicted probabilities, including 89% vs 80%, 87% vs 86%, 100% vs 89% and 100% vs 94% in quartiles 1 to 4, respectively. Harrell's concordance value was 0.487 (95% CI 0.369-0.605), indicating that the predictive accuracy of the nomogram in our patients was less than 50%.


CONCLUSIONS
The Prostogram did not predict recurrence after permanent prostate brachytherapy in this series. Institutional variability requires that clinicians be cautious when using the Prostogram to counsel patients about the probability of success after permanent prostate brachytherapy.
Frank
Steven J
SJ
Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.
Levy
Lawrence B
LB
Kuban
Deborah A
DA
Lee
Andrew K
AK
Kudchadker
Rajat J
RJ
Bruno
Teresa L
TL
van Vulpen
Marco
M
Swanson
David A
DA
D001918:Brachytherapy; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D049451:Nomograms; D011237:Predictive Value of Tests; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D016896:Treatment Outcome
D007457:Iodine Radioisotopes