Predicting the risk of pelvic node involvement among men with prostate cancer in the contemporary era.
OBJECTIVE
The "Roach formula" for the risk of pelvic lymph node metastases [(2/3) ( *) PSA + (Gleason score - 6) ( *) 10] was developed in the early prostate-specific antigen (PSA) era. We examined the accuracy of this formula in contemporary patients.


METHODS
We included men in the Surveillance, Epidemiology, and End Results Registry with a diagnosis of clinical T1c-T4 prostate cancer in 2004 who had a surgical lymph node evaluation, Gleason score (typically from prostatectomy), and baseline PSA level (n = 9,387). Expected and observed rates of node positivity were compared.


RESULTS
Ninety-eight percent were clinical T1c/T2, and 97% underwent prostatectomy. Overall, 309 patients (3.29%) had positive lymph nodes. Roach scores overestimated the actual rate of positive lymph nodes in the derivation set by 16-fold for patients with Roach score less than or equal to 10%, by 7-fold for scores greater than 10-20%, and by approximately 2.5-fold for scores greater than 20%. Applying these adjustment factors to Roach scores in the validation data set yielded accurate predictions of risk. For those with Roach score less than or equal to 10%, adjusted expected risk was 0.2% and observed risk was 0.2%. For Roach score greater than 10-20%, adjusted expected risk was 2.0% and observed risk was 2.1%. For Roach score greater than 20-30%, adjusted expected risk was 9.7% and observed risk was 6.5%. For Roach score greater than 30-40%, adjusted expected risk was 13.9% and observed risk was 13.9%.


CONCLUSIONS
Applied to contemporary patients with mainly T1c/T2 disease, the Roach formula appears to overestimate pelvic lymph node risk. The adjustment factors presented here should be validated by using biopsy Gleason scores and extended lymphadenectomies.
Nguyen
Paul L
PL
Harvard Radiation Oncology Program, Boston, MA, USA.
Chen
Ming-Hui
MH
Hoffman
Karen E
KE
Katz
Matthew S
MS
D'Amico
Anthony V
AV
D000368:Aged; D000465:Algorithms; D006801:Humans; D016015:Logistic Models; D008197:Lymph Node Excision / Q000706:statistics & numerical data; D008207:Lymphatic Metastasis / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010388:Pelvis; D017430:Prostate-Specific Antigen / Q000097:blood*; D011468:Prostatectomy / Q000706:statistics & numerical data; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology* / Q000601:surgery; D018570:Risk Assessment / Q000379:methods; D018426:SEER Program
D017430:Prostate-Specific Antigen