Two positive nodes represent a significant cut-off value for cancer specific survival in patients with node positive prostate cancer. A new proposal based on a two-institution experience on 703 consecutive N+ patients treated with radical prostatectomy, extended pelvic lymph node dissection and adjuvant therapy.
BACKGROUND
Currently, the 2002 American Joint Committee on Cancer (AJCC) staging system of prostate cancer does not include any stratification of patients according to the number of positive nodes. However, node positive (N+) patients share heterogeneous outcomes according to the extent of lymph node invasion (LNI).


OBJECTIVE
To test whether the accuracy of cancer specific survival (CSS) predictions may be improved if node positive patients are stratified according to the number of positive nodes.


METHODS
The study cohort included 703 N+ M0 patients treated with radical prostatectomy (RP) and extended pelvic lymph node dissection (ePLND) between September 1988 and January 2003 at two large Academic Institutions. Number of positive nodes was dichotomized according to the most informative cut-off predicting CSS. Kaplan-Meier curves assessed cancer specific survival rates. Predictive accuracy of the current N stage and of the new N classification in predicting CSS was quantified with Harrell's concordance index after adjusting for pathological (T) stage and internally validated with 200 boostraps resamples. Differences in predictive accuracy were compared with the Mantel-Haentzel test.


CONCLUSIONS
Mean follow-up was 113.7 months (median: 112.5, range 3.5-243). The mean number of nodes removed was 13.9 (range: 2-52). The mean number of positive nodes was 2.3 (range: 1-31). The most informative cut-off of positive nodes in predicting CSS was 2. Of all, 532 (75.7%) patients had 2 or less positive nodes, while 171 (24.3%) had more than 2 positive nodes. Patients with 2 or less positive nodes had significantly better CSS outcome at 15 year follow-up compared to patients with more than 2 positive nodes (84% vs 62%; p<0.001). After adjusting for pathological stage, multivariable predictive accuracy of the new N staging (<or=2 or >2 positive nodes) was 65.0% vs 60.1% when the number of positive nodes was not considered (4.9% gain; p<0.001).


CONCLUSIONS
We demonstrated that patients with up to 2 positive nodes experienced excellent CSS, which was significantly higher compared to patients with more than 2 positive nodes. Moreover, a significant improvement in CSS prediction was reached when the number of positive nodes was considered. Thus, our results reinforce the need for a stratification of node positive patients according to the number of positive nodes and may warrant consideration in the next revision of the pathologic TNM classification.
Briganti
Alberto
A
Department of Urology, Vita-Salute University, Milan, Italy. briganti_alberto@yahoo.it
Karnes
Jeffrey R
JR
Da Pozzo
Luigi Filippo
LF
Cozzarini
Cesare
C
Gallina
Andrea
A
Suardi
Nazareno
N
Bianchi
Marco
M
Freschi
Massimo
M
Doglioni
Claudio
C
Fazio
Ferruccio
F
Rigatti
Patrizio
P
Montorsi
Francesco
F
Blute
Michael L
ML
D000368:Aged; D015331:Cohort Studies; D018572:Disease-Free Survival; D005500:Follow-Up Studies; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D016019:Survival Analysis; D015996:Survival Rate; D013997:Time Factors
D017430:Prostate-Specific Antigen