Abstract: PD49-05
Sources of Funding: None

Introduction

The AJCC recently proposed new TNM staging for penile cancer, splitting the orginal T2 group (tumor invading corpus spongiosum or cavernosum) into T2 (invading corpus spongiosum) and T3 (invading corpus cavernosum). We sought to validate the new T staging system for predicting pathologic nodal involvement using the National Cancer Data Base (NCDB).

Methods

Invasive penile cancer cases from 2010-2012 were identified from the NCDB. Pathologic tumor stage was recorded including spongiosal versus carvernosal involvement. Differences in demographic (age, race, comorbid status) and pathologic features (size of tumor, grade, nodal status, LVI, histology, and extranodal extension) between T2 and T3 tumors were compared using χ² and t-tests. Univariate and multivariate logistic regression was performed to determine the odds of positive lymph nodes (pN+) at inguinal lymph node dissection (ILND) relative to T-stage.

Results

There were 367 T2 and 507 T3 patients with penile cancer. The proportion of cases with pN+ disease was 15%, 32%, 46% and 58% for T1, T2, T3 and T4 cases, respectively. Compared to T2 tumors, T3 tumors were larger (mean size 5.8 cm vs. 4.3 cm), more often treated with radical penectomy (36% vs 17%), had higher positive surgical margin rates (12% vs 9%), more aggressive pathology (32% vs 27% poorly differentiated), and were more likely to have lymphovascular invasion (42% vs 31%) (all p < 0.05). In univariate analysis, compared to T1 tumors, T2 (OR 2.8, 95% CI 1.9-4.2) and T3 (OR 4.7, 95% CI 3.3-6.8) were both associated with an increased risk of positive lymph nodes. Although in multivariate analysis, both T2 (OR 2.0, 95% CI 1.2-3.3) and T3 (OR 2.3, 95% CI 1.4-3.6) remained significantly associated with risk of positive lymph nodes compared to T1 disease, there was no increase in risk between T2 and T3 disease (OR 1.1, 95% CI 0.7-1.8, p = 0.56).

Conclusions

The proposed new AJCC staging system for the penile cancer distinguishes spongiosal (T2) from cavernosal (T3) involvement and identifies significant differences in pathologic features of the tumors (grade, LVI and size). There does not appear to be a difference in positive lymph node status between the two grades when other clinical and pathological variables are considered. Further study is required to confirm these findings and the prognostic implications of the proposed new staging system.

Funding

None