The prevalence and clinicopathologic correlate of p16 INK4a, retinoblastoma and p53 immunoreactivity in locally advanced urinary bladder cancer

Abstract

The purpose of the study was to investigate the prognostic value and clinicopathological correlate of tumor p53, p16 and Rb protein expression in patients with locally advanced urinary bladder cancer. Sixty-five patients (44 men and 21 women; 40 to 84 yrs old) with locally advanced urinary bladder cancer (21 pT2, 27pT3, 17pT4) undergoing radical cystectomy and bilateral pelvic lymph node dissection were followed up for 2 to 116 months (mean ± SD: 30.02 ± 6.46 months). Immunohistochemical staining for p53, Rb and p16 proteins were performed on surgically obtained, formalin fixed and paraffin embedded tissue sections. Thirty of the tumors (46.2%) were p53 +, 52 of the tumors (80%) were p16 − and 41 (63%) were Rb −. Only 5 of the tumors (7.7%) had normal expression of all three proteins. The tumor expression status of p53 could not be correlated with p16 ( P = 1.000) or Rb ( P = 1.000). Only a marginal inverse relationship was found between the expression of p16 and Rb ( P = 0.056). Higher grade tumors had significantly lower percentage of p16 abnormality ( P = 0.05), while higher grade (not higher stage) tumors had higher percentage of Rb abnormality ( P = 0.0245). Univariate analysis showed that tumor expression of Rb or p16, alone or combined, had no predictive value on progression-free and disease-specific survival. It did, however, show a significant correlation between progression-free survival and tumor p53 and LN status ( P = 0.032 and P = 0.0304) and a significant correlation between tumor stage disease-specific survival ( P = 0.042). Multivariate analysis showed tumor stage and nodal status to be two significant independent indicators for progression-free survival ( P = 0.0038 and P = 0.0049) and disease-specific survival ( P = 0.0066 and P = 0.0484). It was also noteworthy that, after receiving postoperative adjuvant systemic M-VEC chemotherapy, patients with node-positive p53-normal tumors had significantly better progression-free and disease-specific survivals than those with node-positive p53-abnormal tumors ( P = 0.036 and P = 0.0479, respectively). This study has found tumor expression of p53, p16 and Rb proteins in locally advanced bladder cancer to be frequently abnormal. Although multivariate analysis showed tumor stage and nodal status to be the only two statistically significant parameters, p53 may also serve as an additional prognostic predictor of the outcome of postoperative adjuvant systemic chemotherapy in patients with regional lymph node tumor involvement. Such patients with p53-normal tumors experienced significantly better progression-free and disease-specific survivals than those with p53-abnormal tumors.