Superficial bladder cancer: the primacy of grade in the development of invasive disease.

Tumor characteristics thought to predict for development of deep muscle invasion after resection of superficial bladder cancer were retrospectively analyzed in 252 patients with transitional cell carcinoma of the bladder at Stanford University Medical Center. Stage 0 patients accounted for 190 of the patient population (75.5%), while stage A and B1 comprised 51 (20%) and 11 (4.5%), respectively. The median follow-up time was 62 months. Forty-three patients subsequently developed deep muscle invasion; these included 24 (12.6%), 14 (27.5%), and 5 (45.5%) of stage 0, A, and B1 patients (P = .002), or 15 (10%), 15 (9%), and 13 (33%) of grade 1, 2, and 3 tumors (P = .001), respectively. When analyzed by univariate logistic regression, grade (P = .0001) and stage (P = .0118) were significant predictors for invasive disease. Site of tumor and number of tumors at presentation were not significant factors for invasion deep into the bladder wall. When multiple logistic regression was performed, only grade remained as a significant tumor variable to predict for invasive disease (P less than .0091). Risk of invasive disease did not appear to increase with increasing number of recurrences, remaining at approximately an 11% invasion rate through 12 recurrences. In this analysis, grade was the most significant tumor variable in superficial bladder cancer predicting for the development of invasive carcinoma. Future clinical trials for definitive or adjuvant therapy of this disease must stratify for this variable.