Substaging of T1 bladder carcinoma based on the depth of invasion as measured by micrometer

Abstract

BACKGROUND.A significant number of T1 bladder carcinoma patients are understaged by transurethral resection of the bladder (TURB), indicating a substantial need for more accurate staging. METHODS.The authors studied 55 patients with T1 bladder carcinoma detected by TURB at the Mayo Clinic between December 1979 and July 1984. The mean age of the patients was 66 years (range, 50 -78 years). All patients were treated by cystectomy. The median interval from TURB to cystectomy was 10 days. Grading was performed according to the 1998 World Health Organization/International Society of Urologic Pathology grading system. The 1997 TNM classification was used for pathologic staging. In addition, the depth of invasion was measured from the mucosal basement membrane by micrometer. Receiver operating characteristic (ROC) analysis was used to evaluate the usefulness of depth of invasion as a marker for advanced stage bladder carcinoma (Ն T2). RESULTS.The final pathologic stages were Ta (2 patients), T1 (10 patients), T2a (9 patients), T2b (13 patients), T3 (11 patients), and T4 (10 patients) at cystectomy.There was a significant correlation between the depth of invasion at TURB and the final pathologic stage (Spearman correlation coefficient ϭ 0.63; P Ͻ 0.001). The overall accuracy for the prediction of advanced stage (Ն T2) bladder carcinoma as measured by the area under the ROC curve was 0.89 (standard error, 0.05). Using 1.5 mm as a threshold (with Ͼ1.5 mm indicating advanced stage disease), the sensitivity, specificity, and positive and negative predictive values were 81%, 83%, 95%, and 56%, respectively. Histologic grade at the time of TURB also was associated significantly with final pathologic stage at cystectomy (P ϭ 0.03) whereas stratification of patients according to invasion above or below the muscularis mucosae at TURB was not a significant predictor of final pathologic stage. CONCLUSIONS.The results of the current study show that substaging of T1 bladder carcinoma according to the depth of invasion (as measured by micrometer) provides significant prognostic information. Therefore the authors recommend that it be reported in specimens obtained by TURB. [See also editorial counterpoint on pages 908 -9 and reply to counterpoint on pages 910 -2, this issue.] Cancer 1999;86: 1035-43.

Staging and reporting of urothelial carcinoma of the urinary bladder

“…The use of an ocular micrometer to measure the depth of invasion may be considered. 24,25,38 Patients with invasion less than 1.5 mm have a better prognosis than other T1 bladder cancer patients. 25 Substaging of T2 bladder cancer (T2a verrus T2b) is not feasible in bladder biopsy or TURB specimens, as the entire thickness of the detrusor muscle is not present.…”

“…16,[31][32][33][34][35][36][37] Muscularis mucosae consists of thin and wavy fascicles of smooth muscle frequently associated with large, thin-walled blood vessels ( Figure 9). Muscularis mucosae can be identified in 15-83% of biopsy specimens; 16,24,25,[31][32][33][34][35][36][38][39][40][41][42] however, 6% of radical cystectomy specimens do not have discernable muscularis mucosae. 41 Thus, the large associated vessels have been used as a surrogate marker for muscularis mucosae in all published studies of substaging based on muscularis mucosae invasion.…”

“…24,25,38 Using an ocular micrometer to measure the depth of invasion from the mucosal basement membrane, investigators have found a significant correlation between depth of invasion in the biopsy specimens and final pathological stage at cystectomy. 38,46 A 1.5 mm depth of invasion predicted advanced-stage bladder carcinoma at cystectomy with a sensitivity of 81%, a specificity of 83%, and positive and negative predictive values of 95 and 56%, respectively.…”

“…Ninety-five percent of patients with the depth of invasion Z1.5 mm at TUR specimens have advanced stage (ZpT2) bladder carcinoma at cystectomy. 38 Applying this criterion to 83 consecutive patients diagnosed with pT1 bladder cancer, the investigators found a 5-year progression-free survival of 67% with tumor invasion greater than 1.5 mm. 25 When the depth of invasion was less than 1.5 mm, the 5-year survival rate was 93%.…”

Practical Applications of Immunohistochemistry in the Diagnosis of Genitourinary Tumors

“…Management of bladder tumors depends heavily on the depth of tumor invasion, which the staging system is based upon. 80 However, the interpretation of the depth of tumor invasion within pT1 or pT2 stage is often difficult. Immunohistochemistry may be a useful tool in establishing the correct tumor stage.…”