Adequate Tissue Submission from Transurethral Resection Specimens for Detecting Incidental Prostate Carcinoma:...

To identify an adequate amount of prostate chip submissions with optimal diagnostic accuracy and minimal cassette utilization for the detection of incidental prostate carcinoma (IPC).

We recruited consecutive transurethral resection specimens from patients with bladder outlet obstruction related to benign prostatic hyperplasia (BPH) and excluded patients with known or suspected prostatic carcinoma. Submission in the retrospective cohort depended on weight: either ≤12 g submitted entirely or >12 g submitted partially (initial 12 g with additional sampling). Submission was entire in the prospective cohort. The five different submissions (index test) were: initial 12 g, initial 12 g with additional cassettes per 10 g (12 g + q10 g), 12 g + q5 g, 20 g, and 20 g + q10 g. The diagnostic accuracy of the index test, compared to actual tissue submission (reference standard), was measured by the area under the receiver operating characteristic curve (AUC), with ≥95.0% considered acceptable.

A total of 451 patients (384 retrospective and 67 prospective) were included. The specimens had a median weight of 22 (range: 1-235) g, corresponding to a median cassette use of 10 (1-48) blocks, resulting in 5,010 total blocks. The average weight per block in the prospective cohort was 2 g. IPC detection rates were 6.3% retrospectively, 9.0% prospectively, and 6.7% overall. The first cassette containing carcinoma appeared between the 1st and 24th. Only three tissue submission strategies achieved acceptable diagnostic accuracy using lower estimated cassette numbers: 12 g + q5 g: AUC 98.3%, using 4,362 blocks,  20 g + q10 g: AUC 98.3%, using 4,239 blocks,  20 g: AUC 95.0%, using 3,373 blocks.

Submitting 20 g of prostatic chips offers excellent diagnostic accuracy for IPC detection with reduced cassette utilization.