The probability of overlooking prostatic cancer in transurethrally resected material when different embedding...

When all transurethrally resected material of 53 subsequent patients was microscopically examined, primary adenocarcinoma of the prostate was found in 18 patients and benign disease in 35. Only 9 of the patients with histologically confirmed malignancy of the prostate were clinically diagnosed. The proportion of prostatic chips that contained malignant tissue ranged from 1-96%. A mathematical analysis evaluating the probability of including a carcinoma when different numbers of blocks were processes was performed. The analysis showed that when the patient has a clinically malignant diagnosis the probability of 100% is reached by the processing of one block. If the patient has a clinically benign diagnosis, however, the probability of 98% is first reached by the processing of 8 blocks, if such an amount of material is available.