Minimal or no cancer in radical prostatectomy specimens. Report of 13 cases of the "vanishing cancer phenomenon".

Early detection efforts identify prostate cancer at lower clinical and pathologic stages, often resulting in smaller volumes of tumor in radical prostatectomy specimens. In some cases, complete sampling of the radical prostatectomy specimen for biopsy-proven adenocarcinoma reveals minimal or no residual cancer. We evaluated the clinical and pathologic findings in 13 such cases in an effort to document this finding, which we refer to as the "vanishing cancer phenomenon." The mean number of prostate slides examined per case was 79 (range, 34-248). Carcinoma was absent in two cases, present in a single focus in eight cases, and present in two foci in three cases. Mean cancer volume in the 10 cases with residual tumor was 0.019 cc (range, 0.003-0.038); the largest single dimension of any tumor focus was 3 mm. All cancers were well differentiated or moderately differentiated in the biopsy and prostatectomy. Our results indicate that in some cases cancer may be extremely difficult or impossible to find in the prostatectomy specimen despite exhaustive sampling. The incidence of this "vanishing cancer phenomenon" is probably increasing because more low-stage cancers are being treated by prostatectomy. The inability to identify cancer in a prostate removed for needle biopsy-proven carcinoma may not indicate technical failure.