Clinical staging error in prostate cancer: localization and relevance of undetected tumour areas.

OBJECTIVE

To describe the localization and to assess the clinical implications of areas of undetected prostate cancer in radical prostatectomy (RP) specimens, focusing on patients with unilaterally negative preoperative biopsy cores.

PATIENTS AND METHODS

The study included 149 of 559 consecutive patients (26.7%) who had RP for prostate cancer. Unilateral prostate cancer was diagnosed from prostate biopsies, taken by several physicians, but > or = pT2c disease was present in the RP specimen. The prostate was dissected by standardized transversal cuts and tumour areas were mapped by one genitourinary pathologist. To estimate the tumour size and location, areas of prostate cancer were transferred to a digital grid database representing the prostate by 794 units.

RESULTS

The most frequent location of undetected prostate cancer was in the dorsalateral region and in the apex of the prostate. The mean tumour volume of the false-negative lobe was significantly lower than contralaterally (18.9 vs 47.5 units, P < 0.001). In 36 of 149 patients (24.2%), the tumour volume on the negative biopsy side was equal or higher than on the positive biopsy side; in the final RP specimen, 60 patients (40.3%) had capsular involvement on the negative biopsy side.

CONCLUSION

Significantly many patients with newly diagnosed prostate cancer remain clinically understaged. The apical and dorsolateral region of the prostate are not adequately represented in current biopsy strategies. Undetected tumour areas are often clinically significant by size and capsular involvement, indicating a direct clinical implication when planning nerve-sparing RP or focal therapy. Our results show a continuing need for optimized and standardized biopsy protocols.