Equivocal test results and prognostic staging uncertainties in the evaluation of patients with cancer of the prostate.

In the staging of cancer, equivocal test results may occur in subjectively evaluated imaging procedures whose interpretations raise the possibility of metastases but are too uncertain to rule in or rule out metastatic spread, and in tests whose repetitions in the same patient yield conflicting results about dissemination. We assessed the frequency and prognostic correlates of test results giving equivocal evidence of disseminated (Stage IV) disease in an inception cohort of 280 patients receiving initial treatment for prostatic cancer between 1973-76. Among tests used for clinical staging, lymphangiograms (equivocal in 28 percent of tested patients), bone scans (equivocal in 25 percent of tested patients), and bone radiographs (equivocal in 20 percent of tested patients) most frequently yielded interpretations that equivocally suggested metastatic spread. Eighty-three (45 percent) of the 185 patients without clear-cut dissemination (Stages I-III) had at least one equivocal test result that suggested dissemination and that remained unresolved at the time of selection of therapy. Five-year survival (30 percent) for the 20 patients with local extracapsular spread (Stage III) and multiple equivocal results suggesting dissemination was identical to that for patients with clear-cut dissemination. In contrast, other patients with equivocal dissemination in Stages I-III had survival rates similar to those patients in the same stage and lacking equivocal dissemination. Unresolved equivocal staging results frequently complicate management decisions for patients with prostatic cancer. Survival analyses aid these decisions by demonstrating that equivocal findings of dissemination are prognostically unimportant unless they are multiple and occur in the context of unequivocal extracapsular spread.