'Local recurrence' and 'disease-free survival'. Doubtful parameters when comparing non-randomized studies of prostate...

We reviewed recent literature on studies with external radiation of prostatectomy for localized prostate cancer considering the definitions of 'local recurrence' and 'disease-free survival' and the reporting of patients lost to follow-up. Among studies evaluating external radiation, 5/71 (29%) mention that prostate biopsy is used for some patients in determining local recurrence, versus 6/11 (55%) for prostatectomy. Several studies, 15/28 (54%), present figures for disease-free survival without giving a definition of the parameter. In the majority of the reports no comments are made relative to patients lost to follow-up. Three authors consider patients lost to follow-up as dead with disease. Considerations regarding 'local recurrence' and 'disease-free survival' warrant caution in the interpretation of data based on such parameters. In a comparison of non-randomized studies of localized prostate cancer, cancer-specific survival with prostate cancer death defined as 'death wtih diagnosed distant metastases' may be a robust parameter.