Context: The biologic potential of prostate cancer (pCA) is variable, and the ability to identify tumours that might cause morbidity and mortality is limited.
Objective: This systematic review sought to establish whether measurement of tumour extent in biopsies provides additional prognostic information on the risk of disease progression.
Evidence acquisition: A comprehensive 31-step search strategy was run in MEDLINE, EMBASE, and the Web of Knowledge (January 1990-July 2007) and supplemented by the hand-searching of references in retrieved articles and relevant journals to identify publications related to the measurement of the length of cancer in biopsies and biochemical or clinical recurrence or pCA death. Thirteen papers reporting on at least 100 patients were identified and included patients treated by watchful waiting or hormonal therapy (n=1), radical prostatectomy (n=11), or radiotherapy (n=1). Only two studies reported on clinical progression or mortality. Sources of bias included patient selection and missing data resulting from the retrospective nature of the studies. Confounding factors included differences in biopsy strategies and measurement methods.
Evidence synthesis: The percentage of cancer in biopsies (overall percentage or the greatest percentage in the most involved core) was an independent predictor of prostate-specific antigen (PSA) and clinical outcomes regardless of the form of treatment and was generally superior to simply counting the number of positive cores. The marked variability in study design, conduct, and reporting precluded meta-analysis of the data and precise risk estimation.
Conclusions: Tumour quantitation is a promising prognostic tool in the assessment of risk of pCA progression. However, well-designed, population-based studies, controlling for confounding factors, are required to provide more accurate risk estimation and develop management strategies. This review highlights the need for new approaches in the assessment of pathologic prognostic factors to reach the level of evidence achieved in other areas of medical practice.