Novel analysis evaluates cancer risk after negative prostate biopsy
MedWire News: Researchers have used a novel analytical approach to quantify risk factors for future prostate cancer detection after an initial negative biopsy.
The piecewise exponential regression model was used by the US research team to quantify hazard ratios (HR) for patient subgroups with specific risk factors over time.
“With these models, it is possible to identify distinct subpopulations with dramatically different needs for monitoring and repeat biopsy,” report Peter Gann, from the University of Illinois in Chicago, and fellow writers in the Journal of Clinical Oncology.
The study involved data for 465 men with prostate cancer who underwent an average of 2.9 prostate biopsies during an average follow-up period of 2.8 years.
Risk factors included in the analysis were age, urinary symptoms (frequency, urgency, or reduced stream), prostate volume at ultrasound, prostate-specific antigen (PSA) level, number of repeat biopsies, PSA slope (linear regression of PSA values over 36 months before current biopsy), prostatitis at biopsy, and atypical glands or high-grade prostatic intraepithelial neoplasia (HGPIN).
The most significant predictors of prostate cancer detection during follow-up were PSA (>10 vs 2.5–3.9 ng/ml), atypical glands/HGPIN, gland volume (>50 vs <25 ml), and number of repeat biopsies (two vs zero repeat biopsies) with HRs of 3.90, 2.97, 0.39, and 0.36, respectively.
PSA slope was the only variable not predictive of prostate cancer detection.
Noting that certain combinations of risk factors produced contrasting cancer risk, the researchers then stratified the men according to high-risk (gland volume <25 ml, PSA increasing from 4–7 to >10 ng/ml at 12 months, and HGPIN at baseline), and low-risk (gland volume >50 ml, a steady PSA of 2.5–4 ng/ml, prostatitis on initial biopsy, and negative biopsies at 6 and 12 months) disease.
The 5-year cumulative risk for cancer among the high- and low-risk men was greater than 95% and less than 5%, respectively, representing a 23-fold difference in prostate cancer detection over 5 years.
Gann and team note: “For men who have a negative biopsy, the identification of risk factors for subsequent detection of prostate cancer and the quantification of actual risk remain significant concerns.”
They conclude: “A more detailed understanding of prostate cancer risk after negative biopsy, based on the preceding history of each individual patient, holds the most promise for reducing negative biopsies while maintaining adequate sensitivity.”
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By Sarah Guy