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Keywords:

  • active surveillance;
  • low-risk prostate cancer;
  • PRIAS;
  • upgrading;
  • upstaging

What's known on the subject? and What does the study add?

  • Active surveillance has been widely accepted as a treatment tool for low-risk prostate cancer, and use of the Prostate Cancer Research International: Active Surveillance (PRIAS) criteria can select smaller and less aggressive tumours in low-risk disease.
  • The study shows the pathological outcomes of radical prostatectomy for patients with low-risk disease who met the PRIAS criteria. It found that ∼20% had unfavourable pathological features and only 30% satisfied insignificant cancer criteria with pT2 stage, a Gleason score ≤6 and tumour volume <2.5 mL. It concludes that close follow-up including repeat biopsy or MRI is necessary to minimize unexpected progression of disease.

Objective

  • To assess the effectiveness of the Prostate Cancer Research International Active Surveillance (PRIAS) criteria in identifying indolent cancer.

Patients and Methods

  • Data from 1268 patients undergoing radical prostatectomy without neoadjuvant therapy were retrospectively reviewed.
  • Within this cohort, patients with low-risk disease (n = 211) were classified according to whether they met (Group A, n = 87) or did not meet (Group B, n = 124) the PRIAS criteria.
  • Pathological upstaging, upgrading, tumour volume and 5-year prostate-specific antigen (PSA) recurrence-free survival were compared between the two groups, and factors that predicted upstaging, upgrading and PSA recurrence were analysed by univariate and multivariate methods.

Results

  • Pathological T3 stage was present in 10.3% of patients in Group A and in 18.5% of patients in Group B (P = 0.08). Gleason score upgrading to 4+3 or greater was seen in 19.5% of Group A and in 29.9% of Group B (P = 0.01).
  • The mean (range) tumour volume was 0.81 (0.03–5.09) mL in Group A and 1.40 (0.04–8.21) mL in Group B (P < 0.01). The rates of insignificant cancer with total tumour volume <2.5 mL, Gleason score ≤6 and stage pT2 were 30.6% in Group A and 15.4% in Group B (P = 0.07).
  • With a median follow-up of 44 months, the 5-year PSA recurrence-free survival rates were 91.2% in Group A and 86.4% in Group B (P = 0.47).
  • In multivariate analysis, PSA density and the PRIAS criteria were independent factors that predicted upstaging.

Conclusions

  • Although use of the PRIAS criteria could select more favourable tumours even in low-risk prostate cancer, about one in five men had unfavourable pathological outcomes and only three in ten had insignificant cancer.
  • Close and careful follow-up is necessary to avoid misclassification or progression of disease, especially during the first few years of active surveillance.