Metastatic Prostate Cancer in Men Initially Treated with Active Surveillance

Abstract

Purpose: Active surveillance is an approach to low and low intermediate risk prostate cancer that is designed to decrease overtreatment. Despite close monitoring a small subset of patients progress to metastatic disease. We analyzed the clinical and pathological correlates of surveillance in patients who eventually experienced metastasis.

Materials and methods: This was a single center, prospective cohort study. Eligible patients were treated with an expectant approach. The main outcome measure was metastasis-free survival. Predictive factors for metastasis were identified.

Results: Metastasis developed in 30 of 980 patients, of whom 211 were classified at intermediate risk, including 14 who progressed to metastatic disease. Median followup was 6.3 years, median age was 70 years, median prostate specific antigen was 6.2 ng/ml and median time to metastasis was 8.9 years. Metastases developed in bone in 18 patients (60%) and in lymph nodes in 13 (43%). Prostate specific antigen doubling time less than 3 years (HR 3.7, 95% CI 1.4-9.4, p = 0.0006), Gleason score 7 (HR 3.0, 95% CI 1.2-7.3, p = 0.0018) and a total of 3 or more positive cores (HR 2.7, 95% CI 1.1-6.8, p = 0.0028) were independent predictors of metastasis. Although the intermediate risk group was at higher risk for metastasis, those with Gleason score 6 and prostate specific antigen greater than 10 ng/ml were not at increased risk for metastasis. Metastasis developed in only 2 patients with Gleason score 6 and neither had surgical pathology grading.

Conclusion: Active surveillance appears safe in patients at low risk and in select patients at intermediate risk, particularly those with Gleason score 6 and prostate specific antigen greater than 10 ng/ml. Patients with elements of Gleason pattern 4 on diagnostic biopsy are at increased risk for eventual metastasis when treated with an initial conservative approach.

Keywords: neoplasm grading; neoplasm metastasis; prostatic neoplasms; risk factors; watchful waiting.