Login to Access Video or Poster Abstract: MP77-19
Sources of Funding: none

Introduction

While serial biopsies are a key component of most active surveillance (AS) programs, surveillance protocols differ as to when the first surveillance biopsy should be performed. Some protocols mandate a confirmatory biopsy while in others, the first surveillance biopsy is performed at 1 year. In the present study we sought to determine differential impact of obtaining the first surveillance biopsy either within 6 months or at 9-15 months after diagnosis.

Methods

We retrospectively identified patients who enrolled in a prostate cancer active surveillance (AS) program during 2004-2015 and underwent a biopsy either ≤6 months or between 9-15 months after their initial diagnostic biopsy. Eligibility for enrollment in AS was defined according to MSK criteria (biopsy Gleason: ≤6; biopsy T stage: cT1c or cT2a, diagnostic PSA <10, % positive for each core ≤50%, ≤3 positive cores, or if number of total cores >12, then number of positive cores ≤25% of the total cores). We compared MSK-defined eligibility for AS in patients who received a second biopsy at either ≤6 or 9-15 months after their initial diagnostic biopsy.

Results

A total of 115 patients on AS were identified within the study period. 62 (53.9) and 53 (46.1%) of patients underwent a second biopsy at ≤6 or 9-15 months after their initial diagnostic biopsy, respectively (table). Age, number of biopsy cores and positive cores, serum PSA, and eligibility for AS by MSK criteria were similar between groups. 56(90.3%) and 42 (79.2%) of patients initially met MSK AS criteria. Of these, those rebiopsied at 9-15 months appear more apt to be reclassified as ineligible than patients rebiopsied at ≤6 months (42.9 v. 25.0%, p=0.082). Patients biopsied at ≤6 months had more cores taken at the second biopsy (15(IQR 12-16) vs. 12 (12-12), p<.001)

Conclusions

Surveillance protocols differ as to when the first surveillance biopsy is performed. In patients initially meeting AS inclusion criteria, a delay in confirmatory biopsy may be associated with a higher rate (42.9% v 25.0%) of AS ineligibility. Just as important, 25% of patients immediately learn they do not meet AS criteria. These findings may be due to disease progression rather than under sampling, as patients who were biopsied at ≤6 months had more biopsies performed. These data may be helpful in patient counseling prior to AS enrollment._x000D_

Funding

none