Subsequent prostate cancer detection in patients with prostatic intraepithelial neoplasia or atypical small acinar proliferation

Introduction:

To evaluate the predictors of prostate cancer in follow-up of patients diagnosed on initial biopsy with high-grade prostatic intraepithelial neoplasia (HGPIN) or atypical small acinar proliferation (ASAP).

Methods:

We studied 201 patients with HGPIN and 22 patients with ASAP on initial prostatic biopsy who had subsequent prostatic biopsies. The mean time of follow-up was 17.3 months (range 1–62). The mean number of biopsy sessions was 2.5 (range 2–6), and the median number of biopsy cores was 10 (range 6–14).

Results:

On subsequent biopsies, the rate of prostate cancer was 21.9% (44/201) in HGPIN patients. Of these, 32/201 patients (15.9%), 9/66 patients (13.6%) and 3/18 patients (16.6%) were found to have cancer on the first, second and third follow-up biopsy sessions, respectively. In ASAP patients, the cancer detection rate was 13/22 (59.1%), all of whom were found on the first follow-up biopsy. There was a statistically significant difference between the cancer detection rate in ASAP and HGPIN patients (p < 0.001). Multivariate analysis showed that the independent predictors of cancer were the number of cores in the initial biopsy, the number of cores (> 10) in the follow-up biopsy and a prostate specific antigen (PSA) density of ≥ 0.15 (odds ratio 0.77, 3.46 and 2.7,8 respectively; p < 0.04). Conversely, in ASAP patients none of these variables were found to be associated with cancer diagnosis.

Conclusion:

ASAP is a strong predictive factor associated with cancer when compared with HGPIN. The factors predictive of cancer on follow-up biopsy of HGPIN are number of cores on initial biopsy, more than 10 cores in rebiopsy and elevated PSA density. As the cancer detection rate on repeated biopsy of HGPIN patients is the same as that of patients without HGPIN, perhaps the standard of repeat biopsy in all patients with HGPIN should be revisited.Owing to the widespread use of prostate specific antigen (PSA) as a screening tool for prostate cancer associated with increasing use of transrectal ultrasound (TRUS) guided prostate needle biopsy and the increasing number of sampling cores per biopsy, the histological findings of high-grade prostatic intraepithelial neoplasia (HGPIN) and atypical small acinar proliferation (ASAP) has also increased.The detection rate of HGPIN in TRUS-guided needle biopsies performed owing to an elevated PSA level or an abnormal digital rectal examination (DRE), was found to be between 4% and 25% of patients^1–4 and the cancer detection rate on repeated biopsy was reported from 2% to 47% of patients.^1,3,5,6,7 Conversely, the rate of ASAP on initial biopsy was reported to range from 2.4% to 3.7%^3,8,9 the cancer detection rate on repeated biopsy was found to be as high as 52% in isolated ASAP^3,8,10 and 72% in ASAP associated with HGPIN.^3,11The management of patients found to have HGPIN on initial biopsy varies considerably, ranging from immediate rebiopsy to close observation at varying intervals.^12–15 Our aim was to examine our experience with prostatic rebiopsy in patients with HGPIN, ASAP or both.