Association between previous negative biopsies and lower rates of progression during active surveillance for prostate cancer

Purpose To test any-cause discontinuation and ISUP GG upgrading rates during Active Surveillance (AS) in patients that underwent previous negative biopsies (PNBs) before prostate cancer (PCa) diagnosis vs. biopsy naive patients. Methods Retrospective analysis of 961 AS patients (2008–2020). Three definitions of PNBs were used: (1) PNBs status (biopsy naïve vs. PNBs); (2) number of PNBs (0 vs. 1 vs. ≥ 2); (3) histology at last PNB (no vs. negative vs. HGPIN/ASAP). Kaplan–Meier plots and multivariable Cox models tested any-cause and ISUP GG upgrading discontinuation rates. Results Overall, 760 (79.1%) vs. 201 (20.9%) patients were biopsy naïve vs. PNBs. Specifically, 760 (79.1%) vs. 138 (14.4%) vs. 63 (6.5%) patients had 0 vs. 1 vs. ≥ 2 PNBs. Last, 760 (79.1%) vs. 134 (13.9%) vs. 67 (7%) patients had no vs. negative PNB vs. HGPIN/ASAP. PNBs were not associated with any-cause discontinuation rates. Conversely, PNBs were associated with lower rates of ISUP GG upgrading: (1) PNBs vs. biopsy naïve (HR:0.6, p = 0.04); (2) 1 vs. 0 PNBs (HR:0.6, p = 0.1) and 2 vs. 0 PNBs, (HR:0.5, p = 0.1); (3) negative PNB vs. biopsy naïve (HR:0.7, p = 0.3) and HGPIN/ASAP vs. biopsy naïve (HR:0.4, p = 0.04). However, last PNB ≤ 18 months (HR:0.4, p = 0.02), but not last PNB > 18 months (HR:0.8, p = 0.5) were associated with lower rates of ISUP GG upgrading. Conclusion PNBs status is associated with lower rates of ISUP GG upgrading during AS for PCa. The number of PNBs and time from last PNB to PCa diagnosis (≤ 18 months) appear also to be critical for patient selection. Supplementary Information The online version contains supplementary material available at 10.1007/s00345-022-03983-8.

We hypothesized lower rates of disease progression during AS in PNBs patients, relative to their biopsy naïve counterparts.
To address this void, we focussed on a large contemporary series of AS patients and we tested two commonly used AS outcomes, namely: (1) any-cause discontinuation; (2) discontinuation due to upgrading.
* Mattia Luca Piccinelli mattiapiccinelli@gmail.com Extended author information available on the last page of the article

Study population
This retrospective single-institution data analysis was approved by the Institutional Review Board of the European Institute of Oncology.
Overall, 961 patients with PCa were enrolled in AS between 2008 and 2020. AS inclusion criteria were the following: prostate specific antigen (PSA) ≤ 10 ng/ml; clinical stage (cT) cT1c/cT2a; International Society of Urological Pathology Grade Group (ISUP GG) 1 PCa with ≤ 3 positive cores or ISUP GG2 PCa with pattern 4 < 10% in a single core; PSA-density (PSAD) < 0.2 ng/ml/ml. AS protocol consisted of: repeated PSA testing (every 6 months for 5 years and annually thereafter); clinical assessment every 12 months and repeated surveillance biopsies scheduled at 12, 36 and 84 months. Since 2015, confirmatory mpMRI was employed in AS protocol and offered to all patients at AS begin (≤ 6 months from diagnostic biopsy). Here, all patients with Prostate Imaging Reporting and Data System (PI-RADS) score ≥ 3 underwent confirmatory targeted biopsies, as previously reported [20,21]. Additionally, repeated mpMRI scans were performed before surveillance biopsies. Here, 1-3 targeted-cores were additionally taken in patients with positive mpMRIs (PI-RADS score ≥ 3) [22][23][24].

Variables of interest
We tested the association between PNBs and AS outcomes. Specifically, PNBs were defined as all negative prostate samplings performed before the diagnostic biopsy that allowed for AS begin. Three different definitions of PNBs were used:
Differences in medians and proportions were evaluated by, respectively, the Kruskal-Wallis and chi-square tests. First, Kaplan-Meier (KM) plots tested any-cause discontinuation and ISUP GG upgrading rates over time. Second, multivariable Cox regression models tested associations between patient's or tumour characteristics and rates of AS discontinuation.

Sensitivity analysis: time between last PNB and AS begin
We performed a sensitivity analysis to test the association between time from last PNB to AS begin and the two mentioned outcomes. Median (IQR) time from last PNB to AS begin was 19 (9-40) months. In KM plots, 3-year rates of any-cause and ISUP GG upgrading survival were, respectively, 65% vs. 65% vs. 74% (p = 0.1; Supplementary Fig. 1a)

Discussion
Patient selection at AS begin represents a critical step. To date, novel confirmatory exams have been developed and implemented in daily practice [7][8][9][10][11][12][13][14][25][26][27][28][29]. However, most of these tools are usually performed several months after PCa diagnosis [7][8][9][10][11]. Moreover, possible side effects or elevated costs [25][26][27] limit patient compliance. In consequence, there is an urgent need to find immediately available and low-cost tools to confirm patient eligibility to AS. We focussed on the association between PNBs and two commonly used AS outcomes, namely any-cause and ISUP GG upgrading discontinuation, in a large series of AS patients. Specifically, the protective effect of PNBs was tested in a systematic fashion and accordingly to three PNBs definitions, namely: (1) PNBs status (biopsy naïve vs. PNBs); First, we observed similar rates of any-cause discontinuation between biopsy naïve and PNBs patients, regardless of PNBs definition. However, when ISUP GG upgrading (ISUP GG ≥ 2 with > 10% of pattern 4) rates were tested, PNBs patients were at lower risk of upgrading (HR:0.6; p = 0.04), relative to their biopsy naïve counterparts. Moreover, while we were unable to reach statistical significance (p = 0.1) due to low number of patients, a gradual increase in the protective association between PNBs and ISUP GG upgrading rates was observed with an increasing number of PNBs (HR:0.6 for 1 PNB; HR:0.5 for ≥ 2 PNBs). Last, histology at last PNB was also associated with ISUP GG upgrading rates. Specifically, only patients with HGPIN/ ASAP (HR:0.4; p = 0.04), but not patients with negative findings at last PNB (HR:0.7; p = 0.3), were at lower risk of ISUP GG upgrading over time. Our results are supported by the non-negligible follow-up time (35 months) and by the use of multivariable Cox regression models that were fully adjusted for all available patients and tumour characteristics. To the best of our knowledge, we are the first to specifically focus on the role of PNBs on AS outcomes. Indeed, several previous authors tested the association between findings at confirmatory biopsy (≤ 1 year after PCa diagnosis) and AS outcomes over time [7][8][9][10][11], without considering prostate samplings before AS begin. Due to the novelty of our analysis, only hypothetical considerations could justify patients with negative PNBs vs. patients with HGPIN/ASAP; f ISUP GG upgrading survival in biopsy naïve patients vs. patients with negative PNBs vs. patients with HGPIN/ASAP AS active surveillance, PNBs previous negative biopsies, ISUP GG international society of urological pathology grade group, HGPIN high-grade prostatic intraepithelial neoplasia, ASAP atypical small acinar proliferation our findings. Specifically, we can hypothesize that PNBs patients could be at lower risk of disease misclassification at AS enrolment. This hypothesis is supported by several previous manuscripts that reported lower rates of csPCa at RP in patients that underwent multiple prostate samplings before surgery [15][16][17][18][19]. Indeed, Rosenbaum et al. and Djavan et al. observed decreasing rates of extra-prostatic PCa, aggressive tumour histology and lymph node metastases with an increasing number of prostate biopsies before RP [16,17]. Our results could be used for patients counselling at AS recruitment. Specifically, the use of AS confirmatory tests could be modulated according to PNBs status. Indeed, confirmatory biopsies could be recommended for all patients that were biopsy naïve before PCa diagnosis. Conversely, due to the retrospective nature of the current analysis, the modulation of AS follow-up schemes, in which PNBs patients could be less frequently submitted to repeated biopsies, should be tested in other multi-institutional and ideally prospective studies.
Second, when we repeated our analyses after considering time from last PNB to AS begin, we observed that only patients with last PNB performed ≤ 18 months (HR:0.4; p = 0.02), but not patients with last PNB > 18 months (HR:0.8; p = 0.5) were at lower risk of ISUP GG upgrading. We can argue that only patients with at least one PNB ≤ 18 months are at lower risk of disease misclassification at AS begin. Indeed, prostate samplings performed > 18 months could not be representative of patient situation at the moment of PCa diagnosis. Moreover, these findings could also justify the observed association between histology at last PNB and ISUP GG upgrading rates, where only patients with HGPIN/ASAP, but not patients with negative PNB, were at lower risk of ISUP GG upgrading. Indeed, during the study period, the EAU guidelines recommended prompt prostate re-biopsy for all patients diagnosed with HGPIN/ASAP [1]. In consequence, it is possible that the observed association between HGPIN/ASAP at last PNB and lower rates of ISUP GG upgrading over time is not related to biopsy histology but is a product of time from last PNB.
Taken together, PNBs history appears to be a useful tool for confirming patient eligibility to AS. Specifically, PNBs patients are at lower risk of disease upgrading during AS, relative to their biopsy naïve counterparts. This protective association appears to be even stronger in patients with a history of multiple PNBs before PCa diagnosis. However, time from last PNB to AS begin should be considered as a critical factor. Results from other series, with a specific focus on RP findings after AS, are warranted before recommending AS protocols modifications.
Despite its novelty our study has limitations. First, the current data are retrospective and influenced by inherent selection bias. Second, the long-time span (2008-2020) of the current analysis could limit the applicability of our findings in contemporary clinical practice. However, our multivariable Cox regression models were also adjusted for mpMRI performance at AS begin, as recommended by EAU guidelines [1]. In consequence, our results are not a product of different AS protocols used for PNBs vs. biopsy naïve patients. Indeed, during follow-up, no meaningful differences in number of repeated biopsies or repeated mpMRI scans were observed between PNBs vs. biopsy naïve patients. Third, we were unable to stratify PNBs patients according to the type of prostate biopsies performed before PCa diagnosis. Specifically, information about PNBs schemes, techniques (systematic vs. targeted cognitive vs. targeted fusion vs. RM-guided) or approaches (transrectal vs. transperineal) are missing. However, the median (IQR) number of cores performed during PNBs was  1 3 13 (12-15) and, in consequence, prostate undersampling is unlikely. Fourth, we used specific AS inclusion criteria. In consequence, our results could not be applicable in other AS protocols. Therefore, external validation of our findings is needed for implementing the systematic consideration of PNBs status in AS protocols.

Conclusion
PNBs status is associated with lower rates of ISUP GG upgrading during AS for PCa. The number of PNBs and time from last PNB to PCa diagnosis (≤ 18 months) appear also to be critical for patient selection.

Declarations
Conflict of interest All authors declare to have no potential conflict of interest.
Ethics approval This retrospective data analysis was approved by the Institutional Review Board of the European Institute of Oncology and was conducted according to the ethical guidelines of the Declaration of Helsinki.
Informed consent Informed consent was obtained from all individual participants included in the study.

Consent to publish
Patients signed informed consent regarding publishing their data and photographs. Stefano Luzzago had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
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