Outcome of repeated prostatic biopsy during active surveillance: implications for focal therapy

Characteristics of Cancer Progression on Serial Biopsy in Men on Active Surveillance for Early-stage Prostate Cancer: Implications for Focal Therapy

BACKGROUND

Active surveillance (AS) is a safe and accepted option for managing men with low-risk prostate cancer. Nevertheless, some patients lack confidence in or access to AS. Focal therapy (FT) is a possible alternative to radical treatment for such patients.

OBJECTIVE

We evaluated dominant tumor (DT) progression across serial biopsies to determine whether men on AS could be reasonable candidates for FT.

DESIGN, SETTING, AND PARTICIPANTS

Men enrolled in AS at University of California, San Francisco between 1996 and 2017 with low/intermediate risk were included.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Changes in biopsy grade, volume, and focality of the DT over time were assessed. Focality (good or poor for FT) was defined by the number of cores, laterality, and contiguity of prostate sites containing tumor (based on pathology reports). Candidates (either for targeted/quadrant ablation or for hemigland ablation) were defined based on good focality, grade group (GG) ≤2, and low-volume disease. Patients were classified as favorable (GG ≤ 2 with good focality and concordant multiparametric magnetic resonance imaging [mpMRI]) or unfavorable (poor focality or high-volume disease or discordant mpMRI) for FT at surveillance biopsies.

RESULTS AND LIMITATIONS

A total of 1057 men met the inclusion criteria. The median number of biopsies per patient was three (interquartile range 2-4), and 196 patients (18.5%) underwent five or more biopsies. At confirmatory biopsy, 43% remained candidates for FT (67% for targeted/quadrant ablation and 33% for hemigland ablation) and 20% had a negative biopsy. Of the candidates for FT at initial biopsy, 11% had less favorable characteristics at confirmatory biopsy. Among candidates for FT based on both initial and confirmatory biopsies, 70% remained favorable for hemigland ablation at subsequent biopsies. Limitations include retrospective design and mpMRI information only at surveillance biopsy.

CONCLUSIONS

Serial biopsy findings in men with early-stage cancer on AS show that tumor location remains relatively stable and significant changes in grade and/or volume occur largely in the DT. Combined diagnostic and confirmatory biopsy findings help better select patients for FT than the use of the diagnostic biopsy alone.

PATIENT SUMMARY

In a large cohort of patients on active surveillance for prostate cancer, we evaluated changes across serial biopsies to identify potential candidates for focal therapy (FT). Our findings showed that the dominant tumor remained stable over time and the majority of men were favorable candidates for FT.

Histotripsy: The Next Generation of High-Intensity Focused Ultrasound for Focal Prostate Cancer Therapy

This article reviews the most current methods and technological aspects of high-intensity focused ultrasound (HIFU), which is termed histotripsy. The rationale for focal therapy for prostate carcinoma rather than prostatectomy, which is being used extensively throughout Europe and Asia, is presented, and an argument for why HIFU is the modality of choice for primary therapy and recurrent disease is offered. The article presents a review of the technical advances including higher ultrasound beam energy than current thermal HIFU which allows for more accurate tissue targeting, less collateral tissue damage, and faster treatment times. Finally, the article presents a discussion about the advantage of ultrasound guidance for histotripsy in preference to magnetic resonance imaging guidance primarily based on cost, ease of application, and portability.