Focal therapy for localized prostate cancer: is there a "middle ground" between active surveillance and definitive treatment?

High-Intensity Focused Ultrasound (Sonablate®) for Prostate Cancer: Preliminary Outcomes in Taiwan

PURPOSE

We reported preliminary outcomes of high-intensity focused ultrasound (HIFU) [Sonablate®] in the combination of transurethral resection of the prostate for localized prostate cancer in Taiwan.

METHODS

Seventy-seven patients using Sonablate® HIFU for localized prostate cancer were enrolled in this study from April 2021 to December 2022. Prostate-specific antigen biochemical recurrence, International Index of Erectile Function (IIEF)-5 scores, International Prostate Symptom Score (IPSS), quality of life (QoL) scores, and postoperative complications were recorded during follow-up.

RESULTS

Overall, 19.5% of patients were low-risk, 36.4% were intermediate-risk, and 44.1% were high-risk according to the D'Amico risk classification. The median follow-up was 12.09 ± 5.85 months, and the biochemical-free survival rates for the low-, intermediate-, and high-risk groups were 100% (15/15), 96.4% (27/28), and 79.4% (27/34), respectively. Four patients (5.2%) received salvage radiotherapy and all maintained biochemical-free survival. The mean IPSS and QoL scores before versus after HIFU were 10.4 versus 6.8 (p = 0.003) and 3.2 versus 3.0 (p = 0.096), respectively. There was no statistically significant change in preoperative and postoperative IIEF scores (20.6 vs. 19; p = 0.062) in patients who had an IIEF score of >15 at baseline and received nerve-sparing procedures (subtotal ablation).

CONCLUSIONS

The results of Sonablate® HIFU in Taiwan indicated adequate short-term cancer control, excellent potency, and continence preservation. HIFU can achieve improvement of IPSS with low complication rates.

Outcomes of Salvage Robot-assisted Radical Prostatectomy After Focal Ablation for Prostate Cancer in Comparison to Primary Robot-assisted Radical Prostatectomy: A Matched Analysis

BACKGROUND

Focal therapy (FT) for prostate cancer is less invasive than radical treatment but carries a risk of recurrence. Salvage robot-assisted radical prostatectomy (S-RARP) is a possible option after FT failure.

OBJECTIVE

To evaluate the impact of FT on functional and oncological outcomes following S-RARP.

DESIGN, SETTING, AND PARTICIPANTS

In a retrospective analysis of data from a prospectively collected institutional database, 53 patients who underwent S-RARP following failure of focal ablation were selected as group I; patients who had whole-gland ablation and external beam therapy were excluded. This group was matched to a control sample (matched at ratios of 1:1, 1:2, 1:3, 1:4) of men who had undergone primary RARP, using age, prostate-specific antigen (PSA), PSA density, body mass index, Sexual Health Inventory for Men score, American Urological Association symptom score, Charlson comorbidity index, prostate weight, preoperative Gleason score (GS), and history of smoking as variables.

SURGICAL PROCEDURE

S-RARP after FT was performed using a standardized technique developed at our institute with the da Vinci Xi Surgical System.

MEASUREMENTS

Oncological and functional outcomes were compared between the S-RARP and primary RARP groups.

RESULTS AND LIMITATIONS

There was no difference in estimated blood loss (p = 0.8) between the 1:1 matched groups, but operating room time was significantly longer for S-RARP (p = 0.007). The primary RARP group had a higher proportion of patients who underwent a full nerve-sparing procedure. The S-RARP group had higher incidence of positive surgical margins (40% vs 15%; p = 0.008), GS ≥8 (25% vs 15%; p = 0.07), and positive lymph node status (9.4% vs 5.7%; p = 0.02). There was no significant difference in overall complications between the groups. The primary RARP group had a higher incidence of lymphocele drainage after surgery (15% vs 0%; p = 0.006). The main limitation of the study is its retrospective design.

CONCLUSIONS

S-RALP after FT failure is feasible; however, surgery following FT leads to poorer oncological and functional outcomes. Despite the targeted nature of FT, significant nonfocal collateral damage is evident in tissues surrounding the prostate, which in turn translates to poorer functional outcomes after S-RARP.

PATIENT SUMMARY

We studied the surgical challenges during robot-assisted removal of the prostate after previous focal treatment (FT) for prostate cancer and compared the outcomes to those for robot-assisted prostate removal in patients who had no previous FT. We found that this technique is safe and effective with a limited risk of complications, but poor urinary and sexual functional outcomes.

The Impact of Placement Errors on the Tumor Coverage in MRI-Guided Focal Cryoablation of Prostate Cancer

RATIONALE AND OBJECTIVES

There have been multiple investigations defining and reporting the effectiveness of focal cryoablation as a treatment option for organ-confined prostate cancer. However, the impact of cryo-needle/probe placement accuracy within the tumor and gland has not been extensively studied. We analyzed how variations in the placement of the cryo-needles, specifically errors leading to incomplete ablation, may affect prostate cancer's resulting cryoablation.

MATERIALS AND METHODS

We performed a study based on isothermal models using Monte Carlo simulations to analyze the impact of needle placement errors on tumor coverage and the probability of positive ablation margin. We modeled the placement error as a Gaussian noise on the cryo-needle position. The analysis used retrospective MRI data of 15 patients with biopsy-proven, unifocal, and MRI visible prostate cancer to calculate the impact of placement error on the volume of the tumor encompassed by the -40°C and -20°C isotherms using one to four cryo-needles.

RESULTS

When the standard deviation of the placement error reached 3 mm, the tumor coverage was still above 97% with the -20°C isotherm, and above 81% with the -40°C isotherm using two cryo-needles or more. The probability of positive margin was significantly lower considering the -20°C isotherm (0.04 for three needles) than using the -40°C isotherm (0.66 for three needles).

CONCLUSION

The results indicated that accurate cryo-needle placement is essential for the success of focal cryoablation of prostate cancer. The analysis shows that an admissible targeting error depends on the lethal temperature considered and the number of cryo-needles used.

Perceptions of partial gland ablation for prostate cancer among men on active surveillance: A qualitative study

OBJECTIVES –

Partial gland ablation (PGA) therapy is an emerging treatment modality that targets specific areas of biopsy proven prostate cancer (PCa) to minimize treatment-related morbidity by sparing benign prostate. This qualitative study aims to explore and characterize perceptions and attitudes toward PGA in men with very-low-risk, low-risk, and favorable intermediate-risk PCa on active surveillance (AS).

DESIGN –

92 men diagnosed with very-low-risk, low-risk, and favorable intermediate-risk PCa on AS were invited to participate in semi-structured telephone interviews on PGA.

SETTING –

Single tertiary care center located in New York City.

PARTICIPANTS –

20 men with very-low-risk, low-risk, and favorable intermediate-risk PCa on AS participated in the interviews.

MAIN OUTCOME MEASURES –

Emerging themes on perceptions and attitudes toward PGA were developed from transcripts inductively coded and analyzed under standardized methodology.

RESULTS –

Four themes were derived from twenty interviews that represent the primary considerations in treatment decision-making: (1) the feeling of psychological safety associated with low-risk disease; (2) preference for minimally invasive treatments; (3) the central role of the physician; (4) and the pursuit of treatment options that align with disease severity. Eleven men (55%) expressed interest in pursuing PGA only if their cancer were to progress, while 9 men (45%) expressed interest at the current moment.

CONCLUSIONS –

Though an emerging treatment modality, patients were broadly accepting of PGA for PCa with men primarily debating the risks versus benefits of proactively treating low-risk disease. Additional research on men's preferences and attitudes toward PGA will further guide counseling and shared decision-making for PGA.

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.

Focal therapy, time to join the multi-disciplinary team discussion?

Organ preserving management is common place in renal cancer, breast cancer and many other solid organ tumours. Current strategies in managing intermediate risk prostate cancer include either whole gland treatment, in the form of radical radiotherapy or radical prostatectomy, or active surveillance. The former is associated with significant post-treatment functional morbidity, whilst the latter associated with the burden of surveillance activity and patient anxiety. Focal therapy would logically fit as a middle ground for suitable patients in whom treatment would be recommended, but where much better functional outcomes may be possible. Ideally this comes without restricting the successful prevention of harm from the cancer. Historically limitations in developing tissue preserving focal therapy strategies in prostate cancer, were due to inaccuracies in tumour characterisation prior to treatment and during follow up. Consequently for example many patients undergoing an active surveillance strategy were being upgraded and upstaged within a short period. Recently high level evidence supporting the use of MRI and targeted biopsies, in particular the PROMIS and PRECISION trials have strengthened clinician confidence in accurate disease characterisation, thus making focal therapy to become a more feasible management option. With improved diagnostic strategies and the publication of reassuring medium term oncological and functional outcomes after focal therapy for intermediate risk prostate cancer, has the time come to require consideration of focal therapy within our multi-disciplinary team (MDT) meetings and with patients? In this review we will consider patient selection and the evidence for the various focal ablation options as well as the surveillance of these patients after treatment. The forthcoming trials to determine comparative effectiveness will be discussed.