The clinical significance of persistent cancer cells on prostate biopsy after high-dose-rate brachytherapy boost for intermediate-risk prostate cancer

First UK patient cohort treated with stereotactic ablative radiotherapy for primary kidney cancer

Aims

Stereotactic ablative radiotherapy (SABR) for primary renal cell carcinoma (RCC) is a promising non-invasive ablative treatment option. A prospective interventional clinical trial published showed that treatment was feasible and well tolerated. We present the first single-institution UK cohort of patients with primary RCC receiving protocol-based SABR with prospective follow-up. We also present a protocol that could be used to facilitate more widespread use of the treatment.

Materials and methods

Nineteen biopsy-proven primary RCC patients were treated with either 42 Gy in three fractions on alternate days or 26 Gy in a single fraction based on predefined eligibility criteria using either Linear Accelerator or CyberKnife platform. Prospective toxicity data using CTCAE V4.0 and outcome data such as estimated glomerular filtration rate (eGFR) and tumour response using CT thorax, abdomen and pelvis (CT-TAP) were collected at 6 weeks, 3, 6, 12, 18 and 24 months post treatment.

Results

The 19 patients had a median age of 76 years (interquartile range [IQR] 64-82 years) and 47.4% were males, and they had a median tumour size of 4.5 cm (IQR 3.8-5.2 cm). Single and fractionated treatment was well tolerated and there were no significant acute side effects. The mean drop from baseline in eGFR at 6 months was 5.4 ml/min and that at 12 months was 8.7 ml/min. The overall local control rate at both 6 and 12 months was 94.4%. Overall survival at 6 and 12 months was 94.7% and 78.3%, respectively. After a median follow-up of 17 months, three patients experienced a Grade 3 toxicity, which was resolved with conservative management.

Conclusion

SABR for primary RCC is a safe and feasible treatment for medically unfit patients, which can be delivered in most UK cancer centres using standard Linear Accelerator as well as CyberKnife platforms.

Focal brachytherapy for localized prostate cancer: 5.7-year clinical outcomes and a pair-matched study with radical prostatectomy

OBJECTIVES

To report experience with focal brachytherapy (FB) and compare its clinical outcomes with those of radical prostatectomy (RP) in localized prostate cancer.

METHODS

Fifty-one patients with low- to intermediate-risk prostate cancer underwent low-dose-rate FB. Survival rates free from biochemical failure (BF), additional treatment (AT) including re-FB, and whole-gland or systemic salvage therapy (ST) were calculated and oncological risk factors were investigated. Patient-reported outcomes on genitourinary function were also assessed. Using propensity scoring, 51 pair-matched RP patients were selected. Oncological control, urinary continence, and ejaculation status after FB and RP were compared.

RESULTS

During a median 5.7-year follow-up, BF, AT, and ST occurred in 12 (24%), 10 (20%), and 4 FB patients (8%), respectively. 6 of 10 AT patients were managed with re-FB alone. In the RP cohort, 3 patients (6%) underwent ST. 5-year BF-free survival rate after FB was 79%. Compared to 5-year ST-free survival rate of 94% after RP, ST-free and AT-free survival rates after FB were 93% (P = 0.813) and 87% (P = 0.049), respectively. Multivariate analyses of FB-treated patients showed that time to PSA nadir was negatively associated with BF and AT (hazard ratio 0.84 and 0.83, respectively, P <0.001 for each). The difference in oncological outcomes between low- and intermediate-risk categories was not significant. At 2 years after FB and RP, pad-free continence rates were 100% and 81%, respectively (P = 0.001). Ejaculation was preserved in 67% and 0% of patients who had been capable of ejaculation at baseline, respectively (P <0.001).

CONCLUSION

In low- to intermediate-risk prostate cancer, FB-treated patients achieved superior genitourinary function compared to pair-matched RP patients. The need for ST was not substantially different between the 2 treatment cohorts. Over half of patients requiring AT could be managed by re-focal treatment rather than whole-gland ST. Early PSA nadir may predict poor oncological control after FB.

Medium-term oncological and functional outcomes of hemi-gland brachytherapy using iodine-125 seeds for intermediate-risk unilateral prostate cancer

PURPOSE

To examine medium-term outcomes of hemi-gland low-dose-rate brachytherapy as a primary treatment for intermediate-risk prostate cancer.

METHODS

We recruited intermediate-risk unilateral prostate cancer patients for a prospective trial of hemi-gland brachytherapy. Twenty-four patients underwent hemi-gland iodine-125 seed implantation with a prescribed dose of 160 Gy. Serum prostate-specific antigen (PSA) was measured regularly and follow-up biopsy was scheduled after 2-3 years of treatment. When clinically needed afterward, for-cause biopsy was performed to confirm pathology. Treatment failure (TF)-free survival, which was defined as freedom from radical or systemic therapy, metastases, and cancer-specific mortality, was assessed, as was biochemical failure (BF)-free survival. Urinary and sexual functions were also evaluated.

RESULTS

Median follow-up duration was 61 months. Twenty-two patients (92%) exhibited a declining trend or decreased value of PSA for 12 months or longer after the treatment. Follow-up biopsy in the initial triennium and for-cause biopsy in the subsequent triennium were performed in 16 and four patients, respectively, and cancer was found from the treated lobe in one patient (4% of the cohort) and significant cancer was found from untreated lobes in four patients (17%) in total. Secondary treatments were performed in six patients successfully. Five-year freedom from BF, TF, and metastasis was 71%, 90%, and 100%, respectively. The International Prostate Symptom Score significantly deteriorated at 3 months and reversed itself afterward. The International Index of Erectile Function 5 had no significant decrease.

CONCLUSIONS

Hemi-gland low-dose-rate brachytherapy provides favorable medium-term oncological outcomes with genito-urinary functional preservation for men with intermediate-risk unilateral prostate cancer.

A phase IB clinical trial of 15 Gy HDR brachytherapy followed by hypofractionated/SBRT in the management of intermediate-risk prostate cancer

PURPOSE

High dose-rate (HDR) brachytherapy is commonly administered as a boost to external beam radiation therapy (EBRT). Our purpose was to compare toxicity with increasingly hypofractionated EBRT in combination with a single 15 Gy HDR boost for men with intermediate-risk prostate cancer.

METHODS AND MATERIALS

Forty-two men were enrolled on this phase IB clinical trial to one of three EBRT dose cohorts: 10 fractions, seven fractions, or five fractions. Patients were followed prospectively for safety, efficacy, and health-related quality of life (Expanded Prostate Index Composite). Efficacy was assessed biochemically using the Phoenix definition.

RESULTS

With a median follow up of 36 months, the biochemical disease-free survival was 95.5%. One man developed metastatic disease at 5 years. There was no significant minimally important difference in EPIC PRO for either urinary, bowel, or sexual domains. There was one acute Grade 3 GI and GU toxicity, but no late Grade 3 GU or GI toxicities.

CONCLUSION

Fifteen gray HDR brachytherapy followed by a five fraction SBRT approach results in high disease control rates and low toxicity similar to previously reported HDR protocols with significant improvement in patient convenience and resource savings. While mature results with longer follow up are awaited, this treatment approach may be considered a safe and effective option for men with intermediate-risk disease.

Positive prostate biopsy following radiotherapy can predict metastasis-free survival in localized prostate cancer

Background/aims

To determine the impact of post-treatment biopsy results on 10-year metastasis-free survival (MFS), overall survival (OS) and cause-specific survival (CSS) in localized prostate cancer (PCa) patients treated with high-dose radiotherapy (RT).

Materials/Methods

Retrospective analysis of 232 patients with T1c-T3bN0M0 PCa who underwent a prostate biopsy 24-36 months after high-dose RT. Biopsies were categorized as positive biopsy (PB) if H&E staining showed evidence of residual malignancy and negative biopsy (NB) if no malignant cells were present. Kaplan-Meier estimates of 10-year MFS, OS and CSS rates were calculated for each group and Cox proportional-hazards models were used to estimate the hazard ratios. The median follow-up was 124 months (range 26-267).

Results

Sixty-two of 232 (26.7%) patients had post-treatment positive biopsies (PB). A positive post-treatment biopsy was significantly associated with a lower 10-year MFS (78.4% vs. 95.4%, p = 0.001, HR: 3.9, 95% CI: 1.8-8.3). Although patients with PB had worse outcomes that those with NB, we could not show a statistically significant difference in OS (81.0% vs. 87.9%, p = 0.282, HR: 1.3, 95% CI: 0.7-2.3) or CSS (96.2% vs. 99.4% (p = 0.201, HR. 2.4, 95% CI: 0.6-9.7). After multivariate analysis, the strongest predictor of MFS was the post-treatment biopsy status (p < 0.001, HR: 5.4, 95% CI 2.26-12.85) followed by Gleason score (p = 0.002, HR: 2.24, 95% CI 1.33-3.79).

Conclusion

A positive biopsy following RT can predict MFS in localized prostate cancer. These data highlight the relevance of achieving a local control and support the use of aggressive local therapeutic interventions for PCa.

Medium-term oncological outcomes in a large cohort of men treated with either focal or hemi-ablation using high-intensity focused ultrasonography for primary localized prostate cancer

OBJECTIVE

To report medium-term oncological outcomes in men receiving primary focal treatment with high-intensity focused ultrasonography ( HIFU) for prostate cancer (PCa).

PATIENTS AND METHODS

Consecutive patients with PCa treated with primary focal HIFU at two centres by six treating clinicians were assessed. Patients were submitted to either focal ablation or hemi-ablation using HIFU (Sonablate 500). The primary objective of the study was to assess medium-term oncological outcomes, defined as overall survival, freedom from biopsy failure, freedom from any further treatment and freedom from radical treatment after focal HIFU. The secondary objective was to evaluate the changes in pathological features among patients treated with focal HIFU over time. We also assessed the relationship between year of surgery and 5-year retreatment probability.

RESULTS

A total of 1032 men treated between November 2005 and October 2017 were assessed. The median age was 65 years and median prostate-specific antigen level was 7 ng/mL. The majority of patients had a Gleason score of 3 + 4 or above (80.3%). The median (interquartile range) follow-up was 36 (14-64) months. The overall survival rates at 24, 60 and 96 months were 99%, 97% and 97%, respectively. Freedom from biopsy failure, defined as absence of Gleason 3 + 4 disease, was 84%, 64% and 54% at 24, 60 and 96 months. Freedom from any further treatment was 85%, 59% and 46% at 24, 60 and 96 months, respectively. Approximately 70% of patients who were retreated received a second focal treatment. Freedom from radical treatment was 98%, 91% and 81% at 24, 60 and 96 months. During the study period, we observed an increase in the proportion of patients undergoing focal HIFU with Gleason 3 + 4 disease and with T2 stage disease as defined by multiparametric magnetic resonance imaging. Finally, there was a reduction over time in the proportion of patients undergoing re-treatment within 5 years of first treatment.

CONCLUSIONS

Focal HIFU for PCa is a feasible therapeutic strategy, with acceptable survival and oncological results and a reduction in the 5-year retreatment rates over the last decade. Re-do focal treatment is a feasible technique whose functional and oncological outcomes have still to be evaluated.

High dose-rate brachytherapy in the treatment of prostate cancer

High dose-rate (HDR) brachytherapy involves delivery of a high dose of radiation to the cancer with great sparing of surrounding organs at risk. Prostate cancer is thought to be particularly sensitive to radiation delivered at high dose-rate or at high dose per fraction. The rapid delivery and high conformality of dose results in lower toxicity than that seen with low dose-rate (LDR) implants. HDR combined with external beam radiotherapy results in higher cancer control rate than external beam only, and should be offered to eligible high and intermediate risk patients. While a variety of dose and fractionations have been used, a single 15 Gy HDR combined with 40-50 Gy external beam radiotherapy results in a disease-free survival of over 90% for intermediate risk and 80% for high risk. HDR monotherapy in two or more fractions (e.g., 27 Gy in 2 fractions or 34.5 Gy in 3) is emerging as a viable alternative to LDR brachytherapy for low and low-intermediate risk patients, and has less toxicity. The role of single fraction monotherapy to a dose of 19-20 Gy is evolving, with some conflicting data to date. HDR should also be considered as a salvage approach for recurrent disease following previous external beam radiotherapy. A particular advantage of HDR in this setting is the ease of delivering focal treatments, which combined with modern imaging allows focal dose escalation with minimal toxicity. Trans-rectal ultrasound (TRUS) based planning is replacing CT-based planning as the technique of choice as it minimizes or eliminates the need to move the patient between insertion, planning and treatment delivery, thus ensuring high accuracy and reproducibility of treatment.

Consensus statement from the International Radiosurgery Oncology Consortium for Kidney for primary renal cell carcinoma

Aim: To provide a multi-institutional consensus document for stereotactic body radiotherapy of primary renal cell carcinoma. Materials & methods: Eight international institutions completed a 65-item survey covering patient selection, planning/treatment aspects and response evaluation. Results: All centers treat patients with pre-existing hypertension and solitary kidneys. Five institutions apply size constraints of 5–8 cm. The total planning target volume expansion is 3–10 mm. All institutions perform pretreatment imaging verification, while seven institutions perform some form of intrafractional monitoring. Number of fractions used are 1–12 to a total dose of 25 Gy–80 GyE. Imaging follow-up for local tumor response includes computed tomography (n = 8), PET-computed tomography (n = 1) and MRI (n = 5). Follow-up frequency is 3–6 months for the first 2 years and 3–12 months for subsequent 3 years. Conclusion: Key methods for safe implementation and practice for stereotactic body radiotherapy kidney have been identified and may aid standardization of treatment delivery.

Histological outcomes after focal high-intensity focused ultrasound and cryotherapy

Introduction

Focal therapy has increasingly become an accepted treatment option for patients with localised prostate cancer. Most follow-up protocols use a mixture of protocol biopsies or “for cause” biopsies triggered by a rising PSA. In this paper, we discuss the histological outcomes from these biopsies and their use in guiding subsequent management and trial development.

Methods

We conducted a literature search and reviewed the post-treatment biopsy results from studies on focal HIFU and focal cryotherapy. We subsequently reviewed the results of three recently published consensus statements released discussing many of the issues concerning focal therapy.

Results

Research suggests that 1 in 5 of all post-treatment biopsies after focal therapy are positive. However, the majority of these seemed to be from the untreated portion of the gland or met criteria for clinically insignificant disease. The histological outcomes from focal therapy are promising and confirm its effectiveness in the short to medium term. Furthermore re-treatment is possible whilst maintaining a low-side-effect profile.

Conclusion

Debate is ongoing about the clinical significance of various levels of residual disease after focal therapy and the exact threshold at which to call failure within a patient who has had focal therapy.