The role of targeted focal therapy in the management of low-risk prostate cancer: update on current challenges

Salvage Brachytherapy for Biochemically Recurrent Prostate Cancer following Primary Brachytherapy

Purpose. In this study, we evaluated our experience with salvage brachytherapy after discovery of biochemical recurrence after a prior brachytherapy procedure. Methods and Materials. From 2001 through 2012 twenty-one patients treated by brachytherapy within University of Kentucky or from outside centers developed biochemical failure and had no evidence of metastases. Computed tomography (CT) scans were evaluated; patients who had an underseeded portion of their prostate were considered for reimplantation. Results. The majority of the patients in this study (61.9%) were low risk and median presalvage PSA was 3.49 (range 17.41-1.68). Mean follow-up was 61 months. At last follow-up after reseeding, 11/21 (52.4%) were free of biochemical recurrence. There was a trend towards decreased freedom from biochemical recurrence in low risk patients (p = 0.12). International Prostate Symptom Scores (IPSS) increased at 3-month follow-up visits but decreased and were equivalent to baseline scores at 18 months. Conclusions. Salvage brachytherapy after primary brachytherapy is possible; however, in our experience the side-effect profile after the second brachytherapy procedure was higher than after the first brachytherapy procedure. In this cohort of patients we demonstrate that approximately 50% oncologic control, low risk patients appear to have better outcomes than others.

Impact of multiparametric magnetic resonance imaging on risk group assessment of patients with prostate cancer addressed to external beam radiation therapy

PURPOSE

To investigate the impact of multiparametric magnetic resonance imaging (mpMRI) on risk group assessment of patients with prostate cancer (PCa) initially addressed to external beam radiation therapy (EBRT).

MATERIALS AND METHODS

We prospectively performed mpMRI (3.0Tsystem) in 44 patients addressed to EBRT, using a multiparametric protocol (high-resolution multiplanar T2-weighted, diffusion-weighted and dynamic contrast-enhanced imaging). Risk group was assessed in accordance with the National comprehensive cancer network (NCCN) categories, by combining prostate-specific-antigen level, Gleason score and the T-stage as established by digital rectal examination (clinical risk assessment; c-RA) versus mpMRI (mpMRI-risk assessment; mpMRI-RA). The agreement between c-RA and mpMRI-RA was investigated using Cohen's kappa.

RESULTS

Patients were included in very low/low risk, intermediate risk, high risk, very high risk and metastatic NCCN categories in 10 (22.7%), 18 (40.9%), 15 (34.1%), 1 (2.3%) and 0 cases using c-RA vs. 8 (18.2%), 14 (31.8%), 14 (31.8%), 4 (9.1%) and 4 (9.1%) cases using mpMRI-RA, respectively, with only moderate agreement (k=0.43). mpMRI-RA determined risk downgrading in 2/44 patients (4.5%), and risk upgrading in 16/44 patients (36.3%). After mpMRI, EBRT remained indicated in all patients.

CONCLUSION

mpMRI changed clinical risk stratification in about 41% of patients with PCa, with potential impact on EBRT planning.

From whole gland to hemigland to ultra-focal high-dose-rate prostate brachytherapy: A dosimetric analysis

PURPOSE

To assess the magnitude of dosimetric reductions of a focal and ultra-focal high-dose-rate (HDR) prostate brachytherapy treatment strategy relative to standard whole gland (WG) treatment.

METHODS AND MATERIALS

HDR brachytherapy plans for five patients treated with WG HDR monotherapy were optimized to assess different treatment strategies. Plans were generated to treat the hemigland (HG), one-third gland (1/3G), and one-sixth gland (1/6G), as well as to assess treating the WG with a boost to one of those sub-volumes (WG + HG, WG + 1/3G, WG + 1/6G). Dosimetric parameters analyzed included Target D90%, V100%, V150%, Bladder (B), Rectal (R), Urethral (U) D0.1, 1 and 2cc, Urethral V75%, and the V50% to the contralateral HG. Two-tailed t tests were used for comparison of means, and p-values less than 0.05 were considered statistically significant.

RESULTS

Target objectives (D90 > 100% and V100 > 97%) were met in all cases. Significant organs at risk dose reductions were achieved for all approaches compared with WG plans. 1/6G vs WG plans resulted in the greatest reduction in dose with a mean bladder D2cc 24.7 vs 64.8%, rectal D2cc 32.8 vs 65.3%, urethral D1cc 52.1 vs 103.8%, and V75 14.5 vs 75% (p < 0.05 for all comparisons).

CONCLUSION

Significant dose reductions to organs at risk can be achieved using HDR focal brachytherapy. The magnitude of the reductions achievable with treating progressively smaller sub-volumes suggests the potential to reduce morbidity, but the clinical impact on morbidity and tumor control remain to be investigated.

Apparent diffusion coefficient value as a biomarker reflecting morphological and biological features of prostate cancer

PURPOSE

To assess whether there is an association between the apparent diffusion coefficient (ADC) value and the pathological characteristics of prostate cancer.

METHODS

The study cohort consisted of 29 consecutive patients with prostate cancer treated with radical prostatectomy. All patients underwent diffusion-weighted MRI before the prostate biopsy. In 42 tumor foci, the associations of the ADC values with the clinicopathological characteristics and Ki-67 labeling index (LI) were analyzed.

RESULTS

High-grade cancers (Gleason score [GS] ≥ 4 + 3), larger cancers (maximum diameter (MD) ≥ 16 mm), and highly proliferating cancers (Ki-67 LI ≥ 4.43 %) had significantly lower ADC values, respectively (P < .001, P = .008, and P = .044, respectively). There was no significant difference in ADC value according to age, prostate-specific antigen, presence of extra-prostatic extension, and intra-tumoral stroma proportion. Multivariate analysis showed that GS, Ki-67 LI, and MD had independent and significant correlations with ADC value (P < .001, P = .006, and P = .002, respectively). Low ADC tumors (<0.52 × 10(-3) mm(2)/s) are likely to be high-grade cancer foci compared with high ADC tumors (relative risk: 65.2). The sensitivity and specificity of the ADC value to predict high-grade cancer foci are 81.8 and 93.5 %, respectively.

CONCLUSIONS

A low ADC value reflects the morphological and biological features of prostate cancer. Analyzing the ADC value may make it possible to more precisely predict the cancer aggressiveness of each focus before treatment.

A multi-centre prospective development study evaluating focal therapy using high intensity focused ultrasound for localised prostate cancer: The INDEX study

INTRODUCTION

Focal therapy offers the possibility of cancer control, without the side effect profile of radical therapies. Early single centre prospective development studies using high intensity focused ultrasound (HIFU) have demonstrated encouraging genitourinary functional preservation and short-term cancer control. Large multi-centre trials are required to evaluate medium-term cancer control and reproduce functional recovery. We describe the study design of an investigator-led UK multi-centre, single arm trial using HIFU to deliver focal therapy for men with localised prostate cancer.

METHODS

One-hundred and forty men with histologically proven localised low or intermediate risk prostate cancer (PSA < 15, Gleason ≤ 7, ≤ T2cN0M0) will undergo precise characterisation of the prostate using a combination of multi-parametric (mp)MRI and transperineal template prostate mapping (TPM) biopsies. Unilateral dominant tumours, the so-called index lesion, will be eligible for treatment provided the contra-lateral side is free of 'clinically significant' disease (as defined by Gleason ≥ 7 or maximum cancer core length ≥4 mm). Patients will receive focal therapy using HIFU (Sonablate 500®). Treatment effect will be assessed by targeted biopsies of the treated area and TPM biopsies at 36-months.

RESULTS

Primary outcome is the absence of clinically significant disease based on 36-month post-treatment TPM biopsies. Secondary outcomes address a) genitourinary function using validated patient questionnaires (IPSS, IPSS-QoL, IIEF-15, EPIC-Urinary, EPIC-Bowel, FACT-P, EQ-5D), b) the predictive validity of imaging, and c) risk factors for treatment failure.

CONCLUSIONS

INDEX will be the first multi-centre, medium term follow-up trial to evaluate the outcomes of a tissue preserving strategy for men with localised prostate cancer using the TPM-ablate-TPM strategy.