Shyamal Patel

Targeted Prostate Biopsy Gleason Score Heterogeneity and Implications for Risk Stratification

Objectives: To quantify Gleason score (GS) heterogeneity within multiparametric magnetic resonance imaging (MRI)-targeted prostate biopsies and to determine impact on National Comprehensive Cancer Network (NCCN) risk stratification. Methods: An Institutional Review Board-approved retrospective study was performed on men who underwent Artemis (MRI-transrectal–ultrasound fusion) targeted biopsy (TB) for suspected prostate cancer between 2012 and 2015. Intratarget heterogeneity was defined as a difference in GS between 2 cores within a single target in patients with ≥2 positive cores. Prostate specific antigen, maximum tumor diameter, apparent diffusion coefficient, MRI suspicion score, prostate volume, systematic biopsy (SB) GS, and T-stage were analyzed for correlation with heterogeneity. Changes in NCCN risk based on high versus low GS on TB, SB alone, and SB+TB were compared. Results: Fifty-three patients underwent TB of 73 suspected lesions. Seventy percent (51/73) had ≥2 positive cores, thus meeting inclusion criteria for heterogeneity analysis. Fifty-five percent (28/51) of qualifying targets showed GS heterogeneity. None of the evaluated factors showed a significant relationship with heterogeneity. NCCN low-risk, intermediate-risk, and high-risk groups were 30%, 49%, and 21%, respectively, with SB alone. Adding low GS TB to SB resulted in 17%, 55%, 28% in each risk group, while using high GS+SB resulted in 4%, 54%, and 42%. Overall, the addition of TB resulted in higher NCCN risk groups in 38% of cases. Conclusions: Over half of multiparametric MRI-defined targets demonstrated GS heterogeneity. The addition of high GS from TB leads to risk inflation compared with using SB alone. Further research is needed on how to integrate these findings into current risk stratification models and clinical practice.

Comparison of patient‐reported acute urinary and sexual toxicity scores in a 6‐ versus 2‐fraction course of high‐dose‐rate prostate brachytherapy monotherapy

To identify differences in acute urinary and sexual toxicity between a 6‐fraction and 2‐fraction high‐dose‐rate brachytherapy monotherapy regimen and correlate dosimetric constraints to short‐term toxicity.

Brachytherapy: Where Has It Gone…Again?

TO THE EDITOR: The review by Chinn and Myers about the management of oral cavity cancer mentioned available therapeutic options, but there was one significant omission: brachytherapy. Low-dose-rate and high-dose-rate interstitial brachytherapy have historically been used to treat oral cavity cancers, either as monotherapy or in combination with external-beam radiation, and offer high local control rates and low toxicities. It is an effective technique used in centers throughout the world in the definitive, postoperative, recurrent, and salvage settings. In fact, the use of brachytherapy as a boost in the definitive setting can improve local control rates by 20% compared with external beam radiation alone. Both the American Brachytherapy Society and the Groupe Europeen de Curietherapie–European Society for Radiotherapy and Oncology have developed guidelines for the use of brachytherapy for head and neck cancers. Petereit et al appropriately stated in their article “Brachytherapy: Where has it gone?” that it is our responsibility as oncologists to educate patients, insurance companies, and policy makers about the utility of this tool. Brachytherapy has a significant, evidence-based role in the management of oral cavity cancer and should be considered for treatment in appropriately selected patients. A reply to this Correspondence was not provided.

Another solution that enables ablative radiotherapy for large liver tumors: Percutaneous interstitial high-dose rate brachytherapy.

We thank the authors for outlining an approach for ablative external radiotherapy (RT) via stereotactic body RT for liver lesions that are either large or adjacent to the hilum. We concur that unresectable liver disease warrants local treatment to improve patient outcomes. An excellent modality for ablative RT that was not mentioned is that of percutaneous interstitial high-dose rate brachytherapy. This technique can be performed with computed tomography, magnetic resonance imaging, and/or ultrasound guidance. By using an “inside out” approach, there can be significant dose escalation within the tumor complemented by rapid dose falloff. Thus, low dose spill to adjacent organs at risk is limited and smaller treatment volumes are used because the planning target volume margin is eliminated (implanted catheters move with the target). As a result, lesions that are larger or near the hilum can be treated safely. Depending on the size of the lesion, these treatments are completed in 1 or 2 single-fraction sessions. There is over a decade of literature regarding the use of this technique to treat liver metastases as well as primary liver tumors. Collettini et al treated patients with large hepatocellular carcinomas (mean, 7.1 cm [range, 512 cm]) to a mean dose of 15.8 grays with a mean of 2.7 catheters. With a mean follow-up of 12.8 months, they were able to achieve a local control (LC) rate of 93% with no major toxicities reported. In another study, Ricke et al treated patients with unfavorable large liver metastases (mean, 7.7 cm [range, 5.5-10.8 cm]) and found LC rates of 74% at 6 months and 40% at 1 year. For patients with metastatic lesions adjacent to the liver hilum, one study reported a LC rate of 88% at 1.5 years with a median overall survival of 20 months, whereas another study of liver lesions measuring >4 cm that were adjacent to the hilum demonstrated 1-year LC rates of 81% and 73% for primary and secondary lesions, respectively. Severe toxicities were observed in <5% of interventions, with no treatment-related deaths reported. Interstitial high-dose rate brachytherapy for patients with unresectable liver lesions certainly warrants further investigation and longer follow-up; however, it appears to represent a viable therapeutic option, particularly for patients with tumors that are larger or adjacent to the hilum.

Image-Guided BrachyAblation (IGBA) for Liver Metastases and Primary Liver Cancers

Commonly utilized treatments for primary, secondary, and recurrent cancers of the liver include resection, radiofrequency ablation, percutaneous ethanol injection, transarterial chemoembolization, selective internal radiation therapy, and stereotactic body radiation therapy. Image-guided brachyablation represents another solution for treatment of these lesions with good outcomes. With computed tomography, ultrasound, or MRI guidance, interstitial catheters can be introduced percutaneously into the targeted lesions, allowing the subsequent delivery of ablative doses with sparing of other portions of the liver. In this chapter, we provide a brief overview of the evidence behind interstitial liver brachytherapy and outline a method for performing image-guided brachyablation for liver tumors.

SU-G-201-14: Is Maximum Skin Dose a Reliable Metric for Accelerated Partial Breast Irradiation with Brachytherapy?

PURPOSE To evaluate the reliability of the maximum point dose (Dmax) to the skin surface as a dosimetric constraint, we investigated the correlation between Dmax at the skin surface and dose metrics at various definitions of skin thickness. METHODS 42 patients treated with APBI using a Strut Adjusted Volume Implant (SAVI) applicator between 2010 and 2014 were retrospectively reviewed. Target (PTV_EVAL) and organs at risk (OARs: skin, lung, and ribs) were delineated on a CT following NSABP B-39 guidelines. Six skin structures were contoured: a rind 3cm external to the body surface and 1, 2, 3, 4, and 5mm thick rinds deep to the body surface. Inverse planning simulated annealing optimization was used to deliver 32-34Gy in 8-10 fractions to the target while minimizing OAR doses. Dmax, D0.1cc, D1.0cc, and D2.0cc to the various skin structures were calculated. Linear regressions between the metrics were evaluated using the coefficient of determination (R2 ). RESULTS The average±SD PTV_EVAL volume and cavity-to-skin distances were 71.1±28.5cc and 6.9±5.0mm. The target V90 and V95 were 97.3±2.3% and 95.1±3.2%. The Dmax to the skin structures were 78.7±10.2% (skin surface), 82.2±10.7% (skin-1mm), 89.4±12.6% (skin-2mm), 97.9±15.4% (skin-3mm), 114.1±32.5% (skin-4mm), and 157.0±85.3% (skin-5mm). Linear regression analysis showed D1.0cc and D2.0cc to the skin 1mm and Dmax to the skin-4mm and 5mm were poorly correlated with other metrics (R2 =0.413±0.204). Dmax to the skin surface was well correlated (R2 =0.910±0.047) and D1.0cc to the skin-3mm was strongly correlated with all subsurface skin layers (R2 =0.935±0.050). CONCLUSION Dmax to the skin surface is a relevant metric for breast skin dose. Contouring discontinuities in the skin with a 1mm subsurface rind and the active dwells in the skin 4 and 5mm introduced significant variations in skin DVH. D0.1cc, D1.0cc, and D2.0cc to a 3mm skin rind are more robust metrics in breast brachytherapy.