Treatment times for delivering adjuvant breast radiotherapy at a cancer centre in Ontario, Canada.

BACKGROUND: Time is a valuable commodity that impacts hospital flow, patient experience and economic resources. This study aims to identify factors that affect daily treatment time over a course of radiation therapy (RT) in patients who underwent adjuvant breast RT. METHODS: In all adjuvant breast/chestwall RT patients treated from October 2017 to May 2018, daily set-up, beam delivery time, and overall treatment times were collected. A multivariable linear regression analysis was conducted to identify significant predictive factors related to treatment time. A general linear regression model was used to determine whether there was a learning curve effect throughout the course of treatment that decreased treatment time as patient and staff familiarity with the treatment procedure increased. RESULTS: A total of 567 patients were included with a median age of 61 years. The average overall treatment time for 2-field and 4-field RT was 8.3 (SD 2.4) and 13.1 (SD 5.6) minutes, respectively. Factors that significantly increased overall treatment times in patients prescribed 2-field RT were: bilateral techniques, breath-hold (BH) techniques, prone techniques (PR), reverse decubitus techniques (RD), wide tangents techniques, the use of bolus and number of segments delivered. (p < 0.05). Factors that significantly increased overall treatment times in patients who received 3-field and 4-field RT were: wide tangents volumes, a higher number of monitor units (MUs), bilateral techniques and BH techniques (p < 0.05). Older patients (≥60) who underwent 3-field and 4-field RT demonstrated a statistically significant increase in set-up time (p < 0.0001). Overall treatment time decreased from 10.0 to 9.3 min over the course of treatment, suggesting a minor learning curve (p = 0.009). CONCLUSION: The use of bilateral RT, BH, PR, RD, wide tangents, bolus, increasing treatment volumes, and increasing plan complexity were associated with increased treatment times. Future research should quantify the impact of other factors (BMI, mobility, patient care assessments, and imaging protocols) and utility of technological tools (time-predicting models, machine learning tools, and operations research models) on treatment time to optimize RT scheduling and improve resource management.

Mepitel Film for the Prevention of Acute Radiation Dermatitis in Breast Cancer: A Randomized Multicenter Open-Label Phase III Trial.

PURPOSE: Radiation dermatitis (RD) is common in patients undergoing breast radiotherapy. Mepitel film (MF) can reduce RD, but the results from two randomized controlled trials are conflicting. We aimed to conduct a confirmatory randomized controlled trial in patients at risk of RD. METHODS: Patients were randomly assigned to receive MF or standard care (2:1 ratio). Patients with large breasts after lumpectomy (bra size ≥ 36 inches or cup size ≥ C) or after mastectomy were eligible. Stratification factors included surgery type, dose fractionation, and administration of boost/bolus. The primary end point was grade (G) 2 or 3 RD using the Common Terminology Criteria for Adverse Events v5.0. Secondary end points included patient- and clinician-reported outcomes. RESULTS: Between January 2020 and May 2022, 376 patients were included in the modified intention-to-treat analysis. The incidence of G2 or 3 RD was significantly lower in MF patients compared with standard care (n = 39/251, 15.5%; 95% CI, 11.3 to 20.6% v n = 57/125, 45.6%; 95% CI, 36.7 to 54.8% respectively, odds ratio (OR): 0.20, P < .0001). Benefits of MF remained significant in patients who developed G 3 RD (n = 7, 2.8%; 95% CI, 1.1 to 5.7% v n = 17, 13.6%; 95% CI, 8.1 to 20.9%, OR: 0.19) and moist desquamation (n = 20, 8.0%; 95% CI, 4.9 to 12.0% v n = 24, 19.2%; 95% CI, 12.7 to 27.1%, OR: 0.36). When evaluating the combined patient and health care provider score using Radiation-Induced Skin Reaction Assessment Scale, the MF arm had significantly lower scores (P < .0001). Individual items on the Radiation-Induced Skin Reaction Assessment Scale also favored the MF for both patient- and clinician-reported outcomes. Blistering/peeling, erythema, pigmentation, and edema were significantly reduced in the MF arm. Three patients removed the film prematurely because of rash (n = 2) and excessive pruritus (n = 1). CONCLUSION: MF significantly reduces RD in patients undergoing breast radiotherapy.

A Prospective Study of Magnetic Resonance Imaging-guided Focal Salvage High-dose-Rate Brachytherapy for Radiorecurrent Prostate Cancer: Updated Results of 30 Patients.

PURPOSE: Limited prospective data on focal salvage high-dose-rate (HDR) prostate brachytherapy is available. We sought to explore the toxicities, health-related quality of life (HRQoL), and efficacy of focal salvage HDR brachytherapy in a prospective clinical trial. This report presents the updated results of previously published data. METHODS AND MATERIALS: Patients with locally recurrent prostate cancer after previous external beam radiation therapy and/or brachytherapy were enrolled. Patients received magnetic resonance imaging (MRI)-guided, ultrasound-based focal HDR brachytherapy delivered over 2 fractions of 13.5 Gy delivered 1 to 2 weeks apart. Androgen deprivation therapy (ADT) was not used. RESULTS: Thirty patients were treated between 2012 and 2019. At a median follow-up time of 39 months, the 3-year biochemical failure-free rate was 61.8% (95% confidence interval, 44.0%-86.6%), and the 3-year ADT/salvage therapy-free rate was 86.0% (95% confidence interval, 74.1%-99.8%). Seventeen patients experienced subsequent biochemical failure, 9 received ADT and/or further local salvage, and no patients died of prostate cancer. Of the 28 patients who had posttreatment MRI, 26 had a local treatment response. No acute grade ≥3 genitourinary/gastrointestinal toxicity was observed. One temporary late grade 3 genitourinary toxicity event occurred, but no late grade ≥3 gastrointestinal toxicity was seen. No significant decline in urinary or bowel HRQoL was observed. CONCLUSIONS: Focal salvage HDR brachytherapy has a favorable side effect profile, no significant decline in HRQoL, and the 3-year biochemical control rates are in line with those of other salvage options. Early MRI response at the treated site is common, but does not preclude subsequent biochemical failure.

Symptom Burden Associated With Radiation Dermatitis in Breast Cancer Patients Undergoing Radiotherapy.

PURPOSE: Radiation dermatitis (RD) is a side effect experienced by many patients undergoing radiotherapy (RT) for breast cancer. In the present study, the Edmonton Symptom Assessment System (ESAS), a validated patient-reported symptom screening tool, was used to determine the impacts of RT-induced skin outcomes on ESAS items. Patient- and treatment-related factors and skin treatments to manage RD symptoms, were assessed for association with ESAS scores. METHODS: Patient and treatment characteristics were collected retrospectively for breast cancer patients treated with adjuvant RT between December 2013 and November 2015. Prospective data was collected through clinician-reported surveys. Linear regression analyses were performed to detect the relationship between patient-reported ESAS scores and clinician-reported RD symptoms. RESULTS: A total of 857 patients were included in the analysis. Moderate to severe scores were commonly reported for fatigue (n = 412, 48%), wellbeing (n = 386, 45%) and anxiety (n = 266, 31%). Oral analgesic use was associated with ESAS fatigue, drowsiness, pain, nausea, lack of appetite, shortness of breath, and wellbeing (P < .05), while dressings were only associated with anxiety (P = .02). No RD symptoms were found to be significantly associated with any ESAS items. CONCLUSIONS: The ESAS accurately reflects symptoms of fatigue, anxiety, and wellbeing for breast cancer patients undergoing RT. Our study, however, found no association between ESAS scores and RD severity, which may reflect the shortcomings of the ESAS in assessing symptom burden. Further research is necessary to warrant the development of a new site-specific symptom screening tool for use in RT for breast cancer.

Case series of radiation pneumonitis in breast cancer.

BACKGROUND: Radiation pneumonitis (RP) is a potentially severe inflammatory reaction that occurs in approximately 1-16% of breast cancer patients treated with radiation (RT). METHODS: Case histories and patient demographics were collected from 4 patients who received either hypofractionated (42.56 Gy in 16 fractions) or conventionally fractionated (50 Gy in 25 fractions) RT for breast cancer at a cancer centre from 2018-2020 and experienced clinically symptomatic RP. Lung dose parameters including mean lung dose, V5, and V20 were collected from institutional planning software and compared to institutional guidelines. RESULTS: The 4 cases were all female, aged 42-73 years old and received 2- or 4-field RT with wide or high tangent techniques. The most common symptoms in patients who developed RP were exertional dyspnea and dry cough. Corticosteroid doses in the daily range of 40-60 mg were the primary treatment followed by a highly variable tapering schedule. Two patients experienced a recurrence of symptoms after initial treatment and were restarted on corticosteroids. Patients had several predisposing risk factors including administration of wide tangents, chemotherapy with cyclophosphamide and/or taxanes, age>65 years, and comorbidities such as diabetes. DISCUSSION: Identification of RP is difficult as evidenced by the large gap in time between the appearance of RP symptoms to treatment with corticosteroids in several patients. Irregular tapering schedules may contribute to symptom recurrence. Three of the four patients treated with 4-field wide tangents exceeded the 35% dose constraint for ipsilateral lung V20 or V17.5. CONCLUSION: Careful radiation planning and review of lung dose constraints is essential to reduce risk of RP. Greater standardization of steroid tapering practices is recommended.

Dosimetry and outcomes in patients receiving radiotherapy for synchronous bilateral breast cancers.

BACKGROUND: Synchronous bilateral breast cancer (SBBC) is rare and there is little evidence describing organs at risk (OAR) and limits to the heart and lungs caused by radiotherapy (RT). Quantifying mean heart dose (MHD) and mean lung dose (MLD) from RT in this patient cohort may lead to better understanding of doses to OAR and resultant effects on clinical outcomes. The primary objective was to assess median MHD and MLD in SBBC, while secondary aims included analyses of 1) factors associated with MHD and MLD, 2) V5 and V20 values and 3) factors associated with clinical outcomes. METHODS: Patients planned for adjuvant bilateral whole breast/chest wall (WB) RT from a single institution treated in 2011-2018 were included. Median MHD and MLD (Gy) were stratified by hypofractionated (42.56 Gy/16 fractions, HFRT) and conventional fractionation (50 Gy/ 25 fractions, CFRT) and summarized separately based on the following treatments: 1) locoregional RT, WB tangential RT either 2) no boost 3) sequential boost or 4) simultaneous integrated boost. MHD, MLD, lung V5 and V20 values, and demographics were collected. Linear regression analyses identified factors associated with MHD and MLD and factors associated with clinical outcomes. RESULTS: A total of 88 patients were included. The median MHD for HFRT and CFRT was 1.99 Gy and 2.94 Gy, respectively. The median MLD for HFRT and CFRT was 6.00 Gy and 10.08 Gy, respectively. MHD and MLD were significantly associated with the occurrence of a cardiac or pulmonary event post-radiation. Patients who had a mastectomy or tumoral muscle involvement were more likely to develop a local recurrence, metastasis or new primary while patients who had a lumpectomy or tumor with a positive estrogen receptor status were less likely to experience these events. CONCLUSIONS: Further investigation should be conducted to identify SBBC RT techniques that mitigate dose to OARs to improve clinical outcomes in bilateral breast patients.

Predictive factors associated with radiation dermatitis in breast cancer.

PURPOSE: Radiation dermatitis (RD) is a side effect that frequently arises during radiotherapy (RT) in breast cancer patients. The present study investigates possible predictive factors of RD, as well as the use of skin treatments to manage symptoms. METHODS: Demographic and treatment characteristics were collected retrospectively, while skin symptoms and treatments were collected prospectively for patients who received adjuvant RT between December 2013 and November 2015. Patients were seen weekly by clinicians throughout treatment, during which a clinician-reported survey was completed on RD symptoms and skin treatments. Possible predictive factors were correlated with skin outcomes through a univariate ordinal logistic regression analysis. RESULTS: A total of 1093 patients were included in this analysis. Predictive factors for erythema included dose fractionation (p<0.0001), tissue volume irradiated by tangential fields (p = 0.01), and administration of a boost (p = 0.005). High BMI (≥30 kg/m2) (p = 0.0004) and boost (p = 0.02) were predictive of edema. A dose of 50 Gy/25 (p<0.0001) and a high irradiated tissue volume (p = 0.0001) were predictive of desquamation. A dose of 50 Gy/25 (p = 0.0005) and high BMI (p = 0.02) were predictors of pain. Bolus use was the only factor associated with bleeding (p = 0.02). Patients who developed desquamation were likely to receive corticosteroids/antihistamines (p<0.0001), topical antibiotics/antifungals (p<0.001), and dressings (p<0.0001). CONCLUSION: The findings of this study provide evidence of potential predictors of RD and methods of symptom management based on symptom severity. Prevention of RD is needed among high-risk groups, such as patients with a high BMI or receiving a standard fractionation, boost, or bolus.

A Feasibility Study of Mepitel Film for the Prevention of Breast Radiation Dermatitis in a Canadian Center.

PURPOSE: Severe radiation dermatitis (RD) is distressing and may have adverse long-term effects including fibrosis and telangiectasia. Treatment interruptions due to severe RD may increase the risk of recurrence. Two randomized trials of Mepitel film demonstrated efficacy in preventing severe RD in breast cancer, but this product has not been widely adopted in North America. We aimed to assess the feasibility and efficacy of Mepitel film for prevention of breast RD at a Canadian center. METHODS AND MATERIALS: Patients were stratified based on breast size and receipt of postmastectomy radiation therapy. The primary outcome was RD grade using the Common Terminology Criteria for Adverse Events. Secondary outcomes included moist desquamation, patient- and clinician-reported symptoms of skin toxicity, and cosmetic outcomes. RESULTS: Thirty patients receiving external beam radiation therapy to the breast or chest wall were enrolled. Two patients (6.7%) discontinued use of the Mepitel film before completing radiation therapy. No patients developed grade 3 RD or higher. Five patients (17.9%) developed grade 2 RD: 3 (10.7%) had moist desquamation, and 2 (7.1%) had brisk erythema without moist desquamation. CONCLUSIONS: Mepitel film completely prevented grade 3 RD. Rates of moist desquamation and grade 2 RD were lower with Mepitel film than in studies using aqueous cream, but unlike previous trials of Mepitel film we did not achieve complete prevention of moist desquamation. Further research is needed to confirm the efficacy of Mepitel film versus standard prophylaxis for RD and identify the patients who will benefit the most from the film.

Assessment of Radiation-Induced Malfunction in Cardiac Implantable Electronic Devices.

BACKGROUND: Radiation therapy (RT) is a standard cancer treatment modality, and an increasing number of patients with cardiac implantable electronic devices (CIEDs) are being referred for RT. The goals of this study were as follows: (i) to determine the incidence of CIED malfunction following RT; (ii) to characterize the various types of malfunctions that occur; and (iii) to identify risk factors associated with CIED malfunction following RT. METHODS: A retrospective study of patients with CIEDs who received RT between 2007 and 2018 at 4 Canadian centres (Sunnybrook Health Sciences Centre, Kingston General Hospital, Hamilton Health Sciences Centre, and University of Ottawa Heart Institute) was conducted. Patients underwent CIED interrogation after completion of RT, to assess for late damage to the CIEDs. Data on demographics, devices, and RT were compared for the primary outcome of device malfunction. RESULTS: Of 1041 patients with CIEDs who received RT, 811 patients with complete data were included. Device malfunctions occurred in 32 of 811 patients (4%). The most common device malfunctions were reduced ventricular/atrial sensing (in 13 of 32 [41%]), an increase in lead threshold (in 9 of 32 [22%]), lead noise (in 5 of 32 [16%]), and electrical reset (in 2 of 32 [6%]). Higher beam energy (≥ 10 MV) was associated with malfunction (P < 0.0001). Radiation dose was not significantly different between the malfunction and non-malfunction groups (58.3 cGy vs 65 cGy, respectively, P = 0.71). CONCLUSIONS: Although RT-induced CIED malfunctions are rare (occurring in 4% of patients with a CIED who undergo RT), collaborative efforts between radiation oncologists and cardiac rhythm device clinics to optimize CIED monitoring are needed, to detect and manage CIED malfunctions. Malfunctions are more common in patients receiving higher-beam energy ( ≥ 10 MV ) RT.

CONTEXTE: La radiothérapie (RT) est une modalité standard de traitement du cancer, et un nombre croissant de patients porteurs de dispositifs cardiaques électroniques implantables (DCEI) doivent recevoir un traitement de RT. Les objectifs de cette étude étaient les suivants : (i) déterminer l'incidence d'une défaillance du DCEI après une RT; (ii) caractériser les différents types de défaillances qui se produisent; (iii) déterminer les facteurs de risque associés à la défaillance du DCEI après une RT. MÉTHODOLOGIE: Une étude rétrospective des patients avec un DCEI ayant reçu une RT entre 2007 et 2018 dans quatre centres canadiens (Sunnybrook Health Sciences Centre, Kingston General Hospital, Hamilton Health Sciences Centre et Institut de cardiologie de l'Université d'Ottawa) a été menée. Le DCEI des patients a été interrogé après la fin de la RT, pour en évaluer les dommages tardifs. Les données sur les caractéristiques démographiques, les dispositifs et la RT ont été comparées pour le paramètre d'évaluation principal, soit la défaillance du dispositif. RÉSULTATS: Sur les 1 041 patients avec un DCEI ayant reçu une RT, 811 patients avec des données complètes ont été inclus. Des défaillances du dispositif sont survenues chez 32 des 811 patients (4 %). Les défaillances les plus fréquentes du dispositif étaient une détection ventriculaire/atriale réduite (chez 13 des 32 patients [41 %]), une augmentation du seuil de la sonde (chez 9 des 32 patients [22 %]), un bruit provenant de la sonde (chez 5 des 32 patients [16 %]) et une réinitialisation électrique (chez 2 des 32 patients [6 %]). Une énergie de faisceau plus élevée (≥ 10 MV) était associée à une défaillance (p < 0,0001). La dose de rayonnement ne présentait pas de différence significative entre le groupe où une défaillance a été constatée et l'autre groupe (58,3 cGy vs 65 cGy, respectivement, p = 0,71). CONCLUSIONS: Bien que les défaillances du DCEI causées par la RT soient rares (survenant chez 4 % des patients avec un DCEI qui subissent une RT), une collaboration est nécessaire entre les radio-oncologues et les cliniques de dispositifs de gestion du rythme cardiaque, afin d'optimiser la surveillance du DCEI et de détecter et de gérer ces défaillances. Les défaillances sont plus fréquentes chez les patients recevant une énergie de faisceau plus élevée au moment de la RT ( ≥ 10 MV ) .

Quantitative Effect of Bolus on Skin Dose in Postmastectomy Radiation Therapy.

BACKGROUND: In postmastectomy radiation therapy (PMRT), some centres prescribe the use of a tissue-equivalent bolus to the skin to reduce the risk of chest wall recurrence. The addition of bolus causes an increase in the skin dose, which may lead to increased risk of radiodermatitis. Radiodermatitis can decrease patients' overall quality of life, bringing into question the benefit of using the bolus. The purpose of this retrospective chart review was to quantify the increase in skin dose associated with the use of bolus in the PMRT setting. MATERIALS AND METHODS: We evaluated 70 patients who underwent PMRT at our institution during 2012-2018. Two similar treatment plans were generated for each patient: one with bolus and one without. Skin dose-volume histogram values were evaluated, and statistical analysis was performed using MATLAB R2015b. RESULTS: There was no significant difference in the maximum skin dose within a depth of 5 mm for bolus versus nonbolus plans (P = 0.4). However, within a depth of 3 mm, bolus plans had a maximum skin dose 7% ± 2.5% higher than the nonbolus plans (P < .00001). Mean skin dose within depths of 3 and 5 mm were both significantly higher (P < .00001) for bolus plans. The photon beam energy and chest wall separation showed minimal or no effect on skin dose. CONCLUSION: Given the differing opinions in the literature regarding the role for bolus in PMRT, there is still uncertainty of the optimal treatment method. This retrospective study demonstrates a 20%-30% reduction in mean skin dose when bolus is not used.

Factors Affecting Mean Heart Dose in Patients Receiving Breast Radiotherapy from 2011 to 2018 in a Single Institution.

INTRODUCTION: Breast cancer radiotherapy (RT) can increase the risk of cardiac disease with increasing dose; as such, reducing excessive dosage to the heart is a concern for clinicians. The purpose of the present study was to assess mean heart dose (MHD) in patients with breast cancer receiving RT, where it was hypothesized that MHD decreased over time. METHODS: Patients planned for adjuvant unilateral whole breast/chest wall RT from 2011 to 2018 were included for a retrospective chart-review at a single-institution, academic center. MHD (Gy) was summarized by laterality, fractionation, and heart-sparing techniques. RESULTS: A total of 4,687 patients were included. The median MHD for left-sided conventional RT (50 Gy in 25 fractions) was 2.16 Gy across all years, decreasing until 2015 and increasing after. Median MHD for left-sided hypofractionated RT (42.6 Gy in 16 fractions) was 1.47 Gy, also decreasing until 2015 and increasing after. The increase in MHD after 2015 was attributed to a significant increase in the use of wide tangents (including internal mammary chain) after 2015 (P < .0001). Several treatment factors were associated with higher MHD in both right- and left-sided cancers, including locoregional RT, high tangents, wide tangents, bolus, heart shielding, treatment to the chest wall, higher volume of tissue irradiated by tangential fields, higher baseline breast separation values, and smaller heart volume. After adjusting for laterality and fractionation in the multivariate analysis, locoregional RT, wide tangents, heart shielding, boost, treatment to the chest wall, higher volume of tissue irradiated by tangential fields, higher baseline breast separation, and lower heart volume were significantly associated with higher MHD (P < .0001). DISCUSSION/CONCLUSIONS: MHD should be considered when determining the most appropriate RT techniques for both right- and left-sided cancers as higher MHD was significantly associated with various treatment techniques and patient factors.

Use of Adjuvant Breast Hypofractionation Radiation Treatment at a Cancer Center in Ontario From 2011 to 2018.

BACKGROUND: The adoption of hypofractionated radiotherapy (HFRT) into clinical practice varies widely despite randomized trials and guidelines supporting its equivalence to conventional fractionated radiotherapy (CFRT) for certain patient populations. We assessed the use of HFRT at a single institution from 2011 to 2018, as well as time-savings calculations. PATIENTS AND METHODS: A retrospective cohort study was conducted for patients with breast cancer receiving adjuvant radiotherapy by HFRT or CFRT. Trends in HFRT use (≤ 16 fractions) were stratified according to 4 subgroups: tangential breast RT, locoregional breast RT, tangential chest wall RT, and locoregional chest wall RT. Treatment time savings were approximated using the institutional median treatment time. RESULTS: A total of 5190 patients were included. HFRT use in all subgroups increased from 2011 to 2018. Tangential breast HFRT alone increased from 62.2% in 2011 to 96.9% in 2018. Locoregional breast HFRT and tangential chest wall HFRT use increased from less than 10% in 2011 to 76.2% and 76.9% in 2018. In locoregional chest wall RT, HFRT use of 44.9% was observed in 2018. Increased use of locoregional HFRT was mainly due to institutional policy changes. Time-savings calculations showed that 4002 hours of treatment or an additional 1402 HFRT courses could have been administered if all patients received HFRT. CONCLUSION: The use of HFRT at our center increased in all patient subgroups. More evidence and guidelines for patients receiving chest wall or locoregional HFRT are required because the use of HFRT remains low in these patient cohorts.

Comparison of CTVHR and organs at risk contours between TRUS and MR images in IB cervical cancers: a proof of concept study.

PURPOSE: To compare CTVHR and OAR dimensions and inter-rater agreement between magnetic resonance (MR) and trans-rectal ultrasound (TRUS) images in IB cervical cancer patients. METHODS: IB cervical cancer patients treated with (chemo)radiotherapy plus MR-guided brachytherapy (BT) were prospectively enrolled in this study. Radiation oncologists contoured CTVHR and OARs in pre-BT MR images (MRI) and intra-operative TRUS images. These contours were subsequently compared in regard to volume and dimension. Contour inter-rater agreement analysis was also investigated using kappa index (KI). Stata 15.0 was used for statistical analysis and a p-value < 0.05 was considered statistically significant. RESULTS: TRUS CTVHR volumes were statistically smaller than the respective MRI contoured volumes. TRUS CTVHR thickness was found to be consistently smaller than MRI contours in all patients. No statistical difference was seen in width and height between the two different imaging modalities. MRI contours had a median KI of 0.66 (range: 0.56-0.77) while TRUS-based contours had a median KI of 0.64 (range: 0.47-0.77). Bladder and rectum had very satisfactory KI in both imaging modalities. Vaginal contours had moderate agreement in MR (0.52) and in TRUS images (0.58). CONCLUSION: TRUS images allow good visualization of CTVHR and OARs in IB cervical cancer patients. Inter-rater contour variability was comparable between TRUS and MR images. TRUS is a promising modality on its own for image-guided BT.

Mepitel Film and Mepilex Lite for the prophylaxis and treatment of skin toxicities from breast radiation.

Despite the prevalence of radiation dermatitis in breast cancer patients, current practice guidelines for its treatment are limited. We aimed to discuss the quality of evidence for the barrier-forming Mepitel Film for prophylaxis of radiation dermatitis, and argue for further investigation into evidence-based management of skin toxicities. Two studies assessing Mepitel Film were critically evaluated. Both reported that Mepitel Film decreased radiation dermatitis; moreover, patient-reported outcomes significantly favoured Mepitel Film. However, there has not been global adoption of barrier-forming films such as Mepitel, in part due to the absence of multi-centred randomised trials and the heterogeneity of study designs.

The radiobiological impact of motion tracking of liver, pancreas and kidney SBRT tumors in a MR-linac.

The purpose of this work is to evaluate and quantify the potential radiobiological advantages of tumor tracking using the MR-linac for three disease sites: liver, pancreas and kidney. From each disease site, three patients were selected and 4DCT data sets were used. We applied two planning methods using the Monaco treatment planning system (Elekta AB,Stockholm,Sweden): (1) the conventional ITV method using a 6MV Agility beam and (2) a simulated tracking method using MLC GTV tracking with a 7MV MR-linac beam model incorporating a 1.5 T transverse magnetic field. A 5 mm isotropic PTV margin was added to the ITV or the GTV, and 95% of the PTV volume received 100% of the prescription dose. To evaluate the potential radiobiological advantages of tumor tracking, the normal tissue complication probabilities (NTCPs) were calculated for each organ at risk (OAR) using the Layman Kutcher Burman (LKB) model. The average reduction in the target volume, due to tracking, was 31.1%, 26.3% and 26.9% for liver, pancreas and kidney patients, respectively. For each OAR, the % differences in NTCP between the two methods were calculated. The mean 2 Gy equivalent OAR dose for all patients was less than 29.1 Gy, below which the NTCP for most OARs was not sensitive to equivalent uniform dose (EUD). As a result, a NTCP benefit, due to tracking, was observed in 26% of the data. For all three disease sites, the maximum NTCP improvements were for the normal kidney, the bowels, and the duodenum, with reductions in associated toxicities of 79% (radiation nephropathy), 69% (stricture/fistula) and 25% (ulceration), respectively. This study demonstrates the potential benefit of using a MR-linac tracking system to reduce NTCPs. The normal kidney, the bowels and the duodenum showed the largest NTCP improvements. This, in part, is due to the rapid changes in NTCP for small EUD changes.

Focal Salvage High Dose-Rate Brachytherapy for Locally Recurrent Prostate Cancer After Primary Radiation Therapy Failure: Results From a Prospective Clinical Trial.

PURPOSE: Although increasing data support whole-gland salvage therapy for recurrent prostate cancer, toxicity remains a significant concern. We hypothesized that focal therapy, treating only a portion of the prostate containing recurrent disease, might be equally effective and associated with less toxicity. The objectives of this prospective study were to explore the toxicities, quality of life, and efficacy of focal salvage high-dose-rate (HDR) brachytherapy in patients with multiparametric magnetic resonance imaging (MRI)-visible, biopsy-confirmed local recurrence after previous definitive external beam radiation therapy. MATERIALS AND METHODS: Fifteen patients with locally recurrent prostate cancer after external beam radiation therapy were enrolled in this prospective study. Patients were treated with ultrasound-based HDR brachytherapy with a prescription dose of 27 Gy divided in 2 implants, separated by 1 week, to the clinical target volume, which was defined as the quadrant of the prostate where the MRI-visible recurrent lesion was located. Toxicity, quality of life, and biochemical outcomes were analyzed. Postsalvage MRI was performed to assess radiation therapy response. RESULTS: Median follow-up was 36 months. The median size of the recurrence on MRI was 9 mm (range, 7-20 mm), and clinical target volume at the time of HDR was 6.1 mL (range, 2.2-16.1 mL). Only one grade 3 genitourinary toxicity event was observed. No urinary retention was observed. Three-year prostate-specific antigen failure-free rate was 61%. There was no significant change in Expanded Prostate Cancer Index Composite urinary or bowel domains over time. Of the 14 patients who had a post-HDR MRI, 12 had a treatment response. CONCLUSIONS: Our results suggest that focal salvage HDR brachytherapy is well tolerated and promising. External validation is needed.

Evaluation of a new predictor of heart and left anterior descending artery dose in patients treated with adjuvant radiotherapy to the left breast.

BACKGROUND: Heart-sparing techniques are time and resource intensive, although not all patients require the use of these strategies. This study evaluates the performance of different distance metrics in predicting the need for breath-hold radiotherapy in left-sided breast cancer patients receiving adjuvant radiotherapy. METHODS: Fifty left-sided breast cancer patients treated with breast conserving surgery and adjuvant radiotherapy to the breast from a single institution were retrospectively studied. The left breast and organs at risk were contoured in accordance to guidelines and a plan with tangents was obtained using the free-breathing CT in supine position. Heart (mean heart dose (MHD), heart V25 Gy) and left anterior descending artery dosimetry were computed and compared against distance metrics under investigation (Contact Heart, 4th Arch and 5th Arch). Recursive partitioning analysis (RPA) was used to determine optimal cut-points for distance metrics for dosimetric end points. Receiver operating characteristic curves and Pearson correlation coefficients were used to evaluate the association between distance metrics and dosimetric endpoints. Univariable and multivariable logistic regression analysis was performed to identify significant predictors of dosimetric end points. RESULTS: The mean MHD and heart V25 Gy were 2.3 Gy and 10.4 cm3, respectively. With tangents, constraints for MHD (< 1.7 Gy and V25 Gy < 10 cm3) were unattainable in 80% and 46% of patients, respectively. Optimal RPA thresholds included: Contact Heart (73 mm), 4th Arch (7 mm) and 5th Arch (41 mm). Of these, the 4th Arch had the highest overall accuracy, sensitivity, concordance index and correlation coefficient. All metrics were statistically significant predictors for MHD ≥ 1.7 Gy based on univariable logistic regression. Fifth Arch did not reach significance for heart V25 Gy ≥ 10 cm3. Fourth Arch was the only predictor to remain statistically significant after multivariable analysis. CONCLUSIONS: We propose a novel "4th Arch" metric as an accurate and practical tool to determine the need for breath-hold radiotherapy for left-sided breast cancer patients undergoing adjuvant radiotherapy with standard tangents. Further validation in an external cohort is necessary.

A Systematic Review of Heart Dose in Breast Radiotherapy.

Radiotherapy (RT) for breast cancer improves survival, but poses risk to the heart, resulting from a linear relationship between RT dose and heart disease. This review presents studies worldwide reporting heart doses from whole breast RT after 2014 to update a previous systematic review (Taylor et al, Int J Radiat Oncol Biol Phys, 2015) in order to determine patterns of current heart dosimetry among varying RT regimens. Studies published between January 2014 and September 2017 were included if they reported whole heart dose based on whole breast RT technique or treatment position and had a sample size of ≥ 20 patients. Studies reporting brachytherapy, proton RT only, or boost to tumor bed were excluded. Among 99 studies, whole heart dose was reported by 231 regimens. The mean heart dose for left-sided breast cancer, reported by 84 studies (196 regimens), was 3.6 Gy, compared with a review of those previously reported (5.4 Gy). Regimens employing breathing control in any position had a significantly lower mean heart dose (1.7 Gy) compared with regimens without breathing control (4.5 Gy) (P < .0001). The mean heart dose varied significantly between continents (P < .0001), with heterogeneity reported among countries within Europe (P = .04) although not within other continents. On average, the mean heart dose steadily decreased between 2014 (4.6 Gy) and 2017 (2.6 Gy) (P = .003). Other heart dose parameters including the mean dose to the left anterior descending artery were reported by 80 left-sided regimens, and the mean left anterior descending artery dose was 12.4 Gy.

Characterizing the impact of adaptive planning on image-guided perineal interstitial brachytherapy for gynecologic malignancies.

PURPOSE: To determine the dosimetric impact of organ and implant motion/deformation in the context of adaptive planning in image-guided gynecologic brachytherapy using a 3-fraction transperineal approach. METHODS AND MATERIALS: Twenty-six patients were analyzed. Each patient was treated with three fractions given over a 24-h period using a single insertion. A planning CT scan (±MRI) was acquired before the first fraction. A verification scan was taken within 1 h following the second fraction. A single plan was delivered for Fractions 1 and 2 with an adaptive plan delivered for Fraction 3. Two evaluation frameworks were established. Framework 1 investigated the effects of motion/deformation from both implant and organs. Framework 2 investigated the impact of implant motion/deformation alone. Differences in high-risk clinical target volume (HRCTV) D90%, V100%, and bladder/rectum D2cc were assessed. RESULTS: From implant to verification, the HRCTV D90% and V100% decreased significantly (5.0%, p < 0.01; 3.1%, p < 0.01) and rectal D2cc was significantly higher (12.2%, p = 0.02). Adaptive planning recouped these changes. Implant changes resulted in a reduction in HRCTV dose and coverage, but no significant effect was seen in the bladder or rectum. CONCLUSIONS: Adaptive planning represents an important aspect of perineal-based interstitial image-guided brachytherapy given in three fractions; its absence would result in plan degradation.

Pattern of relapse and dose received by the recurrent intraprostatic nodule in low- to intermediate-risk prostate cancer treated with single fraction 19 Gy high-dose-rate brachytherapy.

PURPOSE: The purposes of this study were to investigate the pattern of relapse in patients with low- or intermediate-risk prostate cancer treated with 19-Gy high-dose-rate brachytherapy (HDR-BT) and to calculate the dose received by the area of recurrence. METHODS AND MATERIALS: Patients included in this analysis were treated under a Phase II randomized trial that evaluated the role of 19-Gy HDR-BT monotherapy in low- and intermediate-risk prostate cancers. Multiparametric prostate MRI and prostate biopsy were performed in patients with suspicious local recurrence. The site of local relapse was compared with the initial site of disease. The dose received by the site of recurrence was investigated through registration of the posttreatment multiparametric prostate MRI with the HDR-BT treatment plan. RESULTS: Eight of 87 treated patients were found to have local recurrence after 19-Gy HDR-BT. Seven of the eight recurrences were at the site of initial bulk disease. Seven patients were found to have a more aggressive histology in the posttreatment biopsy. The mean volume of prostate that had received 100% of prescription dose was 97%. Mean dose to area of recurrence was 29.1 Gy, whereas dose to 98% and dose to 90% of the recurrence were 21.6 Gy and 23.2 Gy, respectively. CONCLUSIONS: The relapse pattern after a single 19-Gy HDR-BT is predominantly associated with the site of initial disease. This lends some rationale to future strategies of further focused dose escalation to initial site of disease, notwithstanding the fact that the calculated biologically equivalent dose using linear-quadratic assumptions is already very high.