Experience with intraoperative radiation therapy in an urban cancer center

Abstract Background/objective Intra-operative radiation therapy (IORT) is a newer partial breast irradiation technique that has been well studied in 2 large randomized trials, the TARGIT-A and ELIOT trials. We initiated our IORT program in 2018 in the context of a registry trial, and aim to report our early results thus far. Methods We instituted an IORT practice using Intrabeam® low energy 50kVp x-rays for selected breast cancer cases in 2018. Patients were enrolled on our institutional registry protocol which allowed for IORT in ER + patients with grade 1–2 DCIS ≤ 2.5 cm or invasive disease ≤ 3.5 cm in patients of at least 45 years of age. Results Between January 2018 and December 2021, 181 patients with clinical stage 0-IIA ER + breast cancer were evaluated. One hundred sixty-seven patients ultimately received IORT to 172 sites. The majority of patients received IORT at the time of initial diagnosis and surgery (160/167; 95.8%). Re-excision post IORT occurred in 16/167 patients (9.6%) due to positive margins. Adjuvant RT to the whole breast +/- LN was ultimately given to 23/167 (13.8%) patients mainly due to positive sentinel LN found on final pathology (12/23; 52%); other reasons were close margins for DCIS (3/23; 13%), tumor size (3/23; 4.3%), and multifactorial (5/23; 17.4%). Five patients (3%) had post-operative complications of wound dehiscence. There were 3 local recurrences (1.6%) at a median follow-up of 27.9 months (range: 0.7– 54.8 months). Conclusions IORT has been proven to be a safe and patient-centered form of local adjuvant RT for our population, in whom compliance with a longer course of external beam radiation can be an issue. Long term efficacy remains to be evaluated through continued follow up. In the era of COVID-19 and beyond, IORT has been an increasingly attractive option, as it greatly minimizes toxicities and patient visits to the clinic. Trial registration All patients were prospectively enrolled on an institutional review board-approved registry trial (IRB number: 2018–9409)

Scalp Irradiation with 3D-Milled Bolus: Initial Dosimetric and Clinical Experience

Background and purpose: A bolus is required when treating scalp lesions with photon radiation therapy. Traditional bolus materials face several issues, including air gaps and setup difficulty due to irregular, convex scalp geometry. A 3D-milled bolus is custom-formed to match individual patient anatomy, allowing improved dose coverage and homogeneity. Here, we describe the creation process of a 3D-milled bolus and report the outcomes for patients with scalp malignancies treated with Volumetric Modulated Arc Therapy (VMAT) utilizing a 3D-milled bolus. Materials and methods: Twenty-two patients treated from 2016 to 2022 using a 3D-milled bolus and VMAT were included. Histologies included squamous cell carcinoma (n = 14, 64%) and angiosarcoma (n = 8, 36%). A total of 7 (32%) patients were treated in the intact and 15 (68%) in the postoperative setting. The median prescription dose was 66.0 Gy (range: 60.0–69.96). Results: The target included the entire scalp for 8 (36%) patients; in the remaining 14 (64%), the median ratio of planning target volume to scalp volume was 35% (range: 25–90%). The median dose homogeneity index was 1.07 (range: 1.03–1.15). Six (27%) patients experienced acute grade 3 dermatitis and one (5%) patient experienced late grade 3 skin ulceration. With a median follow-up of 21.4 months (range: 4.0–75.4), the 18-month rates of locoregional control and overall survival were 75% and 79%, respectively. Conclusions: To our knowledge, this is the first study to report the clinical outcomes for patients with scalp malignancies treated with the combination of VMAT and a 3D-milled bolus. This technique resulted in favorable clinical outcomes and an acceptable toxicity profile in comparison with historic controls and warrants further investigation in a larger prospective study