Dose de-intensified 3-day photon, proton, or brachytherapy: a nonrandomized controlled partial breast irradiation trial.

BACKGROUND: The optimal approach for partial breast irradiation (PBI) is unknown. We investigated a novel de-intensified 3-fraction PBI regimen for photons, protons, and brachytherapy. METHODS: A multicenter nonrandomized controlled trial with primary outcome of adverse cosmesis at 3 years versus pre-PBI. Eligibility criteria were ≥ age 50 years treated with breast-conserving surgery for node-negative estrogen receptor positive (ER+) invasive breast cancer or any ductal carcinoma in-situ (DCIS) measuring ≤ 2.5 cm. Photon and proton PBI were prescribed 21.9 Gy (RBE) and brachytherapy 21 Gy in 3 fractions. Radiotherapy technique and use of adjuvant endocrine therapy was selected at physician and patient discretion. RESULTS: Between June 17, 2015 and July 13, 2017, 161 eligible patients were treated with photons (56), protons (49), or brachytherapy (56). Median patient age was 66.8 years. 126 (78.3%) had invasive breast cancer (all ER+) and 35 (21.7%) had DCIS (88.6% ER+). 54.0% of patients with invasive breast cancer and 25.8% of patients with ER+ DCIS initiated and adhered to prescribed endocrine therapy. The proportion of patients with adverse cosmesis (by trained nurse assessment) was 14.5% at baseline, 2.3% at 3 years (difference -12.2%, 95% CI (-100%, -6.4%)). Adverse cosmesis at last-follow-up, with median follow-up 5 years, was 5.7% by nurse assessment, 5.6% by panel assessment of digital photographs, and 5.2% by patient self-report. There were no observed clinically meaningful changes in other patient reported outcomes, and just two grade 2 or higher adverse events, both grade 2, in the brachytherapy cohort. 5-year local recurrence-free and progression-free survival were 98.0% and 95.5%, respectively. There were no local recurrences amongst 60 patients with invasive breast cancer and Ki67 ≤ 13.25%. CONCLUSIONS: De-intensified 3-day PBI provided favorable disease control, tolerability, and cosmetic outcomes, meeting the pre-specified criteria for acceptability. This approach is an attractive option for small node-negative ER+ BC and DCIS patients. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02453737.

Secondary breast angiosarcoma following accelerated partial breast irradiation with intracavitary multicatheter applicator brachytherapy.

PURPOSE: Secondary angiosarcoma of the breast is a rare complication of breast radiotherapy and is associated with a poor prognosis. There are many reported cases of secondary angiosarcoma following whole breast irradiation (WBI), however development of secondary angiosarcoma following brachytherapy-based accelerated partial breast irradiation (APBI) is not as well characterized. METHODS AND MATERIALS: We reviewed and reported a case of a patient who developed secondary angiosarcoma of the breast following intracavitary multicatheter applicator brachytherapy APBI. RESULTS: A 69-year-old female was originally diagnosed with T1N0M0 invasive ductal carcinoma of the left breast and treated with lumpectomy followed by adjuvant intracavitary multicatheter applicator brachytherapy APBI. Seven years following her treatment, she developed secondary angiosarcoma. However, the diagnosis of secondary angiosarcoma was delayed due to nonspecific imaging findings and a negative biopsy. CONCLUSIONS: Our case highlights the need for secondary angiosarcoma to be considered in the differential diagnosis when patients present with symptoms such as breast ecchymosis and skin thickening following WBI or APBI. Prompt diagnosis and referral to a high-volume sarcoma treatment center for multidisciplinary evaluation is vital.

Proton therapy for the treatment of inflammatory breast cancer.

PURPOSE: Inflammatory breast cancer (IBC) poses a radiotherapeutic challenge due to dermal lymphatic involvement, which often necessitates larger target volumes and chest wall boosts, making advanced planning techniques attractive to reduce exposure to nearby organs. We report our experience with intensity modulated proton therapy (IMPT) for the treatment of IBC. METHODS: Between 2016 and 2020, all IBC patients treated with adjuvant IMPT at our institution were identified. Overall survival (OS) and distant metastasis-free survival (DMFS) were estimated using the Kaplan-Meier method. Adverse events (AEs) were assessed using CTCAE version 5.0. RESULTS: Nineteen patients were identified with median 24-month follow-up. CTVs included skin, chest wall, and regional lymph nodes. Median dose was 50 Gy in 25 fractions, with fifteen receiving chest wall boost (median 56.25 Gy in 25 fractions). During treatment, plan re-optimization was required in 9 (47%). Acute grade 3 dermatitis occurred in 2 (11%). Rib facture occurred in 4 (21%). One patient with pre-existing surgical seroma experienced a grade 3 fistula. Mean heart, left anterior descending artery, and right coronary artery doses were 0.7 Gy, 2.3 Gy, and 0.1 Gy, respectively. Mean ipsilateral lung V20Gy was 14.9%. At 2 years, there were no locoregional recurrences, and OS and DMFS were 89% and 82%, respectively. CONCLUSION: IMPT for IBC is well-tolerated with excellent dosimetry, low rates of AEs, and favorable early locoregional control outcomes. Follow-up for long-term outcomes is ongoing. Our findings suggest that IMPT is feasible and an attractive modality worthy of further investigation in patients with IBC.