3 fraction pencil-beam scanning proton accelerated partial breast irradiation: early provider and patient reported outcomes of a novel regimen

• Published in: Radiation oncology (London, England) England), 2019-11, Vol.14 (1), p.211-9, Article 211
• Main Authors: Mutter, Robert W, Jethwa, Krishan R, Gonuguntla, Karthik, Remmes, Nicholas B, Whitaker, Thomas J, Hieken, Tina J, Ruddy, Kathryn J, McGee, Lisa A, Corbin, Kimberly S, Park, Sean S
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Brachytherapy; Breast - radiation effects; Breast cancer; Breast Neoplasms - psychology; Breast Neoplasms - radiotherapy; Cancer therapies; Complications and side effects; Dermatitis; Disease control; Dose Fractionation, Radiation; Dosimeters; Dosimetry; Edema; Estrogen Receptor alpha - metabolism; Estrogen receptors; Estrogens; Female; Fractionation; Humans; Hyperpigmentation; Imaging, Three-Dimensional; Invasiveness; Irradiation; Lymph nodes; Lymphatic system; Mastectomy; Medical research; Middle Aged; Monte Carlo simulation; Novels; Patient Reported Outcome Measures; Patients; Phenols (Class of compounds); Physicians; Planning; Prospective Studies; Proton beams; Proton Therapy - instrumentation; Proton Therapy - methods; Protons; Quality of Life; Radiation; Radiation therapy; Radiometry - methods; Radiotherapy Dosage; Recurrence; Scanning; Side effects; Skin; Terminology; Terms and phrases; Toxicity; Treatment Outcome; Tumors
• ISSN: 1748-717X; 1748-717X
• DOI: 10.1186/s13014-019-1417-7

To report dosimetry and early adverse effects, aesthetic, and patient-reported outcomes of a prospective study of 3-fraction pencil-beam scanning (PBS) proton accelerated partial irradiation (APBI). Eligibility included women age ≥ 50 years with estrogen receptor positive (ER+), sentinel lymph node negative invasive or in-situ breast cancer measuring ≤2.5 cm. The prescription was 21.9 Gy (RBE 1.1) in 3 daily fractions to the post-operative tumor bed with a 1 cm expansion. Toxicities were collected using Common Terminology Criteria for Adverse Events (CTCAE) version 4.0, 10-point Linear Analog Scale Assessment, Patient-Reported Outcomes Version of the CTCAE, and the Harvard Breast Cosmesis Scale. Seventy-six women were treated between 2015 and 2017. The median breast volume receiving 50% of prescription or more was 28%. Median mean heart, mean ipsilateral lung, and maximum skin dose were 0 Gy, 0.1 Gy, and 20.6 Gy, respectively. With a median follow-up of 12 months, no treatment-related toxicity grade ≥ 2 has been observed. Most common grade 1 adverse events were dermatitis (68%) and skin hyperpigmentation (18%). At 12 months, the only persistent toxicities were one patient with grade 1 breast edema and one patient with a grade 1 seroma. 90% of patients reported quality of life as ≥7 out of 10 (0 indicating "as bad as it can be" and 10 indicating "as good as it can be") and 98% of patients reported excellent or good cosmesis. 3-fraction PBS proton APBI is well tolerated with low rates of physician and patient reported early adverse effects. Follow-up is ongoing to assess late toxicities and disease control outcomes. Further investigation of this novel adjuvant treatment strategy is warranted.