Partial breast radiation therapy with proton beam: 5-year results with cosmetic outcomes

David A Bush; Sharon Do; Sharon Lum; Carlos Garberoglio; Hamid Mirshahidi; Baldev Patyal; Roger Grove; Jerry D Slater

doi:10.1016/j.ijrobp.2014.05.1308

Partial breast radiation therapy with proton beam: 5-year results with cosmetic outcomes

Int J Radiat Oncol Biol Phys. 2014 Nov 1;90(3):501-5. doi: 10.1016/j.ijrobp.2014.05.1308. Epub 2014 Jul 30.

Authors

David A Bush¹, Sharon Do², Sharon Lum³, Carlos Garberoglio³, Hamid Mirshahidi⁴, Baldev Patyal², Roger Grove², Jerry D Slater²

Affiliations

¹ Department of Radiation Oncology, Loma Linda University Medical Center, Loma Linda, California. Electronic address: dbush@llu.edu.
² Department of Radiation Oncology, Loma Linda University Medical Center, Loma Linda, California.
³ Department of Surgical Oncology, Loma Linda University Medical Center, Loma Linda, California.
⁴ Department of Medical Oncology, Loma Linda University Medical Center, Loma Linda, California.

PMID: 25084608
DOI: 10.1016/j.ijrobp.2014.05.1308

Abstract

Purpose: We updated our previous report of a phase 2 trial using proton beam radiation therapy to deliver partial breast irradiation (PBI) in patients with early stage breast cancer.

Methods and materials: Eligible subjects had invasive nonlobular carcinoma with a maximal dimension of 3 cm. Patients underwent partial mastectomy with negative margins; axillary lymph nodes were negative on sampling. Subjects received postoperative proton beam radiation therapy to the surgical bed. The dose delivered was 40 Gy in 10 fractions, once daily over 2 weeks. Multiple fields were treated daily, and skin-sparing techniques were used. Following treatment, patients were evaluated with clinical assessments and annual mammograms to monitor toxicity, tumor recurrence, and cosmesis.

Results: One hundred subjects were enrolled and treated. All patients completed the assigned treatment and were available for post-treatment analysis. The median follow-up was 60 months. Patients had a mean age of 63 years; 90% had ductal histology; the average tumor size was 1.3 cm. Actuarial data at 5 years included ipsilateral breast tumor recurrence-free survival of 97% (95% confidence interval: 100%-93%); disease-free survival of 94%; and overall survival of 95%. There were no cases of grade 3 or higher acute skin reactions, and late skin reactions included 7 cases of grade 1 telangiectasia. Patient- and physician-reported cosmesis was good to excellent in 90% of responses, was not changed from baseline measurements, and was well maintained throughout the entire 5-year follow-up period.

Conclusions: Proton beam radiation therapy for PBI produced excellent ipsilateral breast recurrence-free survival with minimal toxicity. The treatment proved to be adaptable to all breast sizes and lumpectomy cavity configurations. Cosmetic results appear to be excellent and unchanged from baseline out to 5 years following treatment. Cosmetic results may be improved over those reported with photon-based techniques due to reduced breast tissue exposure with proton beam, skin-sparing techniques, and the dose fractionation schedule used in this trial.

Trial registration: ClinicalTrials.gov NCT00614172.

Publication types

Clinical Trial, Phase II

MeSH terms

Adult
Aged
Aged, 80 and over
Breast Neoplasms / mortality
Breast Neoplasms / pathology
Breast Neoplasms / radiotherapy*
Breast Neoplasms / surgery
Carcinoma, Ductal, Breast / mortality
Carcinoma, Ductal, Breast / pathology
Carcinoma, Ductal, Breast / radiotherapy*
Carcinoma, Ductal, Breast / surgery
Disease-Free Survival
Dose Fractionation, Radiation
Esthetics
Female
Follow-Up Studies
Humans
Mastectomy, Segmental
Middle Aged
Proton Therapy / adverse effects
Proton Therapy / methods*
Proton Therapy / mortality
Survival Rate
Treatment Outcome
Tumor Burden

Associated data

ClinicalTrials.gov/NCT00614172