title: Partial breast radiation therapy with proton beam: 5-year results with cosmetic outcomes.
abstract: OBJECTIVE
  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
  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.
authors.affiliation: Department of Radiation Oncology, Loma Linda University Medical Center, Loma Linda, California. Electronic address: dbush@llu.edu.
authors.forename: David A
authors.initials: DA
authors.lastname: Bush
authors.affiliation: Department of Radiation Oncology, Loma Linda University Medical Center, Loma Linda, California.
authors.forename: Sharon
authors.initials: S
authors.lastname: Do
authors.affiliation: Department of Surgical Oncology, Loma Linda University Medical Center, Loma Linda, California.
authors.forename: Sharon
authors.initials: S
authors.lastname: Lum
authors.affiliation: Department of Surgical Oncology, Loma Linda University Medical Center, Loma Linda, California.
authors.forename: Carlos
authors.initials: C
authors.lastname: Garberoglio
authors.affiliation: Department of Medical Oncology, Loma Linda University Medical Center, Loma Linda, California.
authors.forename: Hamid
authors.initials: H
authors.lastname: Mirshahidi
authors.affiliation: Department of Radiation Oncology, Loma Linda University Medical Center, Loma Linda, California.
authors.forename: Baldev
authors.initials: B
authors.lastname: Patyal
authors.affiliation: Department of Radiation Oncology, Loma Linda University Medical Center, Loma Linda, California.
authors.forename: Roger
authors.initials: R
authors.lastname: Grove
authors.affiliation: Department of Radiation Oncology, Loma Linda University Medical Center, Loma Linda, California.
authors.forename: Jerry D
authors.initials: JD
authors.lastname: Slater
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D018270:Carcinoma, Ductal, Breast / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D004954:Esthetics; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D015996:Survival Rate; D016896:Treatment Outcome; D047368:Tumor Burden