title: Early toxicity in patients treated with postoperative proton therapy for locally advanced breast cancer.
abstract: OBJECTIVE
  To report dosimetry and early toxicity data in breast cancer patients treated with postoperative proton radiation therapy.
  
  
  METHODS
  From March 2013 to April 2014, 30 patients with nonmetastatic breast cancer and no history of prior radiation were treated with proton therapy at a single proton center. Patient characteristics and dosimetry were obtained through chart review. Patients were seen weekly while on treatment, at 1 month after radiation therapy completion, and at 3- to 6-month intervals thereafter. Toxicity was scored using Common Terminology Criteria for Adverse Events version 4.0. Frequencies of toxicities were tabulated.
  
  
  RESULTS
  Median dose delivered was 50.4 Gy (relative biological equivalent [RBE]) in 5 weeks. Target volumes included the breast/chest wall and regional lymph nodes including the internal mammary lymph nodes (in 93%). No patients required a treatment break. Among patients with >3 months of follow-up (n=28), grade 2 dermatitis occurred in 20 patients (71.4%), with 8 (28.6%) experiencing moist desquamation. Grade 2 esophagitis occurred in 8 patients (28.6%). Grade 3 reconstructive complications occurred in 1 patient. The median planning target volume V95 was 96.43% (range, 79.39%-99.60%). The median mean heart dose was 0.88 Gy (RBE) [range, 0.01-3.20 Gy (RBE)] for all patients, and 1.00 Gy (RBE) among patients with left-sided tumors. The median V20 of the ipsilateral lung was 16.50% (range, 6.1%-30.3%). The median contralateral lung V5 was 0.34% (range, 0%-5.30%). The median maximal point dose to the esophagus was 45.65 Gy (RBE) [range, 0-65.4 Gy (RBE)]. The median contralateral breast mean dose was 0.29 Gy (RBE) [range, 0.03-3.50 Gy (RBE)].
  
  
  CONCLUSIONS
  Postoperative proton therapy is well tolerated, with acceptable rates of skin toxicity. Proton therapy favorably spares normal tissue without compromising target coverage. Further follow-up is necessary to assess for clinical outcomes and cardiopulmonary toxicities.
authors.affiliation: Memorial Sloan-Kettering Cancer Center, New York, New York.
authors.forename: John J
authors.initials: JJ
authors.lastname: Cuaron
authors.affiliation: Procure Proton Therapy Center, Somerset, New Jersey.
authors.forename: Brian
authors.initials: B
authors.lastname: Chon
authors.affiliation: Procure Proton Therapy Center, Somerset, New Jersey.
authors.forename: Henry
authors.initials: H
authors.lastname: Tsai
authors.affiliation: Procure Proton Therapy Center, Somerset, New Jersey.
authors.forename: Anuj
authors.initials: A
authors.lastname: Goenka
authors.affiliation: Procure Proton Therapy Center, Somerset, New Jersey.
authors.forename: David
authors.initials: D
authors.lastname: DeBlois
authors.affiliation: Memorial Sloan-Kettering Cancer Center, New York, New York.
authors.forename: Alice
authors.initials: A
authors.lastname: Ho
authors.affiliation: Memorial Sloan-Kettering Cancer Center, New York, New York.
authors.forename: Simon
authors.initials: S
authors.lastname: Powell
authors.affiliation: Procure Proton Therapy Center, Somerset, New Jersey.
authors.forename: Eugen
authors.initials: E
authors.lastname: Hug
authors.affiliation: Memorial Sloan-Kettering Cancer Center, New York, New York; Procure Proton Therapy Center, Somerset, New Jersey. Electronic address: cahlono@mskcc.org.
authors.forename: Oren
authors.initials: O
authors.lastname: Cahlon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001940:Breast / Q000528:radiation effects; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D004941:Esophagitis / Q000209:etiology / Q000473:pathology; D005260:Female; D006321:Heart / Q000528:radiation effects; D006801:Humans; D008198:Lymph Nodes / Q000528:radiation effects; D015182:Lymphatic Irradiation; D015412:Mastectomy, Segmental; D008875:Middle Aged; D059351:Organ Sparing Treatments / Q000009:adverse effects / Q000379:methods; D058958:Organs at Risk / Q000473:pathology / Q000528:radiation effects*; D061766:Proton Therapy / Q000009:adverse effects* / Q000379:methods; D011855:Radiodermatitis / Q000473:pathology*; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects / Q000379:methods; D012062:Relative Biological Effectiveness