Partial breast irradiation delivered with proton beam: results of a phase II trial

Clin Breast Cancer. 2011 Aug;11(4):241-5. doi: 10.1016/j.clbc.2011.03.023. Epub 2011 Jun 12.


Background and purpose: A phase II trial sought to determine the safety and efficacy of proton beam irradiation to deliver partial breast radiotherapy after lumpectomy for early-stage breast cancer.

Patients and methods: Eligible patients included women with invasive nonlobular carcinoma ≤ 3 cm. Surgical therapy included lumpectomy with negative margins and negative axillary lymph nodes on sampling. Postoperative proton radiotherapy to the surgical bed with an additional 1-cm margin was delivered by 40 Gy in 10 fractions over a 2-week course. Patients received systemic therapy as recommended after proton treatment. Patients had clinical evaluations every 6 months and annual mammograms.

Results: Fifty patients were enrolled; median follow-up was 48 months. All patients completed the prescribed treatment. Acute toxicities were limited to mild radiation dermatitis. Late skin toxicities included 3 grade 1 telangiectasias. There were no posttreatment infections or ulcerations and no cases of fat necrosis, rib fractures, radiation pneumonitis, or cardiac events. Actuarial 5-year overall survival and disease-free survival rates were 96% and 92%, respectively. No local failures occurred. Ipsilateral breast cancer developed in 1 patient 5.5 years after treatment. Dose-volume histogram analysis showed near-complete elimination of dose to the contralateral breast, lung, and heart.

Conclusion: Proton partial breast radiotherapy appeared to be a feasible method of treatment and provided excellent disease control within the ipsilateral breast. Treatment-related toxicity was minimal and no technical limitations prevented treatment delivery. The incidence of posttreatment complications may be less than that reported when using more invasive techniques; comparative trials should be considered.

Publication types

  • Clinical Trial, Phase II
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Breast Neoplasms / pathology
  • Breast Neoplasms / radiotherapy*
  • Breast Neoplasms / surgery*
  • Carcinoma, Ductal, Breast / pathology
  • Carcinoma, Ductal, Breast / radiotherapy*
  • Carcinoma, Ductal, Breast / surgery*
  • Combined Modality Therapy
  • Female
  • Follow-Up Studies
  • Humans
  • Immunoenzyme Techniques
  • Mastectomy, Segmental*
  • Middle Aged
  • Neoplasm Recurrence, Local / pathology
  • Neoplasm Recurrence, Local / radiotherapy
  • Neoplasm Recurrence, Local / surgery
  • Neoplasm Staging
  • Proton Therapy*
  • Receptors, Estrogen / metabolism
  • Receptors, Progesterone / metabolism
  • Survival Rate
  • Treatment Outcome


  • Receptors, Estrogen
  • Receptors, Progesterone