Adjuvant hypofractionated radiotherapy with simultaneous integrated boost after breast-conserving surgery: results of a prospective trial

Strahlenther Onkol. 2021 Jan;197(1):48-55. doi: 10.1007/s00066-020-01689-7. Epub 2020 Oct 1.


Purpose: We report results of a multicenter prospective single-arm phase II trial (ARO-2013-04, NCT01948726) of moderately accelerated hypofractionated radiotherapy with a simultaneous integrated boost (SIB) in patients with breast cancer receiving adjuvant radiotherapy after breast-conserving surgery.

Methods: The eligibility criteria included unifocal breast cancer with an indication for adjuvant radiotherapy to the whole breast and boost radiotherapy to the tumor bed. The whole breast received a dose of 40 Gy and the tumor bed a total dose of 48 Gy in 16 fractions of 2.5 and 3 Gy, respectively. Radiotherapy could be given either as 3D conformal RT (3D-CRT) or as intensity-modulated radiotherapy (IMRT). The study was designed as a prospective single-arm trial to evaluate the acute toxicity of the treatment regimen. The study hypothesis was that the frequency of acute skin reaction grade ≥2 would be 20% or less.

Results: From November 2013 through July 2014, 149 patients were recruited from 12 participating centers. Six patients were excluded, leaving 143 patients for analysis. Eighty-four patients (58.7%) were treated with 3D-CRT and 59 (41.3%) with IMRT. Adherence to the treatment protocol was high. The rate of grade ≥2 skin toxicity was 14.7% (95% confidence interval 9.8-21.4%). The most frequent grade 3 toxicity (11%) was hot flashes.

Conclusion: This study demonstrated low toxicity of and high treatment adherence to hypofractionated adjuvant radiotherapy with SIB in a multicenter prospective trial, although the primary hypothesis was not met.

Keywords: Acute toxicity; Adverse events; Intensity modulated radiotherapy; Radiation dermatitis; Treatment compliance.

Publication types

  • Clinical Trial, Phase II
  • Multicenter Study

MeSH terms

  • Antineoplastic Agents, Hormonal / adverse effects
  • Antineoplastic Agents, Hormonal / therapeutic use
  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / radiotherapy*
  • Breast Neoplasms / surgery
  • Chemotherapy, Adjuvant
  • Combined Modality Therapy
  • Esthetics
  • Female
  • Hot Flashes / chemically induced
  • Humans
  • Mastectomy, Segmental
  • Pain / etiology
  • Pilot Projects
  • Prospective Studies
  • Radiation Dose Hypofractionation*
  • Radiodermatitis / etiology*
  • Radiotherapy, Adjuvant / adverse effects
  • Radiotherapy, Adjuvant / methods*
  • Radiotherapy, Conformal / adverse effects
  • Radiotherapy, Conformal / methods*
  • Radiotherapy, Intensity-Modulated / adverse effects
  • Radiotherapy, Intensity-Modulated / methods*


  • Antineoplastic Agents, Hormonal