Assessment of Pulmonary Fibrosis after Radiotherapy (RT) in Breast Conserving Surgery: Comparison between Conventional External Beam RT (EBRT) and Intraoperative RT with Electrons (ELIOT)

Abstract

The aim of this study was to assess the frequency and the grade of RT-induced pulmonary fibrosis in patients who underwent EBRT compared to patients who underwent ELIOT. One-hundred-seventy-eight patients enrolled in a prospective randomized phase III trial to compare the efficacy of ELIOT (a single dose of 21 Gy prescribed at the 90% isodose) versus EBRT (50 Gy to the whole breast plus a 10 Gy boost to the tumour bed), underwent a spiral 16-detector row Computed Tomography (CT) examination to assess RT-induced pulmonary fibrosis: 83 patients in the EBRT arm and 95 in the ELIOT arm. All patients (age range 48-75 years) were affected by unicentric infiltrating carcinoma of the breast with diameter < 2.5 cm. This study was approved by our Institutional Ethical Committee and informed consent was obtained from each patient. Two observers, blinded to patient's randomization, independently evaluated each CT examination and assigned a fibrosis score (Grades 0 to 3). Inter-observer agreement for the fibrosis score was evaluated and a consensus between observers was obtained. Differences in fibrosis score between the two arms were evaluated by Chi Square test and Odds Ratio (OR) with 95% Confidence Intervals (CI). Pulmonary fibrosis was diagnosed in 42 patients (23.6%): 38 (90%) were in the EBRT arm and 4 (10%) in the ELIOT arm (p < 0.0001); twenty-six of them were Grade 1 (one ELIOT), fifteen were Grade 2 (three ELIOT) and one was Grade 3. The post-radiotherapy risk in the EBRT arm to develop at least Grade 1 fibrosis was 19 times higher than in the ELIOT one (OR: 19.20; 95%CI: 6.46-57.14) and 6 times higher to develop at least Grade 2 (OR: 5.70; 95%CI: 1.56-20.76). In conclusion, CT detected pulmonary fibrosis in patients treated with ELIOT is significantly less frequent compared to patients treated with EBRT.

Accelerated Partial Breast Irradiation: Executive summary for the update of an ASTRO Evidence-Based Consensus Statement

“…In the available trials, fat necrosis 26,27 was increased with IORT, whereas skin side effects were lower. 24,26 Mild breast fibrosis 26,28,29 occurred with electron beam radiation on ELIOT, with no significant difference compared with WBI in the ELIOT trial.…”

The Emerging Role of Intraoperative Radiation Therapy [IORT] in Breast Cancer

“…There were no differences for fi brosis, retraction, pain, or burning, but there was a higher incidence of radiological determined fat necrosis in the ELIOT group, 5 %, vs. 2 % for the EBRT group, p = 0.04. In addition, ELIOT showed less pulmonary toxicity than the EBRT arm [ 91 ] as diagnosed by follow-up spiral CT (4 in the ELIOT arm and 38 in the EBRT arm). These differences in skin and pulmonary toxicity are not unexpected given the differences in IOERT vs. EBRT radiation techniques.…”

Techniques for Intraoperative Radiation Therapy for Early-Stage Breast Carcinoma

“…A lead shield was then placed between the muscle and remaining glandular tissue to avoid radionecrosis of the chest wall and ribs. Under this technique, high single-fraction dose (over 20 Gy) may be delivered to the operative bed while s paring the underlying chest wall and lung [32].…”