Ten-year results of hypofractionated whole breast RT and intraoperative boost in premenopausal women
Maria Alessia Zerella,
Italy
PH-0219
Abstract
Ten-year results of hypofractionated whole breast RT and intraoperative boost in premenopausal women
Authors: Samantha Dicuonzo1, Chiara Cormio1, Cristiana Iuliana Fodor1, Anna Morra1, Damaris Patricia Rojas1, Maria Alessia Zerella1, Federica Cattani2, Viviana Enrica Galimberti3, Paolo Veronesi3,4, Mattia Zaffaroni1, Roberto Orecchia5, Maria Cristina Leonardi1, Barbara Alicja Jereczek-Fossa1,4
1IEO, European Institute of Oncology, IRCCS, Radiation Oncology, Milan, Italy; 2IEO, European Institute of Oncology, IRCCS, Medical Physics, Milan, Italy; 3IEO, European Institute of Oncology, IRCCS, Breast Surgery, Milan, Italy; 4University of Milan, Oncology and Hemato-oncology, Milan, Italy; 5IEO, European Institute of Oncology, IRCCS, Scientific Directorate, Milan, Italy
Show Affiliations
Hide Affiliations
Purpose or Objective
To
evaluate the efficacy and tolerance of intraoperative electron boost (IOERT)
followed by hypofractionated whole breast irradiation (WBI) for early breast
cancer (BC).
Material and Methods
Premenopausal women with pT1-2
any N BC operated on with breast conserving surgery received 12 Gy
intraoperative boost with electrons (IOERT) to the tumor bed via mobile dedicated
linear accelerator and hypofractionated schedule to whole breast with 3-
dimensional conformal radiotherapy (WBI) and 6-MV photon. The WBI schedule
consisted of 13 fractions of 2.85 Gy over 2.5 weeks. Patients were analyzed to assess local control, disease
free survival (DFS), breast cancer specific survival (BCSS) and overall (OS).
Results
From 6/2004 to 12/2014 518 consecutive BC patients
with a median age of 43 (range, 24-48) were identified. Very young patients, <40 were 163. Median
tumor size was 1.5 cm (standard deviation-SD, 0.70). Nodal negative patients were
356. According to molecular classification, 42% were Luminal A, 31.5% Luminal B
HER2 negative, 11.4% Luminal B HER2 positive, 2.3% HER2 positive, and 13%
Triple Negative. Median IOERT collimator size was 4 cm (range,
4-6) and median electron energy was 7 MeV ( range 5-10). Perioperative
complications, of which clinical liponecrosis accounted for 3.5%, affected
16.4% of the population. After mean interval of 25 days (SD, 7), hypofractionated
WBI was delivered. All
patients completed RT as scheduled and the mean duration of RT was 18. In about
10% the 13-fraction RT lasted more than 20 days. In all but a few cases, chemotherapy, if delivered, started at the end of RT. Median follow-up was 118 months (range, 9-182
months). Five-year and 10-year cumulative incidence of local relapses was 1.5%
(95% CI, 0.7-2.9) and 3.4% (95%CI, 2.0-5.3), respectively. Patients aged <40
had significantly higher local recurrence rate (at 10 years 5.2 vs 2.5%, p
0.045). At multivariate analysis, predictors for local failure were aged
<40, presence of intraductal component (EIC) and smaller IOERT collimator. Ten-year
survival outcomes were as follows: DFS 78.1% (95% CI, 74.0-81.7), BCSS 96.4%
(95% CI, 94.3-97.8%), OS 95.5% (95% CI,
93.2-97.1). No difference between women aged <40 and ≥40 was
observed, while Luminal B HER2 negative showed the worst outcome. Distant
metastases occurred in 8.1%, especially in the Luminal B HER2 negative tumors. Moderate/severe
fibrosis was reported in about 40% of the cases and moderate/severe pain in 12%
of the cases. Radiological liponecrosis was found in 65% of the imaging studies
(data not available for 155/518). Patients who experienced clinical liponecrosis
were more likely to report higher chronic toxicity. Cosmesis was scored as
excellent/good in 85% of the cases.
Conclusion
After
10 years, IOERT boost and hypofractionated WBI resulted to be effective, with
some concerns regarding the rate of tumor bed fibrosis.