Breast Cancer

SS 23 - Breast 3?- General

162 - Influence of Hypofractionated Radiation Therapy Following Mastectomy on Complication in Breast Cancer Patients Undergoing Two-Stage Prosthetic Breast Reconstruction

Tuesday, October 23
1:40 PM - 1:50 PM
Location: Room 303

Influence of Hypofractionated Radiation Therapy Following Mastectomy on Complication in Breast Cancer Patients Undergoing Two-Stage Prosthetic Breast Reconstruction
J. Chang1, N. Kim1, J. H. Oh2, S. Y. Song2, D. H. Lew2, T. S. Roh2, S. Y. KIM3, C. O. Suh1, D. W. Lee2, and Y. B. B. Kim4; 1Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea, Republic of (South), 2Department of Plastic and Reconstructive Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea, Republic of (South), 3Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University Health System, Seoul, Korea, Republic of (South), 4Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea, Republic of (South)

Purpose/Objective(s): To compare the reconstruction-related complication risk between hypofractionated RT and conventional RT and identify a dosimetric predictor for the development of complications.

Materials/Methods: We identified 49 patients received expander placement with acellular dermal matrix immediately after mastectomy, then postmastectomy RT, followed by exchange of the expander for a permanent implant by a single surgeon. Of these patients, 19 underwent conventional 50 Gy RT. The remaining 30 patients underwent hypofractionated RT (mostly, 40.05 Gy/15 fractions), of which 80% received arc-based intensity modulated-RT planning. According to CTCAE v 4.0, grade 1 (faint erythema or dry desquamation), 2 (moderate to brisk erythema or patchy moist desquamation, mostly confined to skin folds), and 3 (moist desquamation, in areas other than skin folds) skin reactions occurred during RT in 18 (36.7%), 9 (18.4%), and 3 (6.1%) patients, respectively. The grade 2 or 3 skin reaction rate was lower after hypofractionated RT than after conventional RT (3.3% vs. 57.9%). The primary outcome was any reconstruction-related complication.

Results: The median follow-up was 23.6 months (range, 6.6–60.2 months). Complications following reconstructive surgery at any time after the completion of post-mastectomy RT occurred in 14 of 49 patients (28.6%). The mean time to complication from the date of RT completion was 8.1 months (SD 4.9, range 3.3-18.2). The complication rate was statistically significantly higher in the group receiving conventional RT than in the group receiving hypofractionated RT (52.6% vs. 13.3%, P = .003). Higher skin reaction in patients during RT indicates more reconstructive complications they suffered after RT (skin toxicity G0 2/19 (10.5%), G1 3/18 (16.7%), G2 7/9 (77.8%), and G3 2/3 (66.7%), P = .001). ). ROC analysis showed that Dmax of chest wall was the best dosimetric predictor for the development of grade 2-3 skin toxicity during RT and reconstruction-related complication after RT. Dmax differed depending on the fractionation scheme and use of bolus. During the follow-up period, no local recurrence was found in the chest wall. Six distant metastases with simultaneous regional recurrence (n = 1) were observed.

Conclusion: The hypothesis-generating findings of this study warrant further investigation into the effect of hypofractionated RT on reconstruction-related complication. Rigorous RT-QA program can be critically important component in upcoming randomized phase III trials of hypofractionation (Alliance A221505 and FABREC).

Author Disclosure: J. Chang: None. N. Kim: None. J. Oh: None. S. Song: None.

Jeesuk Chang, MD

Yonsei Cancer Center

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Yonsei University College of Medicine: Employee: Employee

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