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. 2019 Nov:140:76-83.
doi: 10.1016/j.radonc.2019.05.022. Epub 2019 Jun 8.

Post-mastectomy intensity modulated proton therapy after immediate breast reconstruction: Initial report of reconstruction outcomes and predictors of complications

Na L Smith  1 , Krishan R Jethwa  1 , Jason K Viehman  2 , William S Harmsen  2 , Karthik Gonuguntla  1 , Sarah M Elswick  3 , Jennifer N Grauberger  4 , Adam C Amundson  1 , Thomas J Whitaker  1 , Nicholas B Remmes  1 , Christin A Harless  3 , Judy C Boughey  5 , Minh-Doan T Nguyen  3 , Sean S Park  1 , Kimberly S Corbin  1 , Robert W Mutter  6
Affiliations

Post-mastectomy intensity modulated proton therapy after immediate breast reconstruction: Initial report of reconstruction outcomes and predictors of complications

Na L Smith et al. Radiother Oncol. 2019 Nov.

Abstract

Purpose: To report reconstructive outcomes of patients treated with post-mastectomy intensity modulated proton therapy (IMPT) following immediate breast reconstruction (IBR).

Materials and methods: Consecutive women with breast cancer who underwent implant-based IBR and post-mastectomy IMPT were included. Clinical characteristics, dosimetry, and acute toxicity were collected prospectively and reconstruction complications retrospectively.

Results: Fifty-one women were treated between 2015 and 2017. Forty-two had bilateral reconstruction with unilateral IMPT. The non-irradiated contralateral breasts served as controls. Conventional fractionation (median 50 Gy/25 fractions) was administered in 37 (73%) and hypofractionation (median 40.5 Gy/15 fractions) in 14 (27%) patients. Median mean heart, ipsilateral lung V20Gy, and CTV-IMN V95% were 0.6 Gy, 13.9%, and 97.4%. Maximal acute dermatitis grade was 1 in 32 (63%), 2 in 17 (33%), and 3 in 2 (4%) patients. Surgical site infection (hazard ratio [HR] 13.19, 95% confidence interval [CI] 1.67-104.03, p = 0.0012), and unplanned surgical intervention (HR 9.86, 95% CI 1.24-78.67, p = 0.0068) were more common in irradiated breasts. Eight of 51 irradiated breasts and 2 of 42 non-irradiated breasts had reconstruction failure (HR 3.59, 95% CI 0.78-16.41, p = 0.084). Among irradiated breasts, hypofractionation was significantly associated with reconstruction failure (HR 4.99, 95% CI 1.24-20.05, p = 0.024), as was older patient age (HR 1.14, 95% CI 1.05-1.24, p = 0.002).

Conclusions: IMPT following IBR spared underlying organs and had low rates of acute toxicity. Reconstruction complications are more common in irradiated breasts, and reconstructive outcomes appear comparable with photon literature. Hypofractionation was associated with higher reconstruction failure rates. Further investigation of optimal dose-fractionation after IBR is needed.

Keywords: Breast cancer; Complications; Post-mastectomy; Protons; Radiotherapy; Reconstruction.

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Conflict of interest statement

Declaration of Competing Interest

None.

Figures

Fig. 1.
Fig. 1.
Axial CT slice of the pencil-beam scanning proton therapy treatment plan of a representative patient with immediate tissue expander reconstruction. The 4500–5559 cGy color wash (top) and 2000–5559 cGy color wash (bottom) are shown. Chest wall and regional nodal CTV is contoured in red, internal mammary CTV is contoured in yellow.
Fig. 2.
Fig. 2.
Summary of the reconstruction outcomes of the irradiated and the non-irradiated reconstructed breasts.
Fig. 3.
Fig. 3.
Cumulative incidence of any complication (A), unplanned reoperation (B), SSI (C), and reconstruction failure (D) for irradiated and non-irradiated breasts.
See this image and copyright information in PMC

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