PV QA 4 - Poster Viewing Q&A 4
Purpose/Objective(s):We previously reported the feasibility of intensity modulated proton postmastectomy radiotherapy (P-PMRT) in women with immediate tissue expander (TE) reconstruction with metallic ports. Our purpose is to analyze early complication rates and patient reported outcomes of this novel treatment approach.
Materials/Methods:All patients underwent mastectomy, axillary staging, and immediate TE placement. P-PMRT was delivered to the chest wall and regional lymphatics, including the internal mammary nodes, to a median dose of 50 Gy (RBE1.1) in 25 fractions with a median of two multifield optimized beams. Second-stage implant or autologous reconstruction took place a minimum of 6 months after the completion of P-PMRT. Adverse effects, patient-reported quality of life (QoL), and breast cosmesis were prospectively-assessed with the CTCAEv4.0, linear analog 10-point scales, and the Harvard Breast Cosmesis Scale, respectively.
Results:Between 2015 and 2017, 53 patients underwent mastectomy with immediate TE reconstruction followed by P-PMRT. TE placement was prepectoral in 40 (75%) and subpectoral in 13 (25%). Forty patients (75%) underwent contralateral prophylactic mastectomy with TE reconstruction. Median age was 49 (interquartile range [IQR] 43-57). The tumor was left-sided in 36 (68%), right-sided in 14 (26%), and bilateral in 3 (6%). Chemotherapy [neoadjuvantly (68%) or adjuvantly (15%)] was delivered in 44 (83%) patients, prior to P-PMRT. Median time from surgery to initiation of P-PMRT in the 45 patients who did not receive adjuvant chemotherapy was 59 days (IQR 53 - 71). The median mean heart dose and ipsilateral lung V20 Gy was 0.65 Gy (IQR 0.44 - 0.92) and 13.9 % (IQR 10.3% - 15.3%), respectively. Maximal acute dermatitis grade was 1 in 60%, 2 in 26%, and 3 in 8%. Median follow-up after P-PMRT was 8 months. Six of 56 (11%) irradiated and 1 (3%) non-irradiated implants had been removed due to complications. Other reconstruction complications are shown in the table. QoL was reported as ≥7 in 75% at baseline prior to P-PMRT initiation, with improvement to 83% at 6-months post-treatment. Eighty-six percent of responding patients reported good or excellent cosmesis at 6-month follow-up.
Conclusion:Early toxicity and patient reported outcomes of P-PMRT appear favorable in patients with immediate TE reconstruction, although complications remain higher on irradiated vs non-irradiated sides. Intensity modulated P-PMRT is a promising cardiopulmonary sparing modality for women with immediate reconstruction. Table:
|Complications||Irradiated, n = 53||Non-irradiated, n= 43|
|Total||19 (36%)||2 (5%)|
|Infection||Prior to P-PMPT||2 (4%)||2 (5%)|
|<30 days after completion of P-PMPT||2 (4%)||0|
|>30 days of P-PMPT to second stage procedure||7 (13%)||0|
|After second stage procedure||4 (8%)||0|
|Implant removal||6 (11%)||1 (2%)|
|Mastectomy skin flap necrosis||2 (4%)||0|
|Capsular contracture||1 (2%)||0|
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