47 Effect of Postmastectomy Radiation Therapy on Outcomes for Implant-Based Reconstruction

Background

Postmastectomy radiation therapy (PMRT) reduces local-regional cancer recurrence and increases survival. However, PMRT can increase breast reconstruction complications, possibly requiring surgical revision or implant removal.

Significance

To aid informed decision-making about PMRT’s effects on breast reconstruction.

Methods

Female patients with breast cancer who underwent mastectomy and breast reconstruction followed by PMRT at Maimonides Medical Center between 2018 and 2025 were retrospectively analyzed. Using electronic medical records, patient demographics, pathologic cancer staging, PMRT regimen, grade of radiation dermatitis, reconstruction surgery, chemotherapy, and post-reconstruction complications (PRC) were collected. PRC was defined as any unplanned reconstructive surgery after PMRT completion.

Results

Of 99 patients, 25 (25%) experienced PRC. Mean age was 46.5 years (SD, 9.5). Mean body mass index (BMI) was 27.3 kg/m2 (SD, 5.3). Eighty-eight patients (89%) received 3D conformal RT, while the remainder (11%) received intensity-modulated RT (IMRT); 40 (40%) were treated using chest wall bolus. Fifty patients (51%) experienced grade 2+ dermatitis. Fifty-nine patients (60%) had delayed implant reconstruction after RT completion, 19 (19%) had delayed autologous reconstruction, 19 (19%) had tissue expanders only, and 2 (2%) had immediate reconstruction. Eighteen patients (12%) received no chemotherapy, while 49 (50%) received chemotherapy before mastectomy and 32 (32%) received chemotherapy after mastectomy.

Mean time from mastectomy to PMRT completion was 0.5 years (SD, 0.4). Mean time from PMRT completion to PRC was 1.3 years (SD, 0.8). Infection was the most common PRC (28%), then breast asymmetry (24%), implant exposure (16%), capsular contracture (12%), cancer recurrence (8%), fat necrosis (8%), and suture line dehiscence (4%).

Receiving chemotherapy was associated with lower PRC risk (OR, 0.25; 95% CI, 0.08-0.72; P = .01). Mean time from mastectomy to PMRT completion for participants who received no chemotherapy, received chemotherapy before mastectomy, and received chemotherapy after mastectomy were 0.47 (SD, 0.5), 0.33 (SD, 0.05), and 0.75 years (SD, 0.5), respectively. Patients who did not receive chemotherapy were older (mean, 49.1 years; SD, 11.2) than those who received chemotherapy before (mean, 44.7 years; SD, 9.5) and after (mean, 47.8 years; SD, 8.3) mastectomy.

Trends towards association were seen between PRC and severity of radiation dermatitis (OR, 2.09; 95% CI, 0.82-5.33; P = .12) and chest wall bolus use (OR, 2.07; 95% CI, 0.77-5.5; P = .15). No association was observed between PRC and age (P = .25), BMI (P = .88), cancer stage (P >.73), RT technique (P = .57), or reconstruction type (P = .73).

Conclusion

Patients who received chemotherapy experienced less PRC, possibly due to increased time from mastectomy to PMRT completion and/or younger age and fewer comorbidities. Although prior studies suggest that higher BMI and implant reconstruction are predictive of PRC, we did not find that in our study. Further cohort expansion will help elucidate the significance of such factors.