The impact of immediate breast reconstruction on the technical delivery of postmastectomy radiotherapy.

Purpose: To quantify the impact of immediate breast reconstruction on postmastectomy radiation therapy (PMRT) planning.
Methods: A total of 110 patients (112 treatment plans) who had mastectomy with immediate reconstruction followed by radiotherapy were compared with contemporaneous stage-matched patients who had undergone mastectomy without intervening reconstruction. A scoring system was used to assess optimal radiotherapy planning using four parameters: breadth of chest wall coverage, treatment of the ipsilateral internal mammary chain, minimization of lung, and avoidance of heart. An "optimal" plan achieved all objectives or a minor 0.5 point deduction; "moderately" compromised treatment plans had 1.0 or 1.5 point deductions; and "major" compromised plans had > or =2.0 point deductions.
Results: Of the 112 PMRT plans scored after reconstruction, 52% had compromises compared with 7% of matched controls (p < 0.0001). Of the compromised plans after reconstruction, 33% were considered to be moderately compromised plans and 19% were major compromised treatment plans. Optimal chest wall coverage, treatment of the ipsilateral internal mammary chain, lung minimization, and heart avoidance was achieved in 79%, 45%, 84%, and 84% of the plans in the group undergoing immediate reconstruction, compared respectively with 100%, 93%, 97%, and 92% of the plans in the control group (p < 0.0001, p < 0.0001, p = 0.0015, and p = 0.1435). In patients with reconstructions, 67% of the "major" compromised radiotherapy plans were left-sided (p < 0.16).
Conclusions: Radiation treatment planning after immediate breast reconstruction was compromised in more than half of the patients (52%), with the largest compromises observed in those with left-sided cancers. For patients with locally advanced breast cancer, the potential for compromised PMRT planning should be considered when deciding between immediate and delayed reconstruction.