Patient and treatment characteristics
Patient and treatment characteristics regarding the PMRT receipt status in the autologous and implant-based reconstruction cohorts are listed in detail in Table 1. In total, 438 patients received autologous reconstruction, of whom 107 (24.4%) patients were treated with PMRT, and 52 (13.2%) of 394 patients who received implant-based reconstruction were treated with PMRT. In the autologous reconstruction cohort, patients with age younger than 40 years and BMI≥24 were more common in the PMRT group than in the no-PMRT group (p=0.007 and p=0.004, respectively). Delayed reconstruction was more common in the PMRT group (p=0.044). Systemic therapy was more common in the PMRT group than in the no-PMRT group (p<0.001). In the implant-based reconstruction cohort, systemic therapy was also more common in the PMRT group than in the no-PMRT group (p<0.001), and other factors were well balanced.
Details of the reconstruction complications and failures
The median follow-up time was 58.5 months (range, 12.3~176.0 months). The rates of any complications, major complications, overall reconstruction failures and complication-related reconstruction failures were 17.4%, 5.0%, 2.1% and 1.6% in the autologous reconstruction cohort and 23.6%, 5.8%, 7.1% and 4.6% in the implant-based reconstruction cohort.
The details of the reconstruction complications are presented in Table 2. The most common complications were volume loss (6.6%), infection (3.4%) and fat necrosis (1.8%) in the autologous reconstruction cohort and implant malposition (6.6%), infection (5.1%) and implant contraction (4.6%) in the implant-based reconstruction cohort. In the autologous reconstruction cohort, there were 9 reconstruction failures (3 in the PMRT group and 6 in the no-PMRT group); of these, 7 reconstruction failures were caused by complications or dissatisfaction related to reconstructed breasts, and 2 reconstruction failures were due to disease recurrence or other reasons. In the implant-based reconstruction cohort, there were 28 reconstruction failures (6 in the PMRT group and 22 in the no-PMRT group); of these, 18 reconstruction failures were caused by complications or dissatisfaction related to reconstructed breasts, and 10 reconstruction failures were due to disease recurrence or other reasons.
Univariate and multivariate analysis of reconstruction complications and failures
The univariate analysis is shown in Table 3. In the autologous reconstruction cohort, PMRT was not associated with any complications (20.6% vs. 16.3%, p=0.313), major complications (5.6% vs. 4.8%, p=0.750), overall reconstruction failures (2.8% vs. 1.8%, p=0.813) or reconstruction-related reconstruction failures (2.8% vs. 1.2%, p=0.484). Reconstruction timing was not significantly associated with any of these four endpoints. In the implant-based reconstruction cohort, PMRT was associated with major complications (13.5% vs. 4.7%, p=0.028) but not with any complications (30.8% vs. 22.5%, p=0.192), overall reconstruction failures (11.5% vs. 6.4%, p=0.296) or reconstruction-related reconstruction failures (9.6% vs. 3.6%, p=0.130). Reconstruction timing was significantly associated with all of four endpoints.
The multivariable analysis showed that PMRT was associated with 3.16 times (95% CI 1.17-8.54, p=0.023) higher odds of major complications and 3.22 times (95% CI 1.01-10.20, p=0.047) higher odds of complication-related reconstruction failures but was not associated with any complications (OR 1.73, 95% CI 0.88-3.38, p=0.113) or overall reconstruction failures (OR 2.09, 95% CI 0.76-5.73, p=0.152) in implant-based reconstruction (Table 4). Reconstruction timing was still significantly associated with all four endpoints. In the autologous reconstruction cohort, PMRT was not associated with any complications (OR 1.25, 95% CI 0.70-2.24, p=0.448), major complications (OR 1.10, 95% CI 0.39-3.05, p=0.863), overall reconstruction failures (OR 1.19, 95% CI 0.28-5.19, p=0.813) or reconstruction-related reconstruction failures (OR 1.92, 95% CI 0.39-9.41, p=0.421).
The performance of the predictive nomogram
The AUC of the implant-based reconstruction nomogram was 0.714 (95% CI 0.589-0.838), and the AUC of the autologous reconstruction nomogram was 0.686 (95% CI: 0.476-0.897). The calibration plot showed good accuracy in both nomograms.