Objective: The aim of this study was to identify the comprehensive risk factors for lymphedema, thereby enabling a more informed multidisciplinary treatment decision-making. Summary Background Data: Lymphedema is a serious long-term complication in breast cancer patients post-surgery; however, the influence of multimodal therapy on its occurrence remains unclear. Methods: We retrospectively collected treatment-related data from 5549 breast cancer patients who underwent surgery between 2007 and 2015 at our institution. Individual radiotherapy plans were reviewed for regional nodal irradiation (RNI) field design and fractionation type. We identified lymphedema risk factors and used them to construct nomograms to predict individual risk of lymphedema. Nomograms were validated internally using 100 bootstrap samples and externally using 2 separate datasets of 1877 Asian and 191 Western patients. Results: Six hundred thirty-nine patients developed lymphedema during a median follow-up of 60 months. The 3-year lymphedema incidence was 10.5%; this rate increased with larger irradiation volumes (no RNI vs RNI excluding axilla I–II vs RNI including axilla I–II: 5.7% vs 16.8% vs 24.1%) and when using conventional fractionation instead of hypofractionation (13.5% vs 6.8%). On multivariate analysis, higher body mass index, larger number of dissected nodes, taxane-based regimen, total mastectomy, larger irradiation field, and conventional fractionation were strongly associated with lymphedema (all P < 0.001). Nomograms constructed based on these variables showed good calibration and discrimination internally (concordance index: 0.774) and externally (0.832 for Asian and 0.820 for Western patients). Conclusions: Trimodality breast cancer treatment factors interact to promote lymphedema. Lymphedema risk can be decreased by deintensifying node dissection, chemotherapy regimen, and field and dose of radiotherapy. Deescalation strategies on a multidisciplinary basis might minimize lymphedema risk.
Immunotherapy is currently being examined as a treatment modality for glioblastoma. Maintaining an optimal total lymphocyte count (TLC) after radiotherapy (RT) and using temozolomide may be beneficial in optimizing immunotherapy. However, conventional temozolomide-based chemoradiation is known to induce immunosuppressive effects, including lymphopenia. Therefore, this study aimed to identify potential clinical predictors of acute severe lymphopenia (ASL) in patients receiving chemoradiation for glioblastoma. We identified patients with glioblastoma treated with RT plus temozolomide from 2006 to 2017. ASL was defined as a TLC of < 500/μL within 3 months after initiating RT. Independent predictors of ASL were determined using logistic regression. A total of 336 patients were evaluated. Three-dimensional conformal RT (3D-CRT) and intensity-modulated RT (IMRT) were used in 186 (55.4%) and 150 patients (44.6%), respectively. TLC decreased during RT and remained persistently low during the 1-year follow-up, whereas the levels of other blood cell types recovered. In total, 118 patients (35.1%) developed ASL. During a median follow-up of 19.3 months, patients with ASL showed significantly worse overall survival than did those without ASL (median, 18.2 vs. 22.0 months; P = .028). Multivariable analysis revealed that increased planning target volume (PTV) was independently associated with increased ASL incidence (hazard ratio [HR], 1.02; 95% confidence interval [CI], 1.00–1.03; P = .042), while IMRT was independently associated with decreased ASL incidence (HR, 0.48; 95% CI, 0.27–0.87; P = .015). A propensity-matched comparison showed that the incidence of ASL was lower with IMRT than with 3D-CRT (20% vs. 37%; P = .005). IMRT and low PTV were significantly associated with decreased ASL incidence after RT plus temozolomide for glioblastoma. An IMRT-based strategy is necessary to enhance treatment outcomes in the immune-oncology era.