Browsing by Subject "radiation"
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Item Open Access Nodal Response to Neoadjuvant Chemotherapy Predicts Receipt of Radiation Therapy after Breast Cancer Diagnosis.(International journal of radiation oncology, biology, physics, 2019-10-31) Fayanju, Oluwadamilola M; Ren, Yi; Suneja, Gita; Thomas, Samantha M; Greenup, Rachel A; Plichta, Jennifer K; Rosenberger, Laura H; Force, Jeremy; Hyslop, Terry; Hwang, E ShelleyBACKGROUND:Pathologic complete response (pCR) after neoadjuvant chemotherapy (NACT) is associated with improved overall survival (OS) in breast-cancer patients, but it is unclear how post-NACT response influences radiotherapy administration in patients presenting with node-positive disease. We sought to determine whether nodal pCR is associated with likelihood of receiving nodal radiation and whether radiotherapy among patients experiencing nodal pCR is associated with improved OS. METHODS:cN1 female breast cancer patients diagnosed 2010-2015 who were ypN0 (i.e., nodal pCR, n=12,341) or ypN1 (i.e., residual disease, n=13,668) post-NACT were identified in the National Cancer Database. Multivariate logistic regression was used to identify factors associated with receiving radiotherapy. Cox proportional hazards modeling was used to estimate the association between radiotherapy and adjusted OS. RESULTS:26,009 patients were included. 43.9% (n=5,423) of ypN0 and 55.3% (n=7,556) of ypN1 patients received nodal radiation. Rates of nodal radiation remained the same over time among ypN0 patients (trend test p=0.29) but increased among ypN1 patients from 49% in 2010 to 59% in 2015 (trend test p<0.001). After adjusting for covariates, nodal pCR (vs no stage change) was associated with decreased likelihood of nodal radiation after mastectomy (∼20% decrease) and lumpectomy (∼30% decrease, both p<0.01). After mastectomy, nodal (vs no) radiation conferred no significant survival benefit in ypN0 patients but approached significance for ypN1 patients (hazard ratio [HR] 0.83, 95% CI 0.69-0.99, p=0.04, overall p-value=0.11). After lumpectomy, nodal radiation was associated with improved adjusted OS for ypN0 (HR 0.38, 95% CI 0.22-0.66) and ypN1 patients (HR 0.44, 95% CI 0.30-0.66, both p<0.001), but this improvement was not significantly greater than that associated with breast-only radiation. CONCLUSIONS:ypN0 patients were less likely to receive nodal radiation than ypN1 patients, suggesting that selective omission already occurs and, in the context of limited survival data, could potentially be appropriate for select patients.Item Open Access Theoretical Framework for Nanoparticle Reactivity as a Function of Aggregation State(2010) Hotze, Ernest M; Bottero, Jean-Yves; Wiesner, MarkTheory is developed that relates the reactivity of nanoparticles to the structure of aggregates they may form in suspensions. This theory is applied to consider the case of reactive oxygen species (ROS) generation by photosensitization of C-60 fullerenes. Variations in aggregate structure and size appear to account for an apparent paradox in ROS generation as calculated using values for the photochemical kinetics of fullerene (C-60) and its hydroxylated derivative, fullerol (C-60(OH)(22-24)) and assuming that structure varies between compact and fractal objects. A region of aggregation-suppressed ROS production is identified where interactions between the particles in compact aggregates dominate the singlet oxygen production. Intrinsic kinetic properties dominate when aggregates are small and/or are characterized by low fractal dimensions. Pseudoglobal sensitivity analysis of model input variables verifies that fractal dimension, and by extension aggregation state, is the most sensitive model parameter when kinetics are well-known. This theoretical framework qualitatively predicts ROS production by fullerol suspensions 2 orders of magnitude higher compared with aggregates of largely undifferentiated C-60 despite nearly an order of magnitude higher quantum yield for the undifferentiated C-60 based on measurements for single molecules. Similar to C-60, other primary nanoparticles will exist as aggregates in many environmental and laboratory suspensions. This work provides a theoretical basis for understanding how the structure of nanoparticle aggregates may affect their reactivity.