Effects on Lung Tissue After Breast Cancer Radiation: Comparing Photon and Proton Therapies.

Purpose: In breast cancer, improved treatment approaches that reduce injury to lung tissue and early diagnosis and intervention for lung toxicity are increasingly important in survivorship. The aims of this study are to (1) compare lung tissue radiographic changes in women treated with conventional photon radiation therapy and those treated with proton therapy (PT), (2) assess the volume of lung irradiated to 5 Gy (V5) and 20 Gy (V20) by treatment modality, and (3) quantify the effects of V5, V20, time, and smoking history on the severity of tissue radiographic changes. Patients and Methods: A prospective observational study of female breast cancer patients was conducted to monitor postradiation subclinical lung tissue radiographic changes. Repeated follow-up x-ray computed tomography scans were acquired through 2 years after treatment. In-house software was used to quantify an internally normalized measure of pulmonary tissue density change over time from the computed tomography scans, emphasizing the 6- and 12-month time points. Results: Compared with photon therapy, PT was associated with significantly lower lung V5 and V20. Lung V20 (but not V5) correlated significantly with increased subclinical lung tissue radiographic changes 6 months after treatment, and neither correlated with lung effects at 12 months. Significant lung tissue density changes were present in photon therapy patients at 6 and 12 months but not in PT patients. Significant lung tissue density change persisted at 12 months in ever-smokers but not in never-smokers. Conclusion: Patients treated with PT had significantly lower radiation exposure to the lungs and less statistically significant tissue density change, suggesting decreased injury and/or improved recovery compared to photon therapy. These findings motivate additional studies in larger, randomized, and more diverse cohorts to further investigate the contributions of treatment modality and smoking regarding the short- and long-term radiographic effects of radiation on lung tissue.

Radiation Biological Toximetry Using Circulating Cell-Free DNA (cfDNA) for Rapid Radiation/Nuclear Triage.

Optimal triage biodosimetry would include risk stratification within minutes, and it would provide useful triage despite heterogeneous dosimetry, cytokine therapy, mixed radiation quality, race, and age. For regulatory approval, the U.S. Food and Drug Administration (FDA) Biodosimetry Guidance requires suitability for purpose and a validated species-independent mechanism. Circulating cell-free DNA (cfDNA) concentration assays may provide such triage information. To test this hypothesis, cfDNA concentrations were measured in unprocessed monkey plasma using a branched DNA (bDNA) technique with a laboratory developed test. The cfDNA levels, along with hematopoietic parameters, were measured over a 7-day period in Rhesus macaques receiving total body radiation doses ranging from 1 to 6.5 Gy. Low-dose irradiation (0-2 Gy) was easily distinguished from high-dose whole-body exposures (5.5 and 6.5 Gy). Fold changes in cfDNA in the monkey model were comparable to those measured in a bone marrow transplant patient receiving a supralethal radiation dose, suggesting that the lethal threshold of cfDNA concentrations may be similar across species. Average cfDNA levels were 50 ± 40 ng/mL [±1 standard deviation (SD)] pre-irradiation, 120 ± 13 ng/mL at 1 Gy; 242 ± 71 ng/mL at 2 Gy; 607 ± 54 at 5.5 Gy; and 1585 ± 351 at 6.5 Gy (±1 SD). There was an exponential increase in cfDNA concentration with radiation dose. Comparison of the monkey model with the mouse model and the Guskova model, developed using Chernobyl responder data, further demonstrated correlation across species, supporting a similar mechanism of action. The test is available commercially in a Clinical Laboratory Improvement Amendments (CLIA) ready form in the U.S. and the European Union. The remaining challenges include developing methods for further simplification of specimen processing and assay evaluation, as well as more accurate calibration of the triage category with cfDNA concentration cutoffs.

Florida-California Cancer Research, Education and Engagement (CaRE2) Health Equity Center: Structure, Innovations, and Initial Outcomes.

INTRODUCTION: The Florida-California Cancer Research, Education, and Engagement (CaRE2) Health Equity Center is a triad partnership committed to increasing institutional capacity for cancer disparity research, the diversity of the cancer workforce, and community empowerment. This article provides an overview of the structure, process innovations, and initial outcomes from the first 4 years of the CaRE2 triad partnership. METHODS: CaRE2 serves diverse populations in Florida and California using a "molecule to the community and back" model. We prioritize research on the complex intersection of biological, environmental, and social determinants health, working together with scientific and health disparities communities, sharing expertise across institutions, bidirectional training, and community outreach. Partnership progress and outcomes were assessed using mixed methods and four Program Steering Committee meetings. RESULTS: Research capacity was increased through development of a Living Repository of 81 cancer model systems from minority patients for novel cancer drug development. CaRE2 funded 15 scientific projects resulting in 38 publications. Workforce diversity entailed supporting 94 cancer trainees (92 URM) and 34 ESIs (32 URM) who coauthored 313 CaRE2-related publications and received 48 grants. Community empowerment was promoted via outreaching to more than 3000 individuals, training 145 community cancer advocates (including 28 Community Scientist Advocates), and publishing 10 community reports. CaRE2 members and trainees together have published 639 articles, received 61 grants, and 57 awards. CONCLUSION: The CaRE2 partnership has achieved its initial aims. Infrastructure for translational cancer research was expanded at one partner institution, and cancer disparities research was expanded at the two cancer centers.

Palliative care utilization and racial and ethnic disparities among women with de novo metastatic breast cancer in the United States.

PURPOSE: The potential disparities in palliative care delivery for underrepresented minorities with breast cancer are not well known. We sought to determine whether race and ethnicity impact the receipt of palliative care for patients with metastatic breast cancer (MBC). METHODS: We retrospectively reviewed the National Cancer Database for female patients diagnosed with stage IV breast cancer between 2010 and 2017 who received palliative care following diagnosis of MBC to assess the proportion of patients who received palliative care, including non-curative-intent local-regional or systemic therapy. Multivariable logistic regression analysis was performed to identify variables associated with receiving palliative care. RESULTS: 60,685 patients were diagnosed with de novo MBC. Of these, only 21.4% (n = 12,963) received a palliative care service. Overall, there was a positive trend in palliative care receipt from 18.2% in 2010 to 23.0% in 2017 (P < 0.001), which persisted when stratified by race and ethnicity. Relative to non-Hispanic White women, Asian/Pacific Islander women (aOR 0.80, 95% CI 0.71-0.90, P < 0.001), Hispanic women (adjusted odds ratio [aOR] 0.69, 95% CI 0.63-0.76, P < 0.001), and non-Hispanic Black women (aOR 0.94, 95% CI 0.88-0.99, P = 0.03) were less likely to receive palliative care. CONCLUSIONS: Fewer than 25% of women with MBC received palliative care between 2010 and 2017. While palliative care has significantly increased for all racial/ethnic groups, Hispanic White, Black, and Asian/Pacific Islander women with MBC still receive significantly less palliative care than non-Hispanic White women. Further research is needed to identify the socioeconomic and cultural barriers to palliative care utilization.

Intraoperative radiation therapy for early-stage breast cancer: a single-institution experience.

Background: To assess outcomes and toxicity after low-energy intraoperative radiotherapy (IORT) for early-stage breast cancer (ESBC). Materials and methods: We reviewed patients with unilateral ESBC treated with breast-conserving surgery and 50-kV IORT at our institution. Patients were prescribed 20 Gy to the surface of the spherical applicator, fitted to the surgical cavity during surgery. Patients who did not meet institutional guidelines for IORT alone on final pathology were recommended adjuvant treatment, including additional surgery and/or external-beam radiation therapy (EBRT). We analyzed ipsilateral breast tumor recurrence, overall survival, recurrence-free survival and toxicity. Results: Among 201 patients (median follow-up, 5.1 years; median age, 67 years), 88% were Her2 negative and ER positive and/or PR positive, 98% had invasive ductal carcinoma, 87% had grade 1 or 2, and 95% had clinical T1 disease. Most had pathological stage T1 (93%) N0 (95%) disease. Mean IORT applicator dose at 1-cm depth was 6.3 Gy. Post-IORT treatment included additional surgery, 10%; EBRT, 11%; adjuvant chemotherapy, 9%; and adjuvant hormonal therapy, 74%. Median total EBRT dose was 42.4 (range, 40.05-63) Gy and median dose per fraction was 2.65 Gy. At 5 years, the cumulative incidence of ipsilateral breast tumor recurrence was 2.7%, the overall survival rate was 95% with no breast cancer-related deaths, and the recurrence-free survival rate was 96%. For patients who were deemed unsuitable for postoperative IORT alone and did not receive recommended risk-adapted EBRT, the IBTR rate was 4.7% versus 1.7% (p = 0.23) for patients who were either suitable for IORT alone or unsuitable and received adjuvant EBRT. Cosmetic toxicity data was available for 83%, with 7% experiencing grade 3 breast toxicity and no grade 4-5 toxicity. Conclusions: IORT for select patients with ESBC results in acceptable outcomes in regard to ipsilateral breast tumor recurrence and toxicity.

Frailty and risk of mortality in older cancer survivors and adults without a cancer history: Evidence from the National Health and Nutrition Examination Survey, 1999-2014.

BACKGROUND: Epidemiologic evidence reporting the role of frailty in survival among older adults with a prior cancer diagnosis is limited. METHODS: A total of 2050 older adults (≥60 years old) surviving for at least 1 year after a cancer diagnosis and 9474 older adults without a cancer history from the National Health and Nutrition Examination Survey (1999-2014) were included for analysis. The exposure variable, a 45-item frailty index (FI), was categorized on the basis of validated cutoffs (FI ≤ 0.10 [fit], 0.10 < FI ≤ 0.21 [prefrail], and FI > 0.21 [frail]). All-cause mortality was ascertained via the National Death Index. Multivariable Cox proportional hazards models were used to estimate adjusted hazard ratios (aHRs) and 95% confidence interval (CIs) for the FI, and this was followed by restricted cubic splines depicting dose-response curves. RESULTS: For older cancer survivors, the mean age at the baseline was 72.6 years (SD, 7.1 years); 5.9% were fit, 38.2% were prefrail, and 55.9% were frail. Older adults without a cancer history were slightly younger (mean age, 70.0 years) and less frail (47.9% were frail). At each level of the FI, cancer survivors (1.9 per 100 person-years for FI ≤ 0.10, 3.4 per 100 person-years for 0.10 < FI ≤ 0.21, and 7.5 per 100 person-years for FI > 0.21) had higher mortality than their cancer-free counterparts (1.4 per 100 person-years for FI ≤ 0.10, 2.4 per 100 person-years for 0.10 < FI ≤ 0.21, and 5.4 per 100 person-years for FI > 0.21). The multivariable model suggested a positive association between the FI and all-cause mortality for survivors (aHR for FI > 0.21 vs FI ≤ 0.10, 2.80; 95% CI, 1.73-4.53) and participants without a cancer history (aHR for FI > 0.21 vs FI ≤ 0.10, 2.75; 95% CI, 2.29-3.32). Restricted cubic splines indicated that all-cause mortality risk increased with the FI in a monotonic pattern. CONCLUSIONS: Frailty is associated with a higher risk of death in older cancer survivors and the elderly without a cancer history.

Evaluating Regional Nodal Irradiation Allocation and Association with Oncologic Outcomes in NSABP B-18, B-27, B-40, and B-41.

PURPOSE: There is a lack of level I evidence to guide radiation therapy recommendations for patients receiving neoadjuvant chemotherapy for breast cancer. We used 4 neoadjuvant chemotherapy trials to determine which patients benefit from regional nodal irradiation (RNI). METHODS AND MATERIALS: We obtained data from the NSABP (National Surgical Adjuvant Breast and Bowel Project) B-18, B-27, B-40, and B-41 clinical trials. B-40 and B-41 allowed RNI at physician's discretion. We evaluated locoregional recurrence (LRR), distant recurrence, disease-free survival, and overall survival (OS). Kaplan-Meier, Peto-Peto, χ2, Fisher exact, and Wilcoxon rank-sum tests were used for survival estimates and comparison. RESULTS: Median follow-up for B-18, B-27, B-40, and B-41 was 13.7, 9.7, 4.5, and 5.1 years, respectively, including 742, 2254, 1154, and 504 patients for analysis. On multivariable analysis, factors significantly associated with RNI included tumor size, ypN status, and tumor subtype; Hispanic patients were less likely to receive RNI. Patients with ypN+HER2+ disease who received RNI had improved OS. B-40 patients with ypN+HR+ disease had improved LRR. On multivariable analysis for the B-40 and B-41 study population, RNI was not associated with significantly improved OS, disease-free survival, distant recurrence, or LRR. CONCLUSIONS: RNI was associated with a clinical benefit for patients with ypN+HER2+ and ypN+HR+ disease. RNI was not significantly associated with a clinically beneficial outcome for the entire cohort. Prospective phase 3 clinical trials are needed to establish guidelines for patients who should receive RNI after neoadjuvant treatment, and action is necessary to eliminate the disparity in care delivery shown for Hispanic women.

Measuring Radiation Toxicity Using Circulating Cell-Free DNA in Prostate Cancer Patients.

BACKGROUND: After radiation therapy (RT), circulating plasma cell-free DNA (cfDNA) released in response to RT damage to tissue can be measured within hours. We examined for a correlation between cfDNA measured during the first week of therapy and early and late gastrointestinal (GI) and genitourinary (GU) toxicity. MATERIAL AND METHODS: Patients were eligible for enrollment if they planned to receive proton or photon RT for nonmetastatic prostate cancer in the setting of an intact prostate or after prostatectomy. Blood was collected before treatment and on sequential treatment days for the first full week of therapy. Toxicity assessments were performed at baseline, weekly during RT, and 6 months and 12 months after RT. Data were analyzed to examine correlations among patient-reported GI and GU toxicities. RESULTS: Fifty-four patients were evaluable for this study. Four (7%) and 3 (6%) patients experienced acute and late grade 2 GI toxicity, respectively. Twenty-two (41%) and 18 (35%) patients experienced acute and late grade 2 GU toxicity, respectively. No patients developed grade 3 or higher toxicity. Grade 2 acute GI toxicity, but not grade 2 acute GU toxicity, was significantly correlated with pre-RT cfDNA levels and on all days 1, 2, 3, 4, and 5 of RT (P < .005). Grade 2 late GI toxicity, but not GU toxicity, was significantly correlated with pre-RT cfDNA levels (P = .021). CONCLUSIONS: Based on this preliminary study, cfDNA levels can potentially predict the subset of patients destined to develop GI toxicity during prostate cancer treatment. Given that the toxicity profiles of the various fractionations and modalities are highly similar, the data support the expectation that cfDNA could provide a biological estimate to complement the dose-volume histogram. A test of this hypothesis is under evaluation in a National Cancer Institute-funded multi-institutional study.

Five-Year Breast Surgeon Experience in LYMPHA at Time of ALND for Treatment of Clinical T1-4N1-3M0 Breast Cancer.

BACKGROUND: Breast cancer-related lymphedema (BCRL) is a source of postoperative morbidity for breast cancer survivors. Lymphatic microsurgical preventive healing approach (LYMPHA) is a technique used to prevent BCRL at the time of axillary lymph node dissection (ALND). We report the 5-year experience of a breast surgeon trained in LYMPHA and investigate the outcomes of patients who underwent LYMPHA following ALND for treatment of cT1-4N1-3M0 breast cancer. METHODS: A retrospective review of patients with cT1-4N1-3M0 breast cancer was performed in patients who underwent ALND with and without LYMPHA. Diagnosis of BCRL was made by certified lymphedema therapists. Descriptive statistics and lymphedema surveillance data were analyzed using results of Fisher's exact or Wilcoxon rank-sum tests. Logistic regression and propensity matching were performed to assess the reduction of BCRL occurrence following LYMPHA. RESULTS: In a 5-year period, 132 patients met inclusion criteria with 76 patients undergoing LYMPHA at the time of ALND and 56 patients undergoing ALND alone. Patients who underwent LYMPHA at the time of ALND were significantly less likely to develop BCRL than those who underwent ALND alone (p = 0.045). Risk factors associated with BCRL development were increased patient age (p = 0.007), body mass index (BMI) (p = 0.003), and, in patients undergoing LYMPHA, number of positive nodes (p = 0.026). CONCLUSIONS: LYMPHA may be successfully employed by breast surgeons trained in lymphatic-venous anastomosis at the time of ALND. While research efforts should continue to focus on prevention and surveillance of BCRL, LYMPHA remains an option to reduce BCRL and improve patient quality of life.

Increased Resident Diversity Precedes Increased Faculty Diversity: Data From a University Radiation Oncology Department.

OBJECTIVES: Increasing the percentage of academic faculty who are female and/or an under-represented minority (URM) is a goal in radiation oncology. When studying diversity changes in our University Radiation Oncology Department, we found that increases in resident diversity preceded changes in faculty diversity in every major category. To illustrate these findings, we plotted resident versus faculty diversity each year over the 52-year history of our program. MATERIALS AND METHODS: Plots were generated of the percent of residents versus faculty in our program each year between 1967 and 2020 in the following categories: female, URM, and people of color. RESULTS: By 1995, substantial levels of diversity were present among both residents and faculty with approximate median annual values between 1995 and 2020 of 30% female for both residents and faculty, 15% URM for both residents and faculty, and 30% persons of color for residents and 15% for faculty. In all analyses, increase in resident diversity preceded an increase in faculty diversity and, in the great majority of years, resident diversity was greater than faculty diversity. CONCLUSION: Our experience suggests that it may be easier to increase resident than faculty diversity and that increases in resident diversity may facilitate increasing faculty diversity.

Kinetics of plasma cfDNA predicts clinical response in non-small cell lung cancer patients.

Tyrosine kinase inhibitors (TKIs), VEGF/VEGF receptor inhibitors (VEGFIs) and immune checkpoint inhibitors (ICIs) have revolutionized the treatment of advanced cancers including non-small-cell lung cancer (NSCLC). This study aims to evaluate the utility of plasma cell-free DNA (cfDNA) as a prognostic biomarker and efficacy predictor of chemotherapy (CT) with or without these precision therapies in NSCLC patients. Peripheral cfDNA levels in 154 NSCLC patients were quantified before and after the first target cycle of chemotherapy. The correlations of cfDNA with tumor burden, clinical characteristics, progression-free survival (PFS)/disease-free survival (DFS), objective response ratio (ORR), and therapy regimens were analyzed respectively. Baseline cfDNA, but not post-chemotherapeutic cfDNA, positively correlates with tumor burden. Notably, cfDNA kinetics (cfDNA Ratio, the ratio of post-chemotherapeutic cfDNA to baseline cfDNA) well distinguished responsive individuals (CR/PR) from the non-responsive (PD/SD). Additionally, cfDNA Ratio was found negatively correlated with PFS in lung adenocarcinoma (LUAD), but not lung squamous-cell carcinoma (LUSC) which may be due to a limited number of LUSC patients in this cohort. LUAD patients with low cfDNA Ratio have prolonged PFS and improved ORR, compared to those with high cfDNA Ratio. When stratified by therapy regimen, the predictive value of cfDNA Ratio is significant in patients with chemotherapy plus VEGFIs, while more patients need be included to validate the value of cfDNA Ratio in other regimens. Thus, the kinetics of plasma cfDNA during chemotherapy may function as a prognostic biomarker and efficacy predictor for NSCLC patients.

Journey to Diversity in a University Radiation Oncology Residency Program: The Role of Leadership and Target Goals.

OBJECTIVES: Increasing diversity in radiation oncology with respect to sex, under-represented minorities (URMs), and people of color is a major objective of our profession. The purpose of this project is to plot diversity percentages in our residency program over the past 52 years and explain major causes for change when identified. MATERIALS AND METHODS: Plots of the percent of residents in our program each year between 1967 and 2020 in the following categories: White male, female, URM, and people of color. RESULTS: Between 1967 and 1992 diversity percentage in our program changed little with ∼90% of residents representing White males. Between 1992 and 1995, overall diversity increased by 40 percentage points, a change maintained from 1995 to 2020. Approximate annual percentages over the past 25 years were: female, 35%; URM, 10%; and people of color, 25%.The main reason for increased diversity starting in 1992 was new leadership seeking to promote diversity. Tools that helped promote diversity were measuring our diversity profile and setting target goals. CONCLUSIONS: Our experience provides a model to measure diversity and track performance over time in residency programs, departments, or practice groups. The priority to place on diversity, and specific performance goals, vary by group. For those seeking to increase diversity, our experience shows it is possible to achieve substantial diversity in all categories, but change requires leadership making diversity a priority.

Circulating Cell-Free DNA Correlates with Body Integral Dose and Radiation Modality in Prostate Cancer.

PURPOSE: The RadTox assay measures circulating cell-free DNA released in response to radiotherapy (RT)-induced tissue damage. The primary objectives for this clinical trial were to determine whether cell-free DNA numbers measured by the RadTox assay are (1) correlated with body integral dose, (2) lower with proton RT compared with photon RT, and (3) higher with larger prostate cancer RT fields. PATIENTS AND METHODS: Patients planned to receive proton or photon RT for nonmetastatic prostate cancer in the setting of an intact prostate or postprostatectomy were eligible for the trial. Plasma was collected pre-RT and at 5 additional daily collection points beginning 24 hours after the initiation of RT. Data from 54 evaluable patients were analyzed to examine any correlations among RadTox scores with body-integral dose, RT modality (photon versus proton), and RT field size (prostate or prostate bed versus whole pelvis). RESULTS: Body integral dose was significantly associated with the peak post-RT RadTox score (P = .04). Patients who received photon RT had a significant increase in peak post-RT RadTox score (P = .04), average post-RT RadTox score (P = .04), and day-2 RadTox score (all minus the pre-RT values for each patient) as compared with patients who received proton RT. Field size was not significantly associated with RadTox score. CONCLUSION: RadTox is correlated with body integral dose and correctly predicts which patients receive proton versus photon RT. Data collection remains ongoing for patient-reported RT toxicity outcomes to determine whether RadTox scores are correlated with toxicity.

Concomitant Radiation Recall Dermatitis and Organizing Pneumonia following Breast Radiotherapy: A Case Report.

PURPOSE: Radiation recall dermatitis (RRD) is a rare complication that occurs after completion of radiation therapy (RT) and initiation of a precipitating agent, most commonly chemotherapeutic medications. Various theories attempt to explain the mechanism, including activation of the body's inflammatory pathways through nonimmune activation. Likewise, radiation-induced organizing pneumonia (RIOP) is an infrequent but potentially life-threatening complication of RT that, while not fully understood, is suspected to be partly an autoimmune reaction. PATIENT: We present the case of a 71-year-old female with a history of type 2 diabetes mellitus, hypothyroidism, interstitial cystitis, and osteoarthritis who presented with clinical stage T1N0M0 ER+/PR-/HER2- invasive ductal carcinoma of the lower outer quadrant of the left breast, for which she underwent left segmental mastectomy and sentinel lymph node biopsy followed by completion axillary lymph node dissection. Her final pathologic stage was T1N1M0. RESULT: The patient developed RRD and later RIOP following receipt of radiation and chemotherapy, which resolved with steroid administration. CONCLUSIONS: The rarity of both RRD and RIOP occurring in a patient, as in our case, suggests a shared pathophysiology behind these two complications. As both reactions involve some degree of inflammation and respond to corticosteroids, it seems likely that the etiologies of RRD and RIOP lie within the inflammatory pathway. However, further investigation should evaluate the frequency, duration, and triggering of concomitant RRD and RIOP.

The dose-response characteristics of four NTCP models: using a novel CT-based radiomic method to quantify radiation-induced lung density changes.

Multiple competing normal tissue complication probability (NTCP) models have been proposed for predicting symptomatic radiation-induced lung injury in human. In this paper we tested the efficacy of four common NTCP models applied quantitatively to sub-clinical X-ray computed tomography (CT)-density changes in the lung following radiotherapy. Radiotherapy planning datasets and follow-up chest CTs were obtained in eight patients treated for targets within the lung or hilar region. Image pixel-wise radiation dose exposure versus change in observable CT Hounsfield units was recorded for early (2-5 months) and late (6-9 months) time-points. Four NTCP models, Lyman, Logistic, Weibull and Poisson, were fit to the population data. The quality of fits was assessed by five statistical criteria. All four models fit the data significantly (p < 0.05) well at early, late and cumulative time points. The Lyman model fitted best for early effects while the Weibull Model fitted best for late effects. No significant difference was found between the fits of the models and with respect to parameters D50 and γ50. The D50 estimates were more robust than γ50 to image registration error. For analyzing population-based sub-clinical CT pixel intensity-based dose response, all four models performed well.

An Amino Acid-Based Oral Rehydration Solution Regulates Radiation-Induced Intestinal Barrier Disruption in Mice.

BACKGROUND: Radiotherapy inadvertently affects gastrointestinal (GI) epithelial cells, causing intestinal barrier disruption and increased permeability. OBJECTIVE: We examined the effect of amino acid-based oral rehydration solution (AA-ORS) on radiation-induced changes of intestinal barrier function and epithelial tight junctions (TJs) in a randomized experimental study using a total-body irradiation (TBI) mouse model. METHODS: Eight-week-old male Swiss mice received a single-dose TBI (0, 1, 3, or 5 Gy), and subsequent gastric gavage with AA-ORS (threonine, valine, serine, tyrosine, and aspartic acid) or saline for 2 or 6 d. Intestinal barrier function of mouse ileum was characterized by electrophysiological analysis of conductance, anion selectivity, and paracellular permeability [fluorescein isothiocyanate (FITC)-dextran]. Ultrastructural changes of TJs were evaluated by transmission electron microscopy. Membrane protein and mRNA expression of claudin-1, -2, -3, -5, and -7, occludin, and E-cadherin were analyzed with western blot, qPCR, and immunohistochemistry. Nonparametric tests were used to compare treatment-dose differences for each time point. RESULTS: Saline-treated mice had a higher conductance at doses as low as 3 Gy, and as early as 2 d post-TBI compared with 0 Gy (P < 0.001). Paracellular permeability and dilution potential were increased 6 d after 5 Gy TBI (P < 0.001). Conductance decreased with AA-ORS after 2 d in 3-Gy and 5-Gy mice (P < 0.05 and P < 0.001), and on day 6 after 5 Gy TBI (P < 0.001). Anion selectivity and FITC permeability decreased from 0.73 ± 0.02 to 0.61 ± 0.03 pCl/pNa (P < 0.01) and from 2.7 ± 0.1 × 105 to 2.1 ± 0.1 × 105 RFU (P < 0.001) in 5-Gy mice treated with AA-ORS for 6 d compared with saline. Irradiation-induced ultrastructural changes of TJs characterized by decreased electron density and gap formation improved with AA-ORS. Reduced claudin-1, -3, and -7 membrane expression after TBI recovered with AA-ORS within 6 d, whereas claudin-2 decreased indicating restitution of TJ proteins. CONCLUSIONS: Radiation-induced functional and structural disruption of the intestinal barrier in mice is reversed by AA-ORS rendering AA-ORS a potential treatment option in prospective clinical trials in patients with gastrointestinal barrier dysfunction.

Radiation-induced tumor immunity in patients with non-small cell lung cancer.

BACKGROUND: Radiation-induced tumor immunity (RITI) influences primary tumor growth and development of metastases in preclinical cancer models with conventional radiotherapy. Antigen-specific immune responses have also been shown for prostate cancer treated with radiotherapy. We examined whether RITI can be induced in patients with non-small cell lung cancer (NSCLC) following proton radiotherapy. METHODS: Pre- and post-radiotherapy plasma samples from 26 patients with nonmetastatic NSCLC who received radiotherapy between 2010 and 2012 were evaluated by western blotting for IgG and IgM bands to assess RITI response to tumor antigens from lung cancer cell lines. Statistical analysis was used to evaluate any correlation among IgG or IgM and clinical outcomes. RESULTS: Twenty-one patients received proton therapy at 2 GyRBE/fraction (n = 17) or 6-12 Gy/fraction (n = 4); five received photon therapy at 2-2.5 GyRBE/fraction. Compared with the pretreatment baseline, new IgG or IgM binding was detected in 27% and 50% of patients, respectively. New IgG bands were detected in the 25-37 kD, 50-75 kD, and 75-100 kD ranges. New IgM bands were detected in the 20-25 kD, 25-37 kD, 37-50 kD, 50-75 kD, and 75-100 kD ranges. There was no difference in IgG and/or IgM RITI response in patients treated with photons versus protons, or in patients who received SBRT compared to standard fractionation (P > 0.05). There was no difference in overall survival, metastasis-free survival, or local control based on IgG and/or IgM RITI response (P > 0.05). CONCLUSION: RITI can be induced in patients with NSCLC through upregulated IgG and/or IgM. RITI response was not associated with proton versus photon therapy or with clinical outcomes in this small cohort and should be examined in a larger cohort in future studies.

Cellular senescence and radiation-induced pulmonary fibrosis.

Radiation-induced pulmonary fibrosis (RIPF) is a serious treatment complication that affects about 9%-30% cancer patients receiving radiotherapy for thoracic tumors. RIPF is characterized by progressive and irreversible destruction of lung tissues and deterioration of lung function, which can compromise quality of life and eventually lead to respiratory failure and death. Unfortunately, the mechanisms by which radiation causes RIPF have not been well established nor has an effective treatment for RIPF been developed. Recently, an increasing body of evidence suggests that induction of senescence by radiation may play an important role in RIPF and clearance of senescent cells (SnCs) with a senolytic agent, small molecule that can selectively kill SnCs, has the potential to be developed as a novel therapeutic strategy for RIPF. This review discusses some of these new findings to promote further study on the role of cellular senescence in RIPF and the development of senolytic therapeutics for RIPF.