Risk-adjusted chemoradiation according to human papilloma viral status for anal cancer: a pilot study.

Background and purpose: HPV-associated or positive (HPV+) anal cancer patients may have better outcome compared to those with HPV negative (HPV-) disease. We report a planned interim analysis of a prospective registry study that tailors chemoradiation (CRT) for anal cancer according to HPV status. Materials and methods: HPV+ patients received de-escalated radiation doses of 45, 50.4 and 55.8 Gy, while HPV- received 50.4, 55.8 and 63 Gy for T1, T2 and T3/T4 disease respectively. Chemotherapy consisted of a single dose of mitomycin-C and oral capecitabine on days of RT. All patients were planned by VMAT following CT, PET/CT and MR simulation. This cohort (n = 24) had a minimum 24-month follow-up. Disease free survival (DFS) and local failure rates (LFR) were compared with 180 patients managed by standard CRT (2 cycles of mitomycin-C and 5-fluorouracil, radiation doses 50.4-63 Gy based on T-category) from 2011-2018. Propensity score comparison was performed using a retrospective to prospective 2 to 1 match based on tumor size and N-category. Results: In the HPV+ cohort (n = 20), there were 2 local failures. Two of 4 HPV- patients failed locally. The 30-month DFS and LFR were 79% and 17% respectively. Similar DFS and LFR were observed in the retrospective (80% and 15% respectively) and matched patients (76% and 16% respectively). No grade ≥3 neutropenia and febrile neutropenia were observed in the registry cohort whereas 19% and 14% respectively were seen in the retrospective patients. Conclusion: De-escalation of CRT for HPV+ anal cancer may result in decreased acute toxicities and similar cancer outcomes compared to standard CRT.

Protection From Radiation-Induced Neuroanatomic Deficits by CCL2 Deficiency Is Dependent on Sex.

PURPOSE: Cranial radiation therapy for the treatment of pediatric brain tumors results in changes to brain development that are detectable with magnetic resonance imaging. We have previously demonstrated similar structural changes in both humans and mice. The goal of the current study was to examine the role of inflammation in this response. Because neuroanatomic volume deficits in pediatric survivors are more pronounced in female patients, we also evaluated possible dependence on sex. METHODS AND MATERIALS: Other studies have shown that male mice deficient in the C-C chemokine ligand 2 gene (Ccl2; previously Mcp-1) have a muted neuroinflammatory response after irradiation. We irradiated Ccl2-/- (HOM; female = 12, male = 13), Ccl2-/+ (HET; female = 13, male = 16), and Ccl2+/+ (WT; female = 11, male = 13) mice with a whole brain dose of 7 Gy during infancy. Control mice (with approximately equal group sizes) were anesthetized but not irradiated. In vivo magnetic resonance images were acquired at 4 time points up to 3 months after irradiation, and deformation-based morphometry was used to identify volume differences. RESULTS: Irradiation of WT mice resulted in a deficit in neuroanatomic growth with limited sex dependence. HOM and HET male mice were significantly protected from this radiation-induced damage, whereas HOM and HET female mice were not. CONCLUSIONS: Interventions aimed at mitigating the effects of cranial radiation therapy in pediatric cancer survivors by modulating inflammatory response will need to consider patient sex.

Metformin effects on brain development following cranial irradiation in a mouse model.

BACKGROUND: Cranial radiation therapy (CRT) is a mainstay of treatment for malignant pediatric brain tumors and high-risk leukemia. Although CRT improves survival, it has been shown to disrupt normal brain development and result in cognitive impairments in cancer survivors. Animal studies suggest that there is potential to promote brain recovery after injury using metformin. Our aim was to evaluate whether metformin can restore brain volume outcomes in a mouse model of CRT. METHODS: C57BL/6J mice were irradiated with a whole-brain radiation dose of 7 Gy during infancy. Two weeks of metformin treatment started either on the day of or 3 days after irradiation. In vivo magnetic resonance imaging was performed prior to irradiation and at 3 subsequent time points to evaluate the effects of radiation and metformin on brain development. RESULTS: Widespread volume loss in the irradiated brain appeared within 1 week of irradiation with limited subsequent recovery in volume outcomes. In many structures, metformin administration starting on the day of irradiation exacerbated radiation-induced injury, particularly in male mice. Metformin treatment starting 3 days after irradiation improved brain volume outcomes in subcortical regions, the olfactory bulbs, and structures of the brainstem and cerebellum. CONCLUSIONS: Our results show that metformin treatment has the potential to improve neuroanatomical outcomes after CRT. However, both timing of metformin administration and subject sex affect structure outcomes, and metformin may also be deleterious. Our results highlight important considerations in determining the potential benefits of metformin treatment after CRT and emphasize the need for caution in repurposing metformin in clinical studies.

Metabolic Regulation of Hippocampal Neuronal Development and Its Inhibition After Irradiation.

5'-Adenosine monophosphate-activated protein kinase (AMPK), a key regulator of cellular energy homeostasis, plays a role in cell fate determination. Whether AMPK regulates hippocampal neuronal development remains unclear. Hippocampal neurogenesis is abrogated after DNA damage. Here, we asked whether AMPK regulates adult hippocampal neurogenesis and its inhibition following irradiation. Adult Cre-lox mice deficient in AMPK in brain, and wild-type mice were used in a birth-dating study using bromodeoxyuridine to evaluate hippocampal neurogenesis. There was no evidence of AMPK or phospho-AMPK immunoreactivity in hippocampus. Increase in p-AMPK but not AMPK expression was observed in granule neurons and subgranular neuroprogenitor cells (NPCs) in the dentate gyrus within 24 hours and persisted up to 9 weeks after irradiation. AMPK deficiency in Cre-lox mice did not alter neuroblast and newborn neuron numbers but resulted in decreased newborn and proliferating NPCs. Inhibition of neurogenesis was observed after irradiation regardless of genotypes. In Cre-lox mice, there was further loss of newborn early NPCs and neuroblasts but not newborn neurons after irradiation compared with wild-type mice. These results are consistent with differential negative effect of AMPK on hippocampal neuronal development and its inhibition after irradiation.

Spinal Cord Dose Tolerance to Stereotactic Body Radiation Therapy.

Spinal cord tolerance data for stereotactic body radiation therapy (SBRT) were extracted from published reports, reviewed, and modelled. For de novo SBRT delivered in 1 to 5 fractions, the following spinal cord point maximum doses (Dmax) are estimated to be associated with a 1% to 5% risk of radiation myelopathy (RM): 12.4 to 14.0 Gy in 1 fraction, 17.0 Gy in 2 fractions, 20.3 Gy in 3 fractions, 23.0 Gy in 4 fractions, and 25.3 Gy in 5 fractions. For reirradiation SBRT delivered in 1 to 5 fractions, reported factors associated with a lower risk of RM include cumulative thecal sac equivalent dose in 2 Gy fractions with an alpha/beta of 2 (EQD22) Dmax ≤70 Gy; SBRT thecal sac EQD22 Dmax ≤25 Gy, thecal sac SBRT EQD22 Dmax to cumulative EQD22 Dmax ratio ≤0.5, and a minimum time interval to reirradiation of ≥5 months. Larger studies containing complete institutional cohorts with dosimetric data of patients treated with spine SBRT, with and without RM, are required to refine RM risk estimates.

Salvage surgery for locally recurrent anal cancer after intensity modulated radiation therapy with concurrent chemotherapy.

INTRODUCTION: Chemoradiation (CRT) with intensity modulated radiation treatment (IMRT) has become the standard for anal cancer. In patients who fail this treatment modality, salvage surgery with abdominal perineal resection can result in long term cancer control. We aimed to evaluate a single centre's experience of salvage surgery for local recurrence since the introduction of IMRT. MATERIALS AND METHODS: A retrospective chart review was performed of all patients who underwent definitive CRT for anal carcinoma at a single tertiary referral center since IMRT became standard in 2009. Patients with recurrent or persistent disease after treatment who underwent salvage surgery were included. Details of CRT, salvage surgery and surgical complications, patterns of recurrence after surgery, and survival data were collected and described. RESULTS: Between 2009-2018, 181 patients underwent definitive treatment using IMRT for anal carcinoma. Of 26 patients who had locoregional recurrent or persistent disease, 14 underwent salvage surgery. Nine had multi-visceral resection and 8 required autologous flap reconstruction. Twelve patients had resections with clear margins and 2 had microscopic positive margins. Twelve patients (86%) experienced post-operative complications, and eight (57%) had perineal wound complications. After salvage, four patients (29%) recurred locally. None of the 8 patients with rpT2 disease recurred. After salvage surgery, 5-year disease free survival was 68.4% and 5-year overall survival was 75%. CONCLUSION: Following IMRT based chemoradiation, salvage surgery has high rates of surgical complications; however disease free and overall survival results are excellent particularly for small recurrences.

Intensity Modulated Radiation Therapy Plus Etoposide/Cisplatin for Patients With Limited Advanced Unresectable Thymic Epithelial Tumors: A Prospective Phase 2 Study.

PURPOSE: This prospective phase 2 study evaluated the efficacy and safety of intensity modulated radiation therapy plus etoposide/cisplatin (EP) for patients with unresectable thymic epithelial tumors (TETs). METHODS AND MATERIALS: Patients with limited advanced unresectable TETs whose lesions could be encompassed within radiation fields were enrolled in this study. Two cycles of EP (75 mg/m2 etoposide and 25 mg/m2 cisplatin on days 1-3 and days 29-31) were administered concurrently with radiation therapy, followed by 2 cycles after radiation therapy. The primary endpoint was the objective response rate. The secondary endpoints were the progression-free survival rate, overall survival rate, and incidence of adverse events. RESULTS: Fifty-six patients were enrolled between June 2011 and May 2018. Twenty-two and 34 patients had thymomas and thymic carcinomas, respectively. The median age was 52 (range, 21-76) years, and 30 patients (53.6%) were men. Eight patients (14.3%) had stage III tumors, 6 (10.7%) had stage IVA tumors, and 42 (75.0%) had stage IVB tumors. The objective response rate was 85.7% (95% confidence interval, 76.3%-95.2%). With a median follow-up of 46 (range, 7-101) months, the 1-, 2-, and 5-year progression-free survival rates were 66.1%, 48.0%, and 29.5%, and the 1-, 2-, and 5-year overall survival rates were 91.0%, 76.2%, and 56.2%, respectively. The most common grade 3 to 4 adverse event was leukopenia (42.9%). Pulmonary fibrosis was also observed (5.3%). CONCLUSIONS: Because intensity modulated radiation therapy with EP is effective and safe for limited advanced unresectable TETs, it could be a suitable treatment option for such patients.

Metabolic Regulation of Hippocampal Neuroprogenitor Apoptosis After Irradiation.

The tumor suppressor p53 is an important regulator of cell fate response after DNA damage. Cell fate response following metabolic stresses has also been linked to p53-dependent pathways. In this study, we asked if 5'-adenosine monophosphate-activated protein kinase (AMPK), the master sensor of cellular energy balance, played a role in p53-dependent apoptosis of neural progenitor cells (NPCs) in the hippocampus after irradiation. Adult mice with targeted disruption of p53 or prkaa2 (gene that encodes AMPKα) in the brain were used to determine the role of p53 and AMPK, respectively, in radiation-induced apoptosis of NPCs in the hippocampus. The p53-dependent apoptosis of NPCs was associated with an increase in phospho-AMPK expression in the dentate gyrus at 8 hours after irradiation. Activation of AMPK was seen in granule neurons and subgranular NPCs. Compared with wildtype mice, apoptosis of NPCs was significantly attenuated in AMPK deficient (nestinCre: prkaa2fl/fl) mice after irradiation. AMPK deficiency did not however alter p53 activation in NPCs after irradiation. We conclude that AMPK may regulate apoptosis of hippocampal NPCs after irradiation. These findings suggest that cellular metabolism may play a role in determining cell fate response such as apoptosis after DNA damage in NPCs.

p53 Loss Mitigates Early Volume Deficits in the Brains of Irradiated Young Mice.

PURPOSE: Pediatric cranial radiation therapy results in lasting changes in brain structure. Though different facets of radiation response have been characterized, the relative contributions of each to altered development is unclear. We sought to determine the role of radiation-induced programmed cell death, as mediated by the Trp53 (p53) gene, on neuroanatomic development. METHODS AND MATERIALS: Mice having a conditional knockout of p53 (p53KO) or wildtype p53 (WT) were irradiated with a whole-brain dose of 7 Gy (IR; n = 30) or 0 Gy (sham; n = 28) at 16 days of age. In vivo magnetic resonance imaging was performed before irradiation and at 4 time points after irradiation, until 3 months posttreatment, followed by ex vivo magnetic resonance imaging and immunohistochemistry. The role of p53 in development was assessed at 6 weeks of age in another group of untreated mice (n = 37). RESULTS: Neuroanatomic development in p53KO mice was normal. After cranial irradiation, alterations in neuroanatomy were detectable in WT mice and emerged through 2 stages: an early volume loss within 1 week and decreased growth through development. In many structures, the early volume loss was partially mitigated by p53KO. However, p53KO had a neutral or negative impact on growth; thus, p53KO did not widely improve volume at endpoint. Partial volume recovery was observed in the dentate gyrus and olfactory bulbs of p53KO-IR mice, with corresponding increases in neurogenesis compared with WT-IR mice. CONCLUSIONS: Although p53 is known to play an important role in mediating radiation-induced apoptosis, this is the first study to look at the cumulative effect of p53KO through development after cranial irradiation across the entire brain. It is clear that apoptosis plays an important role in volume loss early after radiation therapy. This early preservation alone was insufficient to normalize brain development on the whole, but regions reliant on neurogenesis exhibited a significant benefit.

A prospective cohort study of patient-reported vomiting, retching, nausea and antiemetic use during neoadjuvant long-course radiation therapy and concurrent 5-fluorouracil-based chemotherapy for rectal adenocarcinoma.

BACKGROUND AND PURPOSE: Antiemetic guidelines suggest daily prophylaxis with a serotonin3 receptor antagonist (5-HT3RA) as an option for patients receiving long-course neoadjuvant radiation therapy and concurrent 5-fluorouracil-based chemotherapy for rectal cancer, despite the risks that 5-HT3RA-induced constipation may pose. We explored the incidence of patient-reported vomiting, retching, nausea and antiemetic intake among patients in this setting to determine if these risks are justified. MATERIALS AND METHODS: We carried out a single-centre non-randomised prospective cohort study of adult patients receiving long-course neoadjuvant radiation therapy and concurrent 5-fluorouracil-based chemotherapy for rectal adenocarcinoma. Patients recorded symptoms and medication intake daily until 7 days following treatment completion. RESULTS: From 33 evaluable patients, we collected 1407 days of patient-reported data. Vomiting was reported by 7 patients (21%), retching by 5(15%) and nausea by 21(64%). No patients were administered prophylactic antiemetics. The median number of days with vomiting was 2, and the cumulative number of days for all affected patients was 22 (1.6% of 1407 evaluable days). There were no differences in PTV or small bowel loop V15Gy, V45Gy and V50Gy volumes between patients that did and did not vomit. CONCLUSIONS: The cumulative incidence of days with vomiting was only 1.6%. 5-HT3RA prophylaxis during long-course neoadjuvant treatment seems unnecessary.

Altered brain morphology after focal radiation reveals impact of off-target effects: implications for white matter development and neurogenesis.

Background: Children with brain tumors treated with cranial radiation therapy (RT) often exhibit cognitive late effects, commonly associated with reduced white matter (WM) volume and decreased neurogenesis. The impact of radiation damage in particular regions or tissues on brain development as a whole has not been elucidated. Methods: We delivered whole-brain or focal radiation (8 Gy single dose) to infant mice. Focal treatments targeted white matter (anterior commissure), neuronal (olfactory bulbs), or neurogenic (subventricular zone) regions. High-resolution ex vivo MRI was used to assess radiation-induced volume differences. Immunohistochemistry for myelin basic protein and doublecortin was performed to assess associated cellular changes within white matter and related to neurogenesis, respectively. Results: Both whole-brain and focal RT in infancy resulted in volume deficits in young adulthood, with whole-brain RT resulting in the largest deficits. RT of the anterior commissure, surprisingly, showed no impact on its volume or on brain development as a whole. In contrast, RT of the olfactory bulbs resulted in off-target volume reduction in the anterior commissure and decreased subventricular zone neurogenesis. RT of the subventricular zone likewise produced volume deficits in both the olfactory bulbs and the anterior commissure. Similar off-target effects were found in the corpus callosum and parietal cortex. Conclusions: Our results demonstrate that radiation damage locally can have important off-target consequences for brain development. These data suggest that WM may be less radiosensitive than volume change alone would indicate and have implications for region-sparing radiation treatments aimed at reducing cognitive late effects.

A systematic review of methodologies, endpoints, and outcome measures in randomized trials of radiation therapy-induced nausea and vomiting.

PURPOSE: Clinical trials in radiation therapy-induced nausea and vomiting (RINV) appear to have varied methodologies, endpoints, and outcome measures. This complicates trial comparisons, weakens practice guideline recommendations, and contributes to variability in supportive care patterns of practice. We systematically reviewed RINV trials to describe and compare their pertinent design features. MATERIALS AND METHODS: Ovid versions of the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, EMBASE, and MEDLINE to January/February 2017 were searched for adult phase III trials of RINV management strategies. Key abstracted data included trial interventions and eligibility criteria, standard radiation therapy (RT) metrics, symptom assessment procedures, symptom definitions and grading systems, pre-specified and reported endpoints, and other outcome measures. RESULTS: From 1166 references identified in the initial database search, we selected 34 trials for analysis that collectively randomized 4529 patients (median 61, range 11-1492). Twenty-eight trials (82%) were published prior to the year 2000. Twenty-seven trials (79%) involved multiple fraction RT and 7 (21%) single fraction RT. Twenty-four trials (71%) evaluated prophylactic interventions, 9 (26%) rescue interventions, and 1 trial did not specify. Thirty-three trials (97%) evaluated pharmacologic interventions. Twenty trials (59%) had patient report symptoms, 5 (15%) healthcare professionals or researchers, and 10 (29%) did not specify. Nausea was not defined in any trial but was reported as a stand-alone symptom in 26 trials (76%) and was graded in 20 (59%), with categorical qualitative scales being the most common method. Vomiting was defined in 3 trials (9%), was reported as a stand-alone symptom in 17 (47%), and was graded in 7 (21%), with continuous numerical scales being the most common method. Retching was defined in 3 trials, was not reported as a stand-alone symptom in any trial, and was graded in 1 (3%). Twenty-one trials (62%) created compound symptom measures that combined individual symptoms. Fifteen trials (44%) reported "emetic episode/event" measures but only 9 defined them. Seventeen trials (50%) reported complicated endpoints (e.g., "response," "control," "success") that combined multiple symptom or compound symptom measures, but 7 did not define them comprehensively. Ten trials (29%) defined a primary endpoint a priori. CONCLUSIONS: Methodologies, endpoints, and outcome measures varied considerably among 34 randomized trials in RINV.

Cellular Senescence in Mouse Hippocampus After Irradiation and the Role of p53 and p21.

Diverse stress signals including irradiation may trigger cellular senescence. We asked whether irradiation induced senescence in mouse hippocampus, and whether p53 or p21 played a role in this response. Following whole-brain irradiation, polymerase chain reaction (PCR) arrays for senescence-associated genes showed increased expression of CDKN1A (p21) and CDKN2A (p19ARF) in mouse hippocampus at 9 weeks. Upregulation of p21 and p19ARF was confirmed using real-time PCR, which also demonstrated increased CDKN2A/p16INKa expression after irradiation. No altered regulation of another 17 senescence-associated genes was observed after irradiation. Immunohistochemistry revealed increased nuclear expression of p16INK4A, p19ARF, p53, p21, phosphorylated p38 (pp38), 4-hydroxy-2-nonenal, and interleukin-6 (IL6) in granule cells of dentate gyrus after irradiation. Increased p16 nuclear immunoreactivity was further observed in type -1 cells, the putative neural stem cells. γ-phosphorylated-histone-2A nuclear foci were also seen in dentate gyrus 9 weeks postirradiation. In nonirradiated mice knockout of the TRP53 or p21 gene, there was increased p16INK4A, p19ARF, and IL6, but not pp38 in dentate gyrus. We conclude that irradiation induces transcript and protein expression profile alterations in mouse dentate gyrus consistent with the senescence phenotype. Absence of p53 or p21 results in increase in baseline expression of senescence markers with no further increase in expression after irradiation.

Effects of Aging on Hippocampal Neurogenesis After Irradiation.

PURPOSE: To assess the influence of aging on hippocampal neuronal development after irradiation (IR). METHODS AND MATERIALS: Male mice, 2, 4, 6, 12, and 18 months of age, were given a single dose of 0 or 5 Gy of IR. A bromodeoxyuridine (BrdU) incorporation study was used to label newborn cells. Neural progenitors, newborn neurons, and microglia in dentate gyrus (DG) were identified by phenotypic markers, and their numbers were quantified by nonbiased stereology 9 weeks after IR. RESULTS: BrdU-positive or newborn cells in DG decreased with aging and after IR. The number of neuroblasts and newborn neurons decreased with aging, and a further significant reduction was observed after IR. Total type 1 cells (the putative neural stem cells), and newborn type 1 cells decreased with aging, and further reduction in total type 1 cells was observed after IR. Aging-associated activation of microglia in hippocampus was enhanced after IR. CONCLUSIONS: The aging-associated decline in hippocampal neurogenesis was further inhibited after IR. Ablation of neural progenitors and activation of microglia may contribute to the inhibition of neuronal development after IR across all ages.

Comparison of the EORTC STO-22 and the FACT-Ga quality of life questionnaires for patients with gastric cancer.

This review compares the development, characteristics, validity, and reliability of two well-known quality of life (QOL) assessment tools used in patients with gastric cancer: the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Stomach (EORTC QLQ-STO22) and the Functional Assessment of Cancer Therapy-Gastric (FACT-Ga). A literature search was conducted using MEDLINE, EMBASE, and Cochrane CENTRAL (inception to April 2015) to identify studies that discussed the development, characteristics, validity and reliability of the EORTC QLQ-STO22 or the FACT-Ga. The QLQ-STO22 was developed with collaboration with patients, healthcare professionals and literature review and was mainly field tested in European countries. Conversely, items on the FACT-Ga were generated from interviews with patients and healthcare professionals concurrently in North America and Asia. While both modules involve a 7-day recall period and use Likert scales, the QLQ-STO22 and FACT-Ga differ in terms of QOL domain focus, quantity and presentation of items, response options, and scoring. However, both tools show good internal consistency, test-retest reliability, sensitivity to change and construct validity. In addition, both questionnaires have been internationally validated within a large sample of patients undergoing a variety of treatments, thus demonstrating their cross-cultural applicability. The EORTC QLQ-STO22 and FACT-Ga are both valid and reliable tools with unique strengths and weaknesses. Selection between instruments should consider specific patient characteristics and goals of the study.

Cut points for mild, moderate, and severe pain among cancer and non-cancer patients: a literature review.

Defining cut points (CPs) for varying levels of pain intensity is important for assessing changes in patient's functional status, and guiding the development and evaluation of treatment options. We aimed to summarize CPs identified in the literature for mild, moderate, and severe pain on the numeric rating scale (NRS), and recommend optimal CPs for cancer and non-cancer patients. We searched MEDLINE and EMBASE (inception to May 2015) for studies that used CPs to classify pain intensity on the NRS among patients with cancer or non-cancer conditions leading to acute or chronic pain. A CP was defined as the upper bound of a mild or moderate pain category. Of 1,556 identified articles, 27 were included for review. Among patients with cancer pain, mild-moderate pain CPs ranged from 1 to 4 (mean, 3.5±1.08), with CP4 being the most recommended CP (80%). For moderate-severe pain, CPs ranged from 4 to 7 (mean, 6.2±0.92), and CP6 (50%) was the optimal CPs. Among patients with non-cancer pain, mild-moderate pain CPs ranged from 2 to 5 (mean, 3.62±0.78), and CP4 was the most frequently used CP (52.9%). For moderate-severe non-cancer pain, CPs ranged from 4 to 8 (mean, 6.5±0.99), and CP6 (41.2%) was the most frequently recommended CP. A wide range of CPs for mild, moderate, and severe pain categories were identified in the literature among both cancer and non-cancer patient populations. Further studies are needed to delineate more accurate and precise CPs for pain intensity.

Treatment age, dose and sex determine neuroanatomical outcome in irradiated juvenile mice.

Pediatric cranial radiation therapy can induce long-term neurocognitive deficits, the risk and severity of these deficits are amplified in females and in those individuals exposed at a younger age and/or those irradiated at higher doses. To investigate the developmental consequences of these factors in greater detail, male and female C57Bl/6J mice between infancy and late childhood (16 and 36 days) were irradiated at a single time point with a whole-brain dose of 0, 3, 5 or 7 Gy. In vivo and ex vivo magnetic resonance imaging (MRI) and deformation-based morphometry was used to identify radiation-induced volume differences. As expected, exposure to 7 Gy of radiation at 16 days of age induced widespread volume deficits that were largely mitigated by increasing treatment age or decreasing dose. Notable exceptions were regions in the olfactory bulbs and hippocampus that displayed both a detectable difference in volume and a loss in neurogenesis for most doses and ages. Furthermore, white matter regions located at the front of the brain remained sensitive to radiation at later treatment ages, compared to regions at the back. Differences due to sex were subtle, with increased radiosensitivity in females detectable only in the mammillary bodies and fornix. Our results reveal anatomical alterations in brain development consistent with expectations based on pediatric patient neurocognitive outcomes. This data demonstrates that neuroimaging of the mouse is an effective tool for investigating radiation-induced late effects.

miRNA-95 mediates radioresistance in tumors by targeting the sphingolipid phosphatase SGPP1.

Radiation resistance poses a major clinical challenge in cancer treatment, but little is known about how microRNA (miR) may regulate this phenomenon. In this study, we used next-generation sequencing to perform an unbiased comparison of miR expression in PC3 prostate cancer cells rendered resistant to fractionated radiation treatment. One miR candidate found to be upregulated by ionizing radiation was miR-95, the enforced expression of which promoted radiation resistance in a variety of cancer cells. miR-95 overexpression recapitulated an aggressive phenotype including increased cellular proliferation, deregulated G2-M checkpoint following ionizing radiation, and increased invasive potential. Using combined in silico prediction and microarray expression analyses, we identified and validated the sphingolipid phosphatase SGPP1, an antagonist of sphingosine-1-phosphate signaling, as a target of miR-95 that promotes radiation resistance. Consistent with this finding, cell treatment with FTY720, a clinically approved small molecule inhibitor of S1P signaling, sensitized miR-95 overexpressing cells to radiation treatment. In vivo assays extended the significance of these results, showing that miR-95 overexpression increased tumor growth and resistance to radiation treatment in tumor xenografts. Furthermore, reduced tumor necrosis and increased cellular proliferation were seen after radiation treatment of miR-95 overexpressing tumors compared with control tumors. Finally, miR-95 expression was increased in human prostate and breast cancer specimens compared with normal tissue. Together, our work reveals miR-95 expression as a critical determinant of radiation resistance in cancer cells.

International radiation oncology trainee decision making in the management of radiotherapy-induced nausea and vomiting.

PURPOSE: This study explored international radiation oncology trainee decision making in the management of radiotherapy-induced nausea and vomiting (RINV). METHODS: Radiation oncology trainees who were members of the national radiation oncology associations of the USA, Canada, Netherlands, Australia, New Zealand, France, Spain and Singapore completed a Web-based survey. Respondents estimated the risks of nausea and vomiting associated with six standardised radiotherapy-only clinical case vignettes modelled after international anti-emetic guidelines and then committed to prophylactic, rescue or no therapy as an initial management approach for each case. RESULTS: One hundred and seventy-six trainees from 11 countries responded. Only 28 % were aware of any anti-emetic guideline. In general, risk estimates and management approaches for the high-risk and minimal risk cases varied less and were more in line with guideline standards than were estimates and approaches for the moderate- and low-risk cases. Prophylactic therapy was the most common approach for the high-risk and a moderate-risk case (83 and 71 % of respondents respectively), while rescue therapy was the most common approach for a second moderate-risk case (69 %), two low-risk cases (69 and 76 %) and a minimal risk case (68 %). A serotonin receptor antagonist was the most commonly recommended prophylactic agent. On multivariate analysis, a higher estimated risk of nausea predicted for recommending prophylactic therapy, and a lower estimated risk of nausea predicted for recommending rescue therapy. CONCLUSIONS: Radiation oncology trainee risk estimates and recommended management approaches for RINV clinical case vignettes varied and matched guideline standards more often for high-risk and minimal risk cases than for moderate- and low-risk cases. Risk estimates of nausea specifically were strong predictors of management decisions.

Probabilities of radiation myelopathy specific to stereotactic body radiation therapy to guide safe practice.

PURPOSE: Dose-volume histogram (DVH) results for 9 cases of post spine stereotactic body radiation therapy (SBRT) radiation myelopathy (RM) are reported and compared with a cohort of 66 spine SBRT patients without RM. METHODS AND MATERIALS: DVH data were centrally analyzed according to the thecal sac point maximum (Pmax) volume, 0.1- to 1-cc volumes in increments of 0.1 cc, and to the 2 cc volume. 2-Gy biologically equivalent doses (nBED) were calculated using an α/ß = 2 Gy (units = Gy(2/2)). For the 2 cohorts, the nBED means and distributions were compared using the t test and Mann-Whitney test, respectively. Significance (P<.05) was defined as concordance of both tests at each specified volume. A logistic regression model was developed to estimate the probability of RM using the dose distribution for a given volume. RESULTS: Significant differences in both the means and distributions at the Pmax and up to the 0.8-cc volume were observed. Concordant significance was greatest for the Pmax volume. At the Pmax volume the fit of the logistic regression model, summarized by the area under the curve, was 0.87. A risk of RM of 5% or less was observed when limiting the thecal sac Pmax volume doses to 12.4 Gy in a single fraction, 17.0 Gy in 2 fractions, 20.3 Gy in 3 fractions, 23.0 Gy in 4 fractions, and 25.3 Gy in 5 fractions. CONCLUSION: We report the first logistic regression model yielding estimates for the probability of human RM specific to SBRT.