Attention-mediated neurocognitive profiles in survivors of pediatric brain tumors: comparison to children with neurodevelopmental ADHD

Comorbid ADHD and Pediatric Sickle Cell Disease: Prevalence and Risk Factors

Sickle cell disease (SCD) is a genetic blood condition that places youth at increased risk for deficits in complex attention suggestive of increased risk for Attention-Deficit/Hyperactivity Disorder (ADHD). We used systematic screening to assess the prevalence of ADHD in a clinic-based sample of youth with SCD and explored factors related to ADHD. Caregivers of 107 children with SCD (ages 7-11 years) completed routine psychosocial screening which included inattentive symptoms of ADHD. Follow-up diagnostic procedures were completed for patients with elevated inattentive symptoms to assess for ADHD diagnoses. Biomedical and social-environmental variables were examined from the screening and medical records. Twenty-six percent of patients showed elevated inattentive symptoms with 13% meeting diagnostic criteria for ADHD diagnoses. Most children (75%) who met criteria for ADHD had not been previously diagnosed. Disease severity did not predict inattentive symptoms or ADHD diagnoses, though a measure of chronic inflammation was associated with ADHD. Family functioning was related to elevated inattentive symptoms but not ADHD diagnoses. Children with SCD show relatively high rates of ADHD with many cases not detected through routine care. Screening for ADHD as part of hematology care may be a feasible strategy to improve identification and access to intervention.

Childhood Physical Health and Attention Deficit/Hyperactivity Disorder: A Systematic Review and Meta-Analysis of Modifiable Factors

Although neurobiologic and genetic factors figure prominently in the development of attention deficit/hyperactivity disorder (ADHD), adverse physical health experiences and conditions encountered during childhood may also play a role. Poor health is known to impact the developing brain with potential lifelong implications for behavioral issues. In attempt to better understand the relationship between childhood physical health and the onset and presence of ADHD symptoms, we summarized international peer-reviewed articles documenting relationships between a select group of childhood diseases or health events (e.g., illnesses, injuries, syndromes) and subsequent ADHD outcomes among children ages 0-17 years. Drawing on a larger two-phase systematic review, 57 longitudinal or retrospective observational studies (1978-2021) of childhood allergies, asthma, eczema, head injury, infection, or sleep problems and later ADHD diagnosis or symptomatology were identified and subjected to meta-analysis. Significant associations were documented between childhood head injuries, infections, and sleep problems with both dichotomous and continuous measures of ADHD, and between allergies with dichotomous measures of ADHD. We did not observe significant associations between asthma or eczema with ADHD outcomes. Heterogeneity detected for multiple associations, primarily among continuously measured outcomes, underscores the potential value of future subgroup analyses and individual studies. Collectively, these findings shed light on the importance of physical health in understanding childhood ADHD. Possible etiologic links between physical health factors and ADHD are discussed, as are implications for prevention efforts by providers, systems, and communities.

Late effects of medulloblastoma treatment: multidisciplinary approach of survivors

PURPOSE

Medulloblastoma is one of the brain tumors with increased life expectancy due to improvements in treatment approaches. Besides the promising results, various undesirable effects can be encountered. This study's aim is to review long-term follow-up outcomes of our cases with medulloblastoma.

METHODS

Age at diagnosis, histological type of medulloblastoma, resection extension, chemotherapy and radiotherapy schemes, follow-up duration, and endocrinological, neuropsychiatric, cardiological, auditory, and visual examination results were evaluated in 20 patients diagnosed between 2007 and 2018 and followed 5 years and more.

RESULTS

Twenty of 53 patients were included to the study. Eleven (55%) were male. Mean age at diagnosis was 6.95 years; mean age at the time of the study was 14 years. Mean follow-up time was 8.95 years. In terms of surgery, 14 (70%) were gross total, 1 (5%) was near total, and 2 (10%) were subtotal resection. In histopathological examination, 14 (70%) were classical medulloblastoma, 4 (20%) were desmoplastic medulloblastoma, and 1 (5%) was anaplastic medulloblastoma. With regard to endocrinological evaluation, 15 (75%) patients had hypothyroidism, 5 (25%) had growth hormone deficiency, 7 (35%) had clinical growth hormone deficiency, and 5 (25%) had sex hormone disorders. In neuropsychiatric examination, 11 (55%) patients had neurological sequelae, 18 (90%) patients had psychiatric issues, and 14 (70%) patients had two or more neuropsychiatric problems simultaneously. One (5%) patient had mitral valve insufficiency. Twelve patients (60%) had hearing loss. According to visual examination, 6 (30%) patients had refraction problem, 4 (20%) had cataract, and 1 (5%) had dry eye.

CONCLUSION

Careful monitoring of long-term side effects is important for improving the quality of life of medulloblastoma patients. Besides endocrinological and other somatic sequelae of the disease and treatment, increased neuropsychiatric problems showed us that only cure is not the issue while treating childhood medulloblastoma.

In vivo modeling recapitulates radiotherapy delivery and late-effect profile for childhood medulloblastoma

Background

Medulloblastoma (MB) is the most common malignant pediatric brain tumor, with 5-year survival rates > 70%. Cranial radiotherapy (CRT) to the whole brain, with posterior fossa boost (PFB), underpins treatment for non-infants; however, radiotherapeutic insult to the normal brain has deleterious consequences to neurocognitive and physical functioning, and causes accelerated aging/frailty. Approaches to ameliorate radiotherapy-induced late-effects are lacking and a paucity of appropriate model systems hinders their development.

Methods

We have developed a clinically relevant in vivo model system that recapitulates the radiotherapy dose, targeting, and developmental stage of childhood medulloblastoma. Consistent with human regimens, age-equivalent (postnatal days 35-37) male C57Bl/6J mice received computerized tomography image-guided CRT (human-equivalent 37.5 Gy EQD2, n = 12) ± PFB (human-equivalent 48.7 Gy EQD2, n = 12), via the small animal radiation research platform and were longitudinally assessed for > 12 months.

Results

CRT was well tolerated, independent of PFB receipt. Compared to a sham-irradiated group (n = 12), irradiated mice were significantly frailer following irradiation (frailty index; P = .0002) and had reduced physical functioning; time to fall from a rotating rod (rotarod; P = .026) and grip strength (P = .006) were significantly lower. Neurocognitive deficits were consistent with childhood MB survivors; irradiated mice displayed significantly worse working memory (Y-maze; P = .009) and exhibited spatial memory deficits (Barnes maze; P = .029). Receipt of PFB did not induce a more severe late-effect profile.

Conclusions

Our in vivo model mirrored childhood MB radiotherapy and recapitulated features observed in the late-effect profile of MB survivors. Our clinically relevant model will facilitate both the elucidation of novel/target mechanisms underpinning MB late effects and the development of novel interventions for their amelioration.

Methylphenidate improves cognitive function and health-related quality of life in survivors of childhood brain tumours

OBJECTIVES

The growing population of survivors of childhood brain tumors present the challenge of long-term quality of survival. The domains most affected by tumor and treatment are those implicated in development of typical intellectual functions: attention, working memory, and processing speed, with consequent effects upon function and quality of life. In this paper we present service evaluation data on the 12-month effect upon processing speed, visual and auditory attentional domains in 29 patients receiving methylphenidate aged 5-16 years (Mean=10.6).

METHODS

Patients received immediate-release methylphenidate and were converted to modified-release as appropriate. Mean optimal dose of immediate-release methylphenidate was 0.34 mg/kg per dose (range 0.2-0.67).

RESULTS

Patients showed a significant positive impact of methylphenidate on attention in all tests of selective visual attention from the Test of Everyday Attention for Children 2. A significant improvement was also shown on response time. Significant change was not found on psychometric measures of sustained auditory or visual attention, or selective auditory attention. Ratings of Health-Related Quality of Life showed a positive benefit of methylphenidate at 12 months. Side effects were minimal and not statistically significant.

CONCLUSIONS

Survivors of childhood brain tumor with attentional and processing speed deficit show clinical benefit from methylphenidate.

Microstructural Cerebellar Injury Independently Associated With Processing Speed in Adult Patients With Primary Brain Tumors: Implications for Cognitive Preservation

PURPOSE

The cerebellum's role in posttreatment neurocognitive decline is unexplored. This study investigated associations between cerebellar microstructural integrity using quantitative neuroimaging biomarkers and neurocognition among patients with primary brain tumors receiving partial-brain radiation therapy (RT).

METHODS AND MATERIALS

In a prospective trial, 65 patients underwent volumetric brain magnetic resonance imaging, diffusion tensor imaging, and memory, executive function, language, attention, and processing speed (PS) assessment before RT and at 3, 6, and 12 months after RT. Delis-Kaplan Executive Function System-Trail Making (D-KEFS-TM) visual scanning and number and letter sequencing and Wechsler Adult Intelligence Scale, Fourth Edition, coding were used to evaluate PS. The cerebellar cortex and white matter (WM) and supratentorial structures subserving the previously mentioned cognitive domains were autosegmented. Volume was measured within each structure at each time point along with diffusion biomarkers (fractional anisotropy and mean diffusivity) in WM structures. Linear mixed-effects models assessed cerebellar biomarkers as predictors of neurocognitive scores. If associated, cerebellar biomarkers were evaluated as independent predictors of cognitive scores controlling for domain-specific supratentorial biomarkers.

RESULTS

Left (P = .04) and right (P < .001) cerebellar WM volume declined significantly over time. Cerebellar biomarkers were not associated with memory, executive function, or language. Smaller left cerebellar cortex volume was associated with worse D-KEFS-TM number (P = .01) and letter (P = .01) sequencing scores. A smaller right cerebellar cortex volume correlated with worse D-KEFS-TM visual scanning (P = .02) and number (P = .03) and letter (P = .02) sequencing scores. Greater right cerebellar WM mean diffusivity, indicating WM injury, was associated with worse D-KEFS-TM visual scanning performance (P = .03). Associations remained significant after controlling for corpus callosum and intrahemispheric WM injury biomarkers.

CONCLUSIONS

Injury to the cerebellum as measured with quantitative biomarkers correlates with worse post-RT PS, independent of corpus callosum and intrahemispheric WM damage. Efforts to preserve cerebellar integrity may preserve PS.

Cognitive deficits and altered functional brain network organization in pediatric brain tumor patients

Survivors of pediatric brain tumors experience significant cognitive deficits from their diagnosis and treatment. The exact mechanisms of cognitive injury are poorly understood, and validated predictors of long-term cognitive outcome are lacking. Resting state functional magnetic resonance imaging allows for the study of the spontaneous fluctuations in bulk neural activity, providing insight into brain organization and function. Here, we evaluated cognitive performance and functional network architecture in pediatric brain tumor patients. Forty-nine patients (7-18 years old) with a primary brain tumor diagnosis underwent resting state imaging during regularly scheduled clinical visits. All patients were tested with a battery of cognitive assessments. Extant data from 139 typically developing children were used as controls. We found that obtaining high-quality imaging data during routine clinical scanning was feasible. Functional network organization was significantly altered in patients, with the largest disruptions observed in patients who received propofol sedation. Awake patients demonstrated significant decreases in association network segregation compared to controls. Interestingly, there was no difference in the segregation of sensorimotor networks. With a median follow-up of 3.1 years, patients demonstrated cognitive deficits in multiple domains of executive function. Finally, there was a weak correlation between decreased default mode network segregation and poor picture vocabulary score. Future work with longer follow-up, longitudinal analyses, and a larger cohort will provide further insight into this potential predictor.

Cognition and Brain System Segregation in Pediatric Brain Tumor Patients Treated with Proton Therapy

Purpose

Pediatric brain tumor patients often experience significant cognitive sequelae. Resting-state functional MRI (rsfMRI) provides a measure of brain network organization, and we hypothesize that pediatric brain tumor patients treated with proton therapy will demonstrate abnormal brain network architecture related to cognitive outcome and radiation dosimetry.

Participants and Methods

Pediatric brain tumor patients treated with proton therapy were enrolled on a prospective study of cognitive assessment using the NIH Toolbox Cognitive Domain. rsfMRI was obtained in participants able to complete unsedated MRI. Brain system segregation (BSS), a measure of brain network architecture, was calculated for the whole brain, the high-level cognition association systems, and the sensory-motor systems.

Results

Twenty-six participants were enrolled in the study for cognitive assessment, and 18 completed rsfMRI. There were baseline cognitive deficits in attention and inhibition and processing speed prior to radiation with worsening performance over time in multiple domains. Average BSS across the whole brain was significantly decreased in participants compared with healthy controls (1.089 and 1.101, respectively; P = 0.001). Average segregation of association systems was significantly lower in participants than in controls (P < 0.001) while there was no difference in the sensory motor networks (P = 0.70). Right hippocampus dose was associated with worse attention and inhibition (P < 0.05) and decreased segregation in the dorsal attention network (P < 0.05).

Conclusion

Higher mean dose to the right hippocampus correlated with worse dorsal attention network segregation and worse attention and inhibition cognitive performance. Patients demonstrated alterations in brain network organization of association systems measured with rsfMRI; however, somatosensory system segregation was no different from healthy children. Further work with preradiation rsfMRI is needed to assess the effects of surgery and presence of a tumor on brain network architecture.

Neurobehavioral Impairment in Pediatric Brain Tumor Survivors: A Meta-Analysis

Purpose: The neurocognitive outcomes of pediatric brain tumor survivors have been extensively studied but the risk and predictors for neurobehavioral impairment are less clearly defined. We systematically analyzed the rates of emotional, psychosocial, and attention problems in pediatric brain tumor survivors. Methods: PubMed, Web of Science, Embase, Scopus, and Cochrane were searched for articles published between January 2012 to April 2022. Eligible studies reported neurobehavioral outcomes for PBTS aged 2 to <23 years with a brain tumor diagnosis before 18 years of age. A random-effect meta-analysis was performed in R. Results: The search yielded 1187 unique publications, of which 50 were included in the quantitative analysis. The estimated risk of having emotional, psychosocial, and attention problems were 15% (95%CI 10−20%), 12% (95%CI 9−16%), and 12% (95%CI 9−16%), respectively. PBTS were more likely to have emotional difficulties (Hedge’s g = 0.43 [95%CI 0.34−0.52]), psychosocial problems (Hedge’s g = 0.46 [95%CI 0.33−0.58]), and attention problems (Hedge’s g = 0.48 [95%CI 0.34−0.63]) compared to normal/healthy control subjects. There was no significant difference in the rates of neurobehavioral impairment between children with and without history of cranial radiotherapy. Conclusions: PBTS are at elevated risk of neurobehavioral impairment. Neurobehavioral monitoring should be considered as the standard of care for PBTS.

Cross-translational models of late-onset cognitive sequelae and their treatment in pediatric brain tumor survivors

Pediatric brain tumor treatments have a high success rate, but survivors are at risk of cognitive sequelae that impact long-term quality of life. We summarize recent clinical and animal model research addressing pathogenesis or evaluating candidate interventions for treatment-induced cognitive sequelae. Assayed interventions encompass a broad range of approaches, including modifications to radiotherapy, modulation of immune response, prevention of treatment-induced cell loss or promotion of cell renewal, manipulation of neuronal signaling, and lifestyle/environmental adjustments. We further emphasize the potential of neuroimaging as a key component of cross-translation to contextualize laboratory research within broader clinical findings. This cross-translational approach has the potential to accelerate discovery to improve pediatric cancer survivors' long-term quality of life.

Suicidal ideation and executive functioning in pediatric cancer

OBJECTIVE

Neurocognitive impairments and psychological distress are among the most common difficulties experienced by children treated for cancer. Elevated rates of suicidal ideation (SI) are documented among cancer survivors, and a link between neurocognitive deficits and SI is evident, yet the relationship between SI and pediatric cancer-related neurocognitive effects has not yet been studied.

PARTICIPANTS AND METHODS

Participants were 166 pediatric cancer patients (57.8% Brain Tumor, 31.3% leukemia, 10.8% other cancers) aged 6-23 (M = 11.57, SD = 3.82; 45.8% female) referred for neuropsychological surveillance. SI prevalence was measured by parent, teacher, or patient endorsement of self-harm related items on informant-report measures (e.g., the Child Behavior Checklist). Executive functioning (Behavior Rating Inventory of Executive Function), ADHD symptoms (ADHD Rating Scale), and performance-based measures were compared between those with SI and those without.

RESULTS

17.5% of pediatric cancer patients experienced SI, of which 44.7% had self-endorsement only, 58.5% parent-endorsement only, 20.6% teacher-endorsement only, and 24.1% had two endorsements. Those with SI had significantly greater impairments in global executive composite scores by both parent- and teacher-report (ps < 0.05). Parents of children with SI endorsed significantly more inattention symptoms (M = 6.10, SD = 15.48) than those without SI (M = 50.56, SD = 8.70; p < 0.01), but hyperactivity symptoms did not differ. Intellectual and executive function performance did not differ between those with and without SI (ps > 0.1).

CONCLUSIONS

An elevated number of children treated for cancer experience SI and related neurocognitive problems. Screening for SI and further assessment of the connection between executive functioning and SI in pediatric cancer populations is needed.

Neuropsychiatric Symptoms After Brain Tumor Resection in Children and Adolescents: A Scoping Review

BACKGROUND

Brain tumors are one of the most common solid tumors in pediatric populations, with their treatments having significant neuropsychiatric impact.

OBJECTIVE

The objective of this study was to review the literature on neuropsychiatric sequelae after surgical resection of brain tumors in children and adolescents.

METHODS

Using a scoping method, we reviewed empirical articles describing pediatric patients with brain tumors who underwent partial or total resection and examined major neuropsychiatric domains postoperatively over time.

RESULTS

The initial search yielded 15,543 articles. After duplicate removal, abstract screening, and review, 44 articles were included. Cognitive deficits were the most widely studied outcomes and found to be associated with tumor location, operative variables, perioperative complications, treatment types, and psychosocial factors. Cerebellar mutism, or posterior fossa syndrome, commonly co-occurred with emotional and behavioral dysregulation after posterior fossa resections. Depression, anxiety, and somatization were frequently grouped together as "distress," with higher rates among pediatric patients with brain tumor than among healthy peers. Problematic school behaviors, antisocial, and attention-deficit traits were increased; however, several other behaviors (e.g., risky sexual behaviors, substance use) were equal or lower when compared to peers. Posttraumatic stress disorder was highly prevalent and often interfered with social functioning. Delirium, eating disorders, and longer-term outcomes received inadequate attention.

CONCLUSION

Identifying risk factors of neuropsychiatric sequelae and their impact after pediatric brain tumor resection is important for prognostication and the development of tailored management strategies for these children and adolescents.

Assessing neuropsychological phenotypes of pediatric brain tumor survivors

INTRODUCTION

Pediatric brain tumor survivors (PBTS) are at risk for both neurocognitive impairments and psychological difficulties, yet these two domains have historically been discretely examined, with assessment of psychosocial outcomes rarely included in studies of cognitive outcomes. Taking a person-centered approach, the current study aimed to more comprehensively evaluate PBTS late effect profiles, including both neurocognitive and psychological sequelae, and predictors of these profiles.

METHOD

PBTS (N = 89) were assessed in a pediatric neuropsychological clinic between May 2009 and May 2018, diagnosed at least 1 year prior, and off-treatment for at least 3 months (M_age  = 6.57 years, SD = 4.53; 46.1% female). Parent- and teacher-report of psychological symptoms, and performance-based measures of neurocognitive functioning were examined using latent profile analysis. The R3STEP procedure identified predictors of class membership.

RESULTS

The optimal model identified four classes characterized by: (1) average functioning across all measures ("Average," n = 47), (2) average psychosocial functioning and impaired neurocognitive functioning ("Cognitive Deficit," n = 25), (3) elevated social problems and significant neurocognitive impairments ("Social/Cognitive Deficit," n = 9), and (4) impaired visual planning and problem-solving and elevated parent-reported psychosocial problems, but average processing speed, working memory, and teacher-reported psychosocial outcomes ("Discrepant," n = 8). Ethnicity, race, radiation treatment, and diagnoses of neurofibromatosis 1, hydrocephalus, and cerebellar mutism syndrome were significant predictors of class membership (ps < 0.05).

CONCLUSION

The present study identified distinct phenotypes with unique patterns of relations among neurocognitive and psychological domains. These findings are a vital first step toward identifying those at highest risk for poor outcomes and informing interventions that effectively address interrelated treatment targets for specific groups.

Generalized approach for radiotherapy treatment planning by optimizing projected health outcome: preliminary results for prostate radiotherapy patients

Research in cancer care increasingly focuses on survivorship issues, e.g. managing disease- and treatment-related morbidity and mortality occurring during and after treatment. This necessitates innovative approaches that consider treatment side effects in addition to tumor cure. Current treatment-planning methods rely on constrained iterative optimization of dose distributions as a surrogate for health outcomes. The goal of this study was to develop a generally applicable method to directly optimize projected health outcomes. We developed an outcome-based objective function to guide selection of the number, angle, and relative fluence weight of photon and proton radiotherapy beams in a sample of ten prostate-cancer patients by optimizing the projected health outcome. We tested whether outcome-optimized radiotherapy (OORT) improved the projected longitudinal outcome compared to dose-optimized radiotherapy (DORT) first for a statistically significant majority of patients, then for each individual patient. We assessed whether the results were influenced by the selection of treatment modality, late-risk model, or host factors. The results of this study revealed that OORT was superior to DORT. Namely, OORT maintained or improved the projected health outcome of photon- and proton-therapy treatment plans for all ten patients compared to DORT. Furthermore, the results were qualitatively similar across three treatment modalities, six late-risk models, and 10 patients. The major finding of this work was that it is feasible to directly optimize the longitudinal (i.e. long- and short-term) health outcomes associated with the total (i.e. therapeutic and stray) absorbed dose in all of the tissues (i.e. healthy and diseased) in individual patients. This approach enables consideration of arbitrary treatment factors, host factors, health endpoints, and times of relevance to cancer survivorship. It also provides a simpler, more direct approach to realizing the full beneficial potential of cancer radiotherapy.

Psychological adjustment outcomes among pediatric brain tumor survivors: A meta-analysis

BACKGROUND

Pediatric brain tumor survivors (PBTS) are at significant risk for psychological adjustment difficulties, including greater depressive and anxious symptomology. Systematic reviews have identified this heightened risk among youth with medical conditions, but these reviews have not been specific to PBTS. Therefore, the current study aimed to directly examine the psychological adjustment of PBTS as compared to healthy peers.

PROCEDURE

A systematic review and meta-analysis was conducted using PubMed, PsychInfo, and Academic Search Premier databases. The search yielded 2833 articles, with 22 articles meeting inclusion criteria.

RESULTS

A statistically significant overall medium effect size (Hedge's g = 0.32) indicated that PBTS exhibited poorer overall psychological adjustment relative to healthy comparison groups. Studies that included younger children were associated with larger between-group differences. When evaluating specific outcomes, PBTS had relatively higher levels of depressive symptoms (Hedge's g = 0.36), anxious symptoms (Hedge's g = 0.11), and general distress (Hedge's g = 0.22), but not more externalizing problems.

CONCLUSIONS

The present study confirmed that PBTS are indeed at greater risk for psychological adjustment difficulties relative to healthy comparison groups. These findings highlight the importance of psychosocial screening among this population. Given that depressive symptoms were the most elevated relative to healthy peers, investigation of such symptomatology among PBTS is particularly important.

Guidelines for Treatment and Monitoring of Adult Survivors of Pediatric Brain Tumors

OPINION STATEMENT

Pathologies of pediatric brain tumors are more varied than those diagnosed in adults and survival outcomes more optimistic. Therapies for pediatric brain tumors are also diverse and treatment options are expanding. The growing number of adult survivors of childhood brain tumors is quite diverse. Medical management of these adults requires understanding the tumor diagnosis and location, the modalities used to treat the tumor, the age of the survivor at the time of diagnosis and treatment, any complications of treatment, and, most importantly, the baseline medical condition and neurological function of each adult survivor. A network of medical, neurological, and mental health providers is critical in the care of a child with a brain tumor. A comparable network should be available to survivors of these tumors since they may transition to adulthood with medical and neurological deficits and can acquire additional late effects of treatments as they age. Optimally, each survivor will have an individualized survivor health plan (SHP) that concisely summarizes the tumor, treatments, potential late effects, and screening that may identify evolving late effects before they impact mental, social or physical functioning. This plan helps patients, families, and the medical team advocate for surveillance aiming to optimize the survivor's quality of life. Failure to support the health and function of these heroic cancer survivors renders the medical advances, the courage, and the struggle that permitted survival meaningless.

Normal tissue damage: its importance, history and challenges for the future

Sir Oliver Scott, a philanthropist and radiation biologist and, therefore, the epitome of a gentleman and a scholar, was an early Director of the BECC Radiobiology Research Unit at Mount Vernon. His tenure preceded that of Jack Fowler, with both contributing to basic, translational and clinical thought and application in radiation across the globe. With respect to this review, Fowler's name in particular has remained synonymous with the use of models, both animal and mathematical, that assess and quantify the biological mechanisms that underlie radiation-associated normal tissue toxicities. An understanding of these effects is critical to the optimal use of radiation therapy in the clinic; however, the role that basic sciences play in clinical practice has been undergoing considerable change in recent years, particularly in the USA, where there has been a growing emphasis on engineering and imaging to improve radiation delivery, with empirical observations of clinical outcome taking the place of models underpinned by evidence from basic science experiments. In honour of Scott and Fowler's work, we have taken this opportunity to review how our respective fields of radiation biology and radiation physics have intertwined over the years, affecting the clinical use of radiation with respect to normal tissue outcomes. We discuss the past and current achievements, with the hope of encouraging a revived interest in physics and biology as they relate to radiation oncology practice, since, like Scott and Fowler, we share the goal of improving the future outlook for cancer patients.