Efficacy and safety of dolutegravir/lamivudine in virologically suppressed female participants: week 48 data from the pooled TANGO and SALSA studies

OBJECTIVES

Women represent >50% of people with HIV globally but have historically been underrepresented in clinical trials. We evaluated the efficacy and safety of switching to dolutegravir/lamivudine (DTG/3TC) vs continuing their current antiretroviral regimen (CAR) by sex assigned at birth (female and male) in virologically suppressed adults with HIV-1 without prior virological failure in a pooled analysis of two randomized controlled trials.

METHODS

This analysis included 48-week data from the phase 3 TANGO and SALSA studies. Primary and key secondary endpoints included proportions of participants with HIV-1 RNA ≥50 and <50 copies/mL at week 48, respectively. Safety was also assessed.

RESULTS

Of 1234 participants, 250 (DTG/3TC, n = 133; CAR, n = 117) were female at birth. Week 48 proportions of participants with Snapshot HIV-1 RNA ≥50 copies/mL were similar regardless of sex at birth (DTG/3TC vs CAR: female, <1% [1/133] vs 2% [2/117]; male, <1% [1/482] vs <1% [3/502]). Proportions with HIV-1 RNA <50 copies/mL were high across sexes and treatment groups (DTG/3TC vs CAR: female, 91% [121/133] vs 89% [104/117]; male, 94% [455/482] vs 94% [471/502]). Immunological response with DTG/3TC was slightly higher in female participants. Incidences of adverse events leading to withdrawal and serious adverse events were low and comparable between treatment groups and across sexes. Weight gain was higher with DTG/3TC than with CAR among female participants aged ≥50 years (treatment difference 2.08 kg [95% confidence interval 0.40-3.75]).

CONCLUSIONS

Results confirm the robustness of DTG/3TC as a switch option in virologically suppressed females with HIV-1, with outcomes similar to those in males.

Intra-islet glucagon signalling regulates beta-cell connectivity, first-phase insulin secretion and glucose homoeostasis

OBJECTIVE

Type 2 diabetes (T2D) is characterised by the loss of first-phase insulin secretion. We studied mice with β-cell selective loss of the glucagon receptor (Gcgrfl/fl X Ins-1Cre), to investigate the role of intra-islet glucagon receptor (GCGR) signalling on pan-islet [Ca2+]I activity and insulin secretion.

METHODS

Metabolic profiling was conducted on Gcgrβ-cell-/- and littermate controls. Crossing with GCaMP6f (STOP flox) animals further allowed for β-cell specific expression of a fluorescent calcium indicator. These islets were functionally imaged in vitro and in vivo. Wild-type mice were transplanted with islets expressing GCaMP6f in β-cells into the anterior eye chamber and placed on a high fat diet. Part of the cohort received a glucagon analogue (GCG-analogue) for 40 days and the control group were fed to achieve weight matching. Calcium imaging was performed regularly during the development of hyperglycaemia and in response to GCG-analogue treatment.

RESULTS

Gcgrβ-cell-/- mice exhibited higher glucose levels following intraperitoneal glucose challenge (control 12.7 mmol/L ± 0.6 vs. Gcgrβ-cell-/- 15.4 mmol/L ± 0.0 at 15 min, p = 0.002); fasting glycaemia was not different to controls. In vitro, Gcgrβ-cell-/- islets showed profound loss of pan-islet [Ca2+]I waves in response to glucose which was only partially rescued in vivo. Diet induced obesity and hyperglycaemia also resulted in a loss of co-ordinated [Ca2+]I waves in transplanted islets. This was reversed with GCG-analogue treatment, independently of weight-loss (n = 8).

CONCLUSION

These data provide novel evidence for the role of intra-islet GCGR signalling in sustaining synchronised [Ca2+]I waves and support a possible therapeutic role for glucagonergic agents to restore the insulin secretory capacity lost in T2D.

Splenic artery embolisation for blunt splenic trauma: 10 years of practice at a trauma centre

INTRODUCTION

Splenic artery embolisation (SAE) has transformed the management of splenic trauma. The aim of this study was to review the outcomes and postprocedural management of blunt splenic trauma patients treated with SAE at a trauma centre over a 10-year period.

METHODS

Details of patients undergoing SAE for blunt trauma between January 2012 and January 2022 were acquired from a prospectively maintained database. Patient records were reviewed for demographic information, splenic injury grades, embolisation efficacy, complications, and associated injuries and mortality. Data relating to Injury Severity Scores (ISS) and postprocedural practice (vaccinations, antibiotic prescribing, follow-up imaging) were also obtained.

RESULTS

Thirty-six patients (24 male, 12 female) with a median age of 42.5 years (range 13-97 years) were identified. American Association for the Surgery of Trauma splenic injury grades were III (n = 7), IV (n = 20) and V (n = 9). Seventeen patients had isolated splenic injury and 19 had additional injuries to other organ systems. Median ISS was 18.5 (range 5-50). SAE succeeded first time in 35/36 cases, and upon the second attempt in 1/36 cases. No patients died because of splenic injury or SAE although four patients with polytrauma died owing to other injuries. SAE complications occurred in 4/36 cases. For survivors, vaccinations were administered in 17/32 cases, and long-term antibiotics were initiated in 14/32 cases. Formal follow-up imaging was arranged in 9/32 cases.

CONCLUSIONS

These data show that SAE is an effective means of controlling splenic haemorrhage secondary to blunt trauma with no patient requiring subsequent laparotomy. Major complications occurred in 11% of cases. Follow-up practice varied regarding further imaging, antibiotic and vaccination administration.

A generalised method for calculating repopulation-corrected tumour EQD2 values in a wide range of clinical situations, including interrupted treatments

Any radiotherapy schedule can be characterised by its 2 Gy per fraction equivalent dose (EQD2). EQD2s are easily calculated for late-responding normal tissues but for tumours significant errors may arise if no allowance is made for any repopulation which occurs in the reference and/or the derived EQD2 schedule. This article presents a systematic approach to calculating tumour EQD2 values utilising the concept of biologically effective dose (BED) with inclusion of repopulation effects. A factor (f) is introduced which allows the inter-dependence between EQD2 and its delivery time (and, hence, the amount of repopulation involved) to be embedded within the formulation without any additional assumptions. There exists a transitional BED below which simple methods of calculating tumour EQD2 remain valid. In cases where simpler approaches are inadequate, the correct EQD2 may be determined from the reference schedule BED (BEDref) by the relationship: EQD2 = A × BEDref - B, where A and B are constants which involve the same radiobiological parameters as are conventionally used in deriving tumour BED values. Some Worked Examples illustrate application of the method to fractionated radiotherapy and indicate that there can be substantial differences with results obtained from using over-simplified approaches. Since reference BEDs are calculable for other types of radiotherapy (brachytherapy, permanent implants, high-LET applications, etc) the methodology allows estimation of tumour EQD2 values in a wide range of clinical circumstances, including cases which involve interrupted treatments.

Academic U.S. Radiation Oncology Department Chairs: Who are They?

PURPOSE/OBJECTIVE(S)

Historically, there has been a gender imbalance in the composition of the academic radiation oncology (RO) workforce. Given the increasing diversity of patients treated by academic radiation oncologists across the US, sufficient representation of women in academic RO, especially in leadership, is of paramount importance. In this study, we sought to better understand the characteristics of individuals currently serving as academic RO chairpersons whose departments are affiliated with ACGME-accredited RO residency training programs.

MATERIALS/METHODS

We created a comprehensive database of academic RO chairpersons in the US by utilizing information from publicly available sources, including residency training program websites, hospital/institutional websites, Doximity, LinkedIn, the American Society of Radiation Oncology (ASTRO) website, the American College of Radiation Oncology (ACRO) website, and the National Plan and Provider Enumeration System National Provider Identifier Registry. We used the Mann-Whitney U test and two-proportion z tests to evaluate for statistical significance among medians and proportions, respectively.

RESULTS

We identified 85/90 chairpersons (94.4%) whose departments are affiliated with an ACGME-accredited RO residency program. 4/85 (4.7%) chairpersons hold interim positions and were excluded from further analyses. Of the remaining 81 chairpersons in permanent positions, 10 (12.3%) are females and 71 (87.7%) are males (p < 0.01). 77 (95.1%) chairpersons are full professors and 19 (23.5%) hold dual MD-PhD degrees. 33 (40.7%) chairpersons hold an official leadership role, such as "director" or "chair," in the cancer institution affiliated with their institution; while such titles are more common among male than female chairpersons, the difference is not statistically significant (43.7% vs 20%, p = 0.15). 74/81 chairpersons secured their current positions a median of 16 years (range 6-33 years) after completing RO residency, with no statistically significant difference between male and female chairpersons (median 16 vs 18 years, respectively; p = 0.38). 36 (44.4%) chairpersons were promoted to chair from another position at their respective institutions (men 70.0% vs females 40.8%, p = 0.08). The majority of chairpersons are ASTRO Fellows (61.7%); notably fewer are ASTRO (3.7%) or ACRO (2.5%) Gold Medalists. There are no statistical differences among male and female chairpersons in the proportion who have received an ASTRO Fellow designation (60.6% vs 70.0%, p = 0.57) or ASTRO (4.2% vs 0.0%, p = 0.51) or ACRO (2.8% vs 0.0%, p = 0.59) Gold Medal.

CONCLUSION

In our benchmark study of the characteristics of current academic US RO chairpersons, we found that significantly more men than women currently serve as RO chairpersons. Future interventions that promote the recruitment, retention, and promotion of talented female academic RO physicians through the academic pipeline are warranted.

Is 80 the New 70? Octogenarians with Oropharyngeal Squamous Cell Carcinoma

PURPOSE/OBJECTIVE(S)

As the human papilloma virus (HPV) pandemic evolves and life expectancy increases, the number of older adults with oropharyngeal squamous cell carcinoma (OPSCC) continues to increase. However, there is a paucity of data regarding the fastest growing subset of this population: octogenarians (OGs). We sought to understand differences in treatment tolerability and clinical outcomes between septuagenarians (SGs) and OGs with OPSCC.

MATERIALS/METHODS

We identified SGs (age 70-79) and OGs (age 80-89) with OPSCC from a cohort of older adults with nonrecurrent, nonmetastatic head and neck squamous cell carcinoma (HNSCC) treated curatively from 2007-2020. We compared demographics, treatment characteristics and toxicities using Fischer's exact test. Time-to-event outcomes, overall survival (OS), locoregional control (LRC), and disease-specific survival (DSS), were evaluated using the Kaplan-Meier method.

RESULTS

Of 293 patients (age 70-89) with HNSCC, 39% (n = 114) had OPSCC: 93 SGs (median age: 73; interquartile range [IQR]: 71-76), and 21 OGs (median age: 81, IQR: 80-84). The median follow-up for included patients was 2.4 years; 82% were male, 64% white, 48% > 20 pack year smoking history, 37% ECOG 1. Patients had AJCC 8th edition Stage: I (27%); II (33%); III (18%); IV (22%) OPSCC. Treatment consisted of adjuvant radiation (RT) (19%), adjuvant chemoradiation (CRT) (8%), surgery alone (6%), induction/concurrent CRT (27%), concurrent CRT (28%), or RT (12%), with no significant differences in stage or treatment modalities noted between SGs and OGs. Of note, 69% of SGs and 76% of OGs were HPV+. Among 107 patients who received any RT, 24% experienced a treatment interruption (19% of SGs vs. 48% of OGs, p = 0.001) and 2 patients (both HPV- SGs) died on treatment due to unrelated health conditions. Percutaneous endoscopic gastrostomy (PEG) tubes were placed prior to or during treatment in 43% of SGs and 62% of OGs, with OGs more likely to have a PEG placed during treatment (p = 0.025). There was no difference in the prevalence of late (> 6 months) CTCAE grade 2+ dysphagia (36%) or xerostomia (31%) between SGs and OGs. Estimated 3-year LRC, DSS, and OS were not significantly different between SGs (LRC:85%; DSS:87%; OS:76%) and OGs (LRC: 81%; DSS:94%; OS: 55%, p-values: 0.98, 0.42, 0.052, respectively). However, HPV+ disease significantly increased estimated 3-year OS for both SGs (HPV+: 84%; HPV-: 56%, p = 0.0006) and OGs (HPV+: 68%; HPV-: 20%, p = 0.008).

CONCLUSION

In our cohort, OGs had a higher proportion of HPV+ OPSCC, which was associated with improved OS. This finding may provide insight into the latency of the virus. While there were similar amounts of toxicities among SGs and OGs, OGs more frequently underwent PEG tube placement and experienced more treatment interruptions. Given high rates of HPV+ OPSCC in OGs, our findings suggest that de-escalation strategies should be further investigated to improve tolerability and maximize outcomes for this neglected population.

Myocarditis following COVID-19 mRNA vaccinations: Twin and sibling case series

ImportanceMyocarditis and myopericarditis are well described adverse events of special interest (AESI) following COVID-19 vaccinations. Whilst the aetiology is still being investigated; there is evidence that genetic predisposition may be a risk factor for the development of myocarditis. Furthermore, hormones are thought to contribute to sex-specific differences in myocarditis, skewed toward a larger risk in adolescent males.

Objective

This unique sibling case series may help highlight potential mechanisms and prognostic factors in the development of myocarditis following COVID-19 vaccination in adolescent males. In this context, twin and familial studies provide a unique epidemiological perspective to investigate the interplay between genetic predisposition and other factors.

Participants

Observational case series of all siblings reported to SAEFVIC with chest pain following COVID-19 vaccinations in Victoria, Australia.

Exposure

mRNA vaccination (Comirnaty BNT162b2 COVID-19 (Pfizer-BioNTech) and Spikevax mRNA-1273 (Moderna).

Findings

Our case series comprises 6 young males; two sets of monozygotic twins and one set of fraternal brothers following reports of chest pain associated with COVID-19 mRNA vaccination. Five patients were diagnosed with myocarditis as per Brighton Collaboration Criteria (Level 2). The remaining sibling, who did not have myocarditis, was subsequently diagnosed with pubertal delay.

Conclusions

Understanding the genetic and hormonal risk factors and aetiology for myocarditis associated with COVID-19 vaccines is paramount. Further evaluation of specific genetic targets or biomarkers is required to understand the implications of population vaccine policy, particularly for adolescent and young adult males at highest risk for this AESI.

Feasibility and safety of shortened hypofractionated high-dose palliative lung radiotherapy – A retrospective planning study

OBJECTIVE

Assess the safety and feasibility of shortened hypofractionated high-dose palliative lung radiotherapy in a retrospective planning study.

METHODS

Fifteen late stage (III or IV) NSCLC lung radiotherapy patients previously treated with the standard palliative 36 Gy in 12 fractions (12F) schedule were non-randomly selected to achieve a representative distribution of tumour sizes, volumes, and location. Plans were produced using 30 Gy in 5 fractions (5F) and 6 fractions (6F) using a 6MV FFF co-planar VMAT technique. Plans were optimised to meet dose-constraints for planning target volumes (PTVs) and organs at risk (OARs) with established OAR constraints expressed as biological equivalent doses (BEDs). The potential safety was assessed using these BEDs and also with reductions of 10% (BED-10%) and 20% (BED-20%) to account for a reduction in tolerance doses from the effects of chemotherapy or surgery.

RESULTS

Mandatory BED constraints were met for all fifteen 5F and 6F plans; BED-10% constraints were met by all 6F plans and six 5F plans. BED-20% constraints were met by six 6F and three 5F respectively.

CONCLUSION

It is potentially safe and feasible to deliver high-dose palliative radiotherapy for late stage NSCLC using the 5F or 6F regimes described, when planned to comparable OAR BEDs as standard radical techniques. It appears toxicity from these regimes should be within acceptable limits provided the dose-constraints described are met. A Phase II study is required to fully assess safety and feasibility, the outcomes of which could reduce the number of patient hospital visits for radiotherapy, thereby benefiting patients and optimising resource utilisation.

Improving the Accuracy of Biologically Effective Dose Estimates, from a Previously Published Study, After Radiosurgery for Acoustic Neuromas

OBJECTIVE

To recalculate biological effective dose values (BED) for radio-surgical treatments of acoustic neuroma from a previous study. BEDs values were previously overestimated by only using beam-on times in calculations, so excluding the important beam-off-times (when deoxyribonucleic acid repair continues) which contribute to the overall treatment time. Simple BED estimations using a mono-exponential approximation may not always be appropriate but if used should include overall treatment time.

METHODS

Time intervals between isocenters were estimated. These were especially important for the Gamma Knife Model 4C cases since manual changes significantly increase overall treatment times. Individual treatment parameters, such as iso-center number, beam-on-time, and beam-off-time, were then used to calculate BED values using a more appropriate bi-exponential model that includes fast and slow components of DNA damage repair over a wider time range.

RESULTS

The revised BED estimates differed significantly from previously published values. The overestimates of BED, obtained using beam-on-time only, varied from 0%-40.3%. BED subclasses, each with a BED range of 5 Gy_2.47, indicated that revised values were consistently reduced when compared with originally quoted values, especially for 4C compared with Perfexion cases. Furthermore, subdivision of 4C cases by collimator number further emphasized the impact of scheduled gap times on BED. Further analysis demonstrated important limitations of the mono-exponential model. Target volume was a major confounding factor in the interpretation of the results of this study.

CONCLUSIONS

BED values should be estimated by including beam-on and beam-off times. Suggestions are provided for more accurate BED estimations in future studies.

Implementation of a youth and young adult e-cigarette cessation program within a dental clinic setting : A SToHN feasibility study

Introduction

While significant progress has been made to decrease tobacco smoking among youth and young adults, e-cigarettes threaten to reverse the progress. The purpose of this study was to test the feasibility of the ReACH Assessment of Knowledge for E-Cigarettes (RAKE) e-cigarette cessation program targeting youth and young adults in Texas.

Methods

Seven dental practitioners and 12 patients participated in this pilot study. Patients aged 15 to 29 who reported current e-cigarette use were recruited by their dental practitioner. All participants completed pre-and post-assessments-practitioners receiving the RAKE training and patients the RAKE cessation intervention. Descriptive statistics were calculated.

Results

After RAKE training, all practitioners reported the RAKE cessation program as useful and an important part of patient care. In addition, after completing the program (5A's), 67% (n=9) patients reported that the program was helpful, and 100% (n=12) would recommend the program to other ENDS users.

Conclusions

Practitioners and patients enhanced their knowledge of e-cigarettes and their harm to health. In addition, practitioners demonstrated their ability to implement the RAKE cessation program within the practice, and patients approved of the use of the program. This study illustrated the feasibility and acceptability of conducting an e-cigarette cessation study in dental practices and a critical need to develop and disseminate the program to young patients.

Scintillation light detection in the 6-m drift-length ProtoDUNE Dual Phase liquid argon TPC

DUNE is a dual-site experiment for long-baseline neutrino oscillation studies, neutrino astrophysics and nucleon decay searches. ProtoDUNE Dual Phase (DP) is a 6  ×  6  ×  6 m 3 liquid argon time-projection-chamber (LArTPC) that recorded cosmic-muon data at the CERN Neutrino Platform in 2019-2020 as a prototype of the DUNE Far Detector. Charged particles propagating through the LArTPC produce ionization and scintillation light. The scintillation light signal in these detectors can provide the trigger for non-beam events. In addition, it adds precise timing capabilities and improves the calorimetry measurements. In ProtoDUNE-DP, scintillation and electroluminescence light produced by cosmic muons in the LArTPC is collected by photomultiplier tubes placed up to 7 m away from the ionizing track. In this paper, the ProtoDUNE-DP photon detection system performance is evaluated with a particular focus on the different wavelength shifters, such as PEN and TPB, and the use of Xe-doped LAr, considering its future use in giant LArTPCs. The scintillation light production and propagation processes are analyzed and a comparison of simulation to data is performed, improving understanding of the liquid argon properties.

O-193 Reproductive outcomes in women with Borderline Ovarian Tumours. Does fertility treatment increase the risk of disease recurrence?

Study question

Does fertility treatment (FT) increase the risk of recurrence of Borderline Ovarian Tumours (BOTs)?

Summary answer

There is a significant association between recurrence of BOTs and exposure to FT (p = 0.025).

What is known already

The association between pregnancy or controlled ovarian stimulation (COS) and risk of recurrence of BOTs is a controversial topic of interest amongst clinicians and women undergoing treatment. Some studies report a risk of non- invasive relapse following ovarian stimulation between 19.4-23%, whereas earlier case-control studies have shown no significant association.It is important to consider that most studies are limited by their retrospective analysis, with an emphasis on the incidence of primary BOTs following exposure to FT. Whereby, data regarding the risk of disease recurrence following spontaneous pregnancy (SP) or COS specifically, remains sparse. 

Study design, size, duration

A retrospective cohort of women who underwent fertility sparing surgery (FSS) for the management of BOTs between the 1st January 2004 and 31st December 2020 at Imperial College Healthcare NHS Trust, with prospective follow up of reproductive outcomes and recurrence of disease following surgery. 

Participants/materials, setting, methods

Subgroup analysis included a control group of all women not exposed to FT or SP and a non-control group of those who achieved either SP or underwent FT following FSS for the management of BOTs. The recurrence rate of BOTs was determined within each subgroup. 

Main results and the role of chance

90 women underwent FSS for BOTs. Subgroup analysis confirmed 38.9% (35/90) were in the control group, 50% (45/90) in the non-control and 11.1% (10/90) lost to follow up. In the non-control group, 35.6% (16/45) achieved SP only and 64.4% (29/45) underwent FT. FT included COS for oocyte cryopreservation only (24.4%; 11/45), intracytoplasmic sperm insemination (ICSI) ± fresh or frozen embryo transfer (24.4%; 11/45) and those who underwent COS but also achieved SP without returning to their cryopreserved gametes (15.5%; 7/45). Within the non-control group, 75.6% (34/45) of women conceived, with a livebirth rate per pregnancy of 58.7% (27/46). The recurrence rate in the control and non-control groups were 20% (7/35) and 22.2% (10/45) respectively (p = 0.025) and 24.1% (7/29) following FT. Recurrence rates were 18.8% (3/16) after SP only, 0% (0/11) following oocyte cryopreservation only, 18.2% (2/11) ICSI ± embryo transfer and 71.4% (5/7) in those who underwent COS and achieved a SP. All recurrence of disease presented as serous BOTs. Within the FT group, logistic regression analysis demonstrated no significant predictors of disease recurrence. A combination of SP and FT is significantly associated with recurrence when compared to the following groups: control (p = 0.000), SP only (p = 0.001) and COS only (p = 0.015).

Limitations, reasons for caution

Due to the partial retrospective nature of the study, certain clinical information was not adequately documented and the subgroups compared were of unequal sample size, whilst overall sample size is also considered low. There was also a lack of control for confounders which may affect disease recurrence.

Wider implications of the findings

Despite the risk of recurrence of BOTs associated with FT, cases are often non invasive and successfully managed with further FSS with excellent prognosis. This evidence should be used to counsel women of reproductive age to ensure they can fulfil their reproductive aspirations, despite a diagnosis of BOT. 

Trial registration number

NA

The influence of hypoxia on LET and RBE relationships with implications for ultra-high dose rates and FLASH modelling

Objective. To investigate relationships between linear energy transfer (LET), fluence rates, changes in radiosensitivity and the oxygen enhancement ratio (OER) in different ion beams and extend these concepts to ultra-high dose rate (UHDR) or FLASH effects. Approach. LET values providing maximum relative biological effect (RBE), designated as LETU, are found for neon, carbon and helium beams. Proton experiments show reduced RBEs with depth in scattered (divergent) beams, but not with scanned beams, suggesting that instantaneous fluence rates (related to track separation distances) can modify RBE, all other RBE-determining factors being equal. Micro-volumetric energy transfer per μm3 (mVET) is defined by LET × fluence. High fluence rates will increase mVET rates, with proportional shifts of LETU to lower values due to more rapid energy transfer. From the relationship between LETU and OER at conventional dose rates, OER reductions in UHDR/FLASH exposures can be estimated and biological effective dose analysis of experimental lung and skin reactions becomes feasible. Main results. The Furusawa et al data show that hypoxic LETU values exceed their oxic counterparts. OER reduces from around 3–1.25 at LETU, although the relative radiosensitivities of the oxic and hypoxic α parameters (the OER(α)) exceed those of the standard OER values. Increased fluence rates are predicted to reduce LETU and OER. Large FLASH single doses will minimise RBE increments due to the β parameter reducing by a factor of 0.5–0.25 consistent with oxygen depletion, causing radioresistance. Similar results will occur for photons. Tissue α/β ratios increase by around 10 in FLASH conditions, agreeing with derived ion-beam dose rate equations. Significance. Increasing dose rates enhance local energy deposition rate per unit volume, probably causing oxygen depletion and radioresistance in pre-existing hypoxic sites during UHDR/FLASH exposures. The modelled equations provide testable hypotheses for further dose rate investigations in photon, proton and ion beams.

Radiotherapy treatment interruptions during the Covid-19 pandemic: The UK experience and implications for radiobiology training

Unintended treatment interruptions during a course of radiotherapy can lead to extended overall treatment times which can allow increased tumour cell repopulation to occur. Extra dose may therefore be required to offset any loss of tumour control. However, the manner in which the extra dose is delivered requires careful consideration in order to avoid the risk of increased normal tissue toxicity. Radiobiological modelling techniques can allow quantitative examination of such problems and may be used to derive revised pattens of radiation delivery which can help restore a degree of tumour control whilst limiting the likelihood of excess normal tissue morbidity. Unintended treatment interruptions can occur in any radiotherapy department but the rapid spread of the Covid-19 pandemic caused a major increase in the frequency of such interruptions due to staff and patient illness and the consequent self-isolation requirements. This article summarises the radiobiological considerations and caveats involved in assessing treatment interruptions and outlines the UK experience of dealing with the new challenges posed by Covid-19. The world-wide need for more education programmes in cancer radiobiology is highlighted.