Update on intraoperative radiotherapy: new challenges and issues

Electron FLASH radiotherapy in vivo studies. A systematic review

FLASH-radiotherapy delivers a radiation beam a thousand times faster compared to conventional radiotherapy, reducing radiation damage in healthy tissues with an equivalent tumor response. Although not completely understood, this radiobiological phenomenon has been proved in several animal models with a spectrum of all kinds of particles currently used in contemporary radiotherapy, especially electrons. However, all the research teams have performed FLASH preclinical studies using industrial linear accelerator or LINAC commonly employed in conventional radiotherapy and modified for the delivery of ultra-high-dose-rate (UHDRs). Unfortunately, the delivering and measuring of UHDR beams have been proved not to be completely reliable with such devices. Concerns arise regarding the accuracy of beam monitoring and dosimetry systems. Additionally, this LINAC totally lacks an integrated and dedicated Treatment Planning System (TPS) able to evaluate the internal dose distribution in the case of in vivo experiments. Finally, these devices cannot modify dose-time parameters of the beam relevant to the flash effect, such as average dose rate; dose per pulse; and instantaneous dose rate. This aspect also precludes the exploration of the quantitative relationship with biological phenomena. The dependence on these parameters need to be further investigated. A promising advancement is represented by a new generation of electron LINAC that has successfully overcome some of these technological challenges. In this review, we aim to provide a comprehensive summary of the existing literature on in vivo experiments using electron FLASH radiotherapy and explore the promising clinical perspectives associated with this technology.

Impact of preoperative magnetic resonance imaging on surgery and eligibility for intraoperative radiotherapy in early breast cancer

We looked at the usefulness of magnetic resonance imaging (MRI) in decision-making and surgical management of patients selected for intraoperative radiotherapy (IORT). We also compared lesion size measurements in different modalities (ultrasound (US), mammogram (MMG), MRI) against pathological size as the gold standard. 63 patients eligible for IORT based on clinical and imaging criteria over a 34-month period were enrolled. All had MMG and US, while 42 had additional preoperative MRI for locoregional preoperative staging. Imaging findings and pathological size concordances were analysed across the three modalities. MRI changed the surgical management of 5 patients (11.9%) whereby breast-conserving surgery (BCS) and IORT was cancelled due to detection of satellite lesion, tumor size exceeding 30mm and detection of axillary nodal metastases. Ten of 42 patients (23.8%) who underwent preoperative MRI were subjected to additional external beam radiotherapy (EBRT); 7 due to lymphovascular invasion (LVI), 2 due to involved margins, and 1 due to axillary lymph node metastatic carcinoma detected in the surgical specimen. Five of 21 (23.8%) patients without prior MRI were subjected to additional EBRT post-surgery; 3 had LVI and 2 had involved margins. The rest underwent BCS and IORT as planned. MRI and MMG show better imaging-pathological size correlation. Significant increase in the mean 'waiting time' were seen in the MRI group (34.1 days) compared to the conventional imaging group (24.4 days). MRI is a useful adjunct to conventional imaging and impacts decision making in IORT. It is also the best imaging modality to determine the actual tumour size.

First Intraoperative Radiation Therapy Center in Africa: First 2 Years in Operation, Including COVID-19 Experiences

PURPOSE

There is a shortage of radiation therapy service centers in low- to middle-income countries. TARGIT–intraoperative radiation therapy (IORT) may offer a viable alternative to improve radiation treatment efficiency and alleviate hospital patient loads. The Breast Care Unit in Johannesburg became the first facility in Africa to offer TARGIT-IORT, and the purpose of this study was to present a retrospective review of patients receiving IORT at this center between November 2017 and May 2020.

PATIENTS AND METHODS

Patient selection criteria were based mainly on the latest American Society of Radiation Oncology guidelines. Selection criteria included early-stage breast carcinoma (luminal A) and luminal B with negative upfront sentinel lymph node biopsy that negated external-beam radiation therapy (EBRT). Patient characteristics, reasons for choosing IORT, histology, and use of oncoplastic surgery that resulted in complications were recorded.

RESULTS

One hundred seven patients successfully received IORT/TARGIT-IORT. Mean age was 60.8 years (standard deviation, 9.3 years). A total of 73.8% of patients presented with luminal A, 15.0% with luminal B, and 5.6% with triple-negative cancer. One patient who presented with locally advanced breast cancer (T4N2) opted for IORT as a boost in addition to planned EBRT. Eighty-seven patients underwent wide local excision (WLE) with mastopexy, and 12 underwent WLE with parenchymal. Primary reasons for selecting IORT/TARGIT-IORT were distance from the hospital (43.9%), choice (40.2%), and age (10.3%).

CONCLUSION

This retrospective study of IORT/TARGIT-IORT performed in Africa confirms its viability, with low complication rates and no detrimental effects with breast conservation, resulting in positive acceptance and the potential to reduce Oncology Center patient loads. Limitations of the study include the fact that only short-term data on local recurrence were available. Health and socioeconomic value models must still be addressed in the African setting.

Adapting care for older cancer patients during the COVID-19 pandemic: Recommendations from the International Society of Geriatric Oncology (SIOG) COVID-19 Working Group

The COVID-19 pandemic poses a barrier to equal and evidence-based management of cancer in older adults. The International Society of Geriatric Oncology (SIOG) formed a panel of experts to develop consensus recommendations on the implications of the pandemic on several aspects of cancer care in this age group including geriatric assessment (GA), surgery, radiotherapy, systemic treatment, palliative care and research. Age and cancer diagnosis are significant predictors of adverse outcomes of the COVID-19 infection. In this setting, GA is particularly valuable to drive decision-making. GA may aid estimating physiologic reserve and adaptive capability, assessing risk-benefits of either providing or temporarily withholding treatments, and determining patient preferences to help inform treatment decisions. In a resource-constrained setting, geriatric screening tools may be administered remotely to identify patients requiring comprehensive GA. Tele-health is also crucial to ensure adequate continuity of care and minimize the risk of infection exposure. In general, therapeutic decisions should favor the most effective and least invasive approach with the lowest risk of adverse outcomes. In selected cases, this might require deferring or omitting surgery, radiotherapy or systemic treatments especially where benefits are marginal and alternative safe therapeutic options are available. Ongoing research is necessary to expand knowledge of the management of cancer in older adults. However, the pandemic presents a significant barrier and efforts should be made to ensure equitable access to clinical trials and prospective data collection to elucidate the outcomes of COVID-19 in this population.

Intraoperative radiotherapy in early breast cancer: observational comparison with whole breast radiotherapy

INTRODUCTION

In early breast cancer (EBC), a single dose of intraoperative radiotherapy (IORT) might be an option to standard whole breast radiotherapy (WBRT). However, there is no consensus about its use and clinical results.

AIM

to analyse the morbidity and oncological outcomes of IORT as monotherapy in EBC.

METHODS

A single centre observational analytic study was performed. A prospective IORT cohort (2015-17) and a retrospective WBRT cohort (2012-17) were selected following the same criteria: ≥ 45 y.o., invasive ductal carcinoma or variants, radiological tumour size ≤ 3 cm, positive oestrogenic receptors, negative HER2, cN0; exclusion criteria: lymphovascular invasion, multicentricity/multifocality, BRCA mutation and neoadjuvant therapy. Clinical, histological, surgical, oncological characteristics and complications were collected.

RESULTS

A total of 425 cases were selected: 217 in IORT cohort and 208 in WBRT cohort. Average age in IORT and WBRT groups was 67±9.5 and 64.8 ± 9.9 y.o. respectively (p = 0.01). ASA 3 risk score patients were 17.7% in IORT and 24 cases in WBRT (p = 0.027). There were no differences in histological results or tumoral stage. Average follow up was 24.4 ± 8 months in IORT and 50.5 ± 18 months in WBRT (p < 0.001). No differences were detected in local recurrence, metastases or mortality. Complications that required reintervention or hospitalization were similar in both groups. A total of 3 and 14 cases developed early severe dermatitis in IORT and WBRT groups respectively (p = 0.01).

CONCLUSION

IORT as monotherapy in selected patients with EBC stands for an alternative option versus WBRT. It seems especially useful in advanced-age patients with severe comorbidities. IORT associates lesser early severe dermatitis.

COVID-19: Global radiation oncology's targeted response for pandemic preparedness

As the global COVID-19 pandemic escalates there is a need within radiation oncology to work to support our patients in the best way possible. Measures are required to reduce infection spread between patients and within the workforce. Departments need contingency planning to create capacity and continue essential treatments despite a reduced workforce. The #radonc community held an urgent online journal club on Twitter in March 2020 to discuss these issues and create some consensus on crucial next steps. There were 121 global contributors. This document summarises these discussions around themes of infection prevention, rationalisation of workload and working practice in the presence of infection.