MR-LINAC, a New Partner in Radiation Oncology: Current Landscape.

Technological advances in radiation oncology are oriented towards improving treatment precision and tumor control. Among these advances, magnetic-resonance-image-guided radiation therapy (MRgRT) stands out, with technological advances to deliver targeted treatments adapted to a tumor's anatomy on the day while minimizing incidental exposure to organs at risk, offering an unprecedented therapeutic advantage compared to X-ray-based IGRT delivery systems. This new technology changes the traditional workflow in radiation oncology and requires an evolution in team coordination to administer more precise treatments. Once implemented, it paves the way for newer indication for radiation therapy to safely deliver higher doses than ever before, with better preservation of healthy tissues to optimize patient outcomes. In this narrative review, we assess the technical aspects of the novel linear accelerators that can deliver MRgRT and summarize the available published experience to date, focusing on oncological results and future challenges.

Interobserver Variability in Contouring Hepatocellular Carcinoma at a Tertiary Center.

BACKGROUND/AIM: The optimal imaging test for delineation of the gross tumor volume (GTV) in hepatocellular carcinoma has not been defined. The hypothesis is that magnetic resonance imaging (MRI) allows for better visualization of the extent of tumor and will optimize the accuracy of tumor delineation for liver stereotactic radiotherapy compared with computed tomography (CT) only. We evaluated the interobserver agreement in GTV of hepatocellular carcinoma in a multicenter panel and compared MRI and CT in GTV delineation. MATERIALS AND METHODS: After the institutional review boards approved the study, we analyzed anonymous CT and MRI obtained from five patients with hepatocellular carcinoma. Eight radiation oncologists at our center used CT and MRI to delineate five GTVs of liver tumors. In both CT and MRI, the GTV volumes were compared. RESULTS: The median GTV volume on MRI was 2.4 cm3 (range=0.59-15.6 cm3) compared to 3.5 cm3 (range=0.52-24.9 cm3) on CT (p=0.36). The GTV volume as defined on MRI was larger or at least as large as the GTV volume on CT in two cases. Variance and standard deviation between observers in CT and MRI were minor (6 vs. 7.87 cm3, and 2.5 vs. 2.8 cm3 respectively). CONCLUSION: In cases with well-defined tumors, CT is easier and reproducible. In cases with no defined tumor in CT, other tools are needed and MRI can be complementary. The interobserver variability in target delineation of hepatocellular carcinoma in this study is noteworthy.

SARS-CoV-2 Virus in Cancer Patients: A New Unknown in an Unsolved Equation.

INTRODUCTION: Cancer patients are more susceptible to infections, and infection can be more severe than in patients without cancer diagnosis. We conducted this retrospective study in patients admitted for SARS-CoV-2 infection in order to find differences in inflammatory markers and mortality in cancer patients compared to others. METHODS: We reviewed the electronic records of patients admitted for SARS-CoV-2 infection confirmed by PCR from March to September 2020. Data on socio-demographics, comorbidities, inflammatory makers, and cancer-related features were analyzed. RESULTS: 2,772 patients were admitted for SARS-CoV-2, to the Hospital Universitario Ramón y Cajal in Madrid during this period. Of these, 2,527 (91%) had no history of neoplastic disease, 164 (5.9%) patients had a prior history of cancer but were not undergoing oncological treatment at the time of infection, and 81 (2.9%) were in active treatment. Mortality in patients without a history of cancer was 19.5%, 28.6% for patients with a prior history of cancer, and 34% in patients with active cancer treatment. Patients in active oncology treatment with the highest mortality rate were those diagnosed with lung cancer (OR 5.6 95% CI: 2.2-14.1). In the multivariate study, active oncological treatment (OR 2.259 95% CI: 1.35-3.77) and chemotherapy treatment (OR 3.624 95% CI: 1.17-11.17), were statistically significant factors for the risk of death for the whole group and for the group with active oncological treatment, respectively. CONCLUSION: Cancer patients on active systemic treatment have an increased risk of mortality after SARS-CoV-2 infection, especially with lung cancer or chemotherapy treatment.

Interobserver variability in gross tumor volume contouring in non-spine bone metastases.

Background and Aim: The optimal imaging test for gross tumor volume (GTV) delineation in non-spine bone metastases has not been defined. The use of stereotactic body radiotherapy (SBRT) requires accurate target delineation. Magnetic resonance imaging (MRI) and/or 18fludesoxyglucose positron emission tomography (18FDG-PET) allow for better visualization of the extent of bone metastases and optimizes the accuracy of tumor delineation for stereotactic radiotherapy compared to computed tomography (CT) alone. We evaluated the interobserver agreement in GTV of non-spine bone metastases in a single center and compared MRI and/or 18FDG-PET and CT in GTV delineation. Methods: Anonymous CT and MRI and/or 18FDG-PET obtained from 10 non-spine bone metastases were analyzed by six radiation oncologists at our center. Images acquired by CT and MRI and/or 18FDG-PET were used to delineate 10 GTVs of non-spine bone metastases in the pelvis, extremities, and skull. The cases showed different characteristics: blastic and lytic metastases, and different primary cancers (lung, breast, prostate, rectum, urothelial, and biliary). In both CT and MRI and/or 18FDG-PET, the GTV volumes were compared. The index of agreement was evaluated according to Landis and Koch protocol. Results: The GTV volume as defined on MRI was in all cases larger or at least as large as the GTV volume on CT (P=0.25). The median GTV volume on MRI was 3.15 cc (0.027-70.64 cc) compared to 2.8 cc on CT (0.075-77.95 cc). Interobserver variance and standard deviation were lower in CT than MRI (576.3 vs. 722.2 and 24.0 vs. 26.9, respectively). The level of agreement was fair (kappa=0.36) between CT and MRI. The median GTV volume on 18FDG-PET in five patients was 5.8 cc (0.46-64.17 cc), compared to 4.1 cc on CT (0.99-54.2 cc) (P=0.236). Interobserver variance and standard deviation in CT, MRI, and 18FDG-PET were 576.3 versus 722.2 versus 730.5 and 24 versus 26.9 versus 27.0, respectively. The level of agreement was slight (kappa=0.08) between CT and 18FDG-PET. Conclusions: Interobserver variance in non-spine bone metastases was equal when MRI and PET were compared to CT. CT was associated with the lowest variance and standard deviation. Compared to CT GTVs, the GTVs rendered from MRI images had fair agreement, while the GTVs rendered from 18FDG-PET had only slight agreement. Relevance for Patients: The delimitation of the treatment volume in non-spine bone metastases with SBRT is important for the results determining its efficacy. It is therefore essential to know the variability and to manage it to achieve the highest quality of treatment.

Brain metastases from non-small cell lung carcinoma: an overview of classical and novel treatment strategies.

Background: The development of brain metastases is a common problem in patients diagnosed with non-small cell lung carcinoma (NSCLC). Technological advances in surgery and radiotherapy have allowed greater local control. Moreover, the emergence of targeted therapies and immunotherapy with greater activity on the central nervous system than classical chemotherapy have given way to new strategies in the treatment of brain metastases. We review the current role of local treatments, surgery and radiotherapy, and the most effective combination strategies with the new systemic treatments. Relevance for patients: Brain metastases frequently occur during the course of NSCLC. In recent years, a range of treatments have appeared, such as targeted treatments or immunotherapy, with greater activity at the brain level than classical chemotherapy. Radiotherapy treatment is also now much more conformal and ablative doses can be delivered to the volume of the metastatic area, providing greater local control and less neurological toxicity. However, surgery is still required in cases where anatomopathological specimens are needed and when compressive effects appear. An important challenge is how to combine these treatments to achieve the best control and minimise patients' neurological impairments, especially because of limited experience with the new target drugs, and the unknown toxicity of the different combinations. Future research should therefore focus on these areas in order to establish the best strategies for the treatment of brain metastases from non-small cell lung cancer. Core tips: In this work, we intend to elucidate the best therapeutic options for patients diagnosed with brain metastases of NSCL, which include: surgery, WBRT, radiosurgery or systemic treatment, and the most effective combinations and timings of them, and the ones with the lowest associated toxicity.

Neoadjuvant treatment in non-small cell lung cancer: New perspectives with the incorporation of immunotherapy.

The aim of neoadjuvant treatment in non-small cell lung cancer (NSCLC) is to eliminate micrometastatic disease to facilitate surgical resection. Neoadjuvant chemotherapy (ChT) in localised NSCLC has numerous advantages over other therapeutic modalities and is considered standard treatment in resectable disease. Treatment with immune checkpoint inhibitors (ICI) improves long-term survival in advanced disease and has a better toxicity profile than conventional therapies. These immunotherapy agents (anti-PD1/PD-L1), administered with or without ChT, are currently being evaluated in the preoperative setting, with initial results showing better pathological response rates and more long-term benefits. Importantly, these drugs do not appear to increase the rate of severe adverse effects and/or postoperative complications. However, several questions still need to be resolved, including the identification of predictive biomarkers; comparative studies of immunotherapy alone vs combined treatment with ChT and/or radiotherapy; the optimal duration of treatment; the timing of surgery; the need for adjuvant treatment; appropriate radiologic evaluation and mediastinal staging; and the correlation between pathological response and survival outcomes. Here we review the current evidence for immunotherapy from a multidisciplinary perspective and discuss current and future controversies.

GOECP/SEOR radiotherapy guidelines for thymic epithelial tumours.

Thymic epithelial tumours (TET) are rare, heterogeneous neoplasms that range from resectable indolent tumours to aggressive thymic carcinomas with a strong tendency to metastasize. The pathological diagnosis is complex, in part due to the existence of several different classification systems. The evidence base for the management of TETs is scant and mainly based on non-randomised studies and retrospective series. Consequently, the clinical management of TETs tends to be highly heterogenous, which makes it difficult to improve the evidence level. The role of technological advances in the field of radiotherapy and new systemic therapies in the treatment of TETs has received little attention to date. In the present clinical guidelines, developed by the GOECP/SEOR, we review recent developments in the diagnosis and classification of TETs. We also present a consensus-based therapeutic strategy for each disease stage that takes into consideration the best available evidence. These guidelines focus primarily on the role of radiotherapy, including recent advances, in the management of TETs. The main aim of this document is to promote the standardisation of clinical practice and lay the foundations for future studies to clarify the main unresolved questions related to the optimal management of TET.

Indoor Radon in EGFR- and BRAF-Mutated and ALK-Rearranged Non-Small-Cell Lung Cancer Patients.

BACKGROUND: Radon gas is the leading cause of lung cancer in the nonsmoking population. The World Health Organization (WHO) recommends indoor concentrations of < 100 Bq/m³. Several molecular alterations have been described in non-small-cell lung cancer (NSCLC), mainly in nonsmokers, with no risk factors identified. We studied the role of indoor radon in NSCLC patients harboring specific driver alterations. PATIENTS AND METHODS: We assessed the radon concentration from EGFR-, BRAF-mutated (m), and ALK-rearranged (r) NSCLC patients measured by an alpha-track detector placed in their homes between September 2014 and August 2015. Clinical characteristics were collected prospectively, and pathologic samples were reviewed retrospectively. RESULTS: Forty-eight patients were included (36 EGFRm, 10 ALKr, 2 BRAFm). Median radon concentration was 104 Bq/m³ (IQR 69-160) overall, and was 96 Bq/m³ (42-915) for EGFRm, 116 (64-852) for ALKr, and 125 for BRAFm, with no significant differences. Twenty-seven patients (56%) had indoor radon above WHO recommendations, 8 (80%) of 10 ALKr, 2 (100%) of 2 BRAFm, and 17 (47%) of 36 EGFRm. CONCLUSION: The median indoor radon concentration was above the WHO recommendations, with no differences between EGFR, ALK, and BRAF patients. Concentrations above the WHO recommendations were most common with ALKr and BRAFm. These findings should be validated in larger studies.

Accelerated hypofractionated breast radiotherapy: FAQs (frequently asked questions) and facts.

The demand for breast cancer care has increased as cancer treatment innovations have proliferated. Adjuvant radiotherapy to the breast is considered to be part of the standard treatment in breast cancer. The role of radiotherapy in terms of reducing loco-regional recurrence and increased survival after conservative surgery, and also after a mastectomy in selected cases, has been previously shown in several randomized trials. Patterns of radiotherapy commonly used for breast cancer comprise a period of approximately five weeks, frequently with the addition of an additional 1-1.5 weeks of a radiation boost to the primary tumour area. In last years, there has been a renewed interest in hypofractionated and accelerated radiotherapy schedules that reduce the overall treatment time to barely three weeks, leading to an improvement in quality of life for patients and also optimizing workload of radiation oncology departments. However, despite the existing evidence supporting the use of hypofractionated treatment regimens, their widespread is still far from complete. Many questions have generated resistance among clinical oncologists for their regular use. The aim of this review is to answer those questions that may arise with the use of moderate hypofractionation in breast cancer.

HDR-plesiotherapy for the treatment of anogenital extramammary Paget's disease.

BACKGROUND: Extramammary Paget disease (EMPD) is a rare condition that most commonly affects the anogenital region in the elderly. It may be associated with an underlying invasive carcinoma. Surgical excision is nowadays considered a standard treatment for extramammary Paget's disease, although this approach might not be suitable for all patients. Good rates of local control and cosmetic outcome have been achieved by using high-dose-rate (HDR) plesiotherapy in the treatment of skin tumors arising in different locations. MATERIAL AND METHODS: We present the results observed in a patient with EMPD treated by HDR plesiotherapy with a custom-made mold up to a final dose of 54 Gy in 12 fractions of 450 cGy over 4 weeks. RESULTS: After a follow-up of 18 months, the patient is alive and without evidence of local or distant relapse. Acute toxicity was acceptable and cosmetic result was considered as excellent. CONCLUSION: This technique represents an attractive alternative for those patients who are not candidates for surgical procedures because of unacceptable risk of disfigurements or functional impairment, medical contraindications or patient preference.

External-beam radiotherapy: A realistic therapeutic option for the gastric antral vascular ectasia.

The gastric antral vascular ectasia (GAVE) is a well recognizable endoscopic entity characterized by the presence of multiple linear angioectatic vessels predominantly located in the antrum, with a typical appearance of "watermelon stomach". This condition typically affects elderly females presenting as iron-deficiency anaemia due to chronic gastric bleeding. Standard treatment is endoscopic ablation of the gastric mucosa. For non-responders, radical surgery is considered a curative treatment but with considerable morbidity and mortality. Radiation therapy is a well-known alternative for many benign diseases, including anomalous vascular hyperproliferative diseases, although its role has not been defined for GAVE. The present case illustrates the efficacy and tolerance of radiotherapy in the treatment of symptomatic gastric watermelon.

High-dose-rate (HDR) plesiotherapy with custom-made moulds for the treatment of non-melanoma skin cancer.

BACKGROUND: Non-melanoma skin tumours (NMSC) are one of the most frequent types of cancer, accounting for nearly one third of newly diagnosed tumours. NMSC are frequently diagnosed in elderly patients and while mortality rates are low, NMSC can be associated with significant morbidity in terms of cosmetic and functional impairment. OBJECTIVE: Surgical excision is nowadays considered the standard treatment for NMSC, although this approach might not be suitable for all the patients. Good rates of local control and cosmetic outcome are achieved by using high-dose-rate (HDR) plesiotherapy. METHODS: Nine consecutive patients with 11 NMSC were treated with custom-made moulds and HDR plesiotherapy reaching a fi nal dose of 44-48 Gy in 11-12 fractions of 4 Gy over 4 weeks. RESULTS: No local or distant relapses have been observed after a mean follow-up of 15 months (range 4-36 months). Acute toxicity was acceptable and cosmetic result was considered as excellent/good in 7 patients. CONCLUSIONS: This modality of treatment offers an alternative for those patients not candidates for surgical procedures because of medical contraindications or risk of disfigurement or functional impairment.