Impact of COVID-19 on Radiation Oncology, an Austrian Experience

The COVID-19 pandemic has an unprecedented impact on cancer treatment worldwide. We aimed to evaluate the effects of the pandemic on the radiation treatment of patients in order to provide data for future management of such crises. We compared the number of performed radiotherapy sessions of the pandemic period from February 2020 until May 2021 with those of 2018 and 2019 for reference. At our department, no referred patients had to be rejected or postponed, nor any significant changes in fractionation schedules implemented. Nevertheless, there was a substantial drop in overall radiotherapy sessions in 2020 following the first incidence wave of up to −25% (in June) in comparison to previous years. For breast cancer, a maximum decline of sessions of −45% (July) was recorded. Only a short drop of prostate cancer sessions (max −35%, May) followed by a rebound (+42%, July) was observed. Over the investigated period, a loss of 4.4% of expected patients never recovered. The severe impact of COVID-19 on cancer treatment, likely caused by retarded diagnosis and delayed interdisciplinary co-treatment, is reflected in a lower count of radiotherapy sessions. Radiation oncology is a crucial cornerstone in upholding both curative treatment options and treatment capacity during a pandemic.

Biological Planning of Radiation Dose Based on In Vivo Dosimetry for Postoperative Vaginal-Cuff HDR Interventional Radiotherapy (Brachytherapy)

(1) Background: Postoperative vaginal-cuff HDR interventional radiotherapy (brachytherapy) is a standard treatment in early-stage endometrial cancer. This study reports the effect of in vivo dosimetry-based biological planning for two different fractionation schedules on the treatment-related toxicities. (2) Methods: 121 patients were treated. Group A (82) received 21 Gy in three fractions. Group B (39) received 20 Gy in four fractions. The dose was prescribed at a 5 mm depth or to the applicator surface according to the distance between the applicator and the rectum. In vivo dosimetry measured the dose of the rectum and/or urinary bladder. With a high measured dose, the dose prescription was changed from a 5 mm depth to the applicator surface. (3) Results: The median age was 66 years with 58.8 months mean follow-up. The dose prescription was changed in 20.7% of group A and in 41% of group B. Most toxicities were grade 1–2. Acute urinary toxicities were significantly higher in group A. The rates of acute and late urinary toxicities were significantly higher with a mean bladder dose/fraction of >2.5 Gy and a total bladder dose of >7.5 Gy. One patient had a vaginal recurrence. (4) Conclusions: Both schedules have excellent local control and acceptable rates of toxicities. Using in vivo dosimetry-based biological planning yielded an acceptable dose to the bladder and rectum.

Variability of α/β Ratios for Prostate Cancer With the Fractionation Schedule: Caution Against Using the Linear-Quadratic Model for Hypofractionated Radiotherapy

Background: Prostate cancer (PCa) is known to be suitable for hypofractionated radiotherapy due to the very low α/β ratio (about 1.5-3 Gy). However, several randomized controlled trials have not shown the superiority of hypofractionated radiotherapy over conventionally fractionated radiotherapy. Besides, in vivo and in vitro experimental results show that the linear-quadratic (LQ) model may not be appropriate for hypofractionated radiotherapy, and we guess it may be due to the influence of fractionation schedules on the α/β ratio. Therefore, this study attempted to estimate the α/β ratio in different fractionation schedules and evaluate the applicability of the LQ model in hypofractionated radiotherapy. Methods: The maximum likelihood principle in mathematical statistics was used to fit the parameters: k, α and β values in the tumor control probability (TCP) formula derived from the LQ model. In addition, the fitting results were substituted into the original TCP formula to calculate 5-year biochemical relapse-free survival for further verification.Results: Information necessary for fitting could be extracted from a total of 23,281 PCa patients. A total of 16,442 PCa patients were grouped according to fractionation schedules. We found that, for patients who received conventionally fractionated radiotherapy, moderately hypofractionated radiotherapy, and stereotactic body radiotherapy, the average α/β ratios were 1.78 Gy (95% CI: 1.59-1.98, P < 0.001), 3.46 Gy (95% CI: 3.08-3.83, P < 0.001), and 4.24 Gy (95% CI: 4.10-4.39, P < 0.001), respectively. Hence, the calculated α/β ratios for PCa tended to become higher when the dose per fraction increased. Among all PCa patients, 14,641 could be grouped according to the risks of PCa in patients receiving radiotherapy with different fractionation schedules. The results showed that as the risk increased, the k and α values decreased, indicating that the number of effective target cells decreased and the radioresistance increased.Conclusions: The LQ model appeared to be inappropriate for high doses per fraction owing to α/β ratios tending to become higher when the dose per fraction increased. Therefore, to convert the conventionally fractionated radiation doses to equivalent high doses per fraction using the standard LQ model, a higher α/β ratio should be used for calculation.

Carbon Ion Dose Constraints in the Head and Neck and Skull Base: Review of MedAustron Institutional Protocols

Background Dose constraints are of paramount importance for the outcome of any radiotherapy treatment. In this article, we report dose-volume constraints as well as currently used fractionation schedules for carbon ion radiotherapy as applied in MedAustron (Wiener Neustadt, Austria). Materials and Methods For fractionation schedules, both German and Japanese regimes were used. From the clinical experience of National Institute of Radiological Sciences (Chiba, Japan) and Heidelberg Ion Therapy (Heidelberg, Germany; formerly GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany) and the work by colleagues in Centro Nazionale Adroterapia Oncologica (Pavia, Italy) recalculating the dose from the microdosimetric kinetic model to the local effect model, we have set the dose constraints for critical organs of the head and neck area. Where no clinical data was available, an educated guess was made, based on data available from photon and proton series. Results We report the constraints for the optic nerve and chiasm, brainstem, spinal cord, cochlea, brain parenchyma, salivary gland, eye and adnexa, and mandibular/maxillary bone; constraints are grouped based on a fractionation scheme (German versus Japanese) and the risk of toxicity (safe, low to middle, and middle to high). Conclusion We think validation of dose constraints should present a relevant part of the activity of any carbon ion radiotherapy facility, and we anticipate future multicentric, joint evaluations.

Comparative Study of Two Thoracic Radiotherapy Schedules for Palliation of Symptom, Radiological Response and Acute Toxicities in Advanced Non-small Cell Lung Cancer

Aim: To compare the effect of two RT schedules for thoracic palliation in advanced NSCLC patients (30 Gy in 10 fractions over two weeks and 27 Gy in 6 fractions over three weeks, 2 fractions per week) on pulmonary symptoms, radiological response of the primary thoracic tumour, pulmonary functions and acute toxicities. Material and method: A hospital based quantitative prospective follow-up study. Total 104 advanced NSCLC patients were randomized into two fractionation arms. Evaluation was done pretreatment and 4 weeks after end of RT. Symptoms palliation and radiological response to RT & radiation pneumonitis were assessed by using RTOG 4-point scale and Revised (RECIST) guideline version 1.1 respectively. Radiotherapy was given by Cobalt-60 teletherapy machine. Results: Total 96 patients were evaluated for symptom palliation, radiological response and acute toxicities. The percentage of patients achieving symptom palliation was slightly higher in the control arm. At 1st month of follow-up, 16.67% & 18.75% patients in Study & control arm showed PR. Post-RT mean FVC and FEV1 showed a tendency for improvement in both mean FVC and FEV1 in compare to baseline. Treatment was well tolerated both arms. Grade I nausea and vomiting developed in 43% and 37.5% patients in Study and Control Arm respectively. 58% & 39% patients developed Grade 1 radiation pneumonitis as cough & dyspnea in study and control arms respectively. Grade 2 radiation pneumonitis was developed in 2 patient of study arm at 3rd week of follow-up but they lost follow up. Around 31% patients developed Grade1 esophagitis as dysphagia in both arms at 1 week of follow-up which was reduced up to 7% by 2nd week. A very few patients developed grade1 skin reaction as dermatitis in 1st week of treatment. The difference in symptom palliation, radiological response, pulmonary functions and acute toxicities in both arms was not statistically significant. Conclusion: The two RT fractionation schedules showed equal efficacy in terms of symptoms palliation, radiological response of the primary thoracic tumor, pulmonary functions and acute toxicities. Thus the 27 Gy/6 fractionation arm appears preferable compared to 30 Gy/10 arm to minimize the patients’ visits and load on the machines.

Comparison of Various Radiotherapy Dose Fractionation Schedules in Palliation of Bone Metastasis

Introduction Bone metastasis is a common manifestation of malignancy. Bone metastases causes various morbidities and affect the quality of life. External beam radiotherapy is the mainstay of treatment of uncomplicated painful bone metastases. Different radiotherapy fractionation schedules are in practice for palliation of painful bone metastases. Objectives This study was aimed to compare and report the outcomes of various fractionation schedules of radiation therapy (RT) in terms of pain relief and quality of life in patients with painful bone metastases. Materials and Methods Eighty patients were randomized into four treatment arms with different RT fractionation schedules, namely, 8 Gy in 1 fraction, 20 Gy in 5 fractions, 24 Gy in 6 fractions, and 30 Gy in 10 fractions. Patients were assessed for pain by visual analog scale (VAS), performance status and quality of life before initiating the treatment, on the day of completion of treatment, and 1 week, 1 month, and 3 months of treatment completion. Results Majority of the metastases constituted from breast followed by lung cancer. Of these, 27.5% had metastases to the thoracic vertebra, 26.25% to the lumbar vertebra, 22.5% to the pelvis, 8.75% to the sternum, 6.25% each to cervical vertebra and femur, and 1.25% each to humerus and ribs. The mean VAS score prior to start of RT was 5.31, 5.21, 5.54, and 4.87 in arms A, B, C, and D, respectively. At the end of treatment, the scores were 3.0, 3.29, 2.77, and 2.47, respectively. At the end of 3 months, the scores were 1.54, 0.57, 0.54, and 0.60, respectively. The pain reduction was significant in all the four arms (p < 0.05). Also, 25% of the patients’ arm A had complete pain relief, whereas 45% of patients in arms B, C, and D had complete pain relief. In arm A, the performance status failed to improve at 3 months when compared with 1-week post-RT but the improvement was significant in the remaining three arms. There was improvement in the quality of life in all the arms, both in terms of function and symptoms. The mean score of symptomatic quality of life based on the EORTC BM22 module prior to start of RT was 38.14, 34.91, 28.85, and 29.17 in arms A, B, C, and D, respectively. There was a significant drop to 9.29, 6.55, 5.13, and 6.11 at 1-month posttreatment in the four arms, respectively. The outcomes in terms of functional quality of life showed a similar trend. Conclusion This study demonstrated that pain reduction by various RT fractionation schedules were similar, and no statistically significant difference was noted. Performance status and quality of life improved in all the four treatment arms post-RT.