Addressing challenges in low-income and middle-income countries through novel radiotherapy research opportunities.

Although radiotherapy continues to evolve as a mainstay of the oncological armamentarium, research and innovation in radiotherapy in low-income and middle-income countries (LMICs) faces challenges. This third Series paper examines the current state of LMIC radiotherapy research and provides new data from a 2022 survey undertaken by the International Atomic Energy Agency and new data on funding. In the context of LMIC-related challenges and impediments, we explore several developments and advances-such as deep phenotyping, real-time targeting, and artificial intelligence-to flag specific opportunities with applicability and relevance for resource-constrained settings. Given the pressing nature of cancer in LMICs, we also highlight some best practices and address the broader need to develop the research workforce of the future. This Series paper thereby serves as a resource for radiation professionals.

Prospective Assessment of the Association Between Circulating Tumor Cells and Control of Brain Disease After Focal Radiation Therapy of Breast Cancer Brain Metastases.

PURPOSE: Predicting the risk of early distant brain failure (DBF) is in demand for management decisions in patients who are candidates for local treatment of brain metastases. This study aimed to analyze the association between circulating tumor cells (CTCs) and brain disease control after stereotactic radiation therapy/radiosurgery (SRT) for breast cancer brain metastasis (BCBM). METHODS AND MATERIALS: We prospectively assessed CTCs before (CTC1) and 4 to 5 weeks after (CTC2) SRT and their relationship with the number of new lesions (NL) suggestive of BCBM before SRT. CTC were quantified and analyzed by immunocytochemistry to evaluate the expression of the proteins COX2, EGFR, ST6GALNAC5, NOTCH1, and HER2. Distant brain failure-free survival (DBFFS), the primary endpoint, diffuse DBFFS (D-DBFFS), and overall survival were estimated. Analysis for DBF within 6 months, with death as competing risk, was performed. RESULTS: Patients were included between 2016 and 2018. CTCs were detected in all 39 patients before and in 34 of 35 patients after SRT. After median follow-up of 16.6 months, median DBFFS, D-DBFFS, and overall survival were 15.3, 14.1, and 19.5 months, respectively. DBF at 6 months was 40% with CTC1 ≤0.5 and 8.82% with CTC1 >0.5 CTC/mL (P = .007), and D-DBF at 6 months was 40% with CTC1 ≤0.5 and 0 with CTC1 >0.5 CTC/mL (P = .005) and 25% with NL/CTC1 >6.8 and 2.65% with NL/CTC1 ≤6.8 (P = .063). On multivariate analysis, DBFFS was inferior with CTC1 ≤0.5 (hazard ratio, 8.27; 95% confidence interval, 2.12-32.3; P = .002), and D-DBFFS was inferior with CTC1 ≤0.5 (hazard ratio, 10.22; 95% confidence interval, 1.99-52.41; P = .005). Protein expression was not associated with outcomes. CONCLUSIONS: These data suggest that CTC1 and NL/CTC1 may have a role as a biomarker of early diffuse DBF and as a subsequent guide between focal or whole-brain radiation therapy in patients with BCBM.

Survival Outcomes With Short-Course Radiation Therapy in Elderly Patients With Glioblastoma: Data From a Randomized Phase 3 Trial.

PURPOSE: To perform a subset analysis of survival outcomes in elderly patients with glioblastoma from a randomized phase 3 trial comparing 2 short-course radiation therapy (RT) regimens in elderly and/or frail patients. METHODS AND MATERIALS: The original trial population included elderly and/or frail patients with a diagnosis of glioblastoma. Patients joined the phase 3, randomized, multicenter, prospective, noninferiority trial; were assigned to 1 of 2 groups in a 1:1 ratio, either short-course RT (25 Gy in 5 fractions, arm 1) or commonly used RT (40 Gy in 15 fractions, arm 2); and were stratified by age (<65 years and ≥65 years), Karnofsky Performance Status (KPS), and extent of surgery. For the subset analysis in this study, only patients aged ≥65 years were evaluated (elderly and frail patients were defined as patients aged ≥65 years with KPS of 50%-70%; elderly and non-frail patients were defined as patients aged ≥65 years with KPS of 80%-100%); 61 of the 98 initial patients comprised the patient population, with 26 patients randomized to arm 1 and 35 to arm 2. RESULTS: In this unplanned analysis, the short-course RT results were not statistically significantly different from the results of commonly used RT in elderly patients. The median overall survival time was 6.8 months (95% confidence interval [CI], 4.5-9.1 months) in arm 1 and 6.2 months (95% CI, 4.7-7.7 months) in arm 2 (P=.936). The median progression-free survival time was 4.3 months (95% CI, 2.6-5.9 months) in arm 1 and 3.2 months (95% CI, 0.1-6.3 months) in arm 2 (P=.706). CONCLUSIONS: A short-course RT regimen of 25 Gy in 5 fractions is an acceptable treatment option for patients aged ≥65 years, mainly those with a poor performance status or contraindication to chemotherapy, which would be indicated in cases of methylated O6 methylguanine-DNA-methyltransferase promoter tumors.

International Atomic Energy Agency Randomized Phase III Study of Radiation Therapy in Elderly and/or Frail Patients With Newly Diagnosed Glioblastoma Multiforme.

PURPOSE: The optimal radiotherapy regimen for elderly and/or frail patients with newly diagnosed glioblastoma remains to be established. This study compared two radiotherapy regimens on the outcome of these patients. PATIENTS AND METHODS: Between 2010 and 2013, 98 patients (frail = age ≥ 50 years and Karnofsky performance status [KPS] of 50% to 70%; elderly and frail = age ≥ 65 years and KPS of 50% to 70%; elderly = age ≥ 65 years and KPS of 80% to 100%) were prospectively randomly assigned to two arms in a 1:1 ratio, stratified by age (< and ≥ 65 years old), KPS, and extent of surgical resection. Arm 1 received short-course radiotherapy (25 Gy in five daily fractions over 1 week), and arm 2 received commonly used radiotherapy (40 Gy in 15 daily fractions over 3 weeks). RESULTS: The short-course radiotherapy was noninferior to commonly used radiotherapy. The median overall survival time was 7.9 months (95% CI, 6.3 to 9.6 months) in arm 1 and 6.4 months (95% CI, 5.1 to 7.6 months) in arm 2 (P = .988). Median progression-free survival time was 4.2 months (95% CI, 2.5 to 5.9) in arm 1 and 4.2 months (95% CI, 2.6 to 5.7) in arm B (P = .716). With a median follow-up time of 6.3 months, the quality of life between both arms at 4 weeks after treatment and 8 weeks after treatment was not different. CONCLUSION: There were no differences in overall survival time, progression-free survival time, and quality of life between patients receiving the two radiotherapy regimens. In view of the reduced treatment time, the short 1-week radiotherapy regimen may be recommended as a treatment option for elderly and/or frail patients with newly diagnosed glioblastoma.

Reirradiation of the eye with plaque brachytherapy: a single institution experience report of eight consecutive patients submitted to retreatment after local relapse of malignant disease of the eye.

PURPOSE: To evaluate the feasibility of reirradiation of the eye with plaque brachytherapy (REPBT) for local recurrence (LR) of malignant disease of the eye as an alternative to enucleation or other local salvage treatments. METHODS AND MATERIALS: It was performed a retrospective analysis of all patients who underwent REPBT for LR. The main parameters evaluated were local control and progression-free survival, besides the toxicity profile. RESULTS: There were eight patients who underwent REPBT, seven due to uveal melanoma and one due to retinoblastoma. The median time between the first plaque brachytherapy and the salvage plaque brachytherapy was 24 months (8-49 months). After a median followup of 30 months (8-70 months), the actuarial 2-year local control and progression-free survival was 87.5% and 60%, respectively. All patients evolved with worsening of the visual acuity and cataract. Other complications observed were maculopathy (two patients) and glaucoma (one patient). CONCLUSIONS: REPBT should be considered as an option for salvage therapy of LR of malignant disease of the eyes as it provides a high probability of tumor control and eye preservation without compromising disease-free survival.