Radiation Oncology — Weekly Evidence Brief

Novel approaches in radiotherapy are improving outcomes across various cancer types. For early-stage HR+ breast cancer, a phase 1 trial demonstrated that single-fraction preoperative stereotactic partial breast irradiation (sPBI) achieved high pathological complete response (pCR) rates, reaching 66.7% at 38 Gy, with 100% local control and low surgical morbidity. Notably, delaying surgery for over 9 months significantly increased pCR to 72.0% 1. In recurrent high-grade gliomas, high-dose stereotactic radiosurgery (SRS) is a feasible salvage option, showing a median overall survival of 9.6 months. However, radiation necrosis occurred in 31.7% of cases, highlighting the need for careful patient selection 2. The integration of deep regional hyperthermia with neoadjuvant chemoradiotherapy in locally advanced rectal cancer also proved feasible and well-tolerated, with high adherence and no severe hyperthermia-related toxicities, supporting its potential as an adjunct therapy 3.

Combining radiotherapy with systemic treatments continues to yield significant benefits. In advanced EGFR-mutant NSCLC, concurrent thoracic radiotherapy (TRT) with first-line EGFR-TKIs substantially extended median progression-free survival (PFS) compared to TKI alone (e.g., 43.1 vs 17.2 months for third-gen TKIs). This benefit was consistent across mutation types and in patients with brain metastases, showing favorable safety with minimal severe toxicities 4. For extensive-stage small-cell lung cancer (ES-SCLC), both first-line and subsequent-line immunotherapy (ICIs) significantly improved overall survival. Crucially, local thoracic radiotherapy maintained its significant survival benefit in the ICI era for ES-SCLC patients 5. Moreover, in unresectable hepatocellular carcinoma (uHCC), a multimodal deep learning model identified that patients receiving external beam radiotherapy (EBRT) combined with transarterial chemoembolization (TACE) and systemic therapy had significantly prolonged overall survival (24.0 months) compared to EBRT plus systemic therapy alone (19.0 months) 6. For colorectal cancer liver metastases, combining brachytherapy with systemic treatment was found to be safe and effective, with RAS gene mutations impacting PFS and OS depending on the line of treatment 7.

Artificial intelligence and radiomics are emerging as powerful tools for enhancing precision in oncology. A deep learning model combining baseline and adaptive radiation therapy CT images demonstrated moderate predictive ability for local recurrence, neck lymph node relapse, and distant metastases in pharyngeal cancer 8. Similarly, a clinical-radiomics nomogram significantly improved prognostic prediction for overall survival in inoperable pancreatic cancer patients undergoing concurrent chemoradiotherapy, achieving a C-index of 0.892 9. For glioblastoma, machine learning models based on 18F-DOPA PET radiomics achieved high accuracy in predicting remaining survival, potentially distinguishing tumor progression from treatment effects 10. Furthermore, knowledge-based planning models for whole breast tangential field radiotherapy showed transferability across international institutions, ensuring comparable PTV coverage and accurate dose predictions, which can standardize and optimize treatment planning 11.

Advanced imaging techniques are crucial for early response assessment and prognostic prediction. In high-risk prostate cancer patients receiving neoadjuvant hormonal treatment, specific [18F]PSMA-1007 PET parameters, such as posttreatment PSMA-expressing volume and pretreatment distant metastases, were significant predictors of biochemical recurrence-free survival 12. For metastatic castration-resistant prostate cancer (mCRPC) undergoing 177Lu-PSMA radioligand therapy, quantitative RECIP 1.0 applied on C2 [177Lu]Lu-PSMA SPECT/CT effectively identified patients with shorter PSA-PFS and overall survival, serving as an independent prognostic tool 13. Moreover, for HER2-positive early breast cancer patients, breast MRI tumor reduction showed good accuracy (78.2%) compared to [18F]FDG-PET for early imaging assessment and could serve as a viable alternative for adaptive treatment strategies when PET is unavailable, potentially expanding access to de-escalation protocols 14.

Organ preservation strategies are gaining traction, especially in esophageal cancer, where active surveillance post-neoadjuvant chemoradiotherapy offers comparable survival outcomes to esophagectomy while significantly improving quality of life 15. For elderly patients with locally advanced head and neck squamous cell carcinoma (HNSCC), cetuximab plus radiotherapy (Cet-RT) was found to be a feasible and well-tolerated treatment option, with a median overall survival of 58 months, suggesting it as a viable approach for this vulnerable population 16. In resected locoregional recurrence of HR-positive HER2-negative breast cancer, adjuvant chemotherapy was associated with improved invasive disease-free survival, particularly in cases of non-ipsilateral breast tumor recurrence or recurrence during adjuvant endocrine therapy 17.