Naoya Murakami

Objectives: To compare the dosimetry and robustness of 2 Radixact Synchrony lung stereotactic body radiotherapy (SBRT) tracking strategies: tumor-based lung tracking with respiratory modelling (LwR) and fiducial-based tracking with respiratory modelling (FwR). Methods: Ten stage I non-small-cell lung cancer patients were retrospectively analyzed. SBRT plans (42 Gy in 4 fractions) were generated on maximum-exhalation computed tomography (CT) using planning target volumes (PTVs) created by 3-7 mm isotropic gross tumor volume (GTV) expansion. Each plan was mapped to all 4-dimensional CT (4DCT) phases via isocenter shifts from phase-specific GTV (LwR) or individual fiducial displacement (FwR). Deformable dose accumulation yielded LwR, nearest FwR, and farthest FwR simulated plans. GTV/PTV V100%, representative organ-at-risk (OAR) doses, and robustness versus target localization error, tumor-fiducial distance, and tumor volume were evaluated. Results: With a 3-mm PTV margin, FwR showed larger losses in GTV coverage and PTV robustness than LwR (maximum decreases of 9.0% and 26.0%). FwR was less robust, particularly with unfavorable tumor-fiducial geometry. Larger PTV margins progressively mitigated FwR coverage degradation while maintaining acceptable OAR doses. Conclusions: For lung SBRT delivered with Radixact Synchrony, LwR was more robust than FwR in this cohort, for which all tumor-fiducial distances exceeded 20 mm. When FwR is required, particularly under suboptimal tumor-fiducial geometry, a 3-mm margin should be used cautiously, and patient-specific evaluation of 5-7 mm margins within OAR dose constraints may be necessary. Advances in knowledge: A 4DCT-based simulation using imaging-derived tracking-error scenarios reveals dosimetric robustness differences between LwR and FwR tracking.

The management of unresectable locally advanced non-small cell lung cancer (NSCLC) has undergone significant transformation over the past three decades. This review summarizes the evolution of radiation therapy for unresectable locally advanced NSCLC, from radiation therapy alone to concurrent chemoradiotherapy, and the subsequent integration of immunotherapy or targeted therapy against driver mutations as consolidation treatment. Technical advances in radiation delivery, including the progression from two-dimensional radiotherapy to three-dimensional conformal radiotherapy (3D-CRT), followed by intensity-modulated radiotherapy (IMRT), have improved therapeutic outcomes while reducing toxicity. The PACIFIC trial established durvalumab, an anti-programmed death ligand 1 (PD-L1) antibody, consolidation as the standard of care following concurrent chemoradiotherapy, resulting in significant improvements in survival. More recently, the LAURA trial demonstrated the efficacy of Osimertinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), consolidation in EGFR-mutated NSCLC. However, radiation pneumonitis remains a potentially fatal radiation-induced toxicity that can prevent patients from receiving optimal treatment. Careful attention to dose-volume parameters, particularly lung V20Gy and mean lung dose, is essential for safe treatment delivery. Risk prediction models have been developed to identify high-risk patients, particularly those with pre-existing interstitial pneumonia. The successful transition to consolidation immunotherapy requires meticulous radiation pneumonitis management to maximize clinical benefit. This review summarizes current evidence and provides guidance for optimizing treatment approaches in this challenging patient population.

Radiation therapy is not mentioned in various guidelines for primary treatment of uterine sarcoma. Radiation therapy is considered useful for palliative purposes, but an optimal radiation schedule has not been established. An 85-year-old woman was recommended to undergo surgery for locally advanced uterine sarcoma of unknown histological subtype, but she refused because of her poor physical and social circumstances. She instead received chemotherapy; however, the lesion progressed, and the patient opted for best supportive care. Palliative radiation therapy was indicated for genital bleeding. She thereafter received the QUAD shot regimen, in which 3.7 Gy was administered twice a day for 2 consecutive days and repeated every 4 weeks for a total dose of 44.4 Gy in 3 cycles. The lesion significantly decreased in size, and no new regional or distant metastases were identified. Although only palliative radiation therapy was initially intended, the favourable response with no new lesion development prompted us to offer additional brachytherapy for curative intent, and the patient accepted. She underwent 2 sessions of uterine cervical intracavitary and interstitial brachytherapy using a gel spacer, and local control of the lesion was achieved at 1-year and 3 months follow-up of treatment without major adverse events. In select patients for whom a favourable response is achieved after the QUAD shot, the addition of intracavitary and interstitial brachytherapy with a gel spacer may result in curative treatment. This therapy could be a very promising and attractive option for patients with uterine sarcoma who have complications or special social circumstances.

The recommended dwell time weight of the needle in intracavitary/interstitial hybrid brachytherapy (HBT) has been 10–20%. This study aimed to investigate the correlation between the weight constraint of the needle and normal organ doses in uterine cervical cancer HBT. This study included 30 cervical cancer patients who received HBT with tandem/ovoid applicators. In our clinical practice, treatment plans were generated without the constraint of the dwell time weight of the needle. The cases where this weight exceeded 20% were replanned. An inverse planning technique with locking downscaled needle dwell time was used to reproduce isodose lines of clinical plans. Replanning repeated with downscaling of the dwell time until the weight of the needle fell 200% of the prescribed dose were evaluated. In 17 of 30 (56.7%) clinical plans, the weight of the needle exceeded 20%. The rectum, bladder and sigmoid colon D2cc significantly increased with the Needle-Lock plan. The overdosage area also increased significantly (P < 0.01). The correlations between the needle number and the increase of D2cc in the rectum and sigmoid colon (P < 0.01) were statistically significant. Limiting needle dwell time weight by 10–20% increased bladder and rectum doses, especially with multiple needles. These findings suggest that needle dwell time weight recommendations could need to be reconsidered based on individual and institutional situation.

Hangeshashinto is a traditional Japanese herbal medicine that is widely recognized for its efficacy in relieving mucositis induced by chemotherapy and radiotherapy. We herein present the cases of two patients with head and neck cancer who were clinically diagnosed with severe drug-induced interstitial lung disease (DILD) following Hangeshashinto administration for radiation-induced mucositis. Although Hangeshashinto has beneficial properties, it is also associated with a relatively low incidence of DILD, including some reports of death. To ensure patient safety, greater attention should be paid when prescribing Hangeshashinto, especially for elderly patients with factors predisposing them to develop severe DILD.

This study developed a system to reduce the treatment planning time for cervical cancer brachytherapy. An in-house Excel spreadsheet was developed to streamline dosimetric evaluation by combining external beam radiotherapy and brachytherapy doses, while also displaying daily dose constraints, a novel feature of the system. This system was validated in 46 consecutive patients who underwent intracavitary and interstitial brachytherapy using several applicators and required more complex dose calculation procedures than intracavitary brachytherapy alone. The proposed system included contouring and catheter reconstruction using multiple treatment planning systems simultaneously and was integrated with Excel spreadsheets for rapid dosimetric evaluation. The median time required for treatment planning was 36 min (range: 12–72 min), which was a much shorter time than those reported previously. This optimized system demonstrated the potential to increase the efficiency of brachytherapy planning to meet prescribed dose constraints without compromising treatment quality.