Dosimetric investigation of radiation-induced trigeminal nerve toxicity in parotid tumor patients.

PURPOSE: We aimed to describe the association between trigeminal nerve (TN) dose and toxicity and determine a threshold value that leads to TN toxicity in patients with parotid tumors treated with adjuvant conventional fractionated radiation therapy. METHODS AND MATERIALS: Eighteen patients who underwent adjuvant radiotherapy (RT) between 2013 and 2018 were included in this retrospective study. TN and its branches were outlined subsequently on the planning CT scans. The doses received by TN were obtained based on the dose-volume histogram. The dose and toxicity relationship was investigated over the total prescribed dose. RT-related toxicity was graded according to Common Terminology Criteria for Adverse Events V4.0 (CTCAEv4.0). RESULTS: The median follow-up was 29.5 months. After RT, 61% of patients had Grade I-II late TN toxicity divided into Grade I in 4 (22%) and Grade II in 7 (39%) patients. TN injury symptoms were as follows: loss of sensation in the chin area in 3, difficulty in jaw movements in 3, and paresthesia in 5 patients. The total RT dose (p = 0.001), Dmax (p = 0.001), PTV-TN Dmax (p = 0.001), D1cc (p = 0.004), D0.5cc (p = 0.001), and D0.1cc (p = 0.01) had a significant effect on TN toxicity. Cut-off values leading to toxicity were determined as 66, 65.5, 65.25, 63.6, and 62.7 Gy for Dmax, PTV-TN Dmax, D0.1cc, D 0.5cc, and D1cc, respectively. CONCLUSIONS: Radiation-induced TN injury in head and neck cancer patients may further be investigated in clinically prospective trials by virtue of high toxicity rates with current RT doses in our retrospectively designed dosimetric study in parotid tumors.

Optimal timing of thoracic irradiation for limited stage small cell lung cancer: Current evidence and future prospects.

Lung cancer is a global health concern as the leading cause of cancer related mortality worldwide. Small cell lung cancer (SCLC) poses a formidable challenge to the treating physicians with the worst prognosis among all lung cancers. However, limited stage SCLC (LS-SCLC) has a relatively better outcome with multimodality management. Efforts have been focused on optimal integration of treatment modalities to achieve an improved therapeutic ratio for patients with LS-SCLC. While chemotherapy and thoracic radiation therapy (TRT) are primary components of initial management for LS-SCLC, there is no consensus on optimal timing of TRT. Within this context, we herein provide a concise overview of current evidence and future prospects regarding the optimal timing of thoracic irradiation for LS-SCLC in light of the literature.

Concise review of radiosurgery for contemporary management of pilocytic astrocytomas in children and adults.

Pilocytic astrocytoma (PA) may be seen in both adults and children as a distinct histologic and biologic subset of low-grade glioma. Surgery is the principal treatment for the management of PAs; however, selected patients may benefit from irradiation particularly in the setting of inoperability, incomplete resection, or recurrent disease. While conventionally fractionated radiation therapy has been traditionally utilized for radiotherapeutic management, stereotactic irradiation strategies have been introduced more recently to improve the toxicity profile of radiation delivery without compromising tumor control. PAs may be suitable for radiosurgical management due to their typical appearance as well circumscribed lesions. Focused and precise targeting of these well-defined lesions under stereotactic immobilization and image guidance may offer great potential for achieving an improved therapeutic ratio by virtue of radiosurgical techniques. Given the high conformality along with steep dose gradients around the target volume allowing for reduced normal tissue exposure, radiosurgery may be considered a viable modality of radiotherapeutic management. Another advantage of radiosurgery may be the completion of therapy in a usually shorter overall treatment time, which may be particularly well suited for children with requirement of anesthesia during irradiation. Several studies have addressed the utility of radiosurgery particularly as an adjuvant or salvage treatment modality for PA. Nevertheless, despite the growing body of evidence supporting the use of radiosurgery, there is need for a high level of evidence to dictate treatment decisions and establish its optimal role in the management of PA. Herein, we provide a concise review of radiosurgery for PA in light of the literature.