ESTRO 2024 - Abstract Book

S1359

Clinical - Head & neck

ESTRO 2024

carcinoma (NPC) cases with intracranial extension (ICE) and its impact on outcome. The secondary objective is to report toxicities.

Material/Methods:

We retrospectively analyzed all patients with histologically proven, non-metastatic NPC with ICE treated at our institute between July 2019 and October 2022. All patients received 2-3 cycles of taxane-based NACT followed by chemoradiation. Baseline PET-CT and MRI were fused with the simulation CT scan. The FDG-avid tumor was delineated with a threshold of 40% SUVmax. For superior delineation of the intracranial extent of the disease, 3D FSPGR MRI scan was fused and contoured. Radiotherapy was given with “risk - adapted” IMRT (4). The HR -CTV included the pre-chemotherapy GTV (excluding the intracranial part) with 5 mm margins, as well as the entire nasopharynx, skull base, sphenoid sinus, parapharyngeal space, medial pterygoid fossae, posterior parts of the nasal cavity, retropharyngeal nodal regions, and the involved nodal levels. The intracranial part of CTV was delineated by giving a margin of 3 to 5 mm depending on the proximity to critical organs at risk. Uninvolved nodal regions constituted the LR-CTV. The HR-PTV and LR-PTV received a dose of 69.94 Gy/ 33 fractions and 59.4 Gy/ 33 fractions, respectively. All patients received concurrent cisplatin chemotherapy 40 mg/m2. Patients were followed up weekly to assess the toxicities, according to RTOG (5). These patients were followed up three monthly after treatment completion to assess the chronic toxicities. A response assessment PET-CT was done three months after the completion of treatment.

Results:

A total of 23 patients were included. The median age was 26 years (18-59 years) with 75% male patients. Most of the patients (66%) received two or three cycles of Gemcitabine-Cisplatin-based NACT, rest of the patients received two cycles of DCF. All patients completed the planned dose of radiotherapy without undue delay or breaks in between treatments. Concurrent cisplatin was administered in 58% of patients, whereas the rest of the patients received carboplatin. The median follow-up was twenty-four months. The two-year overall survival was 79.8%. The two-year progression-free survival was 59.2%. Most of the patients failed systemically (85%). The most common site of distant metastasis was bone, followed by the liver and lung. Only one patient (4%) had isolated regional nodal recurrence, which was included in the HR-PTV. Grade 3 or higher acute mucositis, dermatitis, and odynophagia were seen in 26%, 18%, and 47% of patients, respectively.

Conclusion:

PET-CT and MRI-guided chemoradiation led to accurate delineation of the tumor, which translated into good local control with acceptable toxicities. Radical treatment options should be considered in NPC with ICE.

Keywords: nasopharyngeal, intracranial, PET and MRI

References:

1. Siegel RL, Miller KD, Fuchs HE, Jemal A. Cancer statistics, 2022. CA: a cancer journal for clinicians. 2022 Jan;72(1):7 33,