Oropharyngeal squamous cell carcinoma (SCC) is a common type of head and neck cancer often linked to tobacco, alcohol use, and, in youngers, HPV infection. Standard care for locally advanced SCC involves radiotherapy (RT) and cisplatin, (total doses of 66–70Gy in 30–35fractions). However, some patients with significant comorbidities cannot tolerate chemotherapy, requiring alternative approaches. We present a case of a 66-year-old male with p16-negative oropharyngeal SCC and bulky cervical nodal metastasis, ineligible for chemotherapy.

The patient was treated using adaptive volumetric modulated arc therapy (VMAT) with simultaneous integrated boost (SIB) and central gross tumor volume (GTV) dose escalation. This approach delivered up to 72Gy to the central GTV in 30 fractions; 66 Gy in 30 fractions to the high-risk area; 60Gy in 30 fractions to the intermediate-risk area; 54 Gy in 30 fractions to the low-risk area.

An epithelolysis (grade 3) led to a four-day treatment pause. A mid-treatment CT showed tumor shrinkage, reducing the nodal GTV volume from 107to 33cc, prompting adaptive planning to optimize dose distribution and reduce toxicity. The patient completed RT without further interruptions. At six months post-treatment, no recurrence or severe toxicities were detected and four years post-treatment, the patient remains in complete remission without significant late toxicity.

This case demonstrates the effectiveness of VMAT with SIB in delivering accelerated radiotherapy to a bulky nodal lesion in a patient with p16-negative oropharyngeal SCC unfit for chemotherapy; This allowed for tumor control while minimizing exposure to critical structure.

While treating brain metastasis with whole-brain radiotherapy incorporating a simultaneous integrated boost (WBRT-SIB), the risk of hippocampus injury is high. The aim of this study is to compare dosimetrically between intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) in sparing of hippocampus and organs at risk (OARs) and planning target volume (PTV) coverage.

In total, 16 patients presenting with more than one brain metastases were previously treated and then retrospectively planned using VMAT and IMRT techniques. For each patient, a dual-arc VMAT and another IMRT (five beams) plans were created. For both techniques, 30 Gy in 10 fractions was prescribed to the whole brain (WB) minus the hippocampi and 45 Gy in 10 fractions to the tumour with 0·5 cm margin. Dose–volume histogram (DVH), conformity index (CI) and homogeneity index (HI) of PTV, hippocampus mean and maximum dose and other OARs for both techniques were calculated and compared.

A statistically significant advantage was found in WB-PTV CI and HI with VMAT, compared to IMRT. There were lower hippocampus mean and maximum doses in VMAT than IMRT. The maximum hippocampus dose ranged between 15·5 and 19·2 Gy and between 18·4 and 20·6 Gy in VMAT and IMRT, respectively. The mean dose of the hippocampus ranged between 11·5 and 17·7 Gy and between 13·2 and 18·3 Gy in VMAT and IMRT, respectively.

Using WBRT-SIB technique, VMAT showed better PTV coverage with less mean and maximum doses to the hippocampus than IMRT. Clinical randomised studies are needed to confirm safety and clinical benefit of WBRT-SIB.