Background: Head and neck squamous cell carcinoma (HNSCC) displays a large heterogeneity in treatment response, and consequently in patient prognosis. Despite extensive efforts, no clinically validated model is available to predict tumor response. Here we describe a functional test for predicting tumor response to radiation and chemotherapy on the level of the individual patient. Methods: Resection material of 17 primary HNSCC patients was cultured ex vivo, irradiated or cisplatin-treated, after which the effect on tumor cell vitality was analyzed several days after treatment. Results: Ionizing radiation (IR) affected tumor cell growth and viability with a clear dose-response relationship, and marked heterogeneity between tumors was observed. After a single dose of 5Gy, proliferation in IR-sensitive tumors dropped below 30% of the untreated level, while IR-resistant tumors maintained at least 60% of proliferation. IR-sensitive tumors showed on average a twofold increase in apoptosis, as well as an increased number and size of DNA damage foci after treatment. No differences in the homologous recombination (HR) proficiency between IR-sensitive and –resistant tumors were detected. Cisplatin caused a decrease in proliferation, as well as induction of apoptosis, again with marked variation between the samples. Conclusions: Our functional ex vivo assay discriminated between IR-sensitive and IR-resistant HNSCC tumors, and may also be suitable for predicting response to cisplatin. Its predictive value is currently under investigation in a prospective clinical study.

Human papillomavirus (HPV) is an important risk factor for oropharyngeal squamous cell carcinoma (OPSCC). HPV-positive (HPV+) cases are associated with a different pathophysiology, microstructure, and prognosis compared to HPV-negative (HPV−) cases. This review aimed to investigate the potential of magnetic resonance imaging (MRI) to discriminate between HPV+ and HPV− tumours and predict HPV status in OPSCC patients. A systematic literature search was performed on 15 December 2022 on EMBASE, MEDLINE ALL, Web of Science, and Cochrane according to PRISMA guidelines. Twenty-eight studies (n = 2634 patients) were included. Five, nineteen, and seven studies investigated structural MRI (e.g., T1, T2-weighted), diffusion-weighted MRI, and other sequences, respectively. Three out of four studies found that HPV+ tumours were significantly smaller in size, and their lymph node metastases were more cystic in structure than HPV− ones. Eleven out of thirteen studies found that the mean apparent diffusion coefficient was significantly higher in HPV− than HPV+ primary tumours. Other sequences need further investigation. Fourteen studies used MRI to predict HPV status using clinical, radiological, and radiomics features. The reported areas under the curve (AUC) values ranged between 0.697 and 0.944. MRI can potentially be used to find differences between HPV+ and HPV− OPSCC patients and predict HPV status with reasonable accuracy. Larger studies with external model validation using independent datasets are needed before clinical implementation.

Radiotherapy in the head-and-neck area is one of the main curative treatment options. However, this comes at the cost of varying levels of normal tissue toxicity, affecting up to 80% of patients. Mucositis can cause pain, weight loss and treatment delays, leading to worse outcomes and a decreased quality of life. Therefore, there is an urgent need for an approach to predicting normal mucosal responses in patients prior to treatment. We here describe an assay to detect irradiation responses in healthy oral mucosa tissue. Mucosa specimens from the oral cavity were obtained after surgical resection, cut into thin slices, irradiated and cultured for three days. Seven samples were irradiated with X-ray, and three additional samples were irradiated with both X-ray and protons. Healthy oral mucosa tissue slices maintained normal morphology and viability for three days. We measured a dose-dependent response to X-ray irradiation and compared X-ray and proton irradiation in the same mucosa sample using standardized automated image analysis. Furthermore, increased levels of inflammation-inducing factors—major drivers of mucositis development—could be detected after irradiation. This model can be utilized for investigating mechanistic aspects of mucositis development and can be developed into an assay to predict radiation-induced toxicity in normal mucosa.

Background: Radiotherapy in the head-and-neck area is one of the main curative treatment options. However, this comes at the cost of varying levels of normal tissue toxicity, affecting up to 80% of patients. Mucositis can cause pain, weight loss and treatment delay leading to worse outcomes and decreased quality of life. Therefore, there is an urgent need for an approach to predict normal mucosa response in patients prior to treatment. Methods: We here describe an assay to detect irradiation response in patient healthy oral mucosa tissue. Mucosa specimens from the oral cavity were obtained after surgical resection, cut into thin slices, irradiated, and cultured for three days. Seven samples were irradiated with X-ray and three additional samples were irradiated with both X-ray and protons. Results: Healthy oral mucosa tissue slices maintained normal morphology and viability for three days. We measured a dose-dependent response to X-ray irradiation and compared X-ray and proton irradiation in the same mucosa sample, using standardized automated image analysis. Furthermore, increased levels of inflammation inducing factors - major drivers in mucositis development - could be detected after irradiation. Conclusion: This model can be utilized for investigating mechanistic aspects of mucositis development and can be developed into an assay to predict radiation-induced toxicity in normal mucosa.

Proton radiotherapy is applied for various tumor sites, offering better dose distribution resulting in decreased excess radiation of healthy tissue. Furthermore, the biological effects of proton irradiation may be different from X-ray irradiation, depending on tumor characteristics. This is particularly relevant for head and neck squamous cell carcinoma (HNSCC), which displays high biological heterogeneity. However, this heterogeneous response to various radiation modalities is currently not included in clinical decision making due to lack of response prediction models. Nine oral cavity tumor specimens were obtained after surgical resection, cut into thin slices, irradiated with both X-ray and protons, and cultured ex vivo for up to five days. We subsequently analyzed proliferation, apoptosis, DNA repair and immune cell infiltration. Most tumors (five out of nine) showed similar response to proton and X-ray irradiation. However, in three tumors a significantly larger decrease in viability was measured upon proton irradiation. One of those tumors was homologous recombination deficient (HRD). The other two proton-sensitive tumors showed low numbers of infiltrating immune cells, including tumor infiltrating lymphocytes, while the most X-ray sensitive tumor had a particularly high immune cell infiltration. The ex vivo assay revealed heterogeneous response of HNSCC tumors to proton and X-ray irradiation. The tumors with increased sensitivity to proton irradiation either showed HR deficiency or low immune cell infiltration. However, not all immune-deserted tumors showed this skewing towards X-ray resistance. These findings require validation in a larger cohort of patients.