Tumour samples from 30 participants with HNSCC that undergone curative surgery will be used to establish patient-derived xenografts (PDXs). These tumours will also undergo exome sequencing. This will provide a biobank of PDX models with available genomic information for future research projects. Another 30 participants with recurrent or metastatic HNSCC (RMHNSCC) will be recruited to this study. PDX models will be developed from these patient tumours, followed by genomic sequencing. PDX models are developed by transplanting small tumour pieces into immunocompromised mice. These mice are then treated with different available drugs for RMHNSCC at the discretion of their medical oncologist. These mice will be then followed up to examine the tumour response to treatments. When studied in clinic, PDX models have shown high correlation with patient response to the treatment. The PDX drug testing results will be provided to the treating medical oncologist to guide care at the oncologists discretion. Investigators' hope is that improved chemotherapy responses are observed with this strategy.