New epidemiological and PSMA-expression based insights in salivary gland tumors

Salivary gland tumor research is hampered by low incidence and high diversity of tumors. By using nationwide data and a new imaging technique, some problems can be bypassed.
In this thesis, some epidemiological questions were answered, regarding salivary gland pleomorphic adenoma (SGPA) incidence, recurrence rate and risk of malignant transformation in 3.506 Dutch patients. Subsequently, in a systematic review on natural history of recurrent pleomorphic adenoma, 9.003 Dutch and Danish patients were analyzed. The third paper for the first time reported all steps of malignant transformation of SGPA on a genetical level. In a paper on the risk of breast cancer after salivary gland cancer or SGPA, an increased risk in both cases was reported, based on Dutch data in over 3.600 patients.
The second part of the thesis first systematically described the use of molecular imaging of salivary glands based on presence of prostate-specific membrane antigen (PSMA). Subsequently the potential use of PSMA PET/CT for head neck radiotherapy is described by showing how it can assess and guide salivary gland radiotherapy. Finally, presence of a large bilateral macroscopic collection of salivary gland tissue in the human nasopharynx was suspected on PSMA PET/CT, histologically and radiologically described and 3D-reconstructed in human cadaver tissue (n=2) and PSMA PET/CT scans of 100 patients. The gland collections were named “tubarial glands”. Subsequently, the effect of radiotherapy on these glands in 723 patients with head and neck cancer was evaluated, showing increased xerostomia and dysphagia. The paper was discussed is several published comments.