Page 165 - New epidemiological and PSMA-expression based paradigms in salivary gland tumors

In general, ongoing developments in medical sciences provide new possibilities for in depth evaluation of the origin of disease, for use of diagnostic methods and new treatments and for evaluation of treatment outcomes. This asks for constant awareness of the reality that current knowledge of today is not a fact of life, or a fact of medicine but is just the perspective that we (can) have today based on current techniques.
In patients with rare diseases like salivary gland tumors, it can be even harder to discern new patterns in pathophysiology, diagnostic methods or treatment outcome. This asks for strategies such as the use of big data from nationwide registries, multidisciplinary, multicenter and multi-organization and sometimes international cooperation, as was shown throughout this thesis. Nationwide databases with salivary gland tumor data from the Netherlands and Denmark were used to evaluate incidence of the salivary gland pleomorphic adenoma (SGPA) in Chapter 2 and 3 [1,2]. Incidence of adverse and relatively uncommon outcomes like recurrence and malignant transformation could be investigated in these large cohorts. It must be said that these investigations were only possible thanks to the existence of the high quality nationwide tumor and pathology registries. And having said this, the quality of the input determines the quality of the output. Ongoing research is expected to provide more insight in the difficulties in correct registration of a rare disease like the malignantly transformed SGPA. Molecular diagnostics can be of help as was shown in Chapter 4, in a patient with the first full genetic story behind malignant transformation of the SGPA, the most common salivary gland tumor[3]. Future investigations of more of these rare cases could determine what other pathways can lead to malignant transformation. Also, the optimal way of use of molecular techniques in the diagnostic process could then be further clarified.
Zooming out to the epidemiology-level again, the possibility of connecting nationwide databases with patient data of salivary gland tumors and breast cancer, provided a cohort in which the risk of breast cancer could be investigated. In case of the SGPA, which lacked follow-up data in the nationwide databases, this follow- up problem had to be explored and solved first, as is shown in Chapters 5 and 6 [4]. The increased relative risk supports further exploration of the mechanisms behind this phenomenon which had been noted on a smaller scale by clinical observations and smaller studies. The relation between sex hormones and female
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Conclusions and future perspectives
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