Page 80 - New epidemiological and PSMA-expression based paradigms in salivary gland tumors

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Chapter 5
Materials and Methods
Cohorts: To assess the association between salivary gland tumors and BC risk in women, we used two nationwide Dutch registries. The Netherlands cancer registry (NCR) was used to establish a cohort including all incident malignant major salivary gland tumors (ICD-O-3 codes: C07: Parotid; C08: other and unspecified major salivary gland), diagnosed in the Netherlands between January 1st, 1989 and December 31st, 2014, without limitations regarding inclusion by age or previous other malignancies. All subsequent ductal in-situ as well as invasive first BCs, registered in the NCR, which occurred until December 31st, 2014 in this cohort were identified. The NCR receives its data mainly from the nationwide histopathology and cytopathology network and archive in The Netherlands (PALGA- in Dutch: Pathologisch Anatomisch Landelijk Geautomatiseerd Archief), but also from hospital discharge diagnosis registries (e.g. patients with a clinically or radiologically diagnosed SGC, who did not undergo biopsy or surgical treatment). Vital status and in-situ and invasive breast cancer incidence were complete until December 31st, 2014. Treatment details were reported and usually included surgery with post-operative radiotherapy in selected cases. The latter typically consists of external beam radiotherapy, which is usually up to 70 Gray (Gy) on the tumor and 50 Gy on the neck, and has a horizontal direction and stays above the clavicle. For the SGPA cohort, we selected all women from a previously established SGPA cohort that included all Dutch pathologically confirmed incident SGPA diagnoses in the PALGA registry between January 1st,1992 - December 31st 2012 with (for logistical reasons to reduce the size of the cohort) a 5-year interval [2]. Therefore, all included SGPA patients were from the years 1992, 1997, 2002, 2007 and 2012. PALGA records all cytological and histological diagnoses, including those of benign diseases like SGPA, and has complete coverage of the Netherlands since 1991. PALGA is one of only a few national registries worldwide that include benign tumors, which allowed establishing our nationwide SGPA cohort[2,3]. The Palga registry does not contain standardized information on therapy. However, all patients in this cohort had a histological diagnose, thus had surgery. Radiotherapy is typically applied in selected recurrent SGPA cases. All subsequent DCIS as well as all invasive first BCs, registered in PALGA, which occurred until December 31st, 2013 in this cohort were identified. Basal cell carcinoma and melanoma of the breast were excluded. Patients with BC before SGC or SGPA were excluded as well.