Page 158 - New epidemiological and PSMA-expression based paradigms in salivary gland tumors

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Chapter 10
was assessed comparing our new method (mortality projection) with the gold standard (registered person-time). For our method, national age- and gender- specific mortality data was projected on the cohort to estimate person-time and the Standardized Incidence Ratio (SIR). For validation, the error of mortality projection and its effect on the number of expected breast cancer cases were calculated. This resulted in a cohort of 6,949 women. The person-times, calculated with both methods were 42,418 and 42.443 person-years (error 0.06%). The expected number of breast cancers based on the projection method was 148 and 147 if based on the gold standard. The observed number of breast cancers was 162, resulting in almost identical SIRs of 1.09 (95%CI 0.93-1.26) and 1.10 (95%CI0.94-1.27) respectively.
In conclusion, the mortality projection method is robust and can be applied to calculate risks and rates of a second primary tumor or malignant transformation in a cohort lacking follow-up data.
Chapter 6:
Salivary and mammary gland tumors show morphological similarities and share various characteristics, including frequent overexpression of hormone receptors and female preponderance. Although this may suggest a common etiology, it remains unclear whether patients with a salivary gland tumor carry an increased risk of breast cancer (BC). Our aim was to determine the risk of BC in women diagnosed with salivary gland carcinoma (SGC) or pleomorphic adenoma (SGPA). BC incidence (invasive and in situ) was assessed in 2 nationwide cohorts: one comprising 1,567 women diagnosed with SGC and one with 2,083 women with SGPA. BC incidence was compared with general population rates using standardized incidence ratio (SIR). BC risk was assessed according to age at SGC/ SGPA diagnosis, follow-up time and (for SGC patients) histological subtype. Our results showed that the mean follow-up was 7.0 years after SGC and 9.9 after SGPA diagnosis. During follow-up, 52 patients with SGC and 74 patients with SGPA developed BC. The median time to BC was 6 years after SGC and 7 after SGPA. The cumulative risk at 10 years of follow-up was 3.1% after SGC and 3.5% after SGPA (95% Confidence Interval (95%CI) 2.1-4.7% and 2.6%-4.6%, respectively). BC incidence was 1.59 times (95%CI 1.19-2.09) higher in the SGC-cohort than expected based on incidence rates in the general population. SGPA-patients showed a 1.48 times (95%CI 1.16-1.86) higher incidence.
As an overall interpretation, women with SGC or SGPA have a slightly increased risk of BC. The magnitude of risk justifies raising awareness, but is no reason for BC screening.