Abstract 3256: Risk of second primary cancers in women diagnosed with endometrial cancer in German and Swedish cancer registries
Authors: Chen Tianhui 
Published: July 2017

Abstract
Background: Along with the increasing incidence and favorable prognosis, more women diagnosed with endometrial cancer may develop second primary cancers (SPCs). Nevertheless, most of previous studies have limitations such as small study samples or investigations for selected SPC only. Additionally, to our knowledge, investigations on the risk of a specific SPC after endometrial cancer in two different populations have not been reported. We aimed at investigating risk of second primary cancers (SPCs) in women diagnosed with endometrial cancer in Germany and Sweden to provide insight into etiology and prevention strategies for SPCs.
Methods: Endometrial cancer patients diagnosed at age ≥15 years in Germany during 1997-2011 and in Sweden nationwide during 1997-2012 were selected. For both German and Swedish datasets, standardized incidence ratios (SIRs), calculated as the ratio of observed to expected numbers of cases, were used to assess the risk of a specific SPC in women diagnosed with endometrial cancer. The expected number of a SPC after endometrial cancer was calculated from the strata-specific first same cancer incidence rates in the Swedish and German general population, respectively, multiplied by the corresponding person-years in women with endometrial cancer. Person-years at risk were accumulated for each patient, starting at the date of diagnosis of the first endometrial cancer, and terminating on the diagnosis date of a SPC, date of death, date of emigration, or end of follow-up (end of 2011 for Germany and of 2012 for Sweden), whichever came first.
Results: Among 46,929 endometrial cancer survivors in Germany and 18,646 in Sweden, overall 2,897 and 1,706 SPCs were recorded, respectively. Significantly elevated SIRs were observed in Germany for ovarian (SIR=1.3; 95%CI:1.1-1.5) and kidney cancers [1.6 (1.3-1.8)], while in Sweden the SIRs were 5.4 (4.6-6.3) and1.4 (1.0-1.9), respectively. Elevated risk for second ovarian endometrioid carcinoma was pronounced after early (&lt;55 years) onset endometrial cancer in Germany [9.0 (4.8-15)] and Sweden [7.7 (5.1-11)].In Germany elevated risks were found for second ovarian endometrioid carcinoma after endometrioid histology of first endometrial cancer [6.3 (4.0-9.4)] and for second kidney cancer after clear cell histology of endometrial cancer [4.9 (1.6-11)].
Conclusions: We found exceptionally elevated risk of second ovarian endometrioid carcinoma after endometrial cancer of the same histology or of early onset. Kidney cancer was also increased, particularly after endometrial cancer of clear cell histology. Cancer prevention strategies should focus on these cancers after endometrial cancer diagnosis.
Citation Format: Tianhui Chen. Risk of second primary cancers in women diagnosed with endometrial cancer in German and Swedish cancer registries [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3256. doi:10.1158/1538-7445.AM2017-3256