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Supplementary Tables 1-2 from Risk of Sex-Specific Cancers in Opposite-Sex and Same-Sex Twins in Denmark and Sweden

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posted on 2023-03-31, 13:40 authored by Linda J. Ahrenfeldt, Axel Skytthe, Sören Möller, Kamila Czene, Hans-Olov Adami, Lorelei A. Mucci, Jaakko Kaprio, Inge Petersen, Kaare Christensen, Rune Lindahl-Jacobsen

Supplementary Table 1 - Beginning of follow-up of cancer for Danish and Swedish twins born 1870-2004. Supplementary Table 2 - Cancer risk for sex-specific and all-cause cancers in opposite-sex (OS) and same-sex dizygotic (ssDZ) twins as well as in OS/ssDZ twins compared with the general population born in Denmark and Sweden during 1870 to 2004 and followed from 1943 to 2009 - excluding twins with known monozygotic status and unknown zygosity status.

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ARTICLE ABSTRACT

Background: Increasing evidence shows that some cancers originate in utero. It is hypothesized that elevated exposure to some steroid hormones might increase cancer risk and that hormone transfer between twin fetuses could result in different prenatal exposure to testosterone.Methods: This large-scale prospective twin study compared opposite-sex (OS) and same-sex (SS) twins to test the impact of intrauterine exposures on cancer risk. On the basis of the Danish and Swedish twin and cancer registries, we calculated incidence rate ratios for OS and SS twins, whereas standardized incidence ratios (SIR) with 95% confidence intervals (CI) were calculated for OS/SS twins compared with the general population.Results: A total of 18,001 cancers were identified during 1943–2009. No significant differences were observed between OS and SS twins, neither for the sex-specific cancers nor for cancer at all sites. All-cause cancer was slightly reduced for OS and SS twins compared with the general population, significant for OS males (SIR, 0.95; 95% CI, 0.92–0.98) and for SS males and females (SIR, 0.97; 95% CI, 0.94–0.99).Conclusions: Our data suggest that having a male co-twin—which may entail higher exposure to prenatal testosterone—does not increase the risk of sex-specific cancers in OS females. Furthermore, the study supports that twinning per se is not a risk factor of cancer.Impact: Findings are reassuring, as they fail to provide evidence for the hypothesis that endocrine or other difference in the in utero milieu affects the risk of sex-specific cancers. Cancer Epidemiol Biomarkers Prev; 24(10); 1622–8. ©2015 AACR.

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