This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Hemminki, K. Articles by Försti, A. Search for Related Content PubMed PubMed Citation Articles by Hemminki, K. Articles by Försti, A.

Risks for Familial and Contralateral Breast Cancer Interact Multiplicatively and Cause a High Risk

¹ Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany and ² Center for Family and Community Medicine, Karolinska Institute, Huddinge, Sweden

Requests for reprints: Kari Hemminki, DKFZ, Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany. Phone: 49-6221-421800; Fax: 49-6221-421810; E-mail: k.hemminki{at}dkfz.de.

The reasons for the high risk of contralateral breast cancer are not understood, although polygenic mechanisms have been suggested to be involved. The nationwide Swedish Family-Cancer Database was used to examine the interaction of the risks for contralateral and familial cancer. Relative risks were separately determined for contralateral and familial breast cancers, and these were tested for additive and multiplicative interactions. The Database contained information on 102,176 first breast cancers. Familial risk for breast cancer was 1.76 and the risk for contralateral breast cancer was 3.40, or 5.80 when extrapolated to two breasts. When women had a family history, the risk for contralateral breast cancer was remarkably high, 5.48, or 9.96 when the risk was extrapolated to two breasts, almost identical with 10.21, which was predicted by the multiplicative model. Although the data do not rule out polygenic mechanisms, they suggest that epigenetic imprinting events may be involved for the contralateral breast cancer. [Cancer Res 2007;67(3):868–70]