CMV infection may be linked to breast cancer
MedWire News: An increase in serum cytomegalovirus (CMV) immunoglobulin G (IgG) antibody levels precedes the development of breast cancer in some women, study findings indicate.
It has been hypothesized that breast cancer can be caused by late exposure to common viruses such as CMV and Epstein–Barr virus (EBV), note Brian Cox (University of Otago, Dunedin, New Zealand) and colleagues.
To investigate whether elevation in serum CMV or EBV IgG levels is associated with breast cancer development, Cox and team carried out a nested case–control study within the Janus Serum Bank (Norway) cohort study.
They tested two serum samples for CMV and EBV IgG antibodies: one sample taken at least 4 years before diagnosis (sample 2) and one taken at least 12 months before that (sample 1), from 399 women with invasive breast cancer. Samples were also taken from 399 controls, matched for date of blood samples and age.
The researchers report that 11 cases and three controls seroconverted for CMV IgG between the first and second samples. After adjustment for parity, CMV IgG seroconversion was associated with a 4-fold increased likelihood for breast cancer. Furthermore, the risk for breast cancer increased 1.7-fold per unit difference in CMV optical density (OD) between samples.
In an analysis restricted to parous cases and age-matched parous controls, where 10 cases and two controls seroconverted, CMV seroconversion was associated with a 9.7-fold increased likelihood for breast cancer.
By contrast, only two cases and three controls seroconverted for EBV IgG and EBV seroconversion or change in EBV OD was not associated with an increased risk for breast cancer.
“Our hypothesis that elevation in serum CMV IgG antibody levels precedes the development of breast cancer in some women is supported by the results of this study,” write Cox and co-authors in the British Journal of Cancer.
They note that “the increased risk observed was present for few women in this study, suggesting that CMV infection may only be involved in the development of a minority of breast cancers.”
The researchers conclude that long-term follow-up studies are required to verify their findings.
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By Laura Dean