Two novel genetic variants linked to breast size may also influence the risk of breast cancer, according to a study carried out by US genetics company 23andMe.
'The findings in this study show that some of the same biological pathways underlie both normal breast growth and breast cancer', said lead author Dr Nicholas Eriksson.
'Some studies have found that larger breast size as a young woman is associated with a slightly higher risk for breast cancer. The genetic factors we found support this concept that breast size and breast cancer are related', he said.
Researchers at 23andMe conducted a genome-wide association (GWAS) study, comparing genomic and self-reported data of 16,175 female 23andMe customers
of European ancestry. Self-reported data was collected through online surveys, and
included questions about bra cup size and factors which may affect reported
breast size, including bra band size.
Seven SNPs (single nucleotide polymorphisms) associated with breast size were identified, two of which were also associated with breast cancer. A third variant of 29 genetic variations associated with breast cancer was also identified as having a possible association with breast size, but it did not reach statistical significance, an article on the NHS Choices website points out.
NHS Choices also lists several caveats to the findings, stating that the study does not show that larger breast size increases a woman's risk of developing breast cancer. 'Genome-wide association studies can provide useful information on the genetic features underlying certain conditions, but cannot tell us whether people with these genome variations will go on to develop the condition', it says. 'There are multiple risk factors for breast cancer, ranging from genetic to environmental to lifestyle factors. This study cannot tell us how these factors interact to increase the risk of developing breast cancer'.
The paper notes that more research is needed before the findings 'could be considered concrete'.
'While these results do not directly support the known epidemiological relationships between breast size and cancer, this study contributes to a better understanding of the subtle interactions between breast morphology and breast cancer risk', Dr Eriksson said.