Study reveals magnitude of variation in gene expression measurements within breast cancers

An important new study has revealed the clearest picture yet of precisely how much measurement variation influences gene expression profiles of breast cancer.

The results show, for the first time, which gene expression measurements may benefit from pooling of biopsies from a single tumour, researchers said at the 5th IMPAKT Breast Cancer Conference in Brussels, Belgium.

These findings represent an important step toward allowing doctors to more precisely tailor an individual's treatment to a detailed analysis of their tumour's gene expression.

Over recent years, scientists have identified many genes, and groups of genes, that can provide crucial information about how an individual patient's cancer will respond to treatment with different drugs.

But a number of hurdles need to be cleared before tests to measure the expression of these genes can be used in clinical situations.

One important challenge is the fact that many different cell types can be present within a single tumour (known as intratumoural heterogeneity), each with different patterns of gene expression and potentially different sensitivity to drugs.

- White women are slightly more likely to develop breast cancer than African-American women. However, in women under 45, breast cancer is more common in African-American women than white women. Overall, African-American women are more llkely to die of breast cancer. Asian, Hispanic, and Native-American women have a lower risk of developing and dying from breast cancer.

- In 2011, there were more than 2.6 million breast cancer survivors in the US.

- A woman's risk of breast cancer approximately doubles if she has a first-degree relative (mother, sister, daughter) who has been diagnosed with breast cancer. About 15% of women who get breast cancer have a family member diagnosed with it.

- About 5-10% of breast cancers can be linked to gene mutations (abnormal changes) inherited from one’s mother or father. Mutations of the BRCA1 and BRCA2 genes are the most common. Women with these mutations have up to an 80% risk of developing breast cancer during their lifetime, and they are more likely to be diagnosed at a younger age (before menopause). An increased ovarian cancer risk is also associated with these genetic mutations.

- In men, about 1 in 10 breast cancers are believed to be due to BRCA2 mutations, and even fewer cases to BRCA1 mutations.

- About 85% of breast cancers occur in women who have no family history of breast cancer. These occur due to genetic mutations that happen as a result of the aging process and life in general, rather than inherited mutations.

- The most significant risk factors for breast cancer are (being a woman) and (growing older).