Genes key to breast cancer treatment success

A genetic test could help to predict which breast cancer patients are at greatest risk of cancer recurring after breast cancer treatment, as well as pinpointing women for whom chemotherapy has little benefit, US study findings indicate.

Although it is known that only some women with such breast tumours need to undergo treatment to avert the risk of cancer recurring, it has been difficult to identify which patients could be excluded from therapy, says the research team, led by Dr Norman Wolmark from the National Surgical Adjuvant Breast and Bowel Project, in Pittsburgh, Pennsylvania.

Writing in the New England Journal of Medicine, they explain that numerous attempts have been made to identify biological means of indicating the risk cancer recurrence, but none of them have been recommended as a means of guiding treatment.

The researchers therefore investigated the use of a genetic test that evaluates the presence of 21 genes that have previously been linked to cancer to estimate the risk of cancer recurrence in 668 breast cancer patients.

Using genetic profiles to calculate a recurrence score of between one and 100, with 100 being the highest chance of cancer recurrence in another part of the body, the researchers classified the women as being at low, intermediate or high risk of recurrence.

In all, 51% were found to be at low risk of recurrence, 22% at intermediate risk and the remaining 27% were at high risk of recurrence. These risk calculations were found to correspond well with the actual rates of cancer returning after 10 years, with a 6.8% rate of recurrence in the low-risk group and a 14.3% risk of recurrence among the intermediate group, while 30.5% of those in the high-risk group had recurrent cancer within 10 years.

The researchers conclude that the genetic profile test may be a useful means of predicting cancer recurrence and which breast cancer patients may benefit from further treatment.

The results of the study were also presented at the San Antonio Breast Cancer Symposium in Texas