New Breast Cancer Treatment on Horizon

Most women are protected from breast cancer by their BRCA genes. But some women have inherited mutations in BRCA genes, giving them about an eighty per cent risk of developing breast cancer. The key to stopping cells with mutated BRCA is a protein called PARP.

Healthy human cells replicate (reproduce); their DNA divides and copies itself. If DNA is damaged before replication, it is usually repaired by PARP. If a cell can't repair it's DNA with PARP, it uses a backup system called combination to fix the damage so it can continue to replicate.

Cells with mutated BRCA genes don't have the backup system of recombination; rely completely on PARP to fix DNA damage. The new treatment uses a chemical that knocks out PARP, making all cells rely on recombination. The breast cancer tumour, that forms from the cells with mutated BRCA cannot perform recombination and is therefore unable to replicate and create new cells. The tumour is then unable to grow and eventually dies.
The other cells in the body are likely to be unaffected by the treatment. Link.