The SPOT-Light test can measure how many HER2 genes are present in a sample of breast tumor; the more genes there are, the more likely the tumor will respond to treatment with Herceptin.

Unlike the hormonal treatment Herceptin, which is effective in only 20 per cent of patients with oestrogen-positive breast cancer, chemotherapy works for all women.

Further, the drug Herceptin, which is used to treat HER2-positive breast cancer, was found to target and destroy the cancer stem cells.