Women diagnosed with early stage breast cancer often receive additional chemotherapy to prevent metastases but many of these women are undergoing a stressful therapy they may not need, according to researchers at the Netherlands Cancer Institute.

The institute has developed a test which can be used to predict which women with hormone-sensitive early-stage breast cancer need additional chemotherapy and which do not.

The MammaPrint test determines the activity of 70 genes in the tumour tissue. These results can be used to predict the personal risk for each patient of the tumour spreading elsewhere in the body.

The results of a large European study involving 6,693 patients has provided ‘the final evidence of the test’s reliability’, the institute said on Monday.

Low probability

This study showed that patients with hormone-sensitive breast cancer and who had been found to have a low probability of metastasis by the MammaPrint test, do not need chemotherapy. Previous minor studies have tentatively shown the same result.

‘In both groups the percentage of women remaining disease-free in the following years, remained the same, namely 95%,’ said Emiel Rutgers, a surgeon at the Antoni van Leeuwenhoek hospital, who coordinated the study.

Every year 14,000 women in the Netherlands are diagnosed with breast cancer. Some 80% have hormone-sensitive breast cancer.