Protein test may improve treatment of advanced breast cancer

Testing secondary tumours that have spread around the body for the protein HER-2 may help doctors decide the most effective treatment for some patients with advanced breast cancer, concludes a study published today (Tuesday) in the British Journal of Cancer*.

HER-2 is a useful predictor of how breast cancers will respond to treatment. Breast tumours with high levels of HER-2 are more sensitive to chemotherapy when given with the drug Herceptin.

Generally, the decision to give Herceptin is based on the analysis of HER-2 levels in the original breast tumour, even if the cancer recurs several years later.

But now researchers in Israel have shown that not all secondary tumours are biologically identical to the original tumour, indicating that some patients with advanced breast cancer may not receive the most effective treatment for their disease.

The team compared HER-2 levels in the primary and secondary tumours of 58 patients with advanced breast cancer. In eight of the patients (14 per cent), HER-2 assessment of the primary tumour was different from that of the secondary tumour.

Of those eight patients, seven (12 per cent) tested HER-2 negative in their primary tumour but HER-2 positive in their secondary tumour. As a result, four of these patients were treated with herceptin, a potentially effective treatment for approximately 25% of patients with advanced breast cancer. Of these, three patients responded after having failed chemotherapy.

Lead researcher, Dr Jamal Zidan of Sieff Government Hospital, Safed, Israel, says: “It’s been assumed that secondary breast tumours are biologically identical to the primary tumours they originate from. But breast tumours are made up of many different cells, so it makes sense that a cell that breaks away from a primary tumour could multiply and grow into a secondary tumour with a very different ‘biological fingerprint’.

“This is a relatively small study, and larger studies are needed to verify our work, but we hope this finding will lead to improved treatment for a significant proportion of women with secondary breast cancer.”

Professor John Toy, Medical Director of Cancer Research UK, says: “Taking a sample of a secondary tumour for analysis can sometimes be technically difficult and raise concerns of patient safety. But should the result of this study be confirmed, it suggests that, where possible, secondary tumours should be tested so that patients can receive the most appropriate therapy for their secondary breast cancer.”

ENDS

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