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
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 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%), HER-2 assessment of the primary tumour was different from that of the secondary tumour.
Of those eight patients, seven (12%) 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 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".
The article is Comparison of HER-2 overexpression in primary breast cancer and metastatic sites and its effect on biological targeting therapy of metastatic disease, by J Zidan, I Dashkovsky, C Stayerman, W Basher, C Cozacov and A Hadary.
British Journal of Cancer, vol 33, issue 5.
Over 40,700 women are diagnosed with breast cancer every year in the UK.
It is now the commonest cancer in the UK (excluding non melanoma skin cancer) and by far the most common cancer in women.
For women, the lifetime risk of developing breast cancer is now 1 in 9.
Most of the women who get breast cancer are past their menopause, but almost 8000 diagnosed each year are under 50 years old.
About 290 men are also diagnosed with breast cancer every year.
Thanks to earlier detection and improved treatments, breast cancer death rates in the UK have fallen by 20% in the last ten years.
Herceptin (trastuzumab) is not a chemotherapy drug.
But specialists often give it with chemotherapy.
It is a monoclonal antibody made in the laboratory.
Herceptin attacks cells that make too much of a growth-stimulating protein called HER2neu.
Between 15 and 25 out of every 100 breast cancers (15-25%) make too much of this protein.
The theory is that breast cancers with too much HER2neu are faster growing and more likely to come back after they are first treated.
herceptin will only help if cancer cells make too much HER2neu protein.
To find out, a laboratory test has to be carried out.
The result will be between 0 (none of the protein) to +3 (a lot of the protein).
Herceptin will only help if the cancer scores +3.
If it scores less, then there will not be a good response to herceptin.
Research has shown that women with breast cancers that are strongly positive for HER2neu are more likely to respond to chemotherapy if it is given with herceptin.
They may also live longer.
herceptin is now licensed for use in the UK in women with secondary (advanced) breast cancer.
In March 2002, the National Institute of Health and Clinical Excellence (Nice) approved herceptin for advanced breast cancer in quite specific circumstances.
