Two-fifths of breast cancers 'change form' when they spread
Nearly two-fifths of breast cancers change form when they spread to the lymph nodes in the armpit, UK scientists have found.
Researchers at the Breakthrough Breast Cancer Research Unit at the University of Edinburgh analysed tumour samples from patients whose disease had spread from the breast to the lymph nodes - a process that happens in around 40 per cent of women with the disease.
They wanted to see whether the disease changed type when it spread, as this could have an impact on the kind of treatment required.
The team analysed breast tumours and lymph nodes from 211 women, using biochemical techniques to measure the levels of certain proteins.
They found that the disease in the lymph nodes had changed type in 39 per cent of cases.
Twenty tumours changed from oestrogen receptor (ER) negative to ER positive. This means that hormone therapies which would not have worked for the original ER negative breast tumours could help to treat the disease once it has spread.
In other cases, the tumours had changed from ER positive to ER negative, meaning that hormone therapies such as tamoxifen would no longer be beneficial.
In almost a third of women, the ER status of their tumour had altered. There were also changes in the amounts of other proteins related to treatment, the progesterone receptor and human epidermal growth factor receptor 2 (HER2) - the target of the drug Herceptin.
Lead researcher Dr Dana Faratian, from the Breakthrough Breast Cancer Research Unit, revealed that the team were "surprised" by the high proportion of tumours that changed form when they spread beyond the breast.
"This suggests there is a need to test which type of disease a woman has in the lymph nodes, because it could radically alter the course of treatment she receives," she observed.
"We now need a clinical trial to see how these results could benefit patients."
Breast cancer can be harder to treat once it has reached the lymph nodes, so understanding more about the disease at this stage could help ensure that women receive the most appropriate treatment.
Professor David Harrison, director of the Breakthrough Breast Cancer Research Unit, added : "This research may show why some women whose cancer has spread to the lymph nodes do not respond to treatment. With an additional test we may be able to treat women more effectively and also make more efficient use of NHS resources."
"We know that cancers adapt and evolve as the disease progresses, so understanding how this happens is key to improving cancer treatment," said Dr Joanna Owens, Cancer Research UK's science information manager.
"This research helps to explain why some breast cancer drugs stop working, and it could have a big impact on a doctor's choice of treatment for an individual patient. But it's still early work, and the findings need to be tested in clinical trials."
- Aitken, S., Thomas, J., Langdon, S., Harrison, D., & Faratian, D. (2009). Quantitative analysis of changes in ER, PR and HER2 expression in primary breast cancer and paired nodal metastases Annals of Oncology DOI: 10.1093/annonc/mdp427