Study shows that breast cancer drugs stop working when tumours 'make their own fuel'

A new study has discovered how breast cancer tumours can evolve to "make their own fuel", resisting chemotherapy treatment, thereby rendering drugs powerless . Scientist found that drugs used to ‘starve’ tumours of the hormone that helps them grow often fail because the cancerous growths create their own supply.

Scientists had previously thought that cancer treatments stopped working in some patients as cancers developed resistance is some way.

New research suggests some tumours begin to make their own oestrogen "fuel supply" as drugs called aromatase inhibitors target the hormone.

An international team, led by Imperial College London and the European Institute of Oncology in Milan, hope its findings will increase treatment options for patients whose cancer has returned or spread.

"Once a cancer spreads, the disease is incurable. However, let's not give up this fight too soon - if we take a second biopsy we can find out which treatments would work," research co-author Dr Luca Magnani said.

The scientists analysed tumour samples taken from 150 women treated at the European Institute of Oncology in Milan, and are working on a test to identify if a tumour has started to make its own oestrogen.

Breast cancer is the most common form of the disease and about 70 per cent of breast cancers patients are ER positive, stimulated by hormone oestrogen.

The drug tamoxifen and aromatase inhibitors act in different ways to cut off the oestrogen supply, but both stop working in around one-third of patients.

The latest findings, show that in one-quarter of patients taking aromatase inhibitors, the tumours had increased production of aromatase in the cancer cells.

According to researchers, the tumours do this by increasing the number of aromatase genes, allowing the cancer cells to effectively make their own oestrogen.

"For the first time we have seen how breast cancer tumours become resistant to aromatase inhibitors," said Dr Magnani, of Imperial's department of surgery and cancer.

"The treatments work by cutting off the tumour's fuel supply - oestrogen - but the cancer adapts to this by making its own fuel supply."

Dr Magnani said that, in the meantime, doctors should take a second sample of the tumour when the cancer returns.

The findings are published in the journal Nature Genetics.

 

Press Association