A new type of breast cancer test that could ultimately save some women from unnecessary chemotherapy is reliable, Swiss scientists say.
Core needle biopsy is already commonly used to sample suspect breast tissue for doctors to examine microscopically.
Looking at gene patterns in the samples too may help spot more aggressive cancers needing intensive treatment, but proof of this new test is limited.
The Swiss research published in Breast Cancer Research confirms its worth.
The team from University Hospital Basel found gene expression profiling of needle biopsy samples gave an accurate picture of entire breast tumours, despite only sampling very tiny parts of the cancers.
This information could then be used to distinguish which cancers are aggressive and need intensive treatment, such as intensive chemotherapy after surgery, and which tumours have little chance of returning after being removed surgically.
Far less invasive
The Swiss study also suggests it might be better to obtain the breast tissue for gene analysis using core needle biopsy rather than surgically cutting out a piece of the breast.
Not only is core needle biopsy far less invasive, the authors say it appears to give a better indication of the gene patterns present in the cancer.
In the study, the needle biopsy procedure seemed to trigger the expression of genes involved in wound healing as well as tumour invasion and spread.
This meant that any subsequent surgical samples taken had a modified gene expression profile.
This is important for doctors to appreciate when they are making assessments about the aggressiveness of a cancer and treatment requirements and outcomes, say the researchers.
In the latest study, involving 22 women with breast cancer, the expression of four specific genes known to be involved in breast cancer development was significantly increased in surgical samples compared to earlier core needle biopsy samples.
In comparison, expression of the four genes was not increased in surgical samples taken from 317 women who did not get a core needle biopsy.
'Helpful study'
Dr Rosana Zanetti-Dällenbach and her colleagues from University Hospital Basel warned that the altered gene profile found in the surgical samples obtained after core biopsy might influence a doctor's interpretation of prognosis.
They believe core biopsy gives doctors a cleaner, more accurate and more representative picture.
Professor Karol Sikora, professor of cancer medicine and honorary consultant oncologist at Imperial College School of Medicine, said: "Gene expression profiling tells you the likely natural history of the disease - whether it is going to be aggressive or not - and then you can tailor treatment around it.
"It's a relatively new technique and the difficulty is that it needs validating. We do not have lots of clinical data yet, so this study is helpful."
Maria Leadbeater of Breast Cancer Care said: "This is an interesting study that could mean greater accuracy in predicting how someone with breast cancer responds to their treatment and the potential risk of its recurrence.
"However, this is a small scale study and more extensive work is needed to investigate whether this approach to using core needle biopsies could change the way breast cancer is currently diagnosed and treated."
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