US researchers at the University of Texas Health Science Center, Houston, have opened up the possibility of a simple test for breast cancer with the discovery of cancer marker proteins in saliva.

The study, published online on 10 January 2008 ahead of print in the journal Cancer Investigation (DOI 10.1080/07357900701783883), analysed pooled saliva samples from 30 patients – ten with benign breast tumours, ten with malignant breast tumours and ten healthy patients. The researchers found 49 proteins that differentiated healthy patients from those with benign breast tumours and those with malignant breast tumours, suggesting that patients could be tested for breast cancer with a simple salivary test during a visit to their doctor or dentist.

Dr William Dubinsky, Professor of Integrative Biology and Pharmacology at the University of Texas Medical School, Houston and a co-author of the paper, explained 'Saliva is a complex mixture of proteins. We go through a process that compares different samples by chemically labelling them in such a way that we can not only identify the protein, but determine how much of it is in each sample.'

As well as identifying markers for malignant tumours, the researchers also found unique proteins for fibroadenoma, the most common type of benign breast tumour. 'This is a unique finding,' said Professor Charles Streckfus, lead author and Professor of Diagnostic Sciences at the University of Texas Health Sciences Center Dental Branch, 'as it targets both the benign and malignant tumour, which could potentially reduce the number of false positives and false negatives associated with current cancer diagnostics.'

Professor Streckfus suggested that a test developed from the technique would be ideal for use by dentists. However BDJ and BDA Scientific Advisor Damien Walmsley, commenting on the study, was more cautious. 'Maybe one day it will be feasible to go to the dentist to be screened for a variety of disorders in the body, including breast cancer, though it's more likely that the test will be done in specialist centres or by your GP.' He also stressed dentists' existing role in oral cancer screening, saying, 'The mouth itself is a good indicator of an individual's overall health and dentists already play an important role in diagnosing and detecting oral cancers.'