The National Institute for Health and Care Excellence (NICE) has recommended a gene expression test as an option during surgery for early invasive breast cancer.
Currently, during surgical removal of breast tumours, nearby (armpit) lymph nodes are often biopsied to see whether or not the tumours have spread there. It typically takes two weeks to receive the results of the biopsy; if positive, women are likely to require further surgery to remove affected lymph nodes, as well as being more likely to need chemotherapy.
The RD-100i OSNA test from Sysmex UK recently assessed by NICE is very different in providing extremely rapid results (under an hour) and from the entire lymph node. It examines the level of gene expression of cytokeratin-19 (CK19) in removed lymph node cells; high levels of this protein are associated with breast cancer.
The main advantage of the rapid on-the-spot analysis is that surgeons can proceed immediately to remove additional lymph nodes if the test indicates the cancer has spread. This removes the need for a second operation soon after the first, and allows immediate implementation of treatment for these more aggressive cancers, as well as preventing the anxiety of waiting for biopsy results for patients and families.
Another benefit is that the whole lymph node can be analysed; whilst conventional analysis examines samples from throughout the biopsied tissue to detect small or dispersed cancer cells, it could still miss very small affected areas.
However, around 1% of breast tumours do not express the CK19 protein, and would produce false negative results with the RD-100i OSNA test, so original diagnostic breast tumour biopsies should be screened to identify such tumours before surgical removal and lymph node biopsy.
NICE has also said that a similar test (the Metasin test from TIB MOLBIOL) is ‘promising’ but currently lacks sufficient evidence to support use in routine clinical NHS practice.