A new predictive marker which could help doctors to decide whether breast cancer patients would benefit from chemotherapy has been identified by a team of scientists. 

The study, part-funded by Cancer Research UK and published in the British Journal of Cancer today (Wednesday), shows for the first time how this molecular marker has been singled out as an independent factor in examining a breast cancer patient's tumour. 

Scientists working on the study found that the more the marker - called BCL2 - was present in a patient with early stage breast cancer, the more likely they were to survive. 

This could help doctors assess whether or not chemotherapy will benefit a patient - a big challenge faced by doctors when treating breast cancer. 

Dr Sarah-Jane Dawson, lead author of the study who is based at Cancer Research UK's Cambridge Research Institute, said: "There are a limited number of tools used to assess prognosis in women diagnosed with early stage breast cancer. New markers are urgently needed. BCL2 provides important additional prognostic information that may help guide decision making related to the use of chemotherapy".

Breast cancer is treated with different combinations of surgery, hormonal therapies, radiotherapy, chemotherapy and biological therapy depending on a variety of predictive markers. Any tests that help doctors decide which of these treatments to give can be very helpful.

Until now BCL2 has been associated with the presence of oestrogen receptors but has not been recognised as an independent marker. 

BCL2 retains its ability to predict whether chemotherapy will be beneficial both in the short term and in the long term, even when a breast cancer recurs many years later - making it a particularly valuable test for doctors. 

The study examined 11,212 patients with early-stage breast cancer who had already received treatment. It took into account other predictive markers such as tumour size and grade, whether the cancer had spread to the lymph nodes and the state of oestrogen receptors. 

Oestrogen-receptor-positive breast cancer means that oestrogen receptors have been found in the cancer cells. These receptors pick up oestrogen, fuelling the growth of the tumour. 

Testing for BCL2 is already well-established for blood diseases. It is a simple and inexpensive test, compared to other predictors which are undergoing lengthy trials. 

Dr Lesley Walker, director of cancer information at Cancer Research UK, said: "Chemotherapy can be an unpleasant experience for some patients. This study could help doctors assess whether a patient will actually benefit from this treatment and could save some patients enduring side effects unnecessarily. 

"This is one of the largest studies of its kind and plays an important part in determining the role of BCL2 by looking back at breast cancer cases. But further research with existing patients is needed to decide how BCL2 testing can best be used."