Researchers at the University of Birmingham and University Hospitals Birmingham NHS Trust are launching a breast screening study aimed at improving the treatment of ductal carcinoma in situ (DCIS) by only operating on women who need surgery - rather than all of those who show signs of abnormal cells.

Many unnecessary operations including mastectomies are being performed on women who show signs of DCIS rather than cancer. DCIS means there are abnormal cells in the milk ducts. These abnormal cells are sometimes described as neoplastic or pre-cancerous but they are confined to the milk duct and present no threat to health.

Over time, some DCIS may develop into invasive breast cancer but this is not inevitable and many cases of DCIS will never cause any harm or symptoms and do not require any treatment. Women with DCIS are often unnecessarily treated as though they have cancer and the new study, known as the LORIS trial (Low Risk DCIS Trial), will identify those women who need treatment whilst addressing the current overtreatment of those who do not benefit from it.

Pathologists classify DCIS according to its microscopic appearances and the LORIS trial will focus on DCIS that has been classified as low risk.

The national programme of breast screening - or mammograms - was devised to ensure invasive breast cancers were detected at an early stage so they could be more successfully treated.

However, screening frequently identifies other abnormalities as well as cancers, such as DCIS. This is an incidental result of screening rather than its intention. Many of these screen-detected abnormalities will never lead to any symptoms for the women during their lifetime.

A Breast Screening Review carried out last year concluded that breast screening does save lives but also that many women are having unnecessary breast operations.

The LORIS study will help clinicians learn which women with low risk DCIS can safely avoid surgery. This study is not for patients with high grade DCIS who may be at a higher risk of developing breast cancer in the future.

Dr Daniel Rea, a medical oncologist at the University of Birmingham, is helping to run the trial.

He said: "This is a pro-screening trial. Breast screening is an effective way of reducing breast cancer deaths and is an important component of breast cancer treatment. The surgical approach to DCIS has not kept pace with the changes in the spectrum of breast disease brought about through both the introduction of screening and the on-going series of changes and improvements to the screening service that have been introduced.

"Screening saves lives - and this trial is a step towards strengthening the net benefits of the existing screening programme."

In the study patients with low risk DCIS who take part will either receive surgical treatment as per the status quo, or will be actively monitored without initial surgical treatment. Patients will be monitored for their quality of life and any psychological effects by researchers at Brighton and Sussex Medical School, a partnership between the Universities of Brighton and Sussex.

All women taking part will have careful follow up examinations and will help doctors understand more about DCIS so that future generations will only receive treatment if they need it. The trial will show if it is just as safe not to operate on low risk DCIS as it is to operate on everyone, as is current practice.

It is hoped that the results will inform future practice for screening and reduce the incidence of overtreatment.

The LORIS trial, which is funded by the National Institute for Health Research Health Technology Assessment Programme (NIHR HTA), is being run through the CR-UK Clinical Trials Unit in Birmingham, and will recruit patients from hospitals from all parts of the UK. It will aim to identify almost 1,000 women who have been diagnosed with low risk DCIS to take part.

Anyone who wants more information about the trial should contact