Researchers for the Sloane Project (Birmingham, UK), a UK-wide prospective audit of screen detected noninvasive and atypical hyperplasias of the breast, examined how the size of the DCIS--measured by both imaging and pathology--related to the surgeon's decision of whether to conserve or remove the breast. They discovered that, out of 2,500 women who had DCIS detected by breast screening, approximately 70% of patients had conservation surgery to remove the disease and save the breast. Of those who had conservation surgery, 71% only needed one operation to remove the cancer, 19% needed a further operation, and 10% went on to have a mastectomy.

In situ (noninvasive) breast cancer is confined to the ducts or lobules of the breast and has not spread to the surrounding tissues of the breast or other parts of the body. It is therefore curable if removed completely, but if left untreated may become invasive breast cancer.

This research is part of a large review of screen-detected DCIS and its treatment over the past five years through the Sloane Project, investigating the best treatment methods for DCIS. Dr. Jeremy Thomas, study author and consultant pathologist from the Western General Hospital (Edinburgh, Scotland, UK), said, "This study shows that comparing the size of tumors as measured by imaging to the actual size of the tumor removed at surgery, gives a clear indication of where to focus improvements in practice. The results are very encouraging showing that 90% of patients offered breast conservation for DCIS have a successful surgical outcome, usually from one operation, and avoid mastectomy. Deciding the best surgery option for patients with in situ breast cancer is difficult and requires very careful preoperative assessment to define the extent of disease. A mastectomy would almost always cure the disease but where possible we want to conserve the breast and only remove the tumor. In the future, we would hope to see that, with improvements in imaging and preoperative assessment, more women could avoid having mastectomies.”

Prof. Stephen Duffy, Cancer Research UK's professor of screening at Queen Mary University of London, said, "In the screening era, large numbers of breast cancers are diagnosed at the DCIS stage. We have a responsibility to see that these cancers are not overtreated. Therefore, it is good to see that the vast majority does not get a mastectomy. There is clearly room for improvement in that we can further reduce the need for reoperation. This problem can and doubtless will be reduced by high-quality preoperative imaging.”

Sara Hiom, director of health information at Cancer Research UK (London, UK), said, "In the past, treatment for DCIS was nearly always mastectomy so it's really encouraging to see that now around 60% of women with DCIS have only the affected area removed, along with a border of healthy tissue around it. It's important that women go for breast screening when invited. The program is very successful at detecting early stages of the disease which means treatment can be much more effective.”

The Sloane Project's goal is to record the present situation in the UK regarding the management of in situ breast disease, and to provide a guide to the optimal radiologic assessment, pathologic handling, and reporting (including the features of greatest prognostic and clinical importance), surgical treatment, and adjuvant therapy.

The Sloane Project has been running for six years with more than 7,000 patients entered estimated about 50% of all relevant cases are now entered into the audit. The Sloane Project is now funded by the National Health Service Breast Screening Program (NHSBSP). Between April 1, 2007 and March 31, 2008, 16,792 breast tumors were detected within the NHS Breast Screening Program (NHSBSP), of whom 3,311 (20%) had in situ/noninvasive breast cancer. There has been a marked increase in the incidence of in situ breast cancer since the NHSBSP started in 1988. The reason being that the trademark characteristic of microcalcification present in the majority of in situ breast tumors can be easily visualized radiologically on a mammogram.

The invasive potential of in situ breast cancer is uncertain and accordingly the optimal method of treatment for every case is ambiguous and unclear. A mastectomy would nearly always be curative, however this approach would be extreme in cases where breast-conserving surgery would suffice. Identifying the optimal method of treatment can therefore be difficult.

The research was published January 20, 2010, in the British Journal of Cancer.

Related Links:
Sloane Project
Western General Hospital