West Midlands Breast Screening Programme

West Midlands DCIS Study

Examination of the prognostic characteristics, treatment and outcome of women with breast Ductal Carcinoma In Situ (DCIS) diagnosed in the West Midlands region by the UK NHS Breast Screening Programme.

Ductal carcinoma in situ (DCIS) of the breast is a type of early stage breast cancer in which there is no invasion of the lesion into surrounding tissues. DCIS is often identified in conjunction with invasive disease, but can also occur in the absence of invasive breast cancer. Accurately distinguishing between cases in which DCIS arises with invasive disease, and cases of DCIS only, is essential. DCIS alone is rarely diagnosed symptomatically, accounting for only 44 (1.5%) of 2967 breast cancers in the West Midlands in 1987. DCIS is associated with the formation of microscopic deposits of calcium within the breast duct which are easily detectable on x-ray.

For this reason DCIS is readily diagnosed by x-ray mammography even though in the majority of cases no clinical symptoms are apparent. With the introduction of the NHS Breast Screening Programme in 1988, which uses mammography as the screening method, the numbers of women between the ages of 50 and 64 diagnosed with DCIS in the West Midlands has risen dramatically from 13 in 1987 to 102 in 1997.

The natural history of DCIS is not fully understood, but it is commonly thought that DCIS will progress to invasive breast cancer if untreated and thus effective treatment is essential. Nonetheless it is probable that some DCIS cases would remain non-symptomatic for many years, and particularly in older women, never pose a risk to health. There is thus a risk of both over-diagnosis and over-treatment.

A number of studies have identified pathological characteristics of DCIS at diagnosis which are associated with higher risk of recurrence: these include high nuclear grade and the presence of necrosis. There has been a lack of clear treatment guidelines in relation to DCIS leading to variation in treatment regimen, with the choice between mastectomy and conservation surgery being based largely on clinical preference. Inappropriate use of breast conserving surgery in which some of the lesion remains in the breast after surgery is likely to result in recurrences of DCIS and, in some cases, eventually lead to invasive breast cancer. There is also a lack of clear guidance for the use of adjuvant therapies for DCIS.

Given that significant numbers of women are being diagnosed with DCIS through the NHS Breast Screening Programme, it is essential that every effort is made to ensure that the prognosis of these women is good with minimal risk of recurrence. Clearer guidelines on treatment should be available to reduce the risk of recurrence while avoiding over-treatment.

The West Midlands DCIS study examined a large, unbiased population of DCIS cases detected by the West Midlands NHS Breast Screening Programme between 1st March 1988 and 31st March 1999. Diagnostic details including pathological properties and radiological features were examined. Pathological properties, which have been linked to prognosis in other studies, were examined, both from existing records, and from a pathological review of slides. This was to allow the accuracy of the diagnostic histology to be assessed, particularly in relation to the differentiation between DCIS alone and cases of DCIS mixed with invasive disease. A radiological review was also undertaken to examine radiological features and radiological size in order to identify particular characteristics of screen detected DCIS and their significance when looking at outcome. Treatment immediately following diagnosis, and for any subsequent recurrences was recorded including surgery, radiotherapy, chemotherapy and use of hormonal treatments. This allowed us to assess the influence of diagnostic pathology, radiological features and different treatment options on disease free survival, with the aim of giving clearer guidelines as to the most effective treatment of DCIS to prevent recurrence and the development into invasive disease.

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