Volume 6 Supplement 1
Ductal carcinoma in situ (DCIS): are we overtreating it?
- JM Dixon1
© BioMed Central 2004
Published: 14 July 2004
DCIS continues to increase in incidence as the number of women invited to population breast screening programmes increases. This means that more women are treated every year for DCIS. More women diagnosed with DCIS currently receive some form of treatment and the issue is whether this treatment is necessary and appropriate.
There are few data on the natural history of untreated DCIS. Studies from Nashville by Page  show 28% of patients with low grade DCIS develop invasive disease by 6 years and 40% have developed invasive disease by 30 years. Data from Van Nuys  suggest that the rate of progression in high grade DCIS is much higher, with 60% of women with incompletely excised high grade disease developing progression or invasive cancer by 5 years.
The results of studies on treatment of DCIS can be summarised as follows:
Excision alone is associated with a high rate of local recurrence in approximately 3.8% per year, of which 1.6% per year is invasive disease.
Radiotherapy reduces the recurrence rate in the progression to invasive cancer by between 50 and 60%.
Recurrence rates are lower when radiotherapy is given to patients whose lesion is completely excised with clear margins. The evidence that wider margins is associated with better local control rates does not stand up to scrutiny. Surgeons in the UK are divided as to what they consider to be an adequate clear margin width.
Tamoxifen reduces recurrence rates in oestrogen receptor-positive DCIS but not oestrogen receptor-negative DCIS.
No patients with localised DCIS should have axillary surgery.
As the numbers of patients with DCIS increases, so the number of women being treated by breast-conserving surgery and mastectomy increases. The challenge is to limit the surgery so as to reduce morbidity and select those patients who will have most to gain from radiotherapy and tamoxifen.