Ductal Carcinoma in Situ

Ductal Carcinoma in Situ (DCIS) is a malignant change within the milk ducts of the breast. The incidence of DCIS has increased from around 5% to about 20% as a result of increased detection due to screen programs. 

DCIS may present as:

1. Calcification or mass on imaging
2. A palpable abnormality
3. Nipple discharge 

Strictly speaking, as there is no invasion or spread outside the milk duct, it is premalignant, however given the high risk of developing into an invasive cancer, it is managed with complete excision similar to invasive malignancy.

Like invasive cancer it is divided into 3 grades, low, intermediate and high grade. The higher the grade the greater the risk of invasive malignancy developing. Rates of conversion to invasive disease, will vary from possibly 30-50 % over 10 years. DCIS can be found associated with an invasive cancer when it is excised. 

Treatment for DCIS

1. Surgery

Given the high risk of most DCIS becoming invasive cancer and spreading, complete surgical excision is the standard of care. This requires that on the histological margins of the excision no tumour is seen and ideally 1-2 mm clear, depending on the individual case. Often for small areas, lumpectomy, also call wide local excision is often adequate however more extensive areas may require mastectomy.

2. Radiotherapy

If small and low grade surgical excision may be all that is required, however more extensive or higher grade cases can benefit from adjuvant radiotherapy in order to reduce  the risk of later regrowth of malignancy in the breast (local recurrence). 

3. Hormone Therapy

As there is an increased risk in these patients of malignant recurrence in both breasts, half of which may be more significant invasive disease, if the DCIS is hormone sensitive, hormone block aid may be offered to reduce recurrence in pre and post menopausal women. This should be discussed on an individual basis. 

It should be noted that DCIS, once treated, will rarely spread to other sites and the long term survival from DCIS with appropriate treatment is very high, around 98-99%. If it does spread then it indicates there was some hidden invasive cancer present originally. The long term strategy is to prevent further recurrence and at BreastCare we advocate annual mammography, ultrasound and clinical examination for women with a  history of DCIS.