The Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer

Objective: To help physicians and patients arrive at the most clinically effective approach to the management of ductal carcinoma in situ (DCIS). Options: Mastectomy, wide-excision breast-conserving surgery (BCS) plus radiotherapy and BCS alone. Outcomes: Overall survival, local recurrence, cosmesis, complications of therapy. Evidence: Review of English language literature published between 1976 and December 1996, identified through MEDLINE. Nonsystematic review continued to July 1997. Also reviewed were reference lists of books and relevant articles. Recommendations: • The first step in the diagnosis of DCIS, after history-taking and clinical examination, is a complete mammographic work-up. • Once DCIS is suspected, either image-guided core biopsy or open surgical biopsy must be carried out. • At surgical excision, the suspect area should be removed in 1 piece and a specimen radiograph obtained. Tissue should not be sent for frozen-section examination or hormone receptor analysis. • The pathology report should address those features that bear on treatment choice. • The specimen should, whenever possible, be reviewed by a pathologist experienced in breast disease. • Treatment options for DCIS are mastectomy, wide-excision BCS plus radiotherapy or BCS alone. Treatment should aim to achieve a high degree of local control with the first treatment plan. • Final decisions on treatment should not be made until the pathological findings have been reviewed and the specimen radiograph compared with the mammogram. • Mastectomy is indicated when lesions are so large or diffuse that they cannot be completely removed without causing unacceptable cosmesis or when there is persistent involvement of the margins, especially with high-grade malignant lesions. • Subcutaneous mastectomy should not be used to treat DCIS. • Mastectomy should not be followed by adjuvant local radiotherapy or systemic therapy. • Bilateral mastectomy is not normally indicated for patients with unilateral DCIS. • BCS requires wide excision in patients with DCIS. It should be followed by mammography of the involved breast if the specimen radiograph does not clearly include all microcalcifications. • BCS should normally be followed by radiotherapy. However, omission of radiotherapy may be considered when lesions are small and are low grade, and when pathological assessment shows clear margins. • BCS should be accepted by patients only after they have received a careful explanation of the need for radiotherapy, its side effects and the associated logistic requirements. • Axillary surgery, whether as a full or limited procedure, should not usually be performed in women with DCIS. • Evidence is not available to support the use of tamoxifen in the treatment of women with DCIS. • Patients should be offered the opportunity to participate in clinical trials whenever possible. Validation: The guidelines were reviewed and revised by a writing committee, by expert primary reviewers, by secondary reviewers selected from all regions of Canada, and by the Steering Committee. The final document reflects a consensus of all these contributors. The guidelines are endorsed by the Canadian Association of Radiation Oncologists. Sponsor: The Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer was convened by Health Canada. Completion date: July 1, 1997 Special Supplement See page S83 for a list of the members of the Steering Committee See page S33 for the names of those who also contributed to the authorship of this document This guideline has been peer reviewed. Ductal carcinoma in situ (DCIS) of the breast, also known as intraductal cancer, is a malignant lesion arising from cells within the milk ducts. The term “in situ” denotes that the malignant cells have not extended through the ductal wall and are confined within the basement membrane surrounding the ducts. The clinical significance of this condition is that eventually these cells may breach the ductal basement membrane and invade the surrounding fatty tissue in the breast, thus becoming an invasive cancer. In the past decade the frequency of diagnosis of DCIS has increased fivefold. This is attributed to the increased use and better quality of screening mammography. In the United States, almost one-third of breast neoplasms diagnosed by mammography are DCIS. In Canada, DCIS constitutes 19% of screen-detected breast cancers in women in British Columbia and 26% in Nova Scotia. As the use of screening mammography increases, the incidence of DCIS in Canada is expected to continue to rise. The goal of treatment is to prevent invasive cancer from developing without causing unacceptable morbidity. The traditional treatment for DCIS has been mastectomy. However, since invasive breast cancer has been treated successfully with breast-conserving surgery (BCS) followed by radiotherapy (RT), this has led to the same approach being used for DCIS, even though BCS plus RT has not been evaluated against mastectomy in a randomized clinical trial for the management of DCIS. Before screening was introduced, women with DCIS presented in the same way as those with invasive cancer: with a palpable mass, nipple discharge or Paget’s disease of the nipple. Most clinical experience is therefore based on the management of these conditions. However, experience in the treatment of screen-detected DCIS is more recent. Unfortunately, earlier experience gained with “clinical” DCIS cannot be extrapolated to guide decisions on how to manage screendetected or subclinical disease. Thus, although the early detection and treatment of invasive breast cancer is known to be beneficial, the value of DCIS detection through screening remains to be demonstrated. Furthermore, the natural history of untreated DCIS is not known with any certainty. As a result of this lack of information, there is wide variation in the manner in which DCIS is managed. These guidelines focus on the available evidence, and provide information and recommendations that patients and their physicians may need in order to arrive at the most effective and acceptable approach to the diagnosis and management of DCIS. For women to be able to make fully informed choices, it is essential that the physician make a clear and sympathetic presentation of the evidence and provide ample time for patients to consider the information. A more user-friendly version of this document is available for the lay person, which may be of help in achieving this task.