Clinical Practice Guidelines for Ductal Carcinoma In Situ: CSBrS 2021

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Clinical Practice Guidelines for Ductal Carcinoma In Situ: Chinese Society of Breast Surgery (CSBrS) Practice Guidelines 2021

Ductal carcinoma in situ (DCIS), also known as intraductal carcinoma, is a non-invasive breast cancer confined to the mammary ducts. Despite its non-invasive nature, the diagnosis and treatment of DCIS have been subjects of significant controversy. The Chinese Society of Breast Surgery (CSBrS) has developed the 2021 Clinical Practice Guidelines for the Diagnosis and Treatment of Ductal Carcinoma In Situ to standardize clinical practices and provide a reference for Chinese breast surgeons. These guidelines were formulated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology, ensuring a robust evidence-based approach.

Level of Evidence and Recommendation Strength

The guidelines establish a clear framework for the level of evidence and the strength of recommendations. The level of evidence is categorized into four levels (I-IV), with Level I representing the highest quality of evidence derived from randomized controlled trials or meta-analyses. The strength of recommendations is classified as either strong (A) or weak (B), based on the balance between benefits and risks, as well as the quality of evidence.

The voting committee for these guidelines comprised 84 members, including 70 from breast surgery departments (82.4%), four from medical oncology (4.7%), four from medical imaging (4.7%), two from pathology (2.4%), two from obstetrics and gynecology (2.4%), one from radiotherapy (2.4%), and two epidemiologists (2.4%). This multidisciplinary approach ensures comprehensive and balanced recommendations.

Target Audience

The guidelines are primarily intended for clinicians specializing in breast diseases in China. They aim to provide standardized protocols for the diagnosis, treatment, and management of DCIS, ensuring consistency and quality in clinical practice.

Recommendations

Recommendation 1: Diagnostic Imaging Methods

The guidelines emphasize the importance of diagnostic imaging in the initial evaluation of DCIS. The following imaging methods are recommended:

  1. Breast Ultrasonography: This is a widely used imaging modality in China, particularly for detecting lesions in dense breast tissue. It is classified as Level I evidence with a strong recommendation (A).
  2. Breast Radiography (Mammography): Mammography remains a cornerstone in breast cancer screening and diagnosis. It is also classified as Level I evidence with a strong recommendation (A).
  3. Breast Enhanced MRI: Magnetic resonance imaging (MRI) is recommended for patients with a high suspicion of DCIS or those with inconclusive findings on other imaging modalities. It is classified as Level I evidence with a strong recommendation (A).

Recommendation 2: Diagnostic Mode

The expert panel unanimously agrees that post-operative histopathological diagnosis is the only definitive diagnostic modality for DCIS. Pre-operative histopathological evaluations, such as core-needle biopsy or vacuum-assisted biopsy, may underestimate the extent of the disease. Therefore, post-operative histopathological examination is classified as Level I evidence with a strong recommendation (A).

Recommendation 3: Breast Surgical Treatment

The guidelines outline three primary surgical options for DCIS:

  1. Breast-Conserving Surgery (BCS): This involves the removal of the tumor while preserving the breast. BCS is classified as Level I evidence with a strong recommendation (A). Studies have shown that BCS combined with adjuvant radiotherapy offers survival rates similar to mastectomy.
  2. Mastectomy: This involves the complete removal of the breast and is considered a radical therapy for DCIS. It is classified as Level I evidence with a strong recommendation (A).
  3. Mastectomy + Breast Reconstruction: For patients who do not desire breast-conserving surgery, mastectomy with immediate or delayed breast reconstruction is an option. This is classified as Level I evidence with a strong recommendation (A).

The expert panel emphasizes the importance of achieving negative surgical margins during breast-conserving surgery. A negative margin is defined as a distance of at least 2 mm from the tumor. If positive margins are identified, an extended resection or total mastectomy is recommended.

Recommendation 4: Other Treatments

  1. Adjuvant Radiotherapy After Breast-Conserving Surgery: Adjuvant radiotherapy is strongly recommended for all DCIS patients undergoing BCS. It reduces the risk of local recurrence by 50% to 60%. A 10-year follow-up study of 3,729 patients showed that adjuvant radiotherapy decreased the absolute risk of homolateral breast carcinoma recurrence by 15.2%. This is classified as Level I evidence with a strong recommendation (A).
  2. Administration of Endocrinotropic Agents for Hormone-Receptor-Positive Breast Cancer: For hormone-receptor-positive DCIS, the use of tamoxifen or aromatase inhibitors is recommended. The National Surgical Adjuvant Breast and Bowel Project-B24 study demonstrated that tamoxifen significantly reduced the 5-year cumulative risk of recurrence. For postmenopausal patients, aromatase inhibitors such as anastrozole are recommended. This is classified as Level I evidence with a strong recommendation (A).

Discussion

The guidelines highlight that post-operative histopathological diagnosis is the only definitive diagnostic modality for DCIS. Pre-operative histopathological evaluations, such as core-needle biopsy, may underestimate the extent of the disease. Therefore, a definitive diagnosis should be based on post-operative histopathological examination.

Breast ultrasonography and radiography are the preferred imaging modalities for DCIS patients in China. Enhanced MRI is recommended for patients with a high suspicion of DCIS or inconclusive findings on other imaging modalities. The expert panel emphasizes that mastectomy is a radical therapy for 98% of DCIS patients, but breast-conserving surgery combined with adjuvant radiotherapy offers similar survival rates.

The guidelines stress the importance of achieving negative surgical margins during breast-conserving surgery. If positive margins are identified, an extended resection or total mastectomy is recommended. Intraoperative histopathological evaluation of frozen sections can help reduce the rate of secondary surgeries for positive margins.

Sentinel lymph node biopsy is recommended during mastectomy for patients initially diagnosed with DCIS via core-needle biopsy, as post-operative histopathology may reveal invasive carcinoma. However, axillary lymph node dissection is not recommended for DCIS patients without evidence of invasive breast cancer.

Adjuvant radiotherapy is strongly recommended for all DCIS patients undergoing breast-conserving surgery, as it significantly reduces the risk of local recurrence. The guidelines do not recommend chemotherapy or targeted therapy for DCIS patients, as there is no strong evidence supporting their use in non-invasive breast cancer.

For hormone-receptor-positive DCIS, the use of tamoxifen or aromatase inhibitors is recommended. Tamoxifen is particularly beneficial for premenopausal patients, while aromatase inhibitors are recommended for postmenopausal patients.

Conflicts of Interest

The expert committee for these guidelines declares no conflicts of interest. The guidelines are intended as a reference for breast disease specialists in clinical practice and should not be used as the basis for medical evaluation or in the handling of medical disputes. The Chinese Society of Breast Surgery assumes no responsibility for results involving the inappropriate application of these guidelines and reserves the right to interpret and revise the guidelines as necessary.

doi.org/10.1097/CM9.0000000000001506

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