Does ductal carcinoma in situ (DCIS) require adjuvant radiation therapy (RT) after surgery?

From the Guidelines

Adjuvant radiation therapy (RT) after surgery for ductal carcinoma in situ (DCIS) is generally recommended, but not always required for all patients, as it reduces the risk of local recurrence by approximately 50% 1.

Key Considerations

• The decision to use RT should be individualized based on several factors, including patient age, tumor size, grade, and margin status.
• Certain low-risk patients may be candidates for omission of RT, particularly older women (>65-70 years) with small (<2.5 cm), low-grade DCIS with adequate surgical margins (typically ≥2 mm) who are taking endocrine therapy.
• The standard RT regimen consists of whole breast radiation delivered over 3-6 weeks, with typical doses of 40-50 Gy.
• Shorter hypofractionated schedules (15-16 fractions over 3 weeks) are increasingly used with similar efficacy and reduced side effects.
• Some patients may also be candidates for partial breast irradiation or a boost to the tumor bed, which can lower recurrence rates in non-low-risk DCIS cases 1.

Benefits and Risks

• The benefit of RT is primarily in reducing the risk of both invasive and non-invasive recurrences in the same breast, though it has not been shown to improve overall survival.
• Patients should discuss their individual risk factors with their treatment team to make an informed decision about whether RT is necessary in their specific case.

Recent Guidelines

• The most recent guidelines from 2024 recommend that WBRT after BCS for DCIS halves the risk of local recurrence without impact on survival 1.
• The 2021 St. Gallen International Consensus Guidelines for treatment of early breast cancer also support the use of RT after breast-conserving surgery for DCIS, with consideration of boost in cases with larger areas of DCIS or other factors associated with increased risk of recurrence 1.

From the Research

Ductal Carcinoma In Situ (DCIS) and Adjuvant Radiation Therapy (RT)

• DCIS is associated with low rates of mortality, and outcomes are generally assessed in terms of recurrence 2.
• The use of whole-breast radiation therapy following breast-conserving surgery (BCS) has been consistently associated with a reduced incidence of local DCIS recurrence and local invasive carcinoma 2.

Role of Adjuvant RT After Surgery

• Studies have shown that adjuvant RT after lumpectomy decreases the risk of ipsilateral breast recurrence by almost half 3.
• The consideration for postmastectomy RT should be based on an individualized risk evaluation, including factors such as surgical technique, presence of BRCA mutation, grade and extent of tumor, and proximity of lesion to the margin of resection 4.
• Tamoxifen use has been shown to reduce the risk of recurrent DCIS or invasive carcinoma, particularly in estrogen receptor-positive tumors 2, 5.

Survival Benefits of Adjuvant RT

• A large cohort study found that treatment with lumpectomy and radiotherapy was associated with a significant reduction in breast cancer mortality compared with either lumpectomy alone or mastectomy alone 6.
• The survival benefit of radiation is likely not due to local control, but rather to systemic effects 6.
• The use of adjuvant RT has been shown to reduce the risk of breast cancer mortality in patients with DCIS, particularly when used in combination with lumpectomy 6.

Key Findings

• Adjuvant RT after surgery can reduce the risk of local recurrence and improve survival outcomes in patients with DCIS 2, 3, 6.
• The decision to use adjuvant RT should be individualized, taking into account factors such as tumor characteristics, surgical technique, and patient preferences 4.
• Tamoxifen may be considered as an adjunct to treatment for women with estrogen receptor-positive DCIS 5.