Ductal Carcinoma In Situ (DCIS)
Ductal carcinoma in situ (DCIS) is a noninvasive proliferation of cohesive neoplastic epithelial cells confined to the mammary ductal-lobular systems, exhibiting a range of architectural patterns and nuclear grades. 1
Definition and Epidemiology
- DCIS represents a heterogeneous group of neoplastic lesions in the breast ducts that have not invaded beyond the ductal basement membrane 1
- Before widespread mammography screening, DCIS was uncommon, accounting for only 2-3% of palpable breast cancers 1
- Currently, DCIS accounts for approximately 20% of breast cancers diagnosed in the United States 1, 2
- The American Cancer Society estimates that 55,720 new cases of DCIS will be diagnosed in 2023 1
- Incidence is highest among non-Hispanic White (26.6 per 100,000) and Black (26.5 per 100,000) people 1
Clinical Presentation and Diagnosis
- DCIS most commonly presents as a mammographically detected clinically occult disease 1
- The most common mammographic presentation is microcalcifications (90-98% of cases) 1
- Calcifications in DCIS typically are pleomorphic, varying in size, form, and density, often in linear or segmental arrangements 1
- About 10% of mammographically evident DCIS presents as an uncalcified mass 1
- Definitive diagnosis requires pathologic evaluation of tissue specimen, as imaging cannot determine whether basement membrane invasion has occurred 1
Prognosis
- DCIS has an excellent prognosis with a 10-year overall survival rate of 97.2% to 98.6% 1
- If left untreated, approximately 40% of patients with DCIS will develop invasive breast cancer 3
- Following breast-conservation therapy, about 50% of recurrences are invasive cancer and 50% are DCIS 1
Risk Factors for Progression
- Nuclear grade (higher grade increases risk) 4
- Presence of comedo necrosis 4
- Margin involvement 4
- Larger DCIS lesion size 1
- Younger age 1
- HER2 overexpression 1
Management Options
Surgical Approaches
- Breast-conserving surgery (BCS) or total mastectomy are both appropriate treatment options 1
- There is no difference in overall survival between mastectomy and BCS for DCIS 1
- The current National Comprehensive Cancer Network (NCCN) guidelines for DCIS recommend BCS without lymph node sampling 1
- Mastectomy is associated with a risk for chest wall recurrence of approximately 1% 4
Radiation Therapy
- Randomized trials evaluating radiotherapy after BCS for DCIS have demonstrated a reduction in ipsilateral breast tumor recurrence rates by 50% to 70% 1
- The use of radiotherapy after lumpectomy significantly decreases the rate of recurrence 4
Hormonal Therapy
- Tamoxifen can reduce the risk of invasive breast cancer in women with DCIS 5
- In the NSABP B-24 trial, women with DCIS who took tamoxifen for 5 years lowered their chances of getting invasive breast cancer by 43%, from 17 in 1,000 to 10 in 1,000 per year 5
- Tamoxifen provides risk reduction in both the ipsilateral breast treated with BCS and in the contralateral breast with estrogen receptor-positive tumors 1
Common Pitfalls in DCIS Management
- Underestimating the risk of occult invasive disease: A meta-analysis reported an overall DCIS upstaging rate to invasive cancer of 25.9% at surgical excision 1
- Unnecessary axillary lymph node dissection: The cumulative incidence of axillary node metastasis in patients diagnosed preoperatively with DCIS is low (0%-14%) 1
- Inadequate margin assessment: Proper orientation of the specimen is critical to ensure negative margins while avoiding excess tissue removal 6
- Overtreatment: Many DCIS lesions may never progress to invasive cancer, leading to potential overtreatment of indolent disease 7