What is the diagnosis and treatment of distal Carcinoma In Situ (CIS)?

Diagnosis and Treatment of Ductal Carcinoma In Situ (DCIS)

For DCIS diagnosis, obtain bilateral mammography with magnification views followed by stereotactic core-needle biopsy for nonpalpable lesions, and for treatment, pursue breast-conserving surgery with negative margins plus radiation therapy, reserving mastectomy for extensive disease or positive margins after re-excision. 1

Diagnostic Approach

Initial Imaging

• Obtain bilateral mammography including standard mediolateral oblique and craniocaudal views plus magnification views to accurately characterize microcalcifications and determine disease extent 1, 2
• Magnification views are critical because standard two-view mammography alone underestimates disease extent by two centimeters in up to 50% of cases 3
• Examine the entire ipsilateral breast to identify additional tumor areas that would influence treatment decisions 2
• Evaluate the contralateral breast since bilateral DCIS occurs in approximately 19% of cases 3

Tissue Diagnosis

• Use stereotactic core-needle biopsy as the initial approach for sampling suspicious nonpalpable mammographic abnormalities 1, 2
• Obtain multiple cores and perform specimen radiography to confirm adequate sampling of microcalcifications 2
• Leave some microcalcifications at the biopsy site (when possible) to allow accurate image-directed localization for definitive excision 1, 3

Proceed directly to image-directed open surgical biopsy when:

• Breast is too small to accommodate the stereotactic system 2
• Insufficient breast thickness for the full throw of the automated biopsy device 2
• Calcifications are located very posteriorly or just under the skin 2
• Calcifications are widely separated, making stereotactic coordinates difficult 2
• Individual microcalcifications are not well visualized 2
• Patient is uncooperative 2

Critical Diagnostic Caveat

Definitive diagnosis depends on histopathologic examination because imaging cannot determine whether the basement membrane has been violated, and peritumoral inflammation or fibrosis can mimic invasive disease 2

Pathology Requirements

The pathology report must include these specific features to guide treatment 2:

• Nuclear grade, presence of necrosis, and architectural pattern 2
• Estimated extent (size) of DCIS - though precise measurement is difficult since DCIS is usually nonpalpable and cannot be identified grossly 2
• Margin status - the most important aspect of pathologic evaluation - specifically whether DCIS is transected at the surgical margin, and if not, the distance to the nearest margin 2
• Location of microcalcifications (in DCIS, benign tissue, or both) 2
• Architectural patterns present (micropapillary pattern may involve multiple quadrants independent of nuclear grade) 2

Do not order estrogen/progesterone receptors, DNA content (ploidy), S-phase, or oncogene amplification for noninvasive breast carcinomas 2

Treatment Algorithm

Breast-Conserving Surgery

Pursue breast-conserving surgery when appropriate with goals of complete malignant tissue removal and minimal cosmetic deformity 1

Surgical technique requirements:

• Use guided wire localization for nonpalpable lesions with presurgical localization 1
• Perform intraoperative specimen radiography to confirm complete removal of the mammographic lesion 1
• Obtain postoperative mammogram to document complete removal of the mammographic abnormality 1
• Re-excise the biopsy site when initial margins are positive 1

Radiation Therapy

• Add postoperative radiation therapy after breast-conserving surgery - this approach increased from 38% to 54% utilization between 1985-1993 as evidence accumulated 2
• The NSABP B-17 trial demonstrated benefit of radiation after lumpectomy for DCIS 2

Mastectomy Indications

Consider mastectomy for:

• Extensive disease not amenable to breast conservation 2
• Positive margins after re-excision attempts 2
• Patient preference after informed discussion 2

Mastectomy results in cure rates approaching 100% with only 1-2% relapse rates (regional or systemic), but may represent overtreatment for small, mammographically detected lesions 2

Axillary Management

• Axillary lymph node dissection is unnecessary for pure DCIS 4
• Consider sentinel lymph node biopsy when microinvasion is present 4
• For core biopsy diagnosis of DCIS, strongly consider sentinel lymph node biopsy because 20% of these patients are upstaged to invasive disease on final pathology 5

Treatment Outcomes and Prognosis

• Local recurrence with mastectomy is rare 2
• Local recurrence occurs at higher rates with breast conservation, but the impact on overall survival is probably small 2
• Patients have excellent prognosis with either surgical approach 2
• Nearly all patients who develop non-invasive recurrence following breast-conserving surgery are cured with mastectomy 4
• Approximately 75% of those with invasive recurrence are salvaged 4

Key Clinical Pitfalls

Avoid these common errors:

• Do not rely on mammography alone to determine disease extent - it frequently underestimates DCIS size 2
• Do not assume all calcifications represent DCIS - histopathologic confirmation is mandatory 2
• Do not perform routine axillary dissection for pure DCIS - it provides no benefit 4
• Do not accept positive margins - re-excision is necessary 1
• Recognize that approximately 20% of core biopsy DCIS diagnoses will show invasive carcinoma on final pathology, particularly when diagnosed by core biopsy rather than excisional biopsy 5