Ductal and Lobular Carcinoma In Situ

John P. Christodouleas and Atif Khan

 Background

Ductal carcinoma in situ (DCIS) represents what % of all breast malignancies?

DCIS represents ~25% of all breast malignancies.

Which is more common: DCIS or lobular carcinoma in situ (LCIS)?

DCIS is 5 times more common than LCIS.

Name the 5 most common histologic subtypes of DCIS.

Most common subtypes of DCIS:

1. 
   

   Cribriform

   
   
2. 
   

   Comedo

   
   
3. 
   

   Papillary

   
   
4. 
   

   Medullary

   
   
5. 
   

   Solid

(Mnemonic: C²PMS)

Which histologic subtypes of DCIS have the worst and 2^nd worst prognosis?

The DCIS subtype that has the worst prognosis is comedo, and the 2^nd worst is solid. DCIS is often grouped into comedo and noncomedo subgroups.

What is the most common clinical presentation of DCIS?

DCIS most commonly presents with microcalcifications on a mammogram.

What is the most common clinical presentation of LCIS?

LCIS most commonly presents as an incidental finding. LCIS typically does not result in mammographic or clinical abnormalities.

What is the rate of progression at 10 yrs of DCIS to invasive Dz if left untreated?

~30% of DCIS progress to invasive Dz at 10 yrs if left untreated. (Page DL et al., Cancer 1995)

For a pt with LCIS, what is the risk of the pt to be diagnosed with invasive Dz by 10 yrs?

A pt with LCIS has an ~7% risk of developing invasive cancer at 10 yrs (~1%/yr), but approximately half of invasive Dz occurs at the contralat breast, suggesting that LCIS is probably just a marker for propensity to form invasive Dz. (Chuba PJ et al., J Clin Oncol 2005)

What % of pts with LCIS who subsequently develop invasive Dz develop invasive lobular cancers?

Only 25%–50% of subsequent cancers are invasive lobular cancers (i.e., though LCIS is a proliferative lesion of the lobules, it is mostly a marker for subsequent ductal proliferative lesions).

For a pt with LCIS, what is the risk of invasive Dz in the ipsi breast vs. the contralat breast?

For a pt with LCIS, the risk of subsequent invasive Dz is equal in both breasts.

How many pathologic grades are there for DCIS?

There are 3 pathologic grades for DCIS: low, intermediate, and high.

What % of DCIS are estrogen receptor (ER)+?

75%–85% of DCIS cases are ER+.

Which subtype of LCIS has the worst prognosis?

Of LCIS subtypes, pleomorphic LCIS has the worst prognosis.

 Workup/Staging

What is the initial workup after a DCIS Dx?

DCIS workup: H&P (with emphasis on risk of hereditary breast cancer), diagnostic bilat mammogram, assessment of ER status, +/− genetic counseling

Is an axillary dissection needed for DCIS?

No. An axillary dissection is not needed for DCIS. However, per NCCN 2010, consider if (a) the pt is undergoing mastectomy for Tx or (b) if the location of lumpectomy will compromise future sentinel Bx should it be necessary.

What is the T stage for DCIS?

DCIS has its own designation: Tis.

What is the definition of DCIS with microinvasion, and what is the significance for workup?

DCIS with microinvasion refers to invasion >1 mm in size. If microinvasion is present, then a sentinel LN Bx is indicated, as the LN+ rate is ~4%–8%.

For a pt with DCIS, if there is <1-mm margin at excision, what is the rate of residual Dz at the time of re-excision?

For a pt with DCIS and a <1-mm margin at excision, ~30% will have residual Dz at re-excision. Notably, low- and intermediate-grade DCIS is more likely to grow in a discontinuous pattern (Faverly DR et al., Semin Diagn Pathol 1994). B/c of this, margin status may be, paradoxically, more important in these lesions. In these discontinuous type lesions, gaps of uninvolved tissue between DCIS are typically small (<5 mm in 80% of cases).

For a pt with DCIS, in which situation would re-excision not be indicated with a margin <1 mm?

If a pt with DCIS has an excisional margin <1 mm at the fibroglandular border of the breast (skin or chest wall), then re-excision is not indicated.

 Treatment/Prognosis

What is the Tx paradigm for unifocal DCIS?

There are 2 Tx paradigms for unifocal DCIS:

1. 
   

   Lumpectomy + PORT +/− tamoxifen (if ER+)

   
   
2. 
   

   Mastectomy

What must be done after lumpectomy for DCIS to ensure that all the Dz has been removed?

Post-excision mammography to ensure that all the microcalcifications are removed. Specimen radiograph is done after lumpectomy to ensure that the calcifications are removed.

For a pt with DCIS, what is rate of LR after mastectomy alone?

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