Background

Question 1

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

Answer 1

DCIS represents ∼20% of all breast malignancies.

Question 2

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

Answer 2

DCIS is 5 times more common than LCIS.

Question 3

Name the 5 most common histologic subtypes of DCIS.

Answer 3

Most common subtypes of DCIS: (Mnemonic: C2PMS)

Cribriform
Comedo
Papillary
Medullary
Solid

Question 4

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

Answer 4

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

Question 5

How many pathologic grades are there for DCIS?

Answer 5

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

Question 6

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

Answer 6

75%–85% of DCIS cases are ER+.

Question 7

What is the most common clinical presentation of DCIS?

Answer 7

DCIS most commonly presents with microcalcifications on a mammogram.

Question 8

What is the most common clinical presentation of LCIS?

Answer 8

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

Question 9

What is the incidence of progression of DCIS to invasive Dz if left untreated?

Answer 9

Very difficult to determine; 15%–50% of DCIS cases will progress to invasive Dz if left untreated.

Question 10

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

Answer 10

A pt with LCIS has an ∼7% risk of developing invasive cancer at 10 yrs (∼1%/yr), but the risk of subsequent invasive Dz is equal in both breasts, suggesting that LCIS is primarily a predictor of invasive Dz development, rather than a precursor lesion. (Chuba PJ et al., JCO 2005)

Question 11

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

Answer 11

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).

Question 12

Which subtype of LCIS has the worst prognosis?

Answer 12

Of LCIS subtypes, pleomorphic LCIS has the worst prognosis. It is more commonly associated with invasive Dz and hormone receptor negativity. Consider complete excision with negative margins.