DCIS and LCIS

Lobular carcinoma in situ
<15% of in situ breast cancer
Frequently multicentric (90%) and bilateral (35%)
Most cases are in premenopausal women; average age at dx is 45
Risk factors similar to invasive cancer
Usually incidental finding in biopsy and not associated with a particular mammographic abnormality
LCIS is a marker for an increased risk of invasive breast cancer but it is unclear if it represents a true pre-malignant lesion
Treatment for isolated LCIS is close observation with regular mammograms/MRI; consider chemoprevention with SERM's
If another histology is present, LCIS can be essentially ignored and the lesion is treated according to whatever other histology is present
The presence of LCIS is not thought to change the outcome of other types of breast tumors

Paget's disease of the nipple...a traditional pitfall
Crusting, eczematoid nipple
-If no underlying mass is present, 66-86% of patients have an underlying DCIS
-If an underlying mass is present, 90% are found to have invasive breast cancer
Can be managed with breast conservation, but the entire nipple-areola complex must be excised
Paget's occurs in fewer than 5% of breast cancer cases

Ductal carcinoma in situ
60,000 cases per year; incidence has increased greatly as screening mammography has become more popular
Same risk factors as invasive cancer

All DCIS are considered to be premalignant lesions with a 36% estimated rate of transformation to IDC in 10 years
Subtypes: comedonecrosis, solid, cribriform, micropapillary, papillary
Rates of ER+ and PR+ decrease with grade; rates of Her-2-neu+ increase with grade

Mastectomy may be required for multicentric DCIS (multicentric = more than one quadrant of the breast; multifocal = more than one lesion in a single quadrant)
Otherwise, breast conservation is often performed
No clear groups in whom RT can be withheld (Van Nuys criteria)

Short tabular summary of large randomized DCIS trials

Group	Lumpectomy only	L + RT	Factors predicting recurrence
NSABP B-17	32%	16%	comedonecrosis, margins, tumor larger than 1cm
EORTC 10853	25%	15%	age, grade, margins
Trials using RT and hormones
UKCCCR	14% (RT only)	6% (RT + tam)
NSABP B-24	13% (RT only>	8% (RT + tam)