Despite limited data, coexistent lobular carcinoma in situ should not be a contraindication to breast conservation for women with invasive breast carcinoma

[Lobular intra-epithelial neoplasia: atypical lobular hyperplasia and lobular carcinoma in situ]

OBJECTIVE

To review main knowledge about lobular intra-epithelial neoplasia with special interest for daily practice management.

MAIN RESULTS

Intra-epithelial lobular neoplasias (ILN) are non invasive proliferations within the terminal ducto-lobular unit of monomorphic loosely cohesive small cells. A lack of expression of the E-cadherin adhesion molecule is often observed as in invasive lobular breast cancer. ILN are infrequent, however, a rise in incidence partly, due to the generalization of mammographic screening, is observed. Actually ILN are usually asymptomatic and diagnosed after breast biopsy for unspecified microcalcifications. ILN are associated with an increased risk of breast cancer that persists over 20 years after the initial diagnosis. The average risk is 4.2 % for the ipsilateral breast and 3,5 % for the controlateral breast. However, a great variability in the risk estimation is observed between the studies. There is no consensus on how to treat ILN. Surgical options have varied from biopsy to bilateral mastectomy. Current tendency is favouring lumpectomy.

Pathologic findings from the National Surgical Adjuvant Breast and Bowel Project

BACKGROUND

The current report represents a 12-year clinicopathologic update of an earlier 5-year analysis of 180 patients with lobular carcinoma in situ (LCIS) who were treated with local excision and subsequent surveillance only.

METHODS

Nineteen pathologic characteristics of LCIS were assessed as potential predictors of invasive and noninvasive ipsilateral breast tumor recurrence (IBTR) and contralateral breast tumor recurrence (CBTR) as well as mortality.

RESULTS

Overall, only 26 IBTRs (14.4%) and 14 CBTRs (7.8%) were observed. Nine IBTRs (5.0% of the total cohort) and 10 CBTRs (5.6% of the total cohort) were invasive carcinomas. Eight of 9 IBTRs (88.9%) and 6 of 8 invasive CBTRs (75%) that had histologic sections available for review were of the lobular invasive type. Ninety-six percent of all IBTRs and 100% of invasive IBTRs occurred within the same site as the index LCIS. The numbers of invasive IBTRs were comparable within and after 5 years (5 invasive IBTRs vs. 4 IBTRs). Recurrences of invasive CBTR occurred later than recurrences of invasive IBTR, with 70% of invasive CBTRs recognized after 5 years compared with 44% of invasive IBTRs. It was found that Grade 2-3 LCIS was significantly predictive for invasive IBTR when combined with the number of recurrences of ductal carcinoma in situ (DCIS) alone or with LCIS. Only 2 patients in the cohort (1.1%) succumbed to breast carcinoma; 1 patient had a prior invasive IBTR, and the other patient had an invasive CBTR. The reasons for the lower frequency of invasive recurrences and the higher proportions of the lobular invasive phenotype than noted by others are discussed along with the impact of the findings on the nomenclature, precursor nature, and treatment of LCIS.

CONCLUSIONS

LCIS is a more indolent form of in situ breast carcinoma than DCIS, with which it shares other features of its natural history, particularly very low mortality rates. There is no compelling reason to surgically treat LCIS other than conservatively. The values of other adjuvant modalities in the management of LCIS are discussed. The authors acknowledge that their findings are based on relatively few events and, even at 12 years, may be regarded as "preliminary". Nonetheless, their findings may reflect the true biologic nature of LCIS.

E-cadherin reactivity of 95 noninvasive ductal and lobular lesions of the breast. Implications for the interpretation of problematic lesions

Studies suggest that E-cadherin is useful to classify epithelial breast lesions as ductal or lobular, but extensive experience with this antibody is lacking. We studied reactivity of lesions with classic and indeterminate morphologic features. We reviewed 95 lesions and divided them into unanimous and nonunanimous diagnosis groups; the unanimous group served as benchmark lesions to which E-cadherin reactivity could be standardized and compared. All 37 ductal lesions in the unanimous group had strong, diffuse E-cadherin reactivity. Two of 22 classic lobular carcinoma in situ (LCIS) lesions had sparse E-cadherin-reactive lobular cells within a few terminal duct lobular units. Neither displayed transition from nonreactive to reactive cells. Of 36 lesions in the nonunanimous group, 19 had insufficient morphologic features for definitive classification. Only 6 of 19 were E-cadherin reactive, including several minimally proliferative lesions. The other 17 lesions in the nonunanimous group had LCIS and ductal carcinoma in situ (DCIS) features. All had no E-cadherin, or strong membrane reactivity of constituent cells in varying proportions, without a transition between reactive and nonreactive cells. Results suggest that the majority of morphologically nondiagnostic atypical lesions are lobular, including those associated with DCIS. E-cadherin seems to be absent in most lobular lesions.