HETEROGENEOUS EXPRESSION OF NM23 GENE-PRODUCT IN NONINVASIVE BREAST-CARCINOMA

Background. The two major types of noninvasive breast carcinoma, ducta l carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS), are q uite different in their histopathologic appearance and clinical implic ations. LCIS is only a marker of an increased risk of later developmen t of invasive carcinoma, whereas most DCIS lesions are at least nonobl igate precursors of invasive carcinoma. DCIS is a heterogeneous group of lesions composed of several distinct subtypes, with only the comedo subtype having immediate malignant potential. The authors' purpose wa s to analyze noninvasive carcinomas for the presence of a gene product (nm23) indicative of a favorable prognosis in invasive carcinomas to determine differences (1) among the different types of CIS and (2) in CIS with and without an accompanying invasive component. Methods. Immu nohistochemical methods were used to detect nm23 gene product in archi val material from two groups of patients: Group 1 consisted of 54 case s of purely noninvasive carcinoma, and Group 2 consisted of 55 example s of noninvasive carcinoma associated with an invasive component. Resu lts. Among the cases of CIS with no invasion, LCIS and comedo DCIS exp ressed more nm23 than noncomedo DCIS (P less than or equal to 0.03). T here were no differences among these CIS subtypes in the group with in vasion. Comparing subtypes of CIS in the groups with or without invasi on, only comedo DCIS was significantly different, with greater express ion in the CIS group with no invasion compared with comedo DCIS associ ated with an invasive component (P = 0.04). Conclusions. These results support the special nature of LCIS and the heterogeneous nature of DC IS. The in situ component attending an invasive component may be diffe rent from an anatomically similar lesion without associated invasion. The absence of nm23 in comedo DCIS may be indicative of invasive capac ity.