C-myc gene expression in stage I endometrioid adenocarcinoma of the uterus

Expression of a c-myc proto-oncogene product known as p62 (c-myc) was studied in 18 cases of stage I endometrioid (typical) adenocarcinoma of the uterus by immunohistochemistry and correlated with mucin production and other pathologic features. Cytoplasmic staining of tumor cells for c-myc product was seen in all cases and nuclear staining in three cases. Endometrial stromal cells were invariably negative and myometrial nuclear staining was seen in three cases. Within the tumor itself, whereas intense staining was frequent in high grade tumors with deep myometrial and vascular invasion, faint to moderate staining was frequent in well differentiated tumors with superficial myometrial invasion. A general tendency was also seen for greater staining in the myometrial component of the tumor than in tumor located in the endometrium. Whereas staining in the latter was frequently patchy in distribution, c-myc expression was invariably uniform in the myometrial component. Mucin production was somewhat greater in endometrial than myometrial components but did not correlate with c-myc expression or other pathologic features. This study demonstrates that c-myc is variably expressed in endometrial carcinoma and high c-myc expression can be associated with populations of tumor cells selectively capable of myometrial and vascular invasion.