A retrospective study of the ultrastructure of rectal tumors in patients with favorable and unfavorable prognosis was undertaken. It established favorable postoperative course and prognosis in tumors containing more than half undifferentiated cells. Conversely, tumors in which malignant cells with electron microscopy-identifiable signs of differentiation (retaining features of normal cells) prevailed and those containing equal fractions of well- and poorly differentiated cells involve early development of metastasis and sometimes recurrences.
Adenocarcinoma Adult