Chromosomes of precancerous lesions of the cervix uteri. New data and a review

Abstract

In 28 previously undescribed cases of dysplasia, carcinoma in situ, and micro‐carcinoma of the cervix, direct preparations were used to study the cytogenetic changes. In each case, two separate samples were taken from the fresh cone biopsy (usually anterior and posterior). In those cases where both samples provided successful preparations, evidence could be found, in some cases, to suggest, or prove, that the same clone was present; this evidence consisted of similarity of an abnormal modal number, and similar marker chromosomes in the two samples. In at least two cases, there were unequivocally related cells with distinctive markers on opposite sides of the os. One of these showed severe dyplasia without invasion; the other showed severe dysplasia and carcinoma in situ in the pieces sampled, but microcarcinoma was seen elsewhere in the cone. In all cases there was wide variation in chromosome counts, almost certainly representing genuine variation rather than artefact. Normal diploids were rarely found. Marker chromosomes were identified probably or certainly in 7 out of 9 cases where microcarcinoma was present in some part of the cervix, and in 7 out of 18 where the whole lesion was non‐invasive. This suggests that chromosomal breaks and rearrangements occur in the course of evolution of the disease, but that unequal divisions and chromosome losses (sometimes with initial tetra‐ploidy) may be more important at earlier stages. No chromosomal feature was found to be distinctive of dysplasia, carcinoma in situ, or microcarcinoma, nor is there any particular marker chromosome characteristic for early cervical neoplasia. It is concluded that variation and selection of successful variants is proceeding in these conditions, and that a neoplastic clone, derived from a single cell, can grow around the circumference of the cervical os before the development of an invasive tumor. Copyright © 1971 American Cancer Society