Stereological estimates of nuclear volume in squamous cell carcinoma of the uterine cervix and its precursors

Abstract

Using modern stereology, this study was carried out to obtain base-line data concerning three-dimensional, mean nuclear size in precancerous and invasive lesions of the uterine cervix. Unbiased estimates of the volume-weighted mean nuclear volume (nuclear vv) were obtained by point-sampling of nuclear intercepts in 51 pre-treatment biopsies from patients with invasive squamous cell carcinomas (SCC). Vertical sections from 27 specimens with cervical intraepithelial neoplasia (CIN) grades I through III were also investigated, along with 10 CIN III associated with microinvasion (CIN III + M). On average, nuclear vv was larger in SCC than in CIN III and CIN III + M together (2 P = 8.9 . 10(-5). A conspicuous overlap of nuclear vv existed between all investigated lesional groups. The reproducibility of estimates of nuclear vv in biopsies with SCC was acceptable (r = 0.85 and r = 0.84 in intra- and inter-observer studies, respectively). The efficiency of the sampling scheme was high, with more than 60% and more than 80% of the total observed variance contributed by differences between individual lesions with CIN and SCC, respectively. Estimates of nuclear vv based on sampling within the whole epithelial thickness and on sampling in the lower one-third in CIN I and the lower two-thirds in CIN II lesions were of the same magnitude. Approximate estimates of the absolute variation of nuclear vv were directly proportional to individual estimates of nuclear vv, whereas the relative variation of nuclear vv tended to decrease with increasing mean nuclear volume. Based on the rather small number of cases investigated, estimates of nuclear vv are unable to distinguish between different grades of CIN. However, the estimation of nuclear vv is well-suited for the purposes of objective grading of malignancy in SCC.