Breast cancer risk in women with abnormal cytology in nipple aspirates of breast fluid.

BACKGROUND: We previously showed that women with abnormal cytology in breast fluid obtained by nipple aspiration had an increased relative risk (RR) of breast cancer compared with women from whom fluid was not obtained and with women whose fluid had normal cytology. This study extends the follow-up in the original study group (n = 4046) and presents the first follow-up for a second group of women (n = 3627). METHODS: We collected nipple aspirate fluid from women in the San Francisco Bay Area during the period from 1972 through 1991, classified the women according to the most severe epithelial cytology observed in fluid specimens, and determined breast cancer incidence through March 1999. We estimated RRs for breast cancer using Cox regressions, adjusting for age and year of study entry. All statistical tests were two-sided. RESULTS: For women in the first and second study groups, the median years of follow-up were 21 years and 9 years, respectively, and breast cancer incidences were 7.8% (285 cases in the 3633 women for whom breast cancer status could be determined) and 3.5% (115 of 3271), respectively. Compared with women from whom no fluid was obtained, whose incidences of breast cancer were 4.7% (39 of 825) and 3.3% (65 of 1950) for those in group 1 and group 2, respectively, incidences and adjusted RRs were 8.1% (34 of 422), with RR = 1.4 (95% confidence interval [CI] = 0.9 to 2.3), and 0% (0 of 31), respectively, for those with unsatisfactory aspirate specimens and 8.2% (148 of 1816), with RR = 1.6 (95% CI = 1.1 to 2.3), and 3.1% (25 of 811), with RR = 1.2 (95% CI = 0.8 to 2.0), respectively, for those with normal cytology in aspirates. Compared with women from whom no fluid was obtained, incidences and adjusted RRs for women in group 1 with epithelial hyperplasia and atypical hyperplasia in aspirates were 10.8% (52 of 483), with RR = 2.4 (95% CI = 1.6 to 3.7), and 13.8% (12 of 87), with RR = 2.8 (95% CI = 1.5 to 5.5), respectively, while those for women in group 2 were 5.5% (25 of 457) and 0% (0 of 22), respectively, with a combined RR = 2.0 (95% CI = 1.3 to 3.3). CONCLUSION: The results obtained with the newly followed women independently confirmed previous findings that women with abnormal cytology in nipple aspirates of breast fluid have an increased risk of breast cancer.

Birthplace and yield of nipple aspirate fluid in Chinese women.

The different rates of breast cancer found between Chinese women in Asia compared with Chinese-born women in the United States suggest that dietary and environmental factors may be of etiological significance. We evaluated the proportion of 480 premenopausal Chinese women who yielded nipple aspirate fluid (NAF) by birthplace in Asia versus the United States and by reproductive and other risk factors. Birthplace was used as a surrogate for presumed differences in exposures during gestation, childhood, and adolescence that might influence yield of NAF in premenopausal women. In United States-born Chinese women compared with Asia-born Chinese women, the proportion yielding NAF was 44 of 95 (46.3%) versus 120 of 385 (31.2%), respectively. The relative risk of yield of NAF in United States-born women compared with Asia-born women was odds ratio = 2.37 (95% confidence interval, 1.26-4.47). Independent positive associations of NAF yield were also found with history of parity and breast feeding, cerumen phenotype, and a negative association with ever use of oral contraceptives. These findings support the hypothesis that early environmental exposures may have long-lasting physiological effects discernible in the breast glands of adult women.

Stimulatory influence of soy protein isolate on breast secretion in pre- and postmenopausal women.

Soy foods have been reported to have protective effects against premenopausal breast cancer in Asian women. No studies have been reported on potential physiological effects of dietary soy consumption on breast gland function. We evaluated the influence of the long-term ingestion of a commercial soy protein isolate on breast secretory activity. We hypothesized that the features of nipple aspirate fluid (NAF) of non-Asian women would be altered so as to resemble those previously found in Asian women. At monthly intervals for 1 year, 24 normal pre- and postmenopausal white women, ages 30 to 58, underwent nipple aspiration of breast fluid and gave blood and 24-h urine samples for biochemical studies. No soy was administered in months 1-3 and 10-12. Between months 4-9 the women ingested daily 38 g of soy protein isolate containing 38 mg of genistein. NAF volume, gross cystic disease fluid protein (GCDFP-15) concentration, and NAF cytology were used as biomarkers of possible effects of soy protein isolate on the breast. In addition, plasma concentrations of estradiol, progesterone, sex hormone binding globulin, prolactin, cholesterol, high density lipoprotein-cholesterol, and triglycerides were measured. Compliance was assessed by measurements of genistein and daidzein and their metabolites in 24-h urine samples. Excellent compliance with the study protocol was obtained. Compared with NAF volumes obtained in months 1-3, a 2-6-fold increase in NAF volume ensued during months 4-9 in all premenopausal women. A minimal increase or no response was found in postmenopausal women. No changes were found in plasma prolactin, sex hormone binding globulin, cholesterol, high density lipoprotein cholesterol, and triglyceride concentrations. Compared with concentrations found in months 1-3 (no soy), plasma estradiol concentrations were elevated erratically throughout a "composite" menstrual cycle during the months of soy consumption. No significant changes were seen in plasma progesterone concentrations. No significant changes were found in plasma estrogen levels in postmenopausal women. A moderate decrease occurred in the mean concentration of GCDFP-15 in NAF in premenopausal women during the months of soy ingestion. Of potential concern was the cytological detection of epithelial hyperplasia in 7 of 24 women (29.2%) during the months they were consuming soy protein isolate. The findings did not support our a priori hypothesis. Instead, this pilot study indicates that prolonged consumption of soy protein isolate has a stimulatory effect on the premenopausal female breast, characterized by increased secretion of breast fluid, the appearance of hyperplastic epithelial cells, and elevated levels of plasma estradiol. These findings are suggestive of an estrogenic stimulus from the isoflavones genistein and daidzein contained in soy protein isolate.

Earlobe crease in women: evaluation of reproductive factors, alcohol use, and Quetelet index and relation to atherosclerotic disease.

BACKGROUND: The diagonal earlobe crease (ELC) has been found to be associated with atherosclerotic heart disease. Although atherosclerotic cardiovascular disease is less prevalent among women than among men, no studies have been reported for women on the possible relationship of reproductive factors, contraceptive and menopausal estrogen use, and alcohol use on the expression of the ELC. SUBJECTS AND METHODS: The presence of ELC was determined in 625 white women who were seen as part of a breast research project. Information was obtained on age, height, weight, age at menarche, parity, age at first full-term pregnancy, use of oral contraceptives or menopausal estrogens, alcohol consumption, and smoking. Statistical methods used included estimation of the age-adjusted odds ratios and their 95% confidence intervals, and multiple logistic regression. RESULTS: No association was found between the ELC and reproductive factors and smoking. Only age, Quetelet index, and alcohol use were associated with the ELC. The ELC was negatively associated with alcohol use, and was more marked in women under 59 years of age. The positive association of ELC with the Quetelet index progressively became more marked with advancing age, especially after 60 years of age. CONCLUSION: The negative association found between the ELC and alcohol use is of interest because of the reported protective effect of moderate alcohol consumption on risk of coronary heart disease. No significant association was found between the ELC and reproductive risk factors. Based on events occurring during the embryonic development of the earlobes, a new hypothesis is proposed for the formation and peculiar diagonal localization of the ELC in adult earlobes in association with atherosclerotic vascular disease.

Association of abnormal nipple aspirate cytology and mammographic pattern and density.

The pattern and density of mammograms have been shown to be associated with proliferative histopathology and an increased risk of breast cancer. We recently found that epithelial atypia in nipple aspirate fluid obtained 10-18 years earlier was associated with an increased risk of breast cancer. In the present study we examined the association between the cytology of nipple aspirate fluid and mammographic patterns in 588 volunteers recruited from the mammography clinic at the University of California. Nipple aspirate fluid cytology was classified according to the most severe epithelial change present and mammograms were classified by the Wolfe method and the percentage area of density. A direct relationship was found between mammographic density and cytological abnormality. When controlled for age, body mass index, previous biopsy, and calcification, the odds ratios of high density mammograms (over 50%) with nipple aspirate fluid cytological atypia was 4.4 (95% confidence interval, 0.9-21.5; P = 0.08) when normal cytology was the referent. These preliminary findings indicate that highly dense mammograms are associated with cytological atypia and are consistent with studies reporting an association of histological hyperplasia and atypical hyperplasia with severe mammographic findings. If confirmed by further studies, nipple aspirate cytology may be a useful adjunct to mammographic patterns in the prediction of breast cancer risk, especially among premenopausal women.

Gross cystic disease fluid protein in nipple aspirates of breast fluid of Asian and non-Asian women.

Gross cystic disease fluid protein 15 (GCDFP-15) is universally present in the apocrine metaplastic epithelium of cystic breast disease and breast cancer, but it is rarely found in normal breast epithelium. Therefore GCDFP-15 detected in nipple aspirates of breast fluid (NAF) could serve as a biochemical marker of the presence and possibly extent of apocrine metaplasia within the breast. GCDFP-15 levels were measured in NAF from 37 Asian and 78 non-Asian women using radioimmunoassay. GCDFP-15 (range, 0-81,643 micrograms/ml) was found in the NAF of all but 1 woman and was highly correlated between right and left breasts. Mean concentrations of GCDFP-15 were significantly lower in NAF from Asian compared with non-Asian women. Markedly reduced levels of GCDFP-15 were found in the 17 women who had been parous in the previous 2 years. In women not parous within the prior 2 years, no relationship was found between GCDFP-15 levels and age, weight, age at menarche, first-degree family history of breast cancer, parity, oral contraceptive use, or smoking history. High concentrations of GCDFP-15 were found in the NAF of women with a history of a benign breast biopsy. Because similarly high levels of GCDFP-15 were found in NAF in over 40% of women without a history of benign breast biopsy, and because GCDFP-15 in the breast is produced only by apocrine metaplastic epithelium, we infer that the breasts of these women likely contain a significant degree of apocrine metaplasia.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast cancer risk associated with abnormal cytology in nipple aspirates of breast fluid and prior history of breast biopsy.

The authors previously reported an increased risk of breast cancer in women from the San Francisco Bay Area first enrolled between 1973 and 1980 with proliferative cytologic findings (hyperplasia, moderate hyperplasia, and atypia) compared with women with normal cytologic findings in breast fluids obtained by nipple aspiration and with women from whom breast fluid could not be obtained. To look for factors which might modify the risks associated with cytology, the authors examined several standard breast cancer risk factors: parity, age at first pregnancy, age at menarche, family history of breast cancer, and prior history of breast biopsy. Among women aged 30 years or over, only prior biopsy modified the effect of proliferative cytologic findings on the risk of breast cancer (p < 0.10). For those women with no prior biopsy, breast cancer incidence was 5% (47 of 985) among women with normal cytology and 5% (13 of 277) among women with proliferative findings, whereas among those women with normal cytology and 18% (11 of 62) among women with proliferative cytology. Age-adjusted as well as multivariate-adjusted relative risks indicated that the increased risk of breast cancer associated with proliferative cytologic findings was largely confined to women who had a prior history of breast biopsy.

ASPO Distinguished Achievement Award Lecture. Studies on the epidemiology and natural history of benign breast disease and breast cancer using nipple aspirate fluid.

Nicholas L. Petrakis, M.D., was presented the American Society of Preventive Oncology's Distinguished Achievement Award at the Society's annual meeting on March 15, 1992, in Bethesda, Maryland. The basis for choosing Dr. Petrakis was his distinguished achievements for over 20 years in research and education concerning the etiology and prevention of cancer, with substantial emphasis on breast cancer. Dr. Petrakis obtained a Bachelor of Arts degree from Augustana College, Sioux Falls, South Dakota, and his Doctor of Medicine degree from Washington University, St. Louis, Missouri. He has held numerous principal positions at the University of California, beginning with a position with the U.S. Public Health Service, National Cancer Institute Laboratory of Experimental Oncology, and then the Cancer Research Institute, both at the University of California, San Francisco. Dr. Petrakis has held continuing appointments in the Department of Preventive Medicine and Department of Epidemiology and International Health, beginning as an Assistant Professor. He was subsequently promoted to Associate Professor and Professor of Preventive Medicine. During the years from 1978 to 1989, Dr. Petrakis was chair of the Department of Epidemiology and International Health. Since 1981 he has been Professor of Epidemiology, University of California, Berkeley, School of Public Health. In 1989 he became Professor Emeritus of Preventive Medicine and Epidemiology.(ABSTRACT TRUNCATED AT 250 WORDS)

The association of dietary fat with ability to obtain breast fluid by nipple aspiration.

The ability to obtain breast fluid by nipple aspiration was examined in relation to self-reported dietary fat intake in 1347 white and 153 black women. Study participants were between 20 and 59 years of age, were not pregnant or breastfeeding, and had no history of breast cancer. The proportion of women from whom nipple aspirate fluid was obtained increased with increasing dietary fat consumption; the odds ratio for obtaining breast fluid was 1.4 (95% confidence interval, 1.0-1.8) in white women who consumed over 90 g of fat/day compared with those who consumed less than 50 g of fat/day, adjusting for age, smoking, and parity. Among black women, the association was much stronger; the odds ratio for obtaining nipple aspirate fluid in those who consumed over 90 g of fat/day was 3.6 (95% confidence interval, 1.3-10.1) compared with those who consumed less than 50 g of fat/day. In both blacks and whites, the associations were most pronounced in women aged 30-44 years. These findings suggest a relationship between dietary fat consumption and breast secretion.

Breast cancer incidence in women with abnormal cytology in nipple aspirates of breast fluid.

This is a prospective study of breast cancer risk in relation to nipple aspirate fluid cytology in 2,701 volunteer white women from the San Francisco Bay Area first enrolled between 1973 and 1980. The women were not pregnant or lactating and were free of breast cancer within 6 months of entry into the study. The breast cancer status of this cohort was determined between June 1988 and April 1991. Follow-up was complete for 87% (n = 2,343) of the cohort, representing 29,961 person-years and an average of 12.7 years of follow-up. The overall breast cancer incidence was 4.4% (104 of 2,343) and rose with fluid cytology findings as follows: no fluid obtained, 2.6% (9 of 352); unsatisfactory specimen, 4.8% (15 of 315); normal cytology, 4.3% (56 of 1,291); epithelial hyperplasia, 5.5% (18 of 327); and atypical hyperplasia, 10.3% (6 of 58). Relative risks for breast cancer and their 95% confidence intervals were estimated by Cox regression, adjusting for age and year of entry. Compared with the relative risk for women who yielded no fluid, relative risks were: unsatisfactory specimen, relative risk (RR) = 1.4 (95% confidence interval (CI) 0.6-3.3); normal cytology, RR = 1.8 (95% CI 0.9-3.6); epithelial hyperplasia, RR = 2.5 (95% CI 1.1-5.5); and atypical hyperplasia, RR = 4.9 (95% CI 1.7-13.9). These findings were strongest for and were mainly confined to women aged 25-54 years. Women with atypical hyperplasia and a first-degree family history of breast cancer were six times more likely to develop breast cancer than were women with atypical hyperplasia but without a family history of breast cancer (95% CI 1.0-30.2). These findings provide strong support for our hypothesis that hyperplasia and atypical hyperplasia diagnosed in nipple aspirates of breast fluid are associated with an increased risk of breast cancer.

Individual susceptibility to induced chromosome damage and its implications for detecting genotoxic exposures in human populations.

In a previous study, we observed a bimodal distribution of sensitivity to sister chromatid exchange (SCE) induction by diepoxybutane (DEB) in lymphocytes from healthy individuals. Twenty-four % of the participants had increased sensitivity to in vitro induction of SCEs and chromosomal aberrations. These same participants also had significantly higher frequencies of uninduced or baseline SCE frequencies. In the present study, we measured baseline and DEB-induced SCE frequencies in 55 healthy female volunteers. Eleven of 55 [20%] women were relatively sensitive to DEB induction of SCEs. Baseline SCE frequencies in these sensitive individuals [10.4 +/- 0.7 (SD) SCEs/cell] were significantly higher [P less than 0.001; Student's t test] than baseline SCE frequencies in the remaining 44 individuals [8.0 +/- 0.9 SCEs/cell]. Similar increases in SCEs were observed when the analysis was restricted to the upper 10% of the SCE distribution (high frequency SCE analysis). The phenotype of DEB sensitivity accounted for 58% of the variation among individual SCE scores. Given the population frequency of this sensitivity to SCE induction and the high proportion of variance in SCEs for which it accounts, failure to account for this factor could seriously distort conclusions about SCE measures associated with other environmental exposures. The most likely result of such unexplained variability (type II error) would be bias toward the null hypothesis. Also, the likelihood that individual variations contribute to false positive results is expected to be greatest in studies that compare small numbers of exposed and nonexposed individuals. To summarize, these results confirm our earlier study and show that increased baseline SCE frequencies can be indicative of increased sensitivity to certain classes of mutagenic carcinogens. Identification of DEB-sensitive persons could be used to increase the sensitivity of SCE analysis in monitoring studies to detect exposure to genotoxins.

Characterization by image cytometry of duct epithelial proliferative disease of the breast.

To develop a morphometric model of premalignant breast epithelium, we evaluated 120 lesions classified as nonproliferative disease (n = 20), hyperplasia (n = 20), moderate hyperplasia (n = 20), atypical hyperplasia (n = 20), carcinoma in situ (n = 20), and carcinoma (n = 20) in tissue from surgical biopsy or mastectomy. Atypical hyperplasia, a component of duct epithelial proliferative disease, has frequently been described in breasts with carcinoma. Atypical hyperplasia is generally viewed as premalignant or as a marker of increased risk for breast cancer. Measurements of nuclei in breast lesions were obtained with the Leitz TAS Plus on 4-microns sections stained for DNA with the Azure A Feulgen reaction. Nuclei of duct epithelial lesions had morphometric features that displayed changes from nonproliferative disease to carcinoma. The morphometric data from each lesion were compared among the six disease groups. Means of nuclear area, perimeter, maximum and minimum diameter, and large dark and large light intranuclear areas increased with higher degrees of proliferative abnormality. When the six groups of lesions were compared using the means of the first four nuclear features, atypical hyperplasia was significantly different (P less than 0.05) from carcinoma and non-proliferative lesions, but not from hyperplasia, moderate hyperplasia, or carcinoma in situ. These findings suggest that objective morphometric descriptors for characterizing significant proliferative lesions can be established using image cytometry. The progressive increases also suggest that proliferative breast disease is a continuum that includes premalignant lesions.

Cerumen phenotype and proliferative epithelium in breast fluids of U.S.-born vs. immigrant Asian women: a possible genetic-environmental interaction.

To determine whether a genetic-environmental interaction exists between the breast, a modified apocrine gland, its secretions, and the genetic polymorphic phenotypes of wet and dry cerumen, we examined nipple aspirate fluid (NAF) for proliferative disease in 172 U.S.-born and immigrant Chinese and Japanese women. Cytologic evidence of proliferative epithelial cells (benign hyperplasia and/or atypical hyperplasia) was found in the NAF of 36 women (20.9%). A significantly higher incidence of proliferative epithelial cells was present in the NAF of U.S.-born than in immigrant Asian women (28.6% vs. 16.5%) (p = 0.05). A higher proportion of U.S.-born Asian women with wet cerumen than women with dry cerumen had proliferative epithelial cells in NAF: 39.3% vs. 20.0% (p = 0.08). No significant difference in NAF proliferative cells was found between immigrant women with wet and dry cerumen: 15.8% vs. 17.3%; p = 0.50. A strong association of proliferative epithelial cells and cerumen phenotype was found in parous U.S.-born women (wet = 47.6% vs. dry = 16.0%; p = 0.002). No significant association with wet and dry cerumen phenotype was found in parous immigrant women (wet = 12.2% vs. dry = 20%). These findings support the hypothesis that an apocrine genetic polymorphic trait differentially influences susceptibility of the breast to proliferative disease in Asian women born in environments presumed to be of high risk for breast cancer compared to women from low risk environments.

Factors associated with obtaining nipple aspirate fluid: analysis of 1428 women and literature review.

Studies of cytologic and biochemical constituents of nipple aspirates of breast fluid have contributed to understanding the natural history of benign and malignant breast disease. We conducted multivariate analyses using 1428 women from a recent case-control study of breast disease to determine which factors were independently associated with the ability to obtain breast fluid from nonlactating women. We then compared results from these analyses to the results from five previous studies that also used the aspiration technique of Sartorius. Four factors were consistently associated across studies with increased ability to obtain breast fluid: 1) age up to 35 to 50 years; 2) earlier age at menarche; 3) non-Asian compared to Asian ethnicity; and 4) history of lactation. Exogenous estrogen use, endogenous estrogen concentrations, phase of menstrual cycle, family history of breast cancer, type of menopause, and less than full-term pregnancy consistently did not influence ability to obtain fluid. New findings from this study shed light on some apparently contradictory findings from the previous studies. In particular, this study showed that the effects of age on ability to obtain fluid appeared to be independent of the effects of menopause. Furthermore, discrepancies in previous findings on the effects of parity on ability to obtain fluid may be explained by our finding that the increased ability to obtain fluid from parous compared to nulliparous women applied only to parous women who had breastfed.

Breast fluid cholesterol and cholesterol beta-epoxide concentrations in women with benign breast disease.

Because cholesterol 5,6-epoxides have been reported to be mutagenic, carcinogenic, and cytotoxic, we investigated the relationship of these substances in breast fluid to histopathologically defined breast disease. We measured cholesterol and its oxidation product, 5 beta,6 beta-epoxide, in breast fluids from 68 women with biopsied benign breast disease (BBD) and 135 women with no history of breast disease (controls). Each biopsy was classified according to the most severe epithelial change: (a) nonproliferative epithelia; (b) hyperplasia without atypia; or (c) hyperplasia with atypia. Similar to our previous findings in control women, breast fluid cholesterol and beta-epoxide concentrations in women with BBD were associated with factors of interest in relation to breast cancer: concentrations increased with age and were higher in white than nonwhite women and in women who were past or current smokers; concentrations were lower in women who had given birth or breastfed within 2 yr. Increased breast fluid cholesterol and beta-epoxide concentrations were significantly associated with proliferative BBD (hyperplasia with or without atypia) compared to controls. After adjustment for covariates, the odds ratio for proliferative BBD associated with detectable versus nondetectable beta-epoxide concentrations was 8.5 (95% confidence intervals, 1.1, 68.8). Our findings suggest that the histological progression from normal epithelium to hyperplasia without atypia to atypical hyperplasia is associated with progressively increasing concentrations of both cholesterol and cholesterol beta-epoxide.

Nipple aspirate fluids in adult nonlactating women--lactose content, cationic Na+, K+, Na+/K+ ratio, and coloration.

The presence of lactose in nipple secretions is considered biochemical evidence of breast secretory activity, and has been reported to occur more frequently in white compared to brownish or green colored breast fluid. We studied lactose, Na+, and K+ concentrations, the Na+/K+ ratio, and the coloration of nipple aspirate fluid (NAF) from 49 nonpregnant women. A significant relationship was found between the concentrations of lactose, Na+, and K+, and age and the coloration of NAF. Lactose was present in 22/49 (44.8%) of the NAF samples and declined with age from 100% positivity in women less than or equal to 29 years to 29% in those less than or equal to 35 years. In NAF of deep yellow, brown and green colorations, only traces of lactose were found. Na+ and K+ increased with age and with darker colorations compared to white, pale yellow, or colorless NAF. Lactose was present in NAF samples from both parous and nulliparous younger women, indicating that the breasts of many nonpregnant women respond to prolactin stimulation; hence, lactose may provide a simple marker indicating active physiologic secretory activity of the breast. As reported previously, NAF of darker coloration, containing elevated levels of cholesterol, cholesterol oxidation products, and other substances, suggests retention and impaired reabsorption of these and other products of secretion. Because of the secretion and temporary retention by the breast glands of chemical substances of exogenous and endogenous origin, including mutagens and carcinogens, lactose concentration and coloration of NAF may be useful as markers of secretion and reabsorption in future physiologically based clinical and epidemiologic studies of the pathogenesis of breast disease.

Image cytometric classification of premalignant breast disease in fine needle aspirates.

Image cytometry for the classification of fine needle aspirate (FNA) biopsies was evaluated in samples from 39 women. Eighteen of them had benign lesions, seven had premalignant lesions, nine had carcinoma in situ, and five had carcinoma. The term, premalignant, here refers to lesions with an increased risk of developing into breast cancer (atypical hyperplasia and, to a lesser extent, moderate or florid hyperplasia). The classifications by cytometry were compared with the microscopic diagnoses of the same FNA samples and of tissue from a subsequent surgical biopsy of the same area. One slide from each breast FNA sample was restained in Azure-A Feulgen. Breast epithelial cells were measured using a texture analysis program on the Leitz TAS-plus. The mean, standard deviation (SD), and interquartile range were calculated for each of 12 nuclear parameters from 200 cells per slide. A discriminant analysis was used to develop a statistical model for classifying individual samples. Six of seven atypical proliferative lesions (atypical hyperplasia and moderate hyperplasia) were identified by image cytometry, but were unrecognized by conventional microscopic examination.