Proliferation and DNA ploidy in malignant breast tumors in relation to early oral contraceptive use and early abortions

Oral contraceptive use as a risk factor for premenopausal breast cancer: a meta-analysis

OBJECTIVE

To perform a meta-analysis of case-control studies that addressed whether prior oral contraceptive (OC) use is associated with premenopausal breast cancer.

METHODS

We searched the MEDLINE and PubMed databases and bibliography reviews to identify case-control studies of OCs and premenopausal breast cancer published in or after 1980. Search terms used included breast neoplasms, oral contraceptives, contraceptive agents, and case-control studies. Studies reported in all languages were included. Thirty-four studies were identified that met inclusion criteria. Two reviewers extracted data from original research articles or additional data provided by study authors. We used the DerSimonian-Laird method to compute pooled odds ratios (ORs) and confidence intervals (CIs) and the Mantel-Haenszel test to assess association between OC use and cancer.

RESULTS

Use of OCs was associated with an increased risk of premenopausal breast cancer in general (OR, 1.19; 95% CI, 1.09-1.29) and across various patterns of OC use. Among studies that provided data on nulliparous and parous women separately, OC use was associated with breast cancer risk in both parous (OR, 1.29; 95% CI, 1.20-1.40) and nulliparous (OR, 1.24; 95% CI, 0.92-1.67) women. Longer duration of use did not substantially alter risk in nulliparous women (OR, 1.29; 95% CI, 0.85-1.96). Among parous women, the association was stronger when OCs were used before first full-term pregnancy (FFTP) (OR, 1.44; 95% CI, 1.28-1.62) than after FFTP (OR, 1.15; 95% CI, 1.06-1.26). The association between OC use and breast cancer risk was greatest for parous women who used OCs 4 or more years before FFTP (OR, 1.52; 95% CI, 1.26-1.82).

CONCLUSION

Use of OCs is associated with an increased risk of premenopausal breast cancer, especially with use before FFTP in parous women.

Effect of a low-dose ethinylestradiol and gestodene in combination on the frequency of micronuclei in human peripheral blood lymphocytes of healthy women in vivo

BACKGROUND

Since most oral hormonal contraceptives contain a fixed combination of ethinylestradiol and gestodene as an estrogenic/progestogenic component, we decided to evaluate the possible mutagenic effect of a low-dose contraceptive pills containing 20 microg ethinylestradiol and 75 microg gestodene.

METHODS

A total of 30 healthy women received hormonal contraception during six consecutive menstrual cycles. A single daily dose was 20 microg ethinylestradiol and 75 microg gestodene. The pills were taken orally in a monthly cycle of 3 weeks on and 1 week off. In the investigation of the mutagenic effect of these contraceptive pills in vivo, the cytokinesis block micronucleus (CBMN) test was used, and the frequency of micronuclei (MN) in peripheral blood lymphocytes was determined.

RESULTS

Average MN frequency in women before therapy was 7.40 +/- 0.75 MN/1000 analyzed cells, and after therapy was 7.37 +/- 0.59 MN/1000 analyzed cells (p > 0.05).

CONCLUSION

Our data suggest that oral contraception with 20 microg ethinylestradiol and 75 microg gestodene in combination during six consecutive menstrual cycles does not induce micronuclei in peripheral blood lymphocytes of women.

Tumour biology of a breast cancer at least partly reflects the biology of the tissue/epithelial cell of origin at the time of initiation - a hypothesis

A hypothesis is presented suggesting that initiation of breast epithelial cell freezes the cell at least partly according to the development/differention of cell at the time of initiation. Tumour biology will mimic the physiology of normal cell development at the time of initiation and this is preserved at least partly onwards. Also preferentially, tumours will develop from the cell type that is proliferating at the time of initiation. This may explain the overrepresentation of different types of histology in breast cancer in relation to age of the woman. The development of each tumour may follow at least partly a distinct pathway of evolution.

S-phase fraction and breast cancer--a decade of experience

During the past decade, more than 300 articles, abstracts, and book chapters have been published about S-phase fraction (SPF) determined by DNA flow cytometry and its clinical utility for patients with breast cancer. However, the use of SPF for making treatment decisions for breast cancer patients remains controversial. After reviewing 273 published articles, we conclude: 1) Despite different techniques and cutpoints, correlations between SPF and other prognostic markers are relatively consistent across studies; higher SPF is generally associated with worse tumor grade, absence of steroid receptors, larger tumors, and positive axillary lymph nodes. 2) Higher SPF is generally associated with worse disease-free and overall survival in both univariate and multivariate analyses; SPF values from laboratories that have conducted validation studies can be used, in combination with other factors, to estimate the prognosis of patients with primary breast cancer. 3) There is considerable variability among laboratories regarding assay methodology, cell-cycle analysis techniques, and cutpoints for classifying and interpreting SPF; use of SPF values from different laboratories is problematic, and there remains a need for standardization of these processes and well-designed confirmation studies. We conclude that measurement of SPF does have clinical utility for patients with breast cancer, but standardization and quality control must be improved before it can be routinely used in community settings.

Tumour biological features of BRCA1-induced breast and ovarian cancer

BRCA1 mutations, although implicated in disease predisposition in a major part of the hereditary breast cancer population, do not seem to be crucially involved in tumorigenesis of sporadic breast and ovarian cancers. This suggests that tumours arising in BRCA1 mutation carriers may differ from BRCA1 negative hereditary and sporadic cancer in genetic and biological features, as well as in clinical behaviour. Prior to BRCA1 analysis, 79 breast and 19 ovarian tumours from 57 breast and breast-ovarian cancer families, and 170 tumours from a comparison group of stage II breast cancers were studied with regard to histopathological features; immunohistochemistry [c-erbB-2, p53, oestrogen receptor (ER) and progesterone receptor (PR)], DNA flow cytometry and S-phase fraction. BRCA1 mutations were found in 40 breast and 15 ovarian tumours. The BRCA1 positive breast tumours were significantly more often of ductal type, histological grade III and manifested a heavy lymphocyte infiltration. Additionally, as compared to BRCA1 negative tumours, the BRCA1 positive tumours were significantly more often ER, PgR and c-erbB-2 negative. Furthermore, they were significantly more often DNA non-diploid, as well as being characterised by higher S-phase fraction values. These results suggest that BRCA1-induced breast cancers may manifest distinct tumour biological features of clinical importance.

Endocrine and paracrine hormones in the promotion, progression and recurrence of breast cancer

Both normal and neoplastic breast tissues are stimulated by endocrine and paracrine hormones. Epidemiological studies have demonstrated the significant role that hormones, growth factors and cytokines have in the promotion, progression and recurrence of breast cancer. Significant variations in the hormonal environment occur based on age, the cyclical changes occurring during the menstrual cycle and (mammographically determined) variations in breast composition. These variations have a significant influence on rates of local recurrence of breast cancer and survival. This review analyses data relevant to these issues and suggests means by which operative results may be improved.

Epidemiology of in situ and invasive breast cancer in women aged under 45

The incidence of in situ breast cancer in the USA has increased rapidly in recent years, even among young women. A population-based case-control study of 1616 breast cancer cases aged under 45 in the USA was used to examine risk factors for in situ, local and regional/distant tumours. Almost 60% of in situ tumours were detected by routine mammograms compared with 18% of local tumours and 8% of regional/distant tumours. After adjustment for screening history and established risk factors, family history of breast cancer in a first-degree relative and African-American race were associated with an increased risk of all stages of breast cancer. The associations with nulliparity, a previous breast biopsy and body mass index were significantly stronger for in situ tumours than for local or regional/distant disease. Alcohol consumption was associated with an increasing trend in risk of regional/distant tumours but not of earlier stage tumours, indicating that alcohol may be involved in late-stage events. Analyses by histological type of in situ tumours suggested that both ductal and lobular carcinoma in situ were associated with most established breast cancer risk factors, and the magnitude of association tended to be greater for the ductal form.

Hereditary breast cancer: pathobiology, prognosis, and BRCA1 and BRCA2 gene linkage

BACKGROUND

The purpose of this investigation was to determine if there are pathobiologic differences between BRCA1-related and BRCA2-related hereditary breast cancer (HBC) and non-HBC.

METHODS

On the basis of linkage to chromosomes 17q or 13q and/or the presence of ovarian and male breast cancer, HBC families were classified as either "BRCA1-related" (26 families, 90 breast cancer pathology cases) or "Other" (26 families, 85 cases), in which most BRCA2 cases were likely to reside. Cases were compared with 187 predominantly non-HBC cases. Tumors were assessed for histologic type, grade, and ploidy and S-phase fraction by quantitative DNA flow cytometry. Clinical presentation and available follow-up data were obtained.

RESULTS

BRCA1-related and Other HBC patients each presented at lower stage (P = 0.003) and earlier age than non-HBC patients (mean, 42.8 years and 47.1 years vs. 62.9 years, P = 0.0001). Compared with non-HBC, invasive BRCA1-related HBC had a lower diploidy rate (13% vs. 35%; P = 0.002), lower mean aneuploid DNA index (1.53 vs. 1.73; P= 0.002), and strikingly higher proliferation rates (mitotic grade 3; odds ratio [OR]= 4.42; P= 0.001; aneuploid mean S-phase fraction 16.5% vs. 9.3%, P < 0.0001). Other HBC patients, including patients in two BRCA2- linked families, had more tubular-lobular group (TLG) carcinomas (OR = 2.56, P = 0.007). All trends were independent of age. A nonsignificant trend toward better crude survival in both HBC groups was age- and stage-dependent. Compared with Other HBC, BRCA1-related HBC patients had fewer recurrences (P = 0.013), a trend toward lower specific death rates, and fared no worse than breast cancer patients at large. Other HBC patients, despite neutral prognostic indicators, fared worse.

CONCLUSIONS

BRCA1-related HBCs are more frequently aneuploid and have higher tumor cell proliferation rates compared with Other HBC. Despite these adverse prognostic features, BRCA1-related HBC patients have paradoxically lower recurrence rates than Other HBC patients. The excess of TLG cancers in the "Other" HBC group may be associated with BRCA2 linkage.

DNA ploidy, S-phase, and steroid receptors in more than 127,000 breast cancer patients

Several potential prognostic factors are available today for patients with breast cancer, and many more are being identified and studied. To evaluate the clinical utility of these factors, it will be necessary to measure them on a large number of patients, and then follow these patients so that multivariate survival analyses can be performed. The Oncology Research Network was established in 1986 by the University of Texas Health Science Center at San Antonio and Nichols Institute Reference Laboratories in order to evaluate the clinical utility of new prognostic factors for patients with primary breast cancer. The first generation of prognostic factors included steroid receptors, along with DNA ploidy and S-phase fraction determined by flow cytometry. Currently, laboratory results have been obtained from more than 127,000 patients, and follow-up information is available on a subset of more than 25,000 of these patients. S-phase fraction was related to the ploidy status of the tumor. An increased incidence of aneuploidy and higher S-phase fractions were found in estrogen and progesterone receptor negative tumors, tumors from patients with positive axillary lymph nodes, tumors greater than 2 cm in diameter, and patients younger than 35 years of age. Preliminary survival analyses suggest that S-phase fraction and DNA ploidy, in combination with other prognostic factors, are powerful predictors of early disease relapse. The Oncology Research Network provides an important resource for examining the clinical significance of new laboratory assays and for expediting improvements in existing laboratory techniques.

Significance of S-phase fraction and hormone receptor content in the management of young breast cancer patients

Tumours from 336 breast cancer patients under the age of 50 were analysed for hormone receptor content and by DNA flow cytometry. Sixty-six percent of the tumours were positive for estrogen receptors (ER), 60% were progesterone receptor (PR) positive and 42% showed DNA diploid profiles. DNA hypodiploid tumours were relatively frequent (7%), especially in patients aged 40 years or less (11%). S-phase fraction (SPF), with a mean of 10%, correlated significantly with receptor status, DNA ploidy, lymph node status, tumour size and age. With a median follow-up period of 34 months, the distant recurrence-free interval was independently predicted by lymph node status, tumour size, SPF and PR content. Amongst the 212 patients who had not received adjuvant systemic treatment, receptor status was, in addition to lymph node status and SPF, independently related to distant recurrence rate. A high SPF identified a subgroup with high recurrence rate, comprising approximately one third of the node-negative patients. Similarly, the one third of node-positive patients who had PR-positive tumours with a low S-phase fraction formed a subgroup with low recurrence rate. We conclude that hormone receptor assays and DNA flow cytometry should be useful tools in the management of breast cancer patients less than 50 years of age.

Oral contraceptives and breast cancer. A review with some comments on mathematical models

The relationship between oral contraceptive use and breast cancer is discussed on the basis of information given in review articles, meta-analyses and editorials emphasizing methodological problems related to bias and confounding. Over the last few years a shift in opinion has taken place. Most reviewers now consider that long-term use of oral contraceptives is associated with an increased risk of premenopausal breast cancer and no effect among postmenopausal breast cancer. This result is compatible with an additive effect (in rate measure scale) of oral contraceptive use on breast cancer risk.