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PubMed1999

Breast cancer risk in monozygotic and dizygotic female twins: a 20-year population-based cohort study in Finland from 1976 to 1995.

This population-based study investigated the occurrence of breast cancer over a 20-year period in a cohort of monozygotic (MZ) and dizygotic (DZ) twins in Finland. Altogether, 13,176 female twins of known zygosity who were living in Finland at the end of 1975 were identified from the Finnish Twin Cohort Study and followed-up for cancer through the Finnish Cancer Registry for the years 1976-1995. Standardized incidence ratios (SIRs) were calculated, based on national cancer incidence rates. The relative risk of breast cancer for MZ twins compared to DZ twins was decreased [SIR(MZ)/SIR(DZ) ratio = 0.78; 95% confidence interval (CI), 0.58-1.0]; the decreased risk for MZ twins (SIR = 0.76; 95% CI, 0.58-1.0) accounted for this result, whereas the risk for DZ twins did not differ from the general population risk (SIR = 0.98; 95% CI, 0.84-1.1). There was no risk decrease among MZ twins in other cancers related to reproductive behavior; i.e., number of children and age at first birth seem not to explain the decreased risk of breast cancer. Our results, which are in line with earlier studies on the same topic, suggest that prenatal influences or postnatal behavioral factors may protect MZ female twins from breast cancer.

Adolescent↗
PubMed1998

[Epidemiology of breast cancer].

Breast cancer is the predominant cancer among women in France, accounting for about 32% of all new cases. Increasing incidence rates are reported by the regional registries, while the national mortality rates seem to reach a plateau particularly in the women under 65 years old. During the last 20 years the survival of patients with positive nodes has been increased. Nulliparity and increasing age at first birth are well established risk factors as well as age at menarche and age at menopause (OR approximately equal to 2). The role of other risk factors such as hormone replacement therapy, oral contraception, lactation remain controversial (OR approximately equal to 1-1.5). Total calories consumption, obesity after menopause, and alcohol are possible risk factors (OR approximately equal to 2-3). Previous irradiation of thorax, proliferative benign mastopathy are increasing the risk of breast cancer (OR approximately equal to 3-5). Consumption of fruits and vegetables, as well as physical exercise could decrease the risk (OR approximately equal to 0.6). There is a strong heredity component for about 10-15% of the cases. Approximately in half of these cases a mutated gene (Brca1, Brca2 ...) have been identified.

Adult↗
PubMed1998

Sexual culture of gypsy population.

The number of the gypsy population in Bulgaria has increased with 85,419 persons for the period 1965-1992 that is higher than the prognosis made about a mean rate of increase of 2000 persons per year. The aim of the present study was to describe demographic changes and main problems of intrafamily planning of this population. The primary information was collected by the method of indirect individual inquiry as the opinion of 495 gypsy women at reproductive age was studied. Sexual behaviour of this ethnic group was analysed with the needs and social, economical and cultural status. The results have revealed particular patterns of the sexual behaviour about the beginning of early sexual relationships, use of modern contraceptive methods, number of abortions, etc. It should be noted that only about 61% from the gypsy women use any kind of contraceptive measures but irregularly. The mean number of abortions per woman was 2.41 and about 33% of women had undergone 3 and more abortions-on-demand. The low level of sexual culture and the lack of knowledge about the methods of contraception have led to early first births, high proportion of abortions-on-demand and high rate of increase of the population among gypsies. This may be explained by the life-style traditions of this ethnic group and their intention to the multi-child model of the family. We must emphasize the lack of modern information system for early warning, publicity and formation of sexual habits of this population.

Abortion, Induced↗
PubMed1999

Menstrual and reproductive risk factors for ischemic heart disease.

The role of hormones in ischemic heart disease is of considerable interest, but limited data are available pertaining to risk factors associated with endogenous hormones. We examined the association between menstrual and reproductive factors and ischemic heart disease in a cohort of 867 white, college-educated women who prospectively recorded menstrual cycle data for at least 5 years from their early 20s through their menopause. Ischemic heart disease history was obtained from a self-administered (N = 714) or proxy-administered (N = 153) questionnaire completed at a mean age of 73 years. The analysis included 44,899 person-years of follow-up and 45 cases of myocardial infarction, angioplasty, heart bypass surgery, or ischemic heart disease-related mortality. Ischemic heart disease risk decreased with increasing age at menarche (age-adjusted RR 0.76 per year, 95% CI = 0.60-0.95). Considering menstrual cycle characteristics ages 28-32, there was little overall association with length, variability, or bleeding duration. Ischemic heart disease risk increased with later age at first birth (age-adjusted RR 2.90 for ages 33-43 compared with 25-29) and later age at last birth (age-adjusted RR 3.79 for ages > or =40 compared with 35-39), but there was little association with high parity.

Age Distribution↗
PubMed1999

Serum concentrations of organochlorine compounds and the subsequent development of breast cancer.

A nested case-control study was conducted to examine the association between serum concentrations of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), the primary metabolite of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), and polychlorinated biphenyls (PCBs) and the development of breast cancer up to 20 years later. Cases (n = 346) and controls (n = 346) were selected from cohorts of women who donated blood in 1974, 1989, or both, and were matched on age, race, menopausal status, and month and year of blood donation. Analyses were stratified by cohort participation because median DDE and PCB concentrations among the controls were 59 and 147% higher in 1974 than 1989, respectively. Median concentrations of DDE were lower among cases than controls in both time periods [11.7% lower in 1974 (P = 0.06) and 8.6% lower in 1989 (P = 0.41)]. Median concentrations of PCBs were similar among cases and controls [P = 0.21 for 1974 and P = 0.37 for 1989 (Wilcoxon signed rank test)]. The risk of developing breast cancer among women with the highest concentrations of DDE was roughly half that among women with the lowest concentrations, whether based on concentrations in 1974 [odds ratio (OR), 0.50; 95% confidence interval (CI), 0.27-0.89; P(trend) = 0.02] or in 1989 (OR, 0.53; 95% CI, 0.24-1.17; P(trend) = 0.08). The associations between circulating concentrations of PCBs and breast cancer were less pronounced but still in the same direction (1974: OR, 0.68; 95% CI, 0.36-12.9; P(trend) = 0.2; and 1989: OR, 0.73; 95% CI, 0.37-1.46; P(trend) = 0.6). Adjustment for family history of breast cancer, body mass index, age at menarche or first birth, and months of lactation did not materially alter these associations. These associations remained consistent regardless of lactation history and length of the follow-up interval, with the strongest inverse association observed among women diagnosed 16-20 years after blood drawing. Results from this prospective, community-based nested case-control study are reassuring. Even after 20 years of follow-up, exposure to relatively high concentrations of DDE or PCBs showed no evidence of contributing to an increased risk of breast cancer.

Adult↗
PubMed1999

Influence of family tradition on reproductive behavior of Gypsy population.

INTRODUCTION: Stability of traditional opinion in different ethnic communities determines to a great degree the demographic behavior of their members. AIM: To analyze the influence of family traditions and system of values on the reproduction of gypsy population. MATERIALS AND METHODS: The opinions of 495 Gypsy women in reproductive age was studied by direct individual questionnaire. The answers characterizing the reproductive behavior of two successive generations were analyzed. The following statistical analyzes were applied: descriptive statistics, chi-square and t-tests. All p-values are two-tailed. The statistical analyses were made on a PC using SPSS 5.0.2. RESULTS: Mean age at marriage in different generations under study was similar (it is 15.50 +/- 0.10 years in the present generation vs. 15.58 +/- 0.09 years in the previous generation, p > 0.05). The same is valid for the mean age at the first birth (16.98 +/- 0.11 years vs. 17.04 +/- 0.10 years, respectively, p > 0.05). However, there was a statistically significant difference in the mean number of live-births between the generations (2.37 +/- 0.05 vs. 4.10 +/- 0.09, respectively, p < 0.001). The latter finding might be explained by fact that the women from the present generation are still in their reproductive period. CONCLUSION: It is obvious that family traditions may have, to a certain extent, an influence on the patterns of reproductive behavior in gypsy population. These traditions represent an indispensable part of their lifestyle and their intentions to have many children.

Adult↗
PubMed2000

[Differences when it comes to induced abortion in different Danish counties].

The paper describes actual regional differences in the rate of legally induced abortions as well as different trends observed since abortion on request was introduced in 1973. The analysis is primarily based on national population-based and published data from the Registry of Legally Induced Abortions in the National Board of Health, supplemented with data from a linking with the Fertility Database. The rate of abortion has shown regional differences, being at the highest level in counties with large cities. The observed differences are related to higher age at first birth and fewer children per woman in counties with a high frequency of abortion. A large part of the differences are observed among women below age 30-35. Over time developments have shown a parallelism between the counties, even though some differences have also been observed as regards both induced abortion and fertility. Various background factors do not seem to have the same impact on the choice of induced abortion in all counties.

Abortion, Legal↗
PubMed2000

[Present state and future in reproductive medicine].

It has been almost 21 years since the first birth of IVF baby and rapid advances in assisted reproductive technology (ART) have taken place. Today, several new technology have been developed such as microfertilization and cryopreservation of embryos and ART has become an important and popular tools for treatment of infertility patients with several causes. However, the take home baby rates have still been low around 15%. To improve the results in ART programs, the improvement of embryo viability and the solution of problems of implantation have been required. Recently, sequential culture media for production of high quality blastocysts have been developed and results have been as good as with co-culture. These culture media are now commercially available. Several authors reported that higher clinical pregnancy rate was achieved and high-order multiple pregnancy can be eliminated with blastocyst transfer. It has been expected that blastocyst transfer would become the means to solve the major problem that ART has faced such as the low take home baby rates and high-order multiple pregnancy.

Female↗
PubMed2001

Acculturation and breast-feeding intention and practice in Hispanic women on the US-Mexico border.

OBJECTIVES: To explore the extent to which acculturation indicators predict both breast-feeding history and intentions among Mexican-American mothers having their first births, and among those having subsequent births. DESIGN: Cross-sectional survey in a hospital post-partum unit. METHODS: 3,036 Hispanic women were interviewed post-partum in their hospital room. A survey was administered in English or Spanish, and included questions about prenatal care, diet, work exposures, contraceptive use, and breast-feeding history and intentions. For the purposes of this study, acculturation was measured using a series of indicators including language spoken at home, language ability, country of birth, and country in which last schooling was received. RESULTS: Previous breast-feeding was significantly associated with educational attainment, speaking both English and Spanish at home, having had prenatal care during the previous pregnancy, and with both country variables (country of birth and country where finished school). Women with less education, women who were single, and women who did not receive any prenatal care were less likely to intend to breast-feed than were women with a college education, women with a partner, and women who received any prenatal care. Women born in Mexico (for multiparous women), or having finished school in Mexico (for primiparous women), were more likely to intend to breast-feed. CONCLUSIONS: Acculturation is associated with breast-feeding history and intention to breast-feed. Acculturation is a complex construct and traditional measures of acculturation based on language preference may not be as useful on the US-Mexico border. It is recommended that further study be conducted to determine what factors prevent women from breast-feeding, even though they intend to do so, especially in multi-cultural communities like those around the US-Mexico border.

Acculturation↗
PubMed2000

Cloned mice derived from somatic cell nuclei.

In 1997, a cloned sheep "Dolly" was produced by nuclear transfer of somatic cell. The first birth of cloned mice derived from some somatic cells were succeeded in 1998. At present, it is shown that somatic cells, cumulus cells, fibroblasts and Sertoli cells can be used to the study of cloned animal as nuclear donor. In this study investigation was designed to compare with efficiency on the production of cloned embryos by using the microinjection and the electrofusion methods for nuclear transfer. Oocyte enucleation was performed with a micromanipulator. The oocyte was held by holding pipette, and was enucleated using a beveled pipette. Microinjection method: Cell's nucleus injection was carried out by piezo-micromanipulator. Cytochalasin B treated cumulus cell was aspirated into a injection pipette, and was broken its plasma membrane using the injection pipette. Then, the cumulus cell was injected into the enucleated ooplasm directly. Electrofusion method: The cell was aspirated into a beveled pipette, and then an aspirated cell was inserted into perivitelline space. Then, the pair of enucleated oocyte and cell was fused using electrical cell fusion apparatus. The reconstituted embryos were activated after nuclear transfer using St2+. Reconstituted embryos had been produced by the microinjection showed the embryonic development to over 8-cell stages. But, the rate of fragmentation of reconstituted embryos by the microinjection showed a little high rate in comparison with the electrofusion. When some reconstituted embryos by the microinjection were transplanted to pseudopregnant females' oviduct, 9 fetuses were observed at 14 days post coitum.

Animals↗
PubMed1975

A method for the estimation of fecundability.

A new method for the estimation of the mean and variance of fecundability is described. The data input required for this procedure is the distribution of the interval from marriage to first birth, or from the resumption of the conception risk after contraction to the subsequent birth. The estimates of the mean and variance of fecundability are obtained by fitting a model to the observed interval distribution. To test the method, it is applied to data from five historical populations. The fecundability means in these populations ranged from 0.18 to 0.31 while the co-efficients of variation all had values near 0.56. A short method for the estimation of the mean of fecundability based on the same model, but not requiring a computer, is also presented.

Abortion, Spontaneous↗
PubMed2001

Breast cancer risk factors and HER2 over-expression in tumors.

Few epidemiologic studies have investigated the potential role of HER2 in the etiology of breast cancer. We conducted a case-case study of 156 women with incident, invasive ductal carcinoma. Multivariate unconditional logistic regression was used to estimate the odds ratios for a HER2 positive tumor in relation to known and putative risk factors of breast cancer. HER2 status was detected by immunohistochemistry on archival tissue. HER2 positive breast cancers tended to be larger and were less likely to express estrogen receptors, and the incidence rate was higher in patients less than 40 years old. We observed an association between a self-reported history of benign breast disease and the occurrence of HER2 positive breast cancer (OR, 2.1;95% CI, 1.1-4.1). We did not detect associations between HER2 over-expression and family history of breast cancer, parity, late age at first birth, ever having breast fed an infant, or oral contraceptive use. Our findings merit consideration in light of recent evidence of HER2 amplification or over-expression in benign breast disease. Should the link to breast cancer be established, HER2 positive benign breast disease could potentially serve as an early marker for preventive intervention.

Adult↗
PubMed2002

Lighting during the day and night: possible impact on risk of breast cancer.

Risk of breast cancer varies by about 5-fold among societies, and incidence and mortality have been increasing worldwide for many decades. Migrants from low-risk Asian societies to the U.S. suffer elevated risk of breast cancer in their own lifetimes, and the second or third generation Asian-Americans attain the high risk of the multi-generational European immigrants [1,2]. Something about a modern Western lifestyle apparently increases risk dramatically. Madigan et al. [3] estimate that 41% of the new U.S. cases of breast cancer are explained by "known risk factors"; these include the reproductive factors of age at first birth, menarche, menopause. They ascribe about 30% to reproductive factors when they are analyzed alone. "High income" is estimated to account for about 19% when analyzed by itself. The 41% is an analysis taking all the factors together, and since they are related, the total is less than the sum of estimates for the individual items. By itself, "High income" has no biological interpretation and must reflect attributes of lifestyle and/or environment that increase risk. So, the proportion of breast cancer cases in the U.S. that can be accounted for by known biological risk factors is about one third. Therefore, at least half of breast cancer risk in the U.S., and other Westernized/industrialized societies, is in excess of that found in non-industrialized societies and is without any agreed-upon explanation. Many candidate factors exist, each with a cadre of proponents. The sum of these may turn out to explain the bulk of the excess risk in modern societies. On the other hand, they may not, and worse, may fall woefully short.

Breast Neoplasms↗
PubMed2002

Breast cancer in a multiethnic cohort in Hawaii and Los Angeles: risk factor-adjusted incidence in Japanese equals and in Hawaiians exceeds that in whites.

Few data exist on the extent to which the differences in breast cancer risk between "racial-ethnic" groups in the United States (US) are "explained" by differences in their distribution of risk factors. We have determined this for African-American (AA), native Hawaiian (NH), Japanese-American (JA), Latina-US-born (L-US), Latina-non-US-born (L-NUS), and white (W) women using prospective incidence data on 88,712 postmenopausal women recruited in 1993-1996. We identified 1,757 incident breast cancer cases through 1999 among these women (1,116 cases after excluding women with a simple hysterectomy or missing risk factor data). Data were available on seven "known" risk factors: ages at menarche and first birth; parity; age at and type of menopause; weight; hormone replacement therapy use; and alcohol consumption. The relative risks (RRs) of breast cancer (with the RR in Ws set to 1.0) for the groups were as follows: W = 1.0; AA = 0.78; NH = 1.33; JA = 0.99; L-US = 0.77; and L-NUS = 0.60. After adjustment for the risk factors, the RRs were as follows: W = 1.0; AA = 0.98; NH = 1.65; JA = 1.11; L-US = 0.95; and L-NUSB = 0.84. The slightly greater risk of the JAs compared with the Ws is in sharp contrast to the very low breast cancer rates that were observed in "traditional" Japanese women and in early Japanese migrants. The adjusted RR of NHs is 65% greater than that of Ws, and that of migrant Latinas is 16% lower than that of Ws. Elucidating the causes of the high rates in NHs is now a major focus of our efforts.

Aged↗
PubMed1991

China unveils its monumental two per thousand fertility survey.

The author reports on China's 1988 Two per Thousand Survey, using information from papers presented at an international seminar in Beijing that focused on fertility and contraception. "Seminar papers confirmed the high quality of the survey and its potential for research on topics ranging from rates of sterility to the demography of Tibet. They also suggested that family planning in China is moving on to a wider agenda. The interest of family planners is turning to issues of health, motivation for family planning, and contraception prior to a couple's first birth."

Asia↗
PubMed1988

[[Determinants of the decline in the total marital fertility rate in the early 1970s]].

The author examines "the relationship between the total marital fertility rate and the cohort marital fertility pattern in Japan since the late 1960s. We calculated parity-duration-year-specific marital fertility rates and conducted comparisons among them cohort by cohort and period by period. In addition, we carried out a decomposition of the change in total marital fertility rates into the tempo and quantum components on two different assumptions about future completed fertility. By calculating the first-birth, second-birth and third-birth timing indices, we could specify the effect due to a change of birth timing for each parity on the variation of the total marital fertility rate." It is found that "given that the drop in the total fertility rate in the early 1970s is largely attributable to a decrease in the total marital fertility rate, most of the drop in the total fertility rate in this period is also attributable to the change in second-birth timing over marriage cohorts since the middle 1960s and the temporal disturbance in second-birth timing in marriage cohorts of the early 1970s." (SUMMARY IN ENG)

Asia↗
PubMed2002

Case-control study of increased mammographic breast density response to hormone replacement therapy.

Previous studies have demonstrated an association between current hormone replacement therapy (HRT) use and increased mammographic breast density. Many of these studies have also shown that only 20-35% of women initiating HRT respond in this manner. This subgroup of HRT responders may be at an increased risk of breast cancer. We performed a case-control study to investigate how women who experience increased density in response to HRT (cases) differ from women who do not experience an increase in density with HRT use (controls) with regard to breast cancer risk factors, type of HRT, weight change, and baseline breast density. Participants were female residents of Olmsted County, Minnesota who received routine screening mammograms at the Mayo Clinic. Cases included 172 women identified between the years 1998 and 1999 by Mayo radiologists as having a HRT response. Controls were women who did not experience an increase in mammographic density with HRT use and were matched to cases on age (+/-3 years), menopausal status, duration of HRT, month of initiation of HRT, and months between baseline and follow-up mammograms. Mammograms were obtained from cases and controls before and during HRT therapy. Breast density was read as a four-category Bi-Rads density grade measure and as a quantitative percentage estimate, using a computer-assisted method. Risk factor information was obtained from both chart review and a mammography database of patient-provided information. There was no association between HRT response and first-degree family history of breast cancer [odds ratio (OR), 0.8; 95% confidence interval (CI), 0.4-1.5], parity (OR, 0.8; 95% CI, 0.4-1.7), later age at first birth (OR, 0.8 for age >25 years versus nulliparous women; 95% CI, 0.4-1.8), or history of biopsy (OR, 0.9; 95% CI, 0.6-1.5). There was also no association with baseline weight or change in weight between a woman's baseline and follow-up mammograms. However, there was evidence of an association between HRT response and type of HRT used; women who experienced a mammographic increase in density with HRT had 2.3 greater odds (95% CI, 1.4-3.7) of having taken estrogen-progestin combined therapy than estrogen alone, compared with controls. This association was stronger among women with a baseline weight below the median (OR, 5.2; 95% CI, 1.6-17.6). Also, there was an inverse association between HRT response and baseline density. Because all risk factors examined accounted for only 26% of the variation in the HRT response, genes or other unmeasured factors are thought to be involved.

Aged↗