Search

A matched case-control study was done on 175 pathologically proven new cases of female breast cancer from National Taiwan University Hospital from February 1993 to June 1994 and 457 hospital controls individually matched for age and date of admission. Height and weight during one year before the first full-term pregnancy and one year before admission were collected from a questionnaire interview. Body mass index (BMI) (kg/m2) was derived accordingly. Demographic and reproductive characteristics, and family history of breast cancer were collected and adjusted as potential confounders. Conditional multiple logistic regression analysis was used to estimate the effect for each risk factor regarding body size of different ages. After adjustment for potential confounders, higher weight and BMI during one year before first full-term pregnancy were associated with a moderately lower risk of breast cancer especially in the premenopausal group. The heaviest group (> or = 65 kg) during one year before admission also had a moderately lower breast cancer risk. Height did not show any significant association with breast cancer risk. Weight and BMI gain were associated with an elevated breast cancer risk in the postmenopausal group but with wide confidence limits. The results of this study imply that adipose tissue may interfere with ovarian endocrine in the younger age group, and that there is increased hormonal production after obvious weight gain.

The incidence of breast cancer is increasing rapidly in Taiwan but is still low compared with western countries. The impact of body size factors in western countries inspired us to have a case-control study. A matched case-control study was done on 122 pairs of incident cases of female breast cancer and community controls. Body height and weight were collected from a questionnaire interview and used to derive the body mass index (kg/m2). Demographic and reproductive characteristics were collected and controlled as potential confounders. Conditional multiple logistic regression analysis was used to estimate the multivariate-adjusted odds ratios for each risk factor regarding body size. After adjustment for age, schooling years, age at menarche and parity; body weight and height were positively related to postmenopausal breast cancer but not significantly related to the risk of premenopausal breast cancer. The odds ratios for body mass index were less prominent. Women with a higher breast stem cell mass resulting from better adolescent nutrition had a higher risk for breast cancer; and postmenopausal obesity may increase the breast cancer risk through the increased conversion of adrenal androstenedione to estrogen in adipose tissue after menopause.

Background: Breast cancer is increasing rapidly in Taiwan. A geographic variation, international comparison and migrant study has become essential for the development of hypotheses to account for this., Materials and Methods: Age-adjusted mortality rates of breast cancer patients from all precincts and townships of Taiwan were calculated for a geographic variation study, and summarized for an international comparison. Age-specific and adjusted incidence rates of breast cancer in Taipei City were used for a migrant study., Results: Age-adjusted mortality from breast cancer was highest in the Taipei and lowest in aboriginal areas. Oriental countries have significantly lower mortality rates from breast cancer but the incidence of breast cancer among Chinese women, and the difference between younger and older age groups has increased together with the degree of westernization in residential areas. Chinese women were found to have lower incidence rates than white women of the same area. We concluded that diet, reproductive behavior, and hereditary factors are involved in the development of breast cancer.

The objective of this study is to develop a hypothesis about the carcinogenesis of breast cancer from a descriptive analysis. This study is an application of the age-period-cohort model (APC model) on the mortality rate of breast cancer in Taiwan over the period from 1964 to 1991. Age-specific and age-adjusted mortality rates are described and then age, period, and cohort effects are separately analysed. (Female) breast cancer mortality data in Taiwan from 1964 to 1991 were abstracted from the annual reports of the Taiwan Provincial Department of Health. The population data in Taiwan from 1964 to 1991 were abstracted from the demographic data in Taiwan compiled by the Ministry of Interior, R.O.C. The results show that both age-adjusted and age-specific mortality rates of breast cancer are increasing over the study period and with birth cohorts. The bimodal pattern becomes more apparent in later periods. The Clemmensen's hook is five years later both in the descriptive study and the APC analysis. The findings suggest a possible role of later life overnutrition as the major period effed (promoter) and a change in reproductive behavior as the cohort effect (initiator). The application of the APC model also denotes the possible role of later life overnutrition and a change in reproductive behavior after the birth cohort of 1929. These findings may help us develop hypotheses of carcinogenesis of breast cancer.