The Developing Nature of Menstrual and Reproductive Factors Associated with Breast Cancer Risk among Women in an Urban Region of China.

Abstract

Abstract Introduction: The incidence rate of female breast cancer has increased rapidly over the past 20 years in China. It has become the leading cause of newly diagnosed cancer and a major cause of mortality among women in some large Chinese cities with higher socio-economic status. This was partly explained by the change of lifestyle and reproductive risk factors. However, little data exists on the extent to which the menstrual and reproductive factors with breast cancer risk have changed in other less developed Chinese cities.Method: One cross sectional study was conducted in urban region of Taiyuan of China from September 2008 to March 2009. One thousand and five hundreds healthy women were invited to complete a self-administered questionnaire. Participants' characteristics, including age, education, occupation, weight, height, age at menarche, age at first birth, parity, duration of breastfeeding, and age at menopause were collected and analyzed. Study subjects were divided into six groups: younger than or equal to 20, 21 to 30, 31 to 40, 41 to 50, 51 to 60 and older than 60 years old.Results: One thousand four hundreds and twenty eight women returned the questionnaire. The response rate was 95.2%. Median age of women in this study was 39 years old (range: 16 – 86 years old). There was a 4.8cm difference in the mean height between women born in 1990s and 1940s. The average age at menarche dropped from 16 years for women aged above 60 to 14.3 years for those younger than 20 years old. The average birth rate markedly decreased from 4.4 births per woman in the 1960s to 1.1 births per woman in the 1990s. The mean age at first birth increased 5.6 years through the period from the 1940s to 1980s. The breastfeeding time significantly reduced from 20.3 months to 3.6 months over 40 years.Conclusion: This study indicates that there has been significant change in the menstrual and reproductive factors associated with breast cancer risk in the last 40 years. These changes will certainly influence the incidence rate of breast cancer in the local city. Therefore, measures are needed to enhance the awareness of breast cancer and its early-detection methods among the urban region women in China. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6068.