The Report Of Breast Diseases Screening In Shandong Province And Breast Cancer Risk Factors Analysis

BackgroundIn recent years, the incidence of female breast cancer has been significantly increasing. Breast cancer is one of the most common malignancies in women. It is a serious threat to women's lives and health. Worldwide,1.2 million women are diagnosed with breast cancer and nearly 500,000 people die from breast cancer each year. How to take effective measures to restrain the sustained, rapid rising of the female breast cancer incidence is a hot and difficult work. European and American countries'breast cancer prevention work mainly adopted the "disease census-- set up high-risk groups screening model-- provide objective quantitative index which can be applied widely in patients at high risk of screening -- intervention to regulate and monitor " mode. The 1960s, the United States gradually set up the Breast Cancer Detection Demonstration Project (BCDDP). American women breast cancer risk factors was established in accordance with the results of BCDDP, and set up the Gail model. After almost 10 years verification and adjustment process, in 1998, FDA approved that the Gail-2 model could be used in breast cancer risk assessment. If people score more than 1.66%, it was defined as risk group. If more than 5%, it was defined as high-risk group. The risk groups were given close monitoring and chemical drug intervention. After this project implementation, the incidence of breast cancer has declined. From 1999-2006, the incidence of breast cancer descended by 2.0% each year with 141/100,000 people in 1998, and 128/100,000 people in 2005. Now Britain, Italy and other countries are doing the similar work in order to reduce the incidence of breast cancer. Because breast cancer incidence, risk factor, age of onset and so on had significant regional differences, the standardized incidence rates between different countries or different areas of the same country were different. There was no national census of breast disease in China, and only Beijing, Tianjin and Shanghai and other big cities had complete information. Since the 1970s, there had been no large-scale surveys or nationwide disease surveillance for breast cancer. In recent years, with the increasing of the incidence of breast cancer, more and more health administrative departments and clinical workers organized breast disease census work. Because disease census work needed to invest a lot of human, material and financial resources, there were not big enough census range and sample size to find the related risk and protection factor of breast cancer in our country, and also couldn't set up the screening model for high-risk people of breast cancer that conforms to our country population characteristics. Our group investigated 61,102 women in six cities of Shandong province with the help of Key Clinical Project of Ministry of Health. We hoped to clear the breast disease's situation of Shandong province, and complete preliminary work for establishment the screening model for high-risk people of breast cancer accord with the female physiology and social characteristics of Shandong province.ObjectiveBased on a large-scale cross-sectional epidemiological survey, the study was to establish the breast disease database of Shandong Province and to obtain the physiological characteristics, data of socioeconomic factors and prevalence status of breast diseases. With the help of the above database, to analyse the risk and protective factors of breast cancer for females of Shandong Province, and to provide supports to health administration departments for police making of breast cancer prevention.Methods1. Study populationRandom samples were obtained through multi-stage stratified cluster sampling between July 15 and September 15,2008. The target population included 25-to 70-year-old females of the Han ethnic group in Jinan, Zoucheng, Longkou, Yishui, Gaotang and Gaomi. With the help of local disease control centers, birth control committees, subdistricts and villagers committees, counties or regions were randomly selected from each sampling areas.2. ImplementationData were collected through in-person interviews based on a self-designed structured questionnaire and breast examinations by breast professionals. The questionnaire included six aspects gathered from patient interviews:(1) demographic characteristics: age, marital status, education, occupation, household income, height, body weight, financial status and social status; (2) female physiological and reproductive factors: age at menarche, age at menopause, menstrual cycle history, childbearing history, breastfeeding methods, abortions or miscarriage, contraceptive methods and use of contraceptive medicine; (3) medical and family history:primarily breast-related diseases and family history of breast cancer; (4) dietary habits:frequency of the intake of various types of food; (5) lifestyle habits:smoking (including passive smoking), alcohol intake, tea intake, physical exercise and mental and psychological conditions (the items under psychological status were summed to calculate the overall life satisfaction and current life satisfaction scores); (6) breast-cancer-related knowledge: risk factors for breast cancer and early signs and symptoms of disease (the cumulative scores of these relevant items were counted as the related knowledge score and behavioral prevention score). With the exception of the basic demographic information, all questions had multiple-choice responses and attempts were made to quantify or categorize the answer choices (e.g., yes/no or 1/2/3/4). After the interviews, clinical breast examination was performed independently by two physicians. The clinical breast examination consisted of two components:a basic breast examination (including visual examination and palpation) and standardized auxiliary diagnostic test, such as an ultrasound and/or mammogram, for survey subjects with suspected disease on physical exam. If palpable or suspicious breast nodules or masses were found during any physical examination, further auxiliary diagnostic imaging, such as an ultrasound and/or mammogram, was performed. And finally, a consultation was held to determine whether a biopsy was needed for a patient. Newly identified breast cancer cases and those diagnosed within the last 10 years were both documented, and the pathological results, including estrogen receptor (ER) status, progesterone receptor (PR) status, lymph node status, tumor size and clinical stages were acquired from the hospitals where operations were done. And, the nearest neighbors of the patients, who were healthy and had no blood relationship with the patients, were selected as the control group in accordance with the 1:2 principle. The matching factors were age (same age±2 years) and location (neighbor or co-worker in the same region).3. Database establishment and statistical analysisThe database was established using the software EpiData3.1, and double data entry was performed by specially-trained personnel. Epidata is easy to use; with a data input interface the same as the written questionnaire, allowing side-by-side checks for accuracy. After preliminary data and logic checking, the database was converted into SPSS format. Descriptive analyses were used to examine the distribution of female breast cancer in the population by age, occupation, education, marital status, socioeconomic status and district. Frequencies and percentages of variables were calculated. Statistical methods, including t-test,χ2 test, and univariate and multivariate logistic regression analyses, were used to screen for the risk factors for breast cancer. All data analyses were performed using SPSS16.0.Results1. Study populationA total of 61136 females were registered and interviewed, and 34 subjects with incomplete information were excluded, giving a total study population of 61102 (sampling concordance rate:97.84%). All subjects were selected from Jinan, Zoucheng, Gaotang, Yishui, Gaomi and Longkou of Shandong Province, containing sites in the Yellow River basin and sites in coastal areas, mountains, plains and downtowns. In between,7934 subjects were from urban areas and 53168 from rural areas, with an urban/rural proportion of 1.0/1.5.2. Positive signs by physical examinations and disease diagnosisThe most common positive signs during breast inspection and palpation were as following:nipple inverted (n=1027,1.27%), nipple discharge(n=1590,2.6%), skin affected (orange peel-like changes, dimpling) (n=17,0.2%), breast pain (n=426, 0.7%), palpable lumps (n=1333,2.2%), palpable large or hard axillary lymph nodes (n=389,0.6%). Patients with the above positive signs received breast ultrasound examination, and some received biopsies. The distribution of pathological results was as following:hyperplasia (n=13247,21.68%), mammary duct ectasia (n=147,0.24%), fibroadenoma (n=341,0.56%), breast cancer (n=154), among which 130 (84.4%) were diagnosed within the last 10 years and 7 were identified in this survey, and other diseases (n=85,0.63%).3. Breast cancer characteristicsThis study found 154 cases of breast cancer, with a prevalence rate of 252.04/100,000 and a standardized incidence rate of 181.9/100,000 (adjusted based on the 2007 China's National Population Age Structure). Among these breast cancer cases,130 were diagnosed within the last 10 years, with an mean age at diagnosis of 50.94 years old (SD=8.59). from rural areas and 51 from urban areas; The prevalence of breast cancer of urban and rural area were 340.31/100 000 and 238.87/100 000, respectively, with statistical differences (p=0.054). The high peak of age at diagnosis were between 45 and 55 years old. And among those breast cancer cases diagnosed within the last 10 years, patients diagnosed as breast cancer between 2003 and 2008 were obviously more than those between 1999 and 2002. And especially in the last 3 years,98 patients were diagnosed as breast cancer, taking 75.38% of all, indicating an obvious increase trend in the prevalence of breast cancer in Shandong Province.4. Problems found during survey in rural areasBy the name of breast disease survey, some medical establishments sold drugs to peasants and gained economic profit. As a result, public surveys were not well accepted and epidemiology survey was somehow influenced. Same phenomenon also exsited in other survey of chronic diseases such as hypertension and diabetes.5. Risk factors of breast cancerBy the 2 matching factors, age and locations, breast cancer groups and control groups were matched by 1:2. Byχ2/t analysis, no statistical difference was observed in the following factors between 2 groups, education level, economic status, social status and family income (p>0.05); and no statistical difference was observed in the following factors of physical characteristics:age at menarche, menstrual pattern, first age at full-term birth, miscarriage times, menopausal status, breastfeeding, oral conceptives, history of personal breast hyperplasia, breastfeeding period, accessory breast, inverted nipple (p>0.05), and differences were observed in the birth times, family history of breast cancer and history of benign breast diseases(p<0.05). Conditioned univariate logistic regression analysis identified 5 variables related to breast cancer: history of benign breast tumor (OR=6.0,95%CI:1.62-22.16), economic status (OR=1.69,95%CI:1.03-2.77), birth times (OR=0.38,95%CI: 0.19-0.74), family history of breast cancer (OR=6.0,95%CI:1.21-29.73) and BMI (OR=1.42,95%CI:1.05-1.92). And conditioned multivariate logistic regression analysis showed:BMI (OR=1.51,95%CI:1.1-2.07), birth times (OR=0.38, 95%CI:0.2-0.76) and history of benign breast diseases(OR=5.53,95%CI: 1.48-20.63).Conclusion1. There was an increase and younger trend in prevalence of breast cancer in Shandong Province.2. Epidemiology survey and prevention of breast disease in rural areas should be enforced and standardized3. history of benign breast tumor, economic status, birth times,family history of breast cancer and BMI are the risk factors of breast cancer for females of Shandong Province, especially BMI, birth times and history of benign breast diseases.4. In this study, no statistical difference was observed between case and control groups in the following factors:breastfeeding history, age at menarche, age at menopause, miscarriage and age at first full-term birth.