Breast Cancer Risk From Modifiable and Non-Modifiable Risk Factors among Palestinian Women: A Systematic Review and Meta-Analysis

Objective: Breast cancer (BC) is known as one of the deadliest forms of cancer, and it is increasing globally. Identifying risk factors for BC is a key point in developing preventive strategies to reduce its occurrence. Herein, we aimed to conduct a systematic review and meta-analysis focus on the risk factors for BC in Palestine. Material and Methods: We performed a systematic search via PubMed, MEDLINE, SCOPUS, Science Direct, Cochrane library, Emerald Insight, and Google scholar for identifying studies published on BC risk factors up to March 2021. Pooled odds ratios (OR) are calculated using fixed and random-effect models. Data were processed using Review Manager 5.4 (RevMan 5.4). Results: From a total of 73 articles, seven case-control studies met the criteria for systematic review. Meta-analysis results showed that of the known modifiable risk factors for BC, diabetes mellitus (DM) had the highest odds ratio (OR = 4.97, 95% CI 3.00- 8.25) followed by hypertension (OR = 3.21, 95% CI 1.96-5.23), obesity (BMI >30 Kg/m2) (OR = 2.90, 95% CI 2.00- 4.21), and passive smoking (OR = 1.50, 95% CI 1.12- 2.02). Controversially, breastfeeding (OR = 0.37, 95% CI 0.23- 0.61) was protective factor in BC. Of non-modifiable risk factors for BC has reached menopause had the highest odds ratio (OR = 3.74, 95% CI 2.64- 5.29), followed by family history of BC (OR = 2.63, 95% CI 1.07-6.44) and age (≥ 40 years) (OR = 2.49, 95% CI 1.43-4.34). Conclusions: The most significant predictors of BC in Palestine were DM, hypertension, passive smokers, age (>40), reached menopause, and family history of BC. Almost all these risk factors are consistent with known risk factors for breast cancer in other parts of the world.     

Modifiable (Sleeping Pattern and Stress) and Non-Modifiable Risk Factors Associated with Breast Cancer: A Matched Case-Control Study in Delhi,India

Background: An utmost increase of breast cancer burden during the last several decades was reported in Asian countries. Findings from literature confirm that risk factors of breast cancers can be modifiable and non-modifiable in nature. Objective: The present study is designed to identify specific modifiable and non-modifiable risk factors associated with breast cancer. Methods: A matched case-control study was conducted considering 187 cases as women diagnosed with breast cancer and 187 hospital-controls as women without having breast cancer visiting the hospital. Other than standard risk factors, stress is measured using Perceived Stress Scale (PSS) and stress is measured using Pittsburgh Sleep Quality Index (PSQI). Several modifiable and non-modifiable risk factors were assessed using conditional logistic regression to find out significant association with breast cancer. Results: Regular multi-vitamin uptake (OR = 3.38; 95%CI = 1.69 – 6.77; p-value = 0.001), poor sleep (OR = 11.29; 95%CI = 4.36 – 29.25; p-value < 0.001), irregular sleep (OR = 34.11; 95%CI = 10.03 – 115.92; p-value < 0.001) and severe stress (OR = 6.74; 95%CI = 3.06 – 14.81; p-value < 0.001) were found to be the highest odds ratio among all modifiable risk factor of breast cancer. Also, age at first childbirth less than 30 years (OR = 0.44; 95%CI = 0.25 – 0.78; p-value = 0.005) was found protective against breast cancer. Conclusion: In our study, stress, sleeping pattern, and regular multi-vitamin uptake were found to be significant modifiable risk factors of breast cancer. None of the non-modifiable risk factors were found to be significantly associated with the risk of breast cancer.     

Risk factors for breast cancer among young women in southern Iran

Age standardized incidence rates of breast cancer in developed countries is nearly threefold higher than in developing countries. Iran has had one of the lowest incidence rates for breast cancer in the world, but during the last four decades increasing incidence rates of breast cancer made it the most prevalent cancer in Iranian women. After adjustment for age, Iranian young women are at relatively higher risk of breast cancer than their counterparts in developed countries. The purpose of this study was to investigate some established risk factors of breast cancer in Iranian young women. A hospital-based case control study comprising 521 women with histologically confirmed, incident breast cancer and 521 controls frequency-matched by age and province of residence was conducted. Logistic regression performed to investigate associations of reproductive and anthropometric factors with breast cancer risk. In multivariate analysis, family history [odds ratio (OR): 1.61; 95% confidence interval (CI): 1.07-2.42], oral contraceptives (OC) usage (OR: 1.52; 95% CI: 1.11-2.08), low parity (OR parity ≥ 3 vs. 1-2: 0.33; 95% CI: 0.23-0.49), employment (OR: 1.83; 95% CI: 1.05-3.23) and shorter period of breast feeding (OR ≥ 37 months vs. < 37: 0.61; 95% CI: 0.44-0.84) were related to a higher risk of breast cancer in young women. This was the first study focusing on risk factors of breast cancer in Iranian young women. The trend of decreasing parity and shortened duration of breast feeding along with OC usage might partly explain the rapid rising of breast cancer incidence in Iranian young women.     

The Investigation of Risk Factors Impacting Breast Cancer in Guilan Province

Introduction: Breast cancer is multifactorial therefore more recognition of risk factors is important in its prevention. Objective: This study was conducted in order to determine the factors influencing breast cancer in women referred to health centers in Guilan province in 2015-2016. Method: In a case- control study, 225 women with breast cancer were investigated. The control group consisted of 225 healthy women of the relatives (third-rank) whose phone numbers were obtained from the patients. Data were collected through telephone interviews. Results: The risk of breast cancer raised in women who have a family history of other cancers (OR= 3.5; 95% CI= 1.96-6.6) ,exposure to X-Ray (OR= 2.5; 95% CI=1.1-5.5), having more than 4 children (OR= 2.695% CI=1.2-4.8), age more than 36 years at first pregnancy(OR=2.3; 95% CI=0.7-5.1),primary levelof education (OR= 5.4;95% CI=2.8-11.2) and inadequate intake of fruit (OR=1.5; 95% CI=1-2.2). Also, presence of the following factors reduced breast cancer risk: regular menstruation (OR= 0.66; CI=0.4- 0.9), duration of breastfeeding more than 12 months, less than 6 months and 7-12 months (OR=0.23; 95% CI=0.09-0.59 , OR=0.29; 95% CI=0.17-0.49 and OR=0.03; 95% CI=0.01-0.08) and parity (OR=0.4; 95% CI=0.27-0.83) In multiple linear regression analysis of higher education (OR=0.16; 95% CI=0.03-0.77), using contraceptives for more than 16 years (OR=2.3; 95% CI=1.4-3.9), family history of other cancers (OR=6.1; 95% CI=1.9-19.3) and a history of X-Ray exposure (OR=4.4; 95% CI=1.07-18.1) were considered as predictive factors. Conclusion: The results of this study emphasize the importance of informing women about breast cancer risk factors. So, identification of these risk factors is required as important means of prevention and treatment of breast cancer.     

Risk Factor Analysis for Breast Cancer in Premenopausal and Postmenopausal Women of Punjab,India

Objective: Amritsar, the second largest town of agrarian state of Punjab, India reports high number of breast cancer cases every year. The present study investigated the etiology of breast cancer using various obesity indices and other epidemiological factors among breast cancer patients residing in and around Amritsar city. Methods: In this case control study, risk factors for breast cancer were analyzed in 542 female subjects: 271 females with breast cancer patients and 271 unrelated healthy females matched for age as control females. Results: Bivariate analysis for risk factors in cases and controls showed a lower risk (OR=0.65, 95% CI 0.43-0.99, p=0.04) in obese cases with BMI≥25kg/m2 as compared to subjects with normal BMI. Risk factor analysis showed that parameter which provided risk for cancer in postmenopausal women was obesity and in premenopausal women was parity. Postmenopausal women with BMI (overweight: OR=0.39, 95% CI 0.17-0.92, p=0.03; obese: OR= 0.26, 95% CI 0.13-0.52, p=0.00), WC (OR=0.17, 95% CI 0.05-0.52, p=0.00) and WHtR (p=0.02) had highr risk. Premenopausal women with 3 or less than 3 children had a higher risk (OR=5.54, 95 % CI 2.75-11.19, p=0.00) than postmenopausal women when compared to women with more than 3 children. Binary logistic regression analysis revealed that low parity (≤3) substantially increased the risk for breast cancer (OR=4.80, 95% CI 2.34-9.85, p=0.00) in premenopausal women. Conclusion: Obesity, parity associated breast cancer risk and reduced breastfeeding cumulatively predispose the premenopausal women of this region to higher risk of breast cancer.     

Risk factors for uncommon histologic subtypes of breast cancer using centralized pathology review in the Breast Cancer Family Registry

Epidemiologic studies of histologic types of breast cancer including mucinous, medullary, and tubular carcinomas have primarily relied on International Classification of Diseases-Oncology (ICD-O) codes assigned by local pathologists to define histology. Using data from the Breast Cancer Family Registry (BCFR), we compared histologic agreement between centralized BCFR pathology review and ICD-O codes available from local tumor registries among 3,260 breast cancer cases. Agreement was low to moderate for less common histologies; for example, only 55 and 26 % of cases classified as mucinous and medullary, respectively, by centralized review were similarly classified using ICD-O coding. We then evaluated risk factors for each histologic subtype by comparing each histologic case group defined by centralized review with a common set of 2,997 population-based controls using polytomous logistic regression. Parity [odds ratio (OR) = 0.4, 95 % confidence interval (95 % CI): 0.2-0.9, for parous vs. nulliparous], age at menarche (OR = 0.5, 95 % CI: 0.3-0.9, for age ≥13 vs. ≤11), and use of oral contraceptives (OCs) (OR = 0.5, 95 % CI: 0.2-0.8, OC use >5 years vs. never) were associated with mucinous carcinoma (N = 92 cases). Body mass index (BMI) (OR = 1.05, 95 % CI: 1.0-1.1, per unit of BMI) and high parity (OR = 2.6, 95 % CI: 1.1-6.0 for ≥3 live births vs. nulliparous) were associated with medullary carcinoma (N = 90 cases). We did not find any associations between breast cancer risk factors and tubular carcinoma (N = 86 cases). Relative risk estimates from analyses using ICD-O classifications of histology, rather than centralized review, resulted in attenuated, and/or more imprecise, associations. These findings suggest risk factor heterogeneity across breast cancer tumor histologies, and demonstrate the value of centralized pathology review for classifying rarer tumor types.     

Risk factors for breast cancer in nulliparous women

The relation between hormonal and lifestyle factors and breast cancer risk in nulliparae was investigated using data from two case-control studies conducted in Italy between 1983 and 1994. The study included 1041 nulliparae with histologically confirmed incident breast cancer and 1002 nulliparous controls admitted to hospital for a wide range of acute, non-neoplastic, nonhormone-related diseases. In premenopausal nulliparae, there was an inverse relation with age at menarche [odds ratios (OR) 0.45; 95% confidence intervals (CI) 0.24-0.86 for > or = 15 years vs < 12], while no association emerged in postmenopausal. Breast cancer risk increased with age at menopause, the OR being 1.91 (95% CI 1.26-2.90) for nulliparae reporting age at menopause > or = 53 years compared with < 45. Abortion was not related to breast cancer risk, the OR being 0.92 for any spontaneous, 0.97 for any induced and 0.77 for > or = 2 total abortions compared to none. The OR was 1.75 (95% CI 1.03-2.97) for women reporting their first abortion at age > or = 30 years compared with < 30. Oral contraceptives and hormone replacement therapy in menopause were moderately related to risk. The OR was 2.71 (95% CI 1.85-3.95) in nulliparae with a family history of breast cancer and 1.60 (95% CI 1.20-2.14) in those with a history of benign breast disease. Compared with nulliparae reporting a low physical activity, the OR was 0.79 (95% CI 0.54-1.16) for those reporting intermediate/high activity. Breast cancer risk increased with total energy intake, the OR being 1.65 (95% CI 0.99-2.75) in the highest tertile; beta-carotene was inversely related to risk (OR 0.60, 95% CI 0.38-0.95) for the highest tertile. Thus, most risk factors for breast cancer in nulliparae were similar to those in women generally.     

Predictors of Breast Cancer Screening Among Korean American Women: Is Having an Annual Checkup Critical?

Objective: Korean American (KA) immigrant women underutilize breast cancer screening. This study examinedfactors predicting breast cancer screening behavior among KA women in the United States. Methods: 233 KA womenaged 19 to 85 were recruited in the metro area of Atlanta, Georgia. Andersen’s behavioral model theoretically guidedthe study. Result: Of the predisposing factors, age (OR=1.043, p<.01, 95% CI [1.017, 1.069]) and marital status(OR=2.154, p<.05, 95% CI [1.022, 4.539]) were significantly associated with clinical breast exam (CBE), while income(OR=2.289, p<.05, 95% CI [1.060, 4.945]) and annual checkup (OR=2.725, p<.01, 95% CI [1.342, 5.533]) werelinked to CBE as enabling factors. For the receipt of mammographic screening, annual checkup was only significantlyassociated among enabling factors (OR=4.509, p<.05, 95% CI [1.263, 16.102]), while family cancer history wasidentified as the only significant need factor (OR=.112, p<.01, 95% CI [.023, .552]). Conclusion: Differing factorsexplained the receipt of CBEs and mammographic use among KA women. Specifically, the findings shed light on theimportance of having an annual checkup for the uptake of both CBEs and mammographic use. Intervention strategiesshould focus on promoting health accessibility for KA women to adhere to recommended breast cancer screening.     

Caffeine, alcohol, smoking, and the risk of incident epithelial ovarian cancer

BACKGROUND: Smoking, caffeine, and alcohol intake are all potentially modifiable factors that have an unclear association with ovarian cancer risk. Therefore, the associations between these exposures and ovarian cancer risk were prospectively examined among 110,454 women in the Nurses' Health Study (NHS) for the smoking analyses and 80,253 women for the dietary analyses. METHODS: Women completed biennial questionnaires assessing ovarian cancer risk factors beginning in 1976, with food frequency questionnaires administered every 2 to 4 years starting in 1980. For the smoking analyses, 737 confirmed cases of epithelial ovarian cancer were identified and for the dietary aims, 507 cases were identified through June 1, 2004. RESULTS: Compared with never-smokers, neither current nor past smoking was associated with ovarian cancer risk overall; however, both were associated with mucinous tumors (n = 69; rate ratio [RR], past = 2.02 [95% confidence interval (CI), 1.15-3.55]; RR, current = 2.22 [95% CI, 1.16-4.24]). A modest inverse association between caffeine intake and ovarian cancer risk was observed (RR, top vs bottom quintile = 0.80; 95% CI, 0.60-1.07 [P = .03]), which was strongest for women who had never used either oral contraceptives (RR = 0.65; 95% CI, 0.46-0.92 [P for heterogeneity = .02]) or postmenopausal hormones (RR = 0.57; 95% CI, 0.36-0.91 [P for heterogeneity = .13]). Alcohol was not associated with ovarian cancer risk. CONCLUSIONS: The results of the current study suggest that cigarette smoking may only increase the risk for mucinous ovarian tumors, and alcohol intake was not associated with risk. However, an inverse association was observed between caffeine intake and ovarian cancer risk, particularly in women not using hormones; this finding merits further study.     

Risk Factors for breast cancer among japanese women: A case-control study in Ibaraki, Japan

BACKGROUND: The number of epidemiologic studies on breast cancer risk factorsin Japanese women is still quite limited. Our objective was to clarify the relationship between lifestyle, body size and breast cancer risk. METHODS: A matched case-control study was conducted in Ibaraki, Japan. The participants were 148 women aged 26-69 diagnosed with breast cancer at Tsukuba University Hospital or Tsukuba Medical Center Hospital between January, 1990 and March, 1997. Two controls were individually matched to the cases by age and residence. A self-administered questionnaire was used to obtain information on the family history of breast cancer, reproductive history, education, body size and lifestyle factors. Conditional logistic regression analysis was used to estimate oddsratios (ORs)and 95% confidence intervals (95% CI). RESULTS: After adjustment for potential confounders, heavy weight and higher body mass index were associated with an increased risk of breast cancer among postmenopausal women (OR = 1.76, 95% CI = 0.69, 4.48; OR = 1.57, 95% CI=0.61, 3.99, respectively). Current or ex-smokers were found to be at an increased risk for breast cancer (OR = 3.33; 95% CI = 1.63, 6.80). Women who take hot baths had a decreased risk for breast cancer (OR = 0.67; 95% CI = 0.43, 1.06). Recreational physical activity was associated with a reduced risk of breast cancer (PTrend = 0.005).OR for breast cancer among physically active women was 0.36 (95% CI = 0.19, 0.70), as compared with inactive women. Taller women had an increased risk of breast cancer relative to shorter women (OR = 1.49; 95% CI = 0.83, 2.70). No significant association between alcohol consumption and breast cancer risk was detected. CONCLUSION: Our results suggest that several potentially modifiable lifestyle factors may be useful for the prevention of breast cancer.     

BRCA1 and BRCA2 mutation carriers, oral contraceptive use, and breast cancer before age 50.

BACKGROUND: Understanding the effect of oral contraceptives on risk of breast cancer in BRCA1 or BRCA2 mutation carriers is important because oral contraceptive use is a common, modifiable practice. METHODS: We studied 497 BRCA1 and 307 BRCA2 mutation carriers, of whom 195 and 128, respectively, had been diagnosed with breast cancer. Case-control analyses were conducted using unconditional logistic regression with adjustments for family history and familial relationships and were restricted to subjects with a reference age under 50 years. RESULTS: For BRCA1 mutation carriers, there was no significant association between risk of breast cancer and use of oral contraceptives for at least 1 year [odds ratio (OR), 0.77; 95% confidence interval (95% CI), 0.53-1.12] or duration of oral contraceptive use (P(trend) = 0.62). For BRCA2 mutation carriers, there was no association with use of oral contraceptives for at least 1 year (OR, 1.62; 95% CI, 0.90-2.92); however, there was an association of elevated risk with oral contraceptive use for at least 5 years (OR, 2.06; 95% CI, 1.08-3.94) and with duration of use (OR(trend) per year of use, 1.08; P = 0.008). Similar results were obtained when we considered only use of oral contraceptives that first started in 1975 or later. CONCLUSIONS: We found no evidence overall that use of oral contraceptives for at least 1 year is associated with breast cancer risk for BRCA1 and BRCA2 mutation carriers before age 50. For BRCA2 mutation carriers, use of oral contraceptives may be associated with an increased risk of breast cancer among women who use them for at least 5 years. Further studies reporting results separately for BRCA1 and BRCA2 mutation carriers are needed to resolve this important issue.     

Risk factors for hormone receptor-defined breast cancer in postmenopausal women.

The effect of classic breast cancer risk factors on hormone receptor-defined breast cancer is not fully clarified. We explored these associations in a Swedish population-based study. Postmenopausal women ages 50 to 74 years, diagnosed with invasive breast cancer during 1993 to 1995, were compared with 3,065 age frequency-matched controls. We identified 332 estrogen receptor (ER-) and progesterone receptor (PR-) negative, 286 ER+PR-, 71 ER-PR+, 1,165 ER+PR+, and 789 tumors with unknown receptor status. Unconditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI). Women ages >or=30 years, compared with those ages 20 to 24 years at first birth, were at an increased risk of ER+PR+ tumors (OR, 1.5; 95% CI, 1.2-1.8) but not ER-PR- tumors (OR, 1.1; 95% CI, 0.8-1.6). Women who gained >or=30 kg in weight during adulthood had an approximately 3-fold increased relative risk of ER+PR+ tumors (OR, 2.7; 95% CI, 1.9-3.8), but no risk increase of ER-PR- tumors (OR, 1.0; 95% CI, 0.5-2.1), compared with women who gained <10 kg. Compared with never users, women who used menopausal estrogen-progestin therapy for at least 5 years were at increased risk of ER+PR+ tumors (OR, 3.0; 95% CI, 2.1-4.1) but not ER-PR- tumors (OR, 1.3; 95% CI, 0.7-2.5). In conclusion, other risk factors were similarly related to breast cancer regardless of receptor status, but high age at first birth, substantial weight gain in adult age, and use of menopausal estrogen-progestin therapy were more strongly related to receptor-positive breast cancer than receptor-negative breast cancer.     

Never smokers and lung cancer risk: a case-control study of epidemiological factors

We performed an analysis of potential epidemiological risk factors for lung cancer using data from 280 cases and 242 hospital-based controls, all lifetime never smokers (those who had smoked <100 cigarettes in their lifetimes) and frequency matched on age, gender and ethnicity. The data on demographic characteristics, medical history of respiratory diseases (asthma, emphysema, pneumonia and hay fever), weight and height, family history, female characteristics and environmental tobacco smoke (ETS) and dust exposure were derived from personal interviews. We performed a logistic regression analysis of these variables adjusting for age, gender, ethnicity, income and years of education. Exposure to ETS (OR = 2.08, 95% CI [1.25-3.43]) and dusts (OR = 2.43, 95% CI [1.53-3.88]) were associated with significantly increased risk. In the analysis for joint effects, exposure to both ETS and dusts conferred a higher risk (OR = 3.25, 95% CI [1.58-6.70]) than exposure to either alone. Family history of any cancer with onset before age 50 in at least 1 first degree relative was a significant risk predictor (OR = 1.70, 95% CI [1.10-2.64]). Individuals with a self-reported physician-diagnosed history of hay fever, but not asthma, had a decreased lung cancer risk (OR = 0.57, 95% CI [0.35-0.92]). In the multivariate analysis, exposure to ETS and dusts, and family history of cancer with onset before age 50 were significant risk factors, while a history of hay fever (occurring without asthma) was significantly protective.     

Reproductive Risk Factors Differ Among Breast Cancer Patients and Controls in a Public Hospital of Paraiba,Northeast Brazil

The incidence and mortality rates of breast cancer in Northeast Brazil are increasing and little is known aboutprevailing reproductive factors contributing to this increase. A case-control study was conducted in a publichospital of Campina Grande, state of Paraíba, including 81 women with diagnosed invasive breast cancer and 162age matched (±5 years) controls. Binominal logistic regression analysis was applied to estimate odds ratio (OR)and confidence intervals (CI) of risk factors. In this model, age at menarche ≤12 (OR= 2.120; CI: 1.043- 4.308;p=0.038), single parity (OR=3.748; CI: 1.459- 9.627; p=0.06) and reproductive period >10 years (OR=3.042;CI: 1.421- 6.512; p=0.04) were identified as independent variables that significantly increased breast cancerrisk of parous women. Compared to parous women who never practised breastfeeding, total breastfeeding time> 24 months decreased the risk of breast cancer (OR=0.258; CI: 0.084- 0.787; p= 0.017). The results indicatedthat modifiable reproductive factors contribute to breast cancer risk in women included in the present study.Women’s knowledge about factors such as the protective effect of breastfeeding could reduce the risk of breastcancer.     

Clinical Risk Factor Analysis for Breast Cancer: 568,000 Subjects Undergoing Breast Cancer Screening in Beijing, 2009

Objectives: Although there are many reports about the risk of breast cancer, few have reported clinicalfactors including history of breast-related or other diseases that affect the prevalence of breast cancer. This studyexplores these risk factors for breast cancer cases reported in Beijing in 2009. Materials and Methods: Datawere derived from a Beijing breast cancer screening performed in 2009, of 568,000 women, from 16 districts ofBeijing, all aged between 40 and 60 years. In this study, multilevel statistical modeling was used to identify clinicalfactors that affect the prevalence of breast cancer and to provide more reliable evidence for clinical diagnosticsby using screening data. Results and Conclusion: Those women who had organ transplants, compared withthose with none, were associated with breast cancer with an odds ratio (OR) = 65.352 [95% confidence interval(CI): 8.488-503.165] and those with solid breast mass compared with none had OR = 1.384 (95% CI: 1.022-1.873). Malignant tendency was strongly associated with increased risk of breast cancer, OR = 207.999(95%CI: 151.950-284.721). The risk of breast cancer increased with age, OR1 = 2.759 (95% CI: 1.837-4.144, 56-60 vs.40-45), OR2 = 2.047 (95% CI: 1.394-3.077, 51-55 vs. 40-45), OR3 = 1.668 (95% CI: 1.145-2.431). Normal resultsof B ultrasonic examination show a lower risk among participants, OR= 0.136 (95% CI: 0.085-0.218). Thosewomen with ductal papilloma compared with none were associated with breast cancer, OR=6.524 (95% CI:1.871-22.746). Therefore, this study suggests that clinical doctors should pay attention to these high-risk factors.     

Risk factors of breast cancer in north of Iran: a case-control in Mazandaran Province.

INTRODUCTION: Breast cancer is the most common cancer among Iranian women. This study aimed to determine risk factors for breast cancer in the north of Iran. METHOD: A matched case-control study was conducted in Mazandaran province of Iran in 2004 of 250 biopsy proven cases of breast cancer and 500 neighbor controls that were matched by age within a 3 year period. Statistical analysis was carried out using conditional logistic regression with the backward elimination method and crude and adjusted odds ratios with related 95% CIs were estimated with Stata 8.0 software RESULTS: Multivariate analysis showed that higher education (OR=4.70, 95%CI: 1.71-12.88), late menopause (OR=4.18, 95%CI: 2.54-6.88), history of induced abortion (OR=1.62, 95%CI: 1.13-2.31), positive first-degree family history of breast cancer (OR=3.14, 95%CI: 1.37-7.20), and BMI (OR=1.02, 95%CI: 1.01-1.03) were risk factors for breast cancer. Furthermore, having more episodes of full term pregnancy (OR=0.87, 95%CI: 0.80-0.95), longer duration of breast feeding (OR=0.993, 95%CI: 0.989-0.997) and parity more than 2 were shown to be protective factors. CONCLUSIONS: Our study revealed the role of some modifiable determinants of breast cancer that can be focused by public health intervention in the northern community of Iran. Accordingly, the women who have one or more of the following risk factors should take the special attention to risk of breast cancer: obesity, being menopause, positive family history of breast cancer and history of induced abortion. The protective effect of longer duration of breast feeding should be encouraged too.     

Effect of hormone replacement therapy on breast cancer risk: estrogen versus estrogen plus progestin

BACKGROUND: Hormone replacement therapy (HRT) given as unopposed estrogen replacement therapy (ERT) gained widespread popularity in the United States in the 1960s and 1970s. Recent prescribing practices have favored combination HRT (CHRT), i.e., adding a progestin to estrogen for the entire monthly cycle (continuous combined replacement therapy [CCRT]) or a part of the cycle (sequential estrogen plus progestin therapy [SEPRT]). Few data exist on the association between CHRT and breast cancer risk. We determined the effects of CHRT on a woman's risk of developing breast cancer in a population-based, case-control study. METHODS: Case subjects included those with incident breast cancers diagnosed over 4(1/2) years in Los Angeles County, CA, in the late 1980s and 1990s. Control subjects were neighborhood residents who were individually matched to case subjects on age and race. Case subjects and control subjects were interviewed in person to collect information on known breast cancer risk factors as well as on HRT use. Information on 1897 postmenopausal case subjects and on 1637 postmenopausal control subjects aged 55-72 years who had not undergone a simple hysterectomy was analyzed. Breast cancer risks associated with the various types of HRT were estimated as odds ratios (ORs) after adjusting simultaneously for the different forms of HRT and for known risk factors of breast cancer. All P values are two-sided. RESULTS: HRT was associated with a 10% higher breast cancer risk for each 5 years of use (OR(5) = 1.10; 95% confidence interval [CI] = 1.02-1.18). Risk was substantially higher for CHRT use (OR(5) = 1.24; 95% CI = 1.07-1.45) than for ERT use (OR(5) = 1. 06; 95% CI = 0.97-1.15). Risk estimates were higher for SEPRT (OR(5) = 1.38; 95% CI = 1.13-1.68) than for CCRT (OR(5) = 1.09; 95% CI = 0. 88-1.35), but this difference was not statistically significant. CONCLUSIONS: This study provides strong evidence that the addition of a progestin to HRT enhances markedly the risk of breast cancer relative to estrogen use alone. These findings have important implications for the risk-benefit equation for HRT in women using CHRT.     

CHEK2 1100delC Variant and Breast Cancer Risk in Caucasians: A Meta-analysis Based on 25 Studies with 29,154 Cases and 37,064 Controls

Links between the CHEK2 1100delC heterozygote and breast cancer risk have been extensively explored.However, both positive and negative associations with this variant have been reported in individual studies. Fora detailed assessment of the CHEK2 1100delC heterozygote and breast cancer risk, relevant studies published asrecently as May 2012 were identified using PUBMED and EMBASE and selected using a priori defined criteria.The strength of the relationship between the CHEK2 1100delC variant and breast cancer risks was assessed byodds ratios (ORs) under the fixed effects model. A total of 29,154 cases and 37,064 controls from 25 case-controlstudies were identified in this meta-analysis. The CHEK2 1100delC heterozygote was more frequently detectedin cases than in controls (1.34% versus 0.44%). A significant association was found between CHEK2 1100delCheterozygote and breast cancer risk (OR=2.75, 95% CI: [2.25, 3.36]). The ORs and CIs were 2.33 (95% CI: [1.79,3.05]), 3.72 (95% CI: [2.61, 5.31]) and 2.78 (95% CI: [2.28, 3.39]) respectively in unselected, family, early-onsetbreast cancer subgroups. The CHEK2 1100delC variant could be a potential factor for increased breast cancerrisk in Caucasians. However, more consideration is needed in order to apply it to allele screening or other clinicalwork.     

重庆市妇女乳腺癌危险因素的病理对照研究

目的 研究女性乳腺癌的危险因素。方法 在重庆市进行了首次１：１流行病学病例对照研究。结果 多因素条件Ｌｏｇｉｓｔｉｃ回归分析显示了下列因素对乳腺癌的影响：女性初潮年龄（ＯＲ＝０．７９，９５％ＣＩ＝０．６７－０．９２），月经紊乱史（ＯＲ＝１．４７，９５％，ＣＩ＝１．０７－２．０２），高龄初产（ＯＲ＝１．５５，９５％ＣＩ＝１．２０－１．９８），乳腺良性疾病史（ＯＲ＝２．３３，９５％ＣＩ＝１．０２－５．