Analysis of menstrual, reproductive, and life-style factors for breast cancer risk in Turkish women

The aim of this study was to investigate the association between menstrual, reproductive, and life-style factors and breast cancer in Turkish women. In a hospital-based case-control study in Ankara, 622 patients with histologically confirmed breast cancer were compared with 622 age-matched controls, admitted to the same hospital for acute and non-neoplastic diseases. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI) related to risk factors. Overall, menopausal status and age at menopause were found to be significantly associated with breast cancer. Having a full-term pregnancy and early age at first birth were associated with decreased breast cancer risk (OR=0.45, 95% CI=0.30–0.66; OR=0.34, 95% CI=0.22–0.53, respectively). Postmenopausal women with lactation longer than 48 mo had reduced risk of breast cancer (OR=0.36, 95% CI=0.14–0.93). In conclusion, decreased parity, late age at first birth, early menopause, and shorter duration of lactation were the most important determinants of breast cancer risk in Turkish women.     

Effects of Menstrual and Reproductive Factors on the Risk of Breast Cancer: Meta-analysis of the Case-Control Studies in Japan

To elucidate the magnitude of the effect of menstrual and reproductive factors on breast cancer occurrence among Japanese women, we reviewed eight case-control studies previously conducted in Japan and used a quantitative method (meta-analysis) to summarize the data. While individual studies have different methods and populations, the estimated odds ratios (ORs) in the studies were statistically homogeneous for all study variables. It was confirmed that early age at menarche, late age at first birth, and premenopausal status are significantly associated with risk of breast cancer; an estimated combined OR of 0.68 (95% confidence interval (CI): 0.59-0.77) was obtained for women with onset of menstruation after age 16 compared to those before age 14. Nulliparous women had higher risk than women with first birth before age 25 (OR=1.56 95%, CI: 1.27-1.91). The OR for women with first birth after age 35 was 2.26 (95% CI: 1.85-2.77) compared to women at first birth before age 25. Premenopausal women had a higher risk than women with menopause before age 50 (OR=2.21, 95% CI: 1.53-3.20). We also found a significant protective effect of high parity after controlling for age at first birth and the other menstrual factors. The OR estimate for 3 or more births compared to nulliparity was 0.68 (95% CI: 0.54-0.86). The meta-analysis provided quantitative estimates of breast cancer risk among Japanese women with improved precision.     

Risk factors for breast cancer in Turkish women: a hospital-based case-control study

The aim of this study was to investigate the association between risk factors and breast cancer in Turkish women. In a hospital-based case-control study in Istanbul, 405 patients with histologically confirmed breast cancer were compared with 1050 controls, who were admitted to different departments of the same hospital. Unadjusted odds ratios (ORs) and 95% confidence intervals (CIs) for each risk factor were obtained from logistic regression analyses. Risk factors for breast cancer were found to be early menarche age (OR 3.87, 95% CI 2.46-6.08), use of alcohol (OR 3.87, 95% CI 1.79-8.37), history of diabetes (OR 3.31, 95% CI 2.36-4.64) or hypertension (OR 3.44, 95% CI 2.07-5.71), oral contraceptive use (OR 1.98, 95% CI 1.38-2.85) and hormone replacement therapy (HRT) use (OR 1.94, 95% CI 1.15-3.29). The findings of the present study indicated that history of diabetes or hypertension, use of alcohol, oral contraceptive and HRT, never having breastfed and delayed age at first birth associated with changing of lifestyle led to an increased risk of breast cancer in Turkish women.     

Risk Factors for Breast Cancer in Iranian Women Aged Less than 40 Years

This case-control study was carried out in a university-affiliated teaching hospital, Tehran city, Iran. A total of312 newly diagnosed cases aged less than 40 years old participated and were matched for age and ethnicity with312 controls. The results showed that in women who never married (OR=2.42 95%CI=1.51-3.88) (P<0.001), hada family history of breast cancer (OR=7.07 95%CI=2.95-16.99) (P<0.001), a low age of menarche (OR=0.1 95%CI=0.04-0.23) (P<0.001)), lower parity (OR=13.3 95% CI=3.89-45.66) (P<0.001) and took oral contraceptive pills(OR= 2.83 95% CI=1.87-4.24) (P<0.000) were at increased risk. A direct association with age at first birth wasalso evident(P=0.041), with a significantly inverse association between duration of lactation and breast cancer risk(p=0.016). On multivariate logistic regression, parity, family history of breast cancer, use of oral contraceptivepills, and age at first birth remained significant. In women lower than 40 years of age, breast cancer risk wassignificantly higher in women with parity ≥4 compared with nulliparity but no association emerged with historyof breast-feeding. Other risk factors were similar to those described in breast cancer epidemiology at any age.     

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.     

克拉玛依市区女性乳腺癌危险因素的病例对照研究

 目的　探讨克拉玛依市区女性乳腺癌的危险因素。方法　用病例对照研究方法调查129例女性乳腺癌和对应的129名对照者,用Logistic回归模型进行乳腺癌危险因素分析。结果　乳腺癌的危险因素有乳腺癌家族史（OR＝2.744,95 % CI＝1.884～4.674）、乳腺增生症（OR＝1.423,95 % CI＝1.160～1.810）、 乳腺炎（OR＝2.363,95 % CI＝2.039～3.934）、子宫肌瘤（OR＝1.623,95 % CI＝1.263～2.024）、 流产（OR＝1.723,95 % CI＝1.143～2.600）、 饮酒（OR＝1.243,95 % CI＝1.040～1.483）、精神创伤（OR＝2.184,95 % CI＝1.753～3.025）、长期接触电离辐射（OR＝1.374,95 % CI＝1.152～1.699）; 保护因素有初潮年龄增大（OR＝0.773,95 % CI＝0.674～0.956）、累计哺乳时间（OR＝0.672,95 % CI＝0.480～0.941）、坚持运动（OR＝0.572,95 % CI＝0.391～0.837）。结论　以上11个因素为克拉玛依市区女性乳腺癌重要的危险因素和保护因素。     

Obstetric history and mammographic density: a population-based cross-sectional study in Spain (DDM-Spain)

High mammographic density (MD) is used as a phenotype risk marker for developing breast cancer. During pregnancy and lactation the breast attains full development, with a cellular-proliferation followed by a lobular-differentiation stage. This study investigates the influence of obstetric factors on MD among pre- and post-menopausal women. We enrolled 3,574 women aged 45-68 years who were participating in breast cancer screening programmes in seven screening centers. To measure MD, blind anonymous readings were taken by an experienced radiologist, using craniocaudal mammography and Boyd's semiquantitative scale. Demographic and reproductive data were directly surveyed by purpose-trained staff at the date of screening. The association between MD and obstetric variables was quantified by ordinal logistic regression, with screening centre introduced as a random effect term. We adjusted for age, number of children and body mass index, and stratified by menopausal status. Parity was inversely associated with density, the probability of having high MD decreased by 16% for each new birth (P value < 0.001). Among parous women, a positive association was detected with duration of lactation [>9 months: odds ratio (OR) = 1.33; 95% confidence interval (CI) = 1.02-1.72] and weight of first child (>3,500 g: OR = 1.32; 95% CI = 1.12-1.54). Age at first birth showed a different effect in pre- and post-menopausal women (P value for interaction = 0.030). No association was found among pre-menopausal women. However, in post-menopausal women the probability of having high MD increased in women who had their first child after the age of 30 (OR = 1.53; 95% CI = 1.17-2.00). A higher risk associated with birth of twins was also mainly observed in post-menopausal women (OR = 2.02; 95% CI = 1.18-3.46). Our study shows a greater prevalence of high MD in mothers of advanced age at first birth, those who had twins, those who have breastfed for longer periods, and mothers whose first child had an elevated birth weight. These results suggest the influence of hormones and growth factors over the proliferative activity of the mammary gland.     

Effect of pregnancy as a risk factor for breast cancer in BRCA1/BRCA2 mutation carriers

Early age at first birth and multiparity have been associated with a decrease in the risk of breast cancer in women in the general population. We examined whether this relationship is also present in women at high risk of breast cancer due to the presence of a mutation in either of the 2 breast cancer susceptibility genes, BRCA1 or BRCA2. We performed a matched case-control study of 1,260 pairs of women with known BRCA1 or BRCA2 mutations, recruited from North America, Europe and Israel. Women who had been diagnosed with breast cancer were matched with unaffected control subjects for year of birth, country of residence, and mutation (BRCA1 or BRCA2). Study subjects completed a questionnaire detailing their reproductive histories. Odds ratios (ORs) and 95% confidence intervals (CIs) were derived by conditional logistic regression. Among BRCA1 carriers, parity per se was not associated with the risk of breast cancer (OR for parous vs. nulliparous = 0.94; 95% CI = 0.75-1.19; p = 0.62). However, women with a BRCA1 mutation and 4 or more children had a 38% decrease in breast cancer risk compared to nulliparous women (OR = 0.62; 95% CI = 0.41-0.94). In contrast, among BRCA2 carriers, increasing parity was associated with an increased risk of breast cancer; women with 2 or more children were at approximately 1.5 times the risk of breast cancer as nulliparous women (OR = 1.53; 95% CI = 1.01-2.32; p = 0.05). Among women with BRCA2 mutations and who were younger than age 50, the (adjusted) risk of breast cancer increased by 17% with each additional birth (OR = 1.17; 95% CI = 1.01-1.36; p = 0.03). There was no significant increase in the risk of breast cancer among BRCA2 carriers older than 50 (OR for each additional birth = 0.97; 95% CI = 0.58-1.53; p = 0.92). In the 2-year period following a birth, the risk of breast cancer in a BRCA2 carrier was increased by 70% compared to nulliparous controls (OR = 1.70; 95% CI = 0.97-3.0). There was a much smaller increase in breast cancer risk among BRCA2 carriers whose last birth was 5 or more years in the past (OR = 1.24; 95% CI = 0.79-1.95). A modest reduction in risk of breast cancer was observed among BRCA1 carriers with 4 or more births. Among BRCA2 carriers, increasing parity was associated with a significant increase in the risk of breast cancer before age 50 and this increase was greatest in the 2-year period following a pregnancy.     

Differences in breast cancer risk factors by tumor marker subtypes among premenopausal Vietnamese and Chinese women.

We evaluated associations between reproductive and lifestyle risk factors with breast cancer tumor marker status in a case-control study. Cases were premenopausal women living in Vietnam and China who were eligible for a clinical trial of oophorectomy and tamoxifen as treatment for breast cancer (n = 682). Controls were nonrelative hospital visitors, matched on age to the cases (n = 649). Immunohistochemical analysis was used to identify the presence of estrogen receptor (ER) and progesterone receptor and the overexpression of HER-2/neu oncogene. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using unconditional logistic regression, adjusted for known confounders. Overall, 280 (61%) tumor samples were ER positive and 176 (38%) were ER negative. HER-2/neu overexpression was detected in 161 (35%) samples, whereas 286 (26%) samples were HER-2/neu negative. We observed an inverse trend between increasing parity and decreasing breast cancer risk (P = 0.002). Women ages > or =25 years at first birth had increased breast cancer risk compared with women ages <25 years at first birth (OR, 1.53; 95% CI, 1.20-1.95). Women who consumed alcohol had increased risk of breast cancer compared with women who did not (OR,1.85; 95% CI, 1.32-2.61). Compared with controls, OR estimates for breast cancer by parity and age at first birth were significantly associated with ER and/or HER-2/neu tumor status by Wald test (P < 0.05). Family history, age at menarche, cumulative lactation, body mass index, and education were not significantly related to breast cancer risk. Our findings support the hypothesis that some breast cancer risk factors differ by ER and HER-2/neu tumor marker subtypes.     

Oral contraceptive use, reproductive factors, and colorectal cancer risk: findings from Wisconsin.

We investigated the association of oral contraceptive (OC) use and reproductive factors with colorectal cancer risk in a large population-based case-control study. Cases were women ages 20 to 74 years, living in Wisconsin, with a new diagnosis of colon (n = 1,122) or rectal (n = 366) cancer. Control participants were randomly selected from population lists of similarly aged female Wisconsin residents (n = 4,297). Risk factor information was collected through structured telephone interviews. Compared with never users, OC users had an odds ratio (OR) of 0.89 [95% confidence interval (95% CI), 0.75-1.06] for colorectal cancer. OC use associations did not differ significantly between colon and rectal cancer sites; however, when compared with never users, recent OC users (<14 years) seemed at reduced risk of rectal cancer (OR, 0.53; 95% CI, 0.28-1.00). Women with age at first birth older than the median (23 years) had 0.83 times the risk of colon cancer compared with women with age at first birth below the median (95% CI, 0.70-0.98). We observed an inverse trend between increasing parity and rectal cancer risk (P = 0.05). Compared with nulliparous women, women with five or more births had 0.66 times the risk of rectal cancer (95% CI, 0.43-1.02). Compared with postmenopausal women, premenopausal women were at reduced risk (OR, 0.67; 95% CI, 0.47-0.97) of colorectal cancer. No significant associations were observed between colorectal cancer risk and age at menarche or age at menopause. These findings suggest differential roles of reproductive factors in colon and rectal cancer etiology.     

Association between Early Menopause,Gynecological Cancer,and Tobacco Smoking: A Cross-Sectional Study

Background: The rates of smoking among women are rising. Previous studies have shown that smoking is associated with early menopause. However, the association of gynecological cancer, including breast and cervical cancer, with early menopause and smoking, remains unclear. Therefore, this study aimed to determine the association between smoking and early menopause, breast cancer, and cervical cancer. Methods: This cross-sectional study used data from the Korean National Health and Nutritional Survey Examination (KHANES) (2016–2018). Early menopause was defined as menopause before 50 years of age. Results: A total of 4,481 participants were included in the analysis. There was no association between early menopause and cervical cancer (adjusted odds ratio [aOR]: 1.435, 95% confidence interval [CI]: 0.730–2.821), but women who had experienced early menopause had a significantly higher risk of breast cancer than women who had experienced normal menopause (aOR: 1.683, 95% CI: 1.089–2.602, p=0.019). Early menopause was not associated with an increased risk of breast cancer in ever-smoker (aOR: 0.475, 95% CI: 0.039–5.748), but was associated with a significantly increased risk of breast cancer in never-smokers (aOR: 1.828, 95% CI: 1.171–2.852). Conclusions: Early menopause was associated with an increased risk of breast cancer in women who had never smoked, but not in women who had ever smoked.     

Risk factors for breast cancer in Turkish women with early pregnancies and long-lasting lactation--a case-control study

A hospital-based case-control study was carried out among 504 women with breast cancer and 610 controls to analyse the risk factors for breast cancer in Turkey. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for each risk factor were obtained from logistic regression analysis. Risk factors for breast cancer were found to be long-term lactation (> or = 5 years versus never OR 0.31, 95% CI 0.12-0.79), young age at menarche (< 15 years versus > or = 15 OR 1.72, 95% CI 1.30-2.28), late age at first full-term pregnancy (> or = 30 versus < 20 OR 2.86, 95% CI 1.32-6.21), oral contraceptive use (ever versus never OR 1.51, 95% CI 1.10-2.08), positive family history (positive versus negative OR 2.81, 95% CI 1.35-5.82), and menstrual irregularity (yes versus no OR 1.61, 95% CI 1.05-2.49). The results of the present study will lead to a better understanding of the risk factors for breast cancer in a developing country.     

Reproductive factors, hormone use and the risk of lung cancer among middle-aged never-smoking Japanese women: a large-scale population-based cohort study

Although a link between female hormonal factors and the risk of lung cancer has been suggested, few studies have examined this association in detail. We investigated the associations between reproductive factors, hormone use and the risk of lung cancer in a population-based prospective study. Self-administered questionnaires were distributed to 44,677 lifelong never-smoking women in 1990-1994 to assess menstrual and reproductive factors and hormone use. After 8-12 years of follow-up, 153 lung cancer cases were diagnosed. Relative risk (RR) and 95% confidence intervals (CI) were calculated using the Cox proportional hazards model. Age at menopause, age at menarche, number of children, age at first live birth, breast feeding and use of hormones were not associated with a risk of lung cancer, either overall or among postmenopausal women or women with natural menopause. Compared to women with both late age at menarche (> or =16) and early age at menopause (< or =50), those with either early age at menarche or late age at menopause had a >2-fold, significant increase in the risk of lung cancer. Induced menopausal women with experience of hormone replacement therapy had a significantly elevated risk compared to naturally menopausal women without female hormone use, with an RR of 2.40 (95% CI 1.07-5.40). These findings suggest that both endogenous and extraneous estrogen may be involved in the etiology of lung cancer.     

Lactation and breast cancer risk: a case-control study in Connecticut

In this report, we examined the relationship between lactation and breast cancer risk, in a case-control study of breast cancer, conducted in Connecticut between 1994 and 1998. Included were 608 incident breast cancer cases and 609 age frequency matched controls, aged 30-80 years old. Cases and controls were interviewed by trained study interviewers, using a standardized, structured questionnaire, to obtain information on lactation and other major risk factors. Parous women who reported ever lactation had a borderline significantly reduced risk of breast cancer (OR = 0.83, 95% CI, 0.63-1.09). An OR of 0.53 (95% CI, 0.27-1.04) was observed in those having breastfed more than 3 children compared to those who never lactated. Women having breastfed their first child for more than 13 months had an OR of 0.47 (95% CI, 0.23-0.94) compared to those who never breastfed. Lifetime duration of lactation also showed a risk reduction while none of the ORs were statistically significant. Further stratification by menopausal status showed a risk reduction related to lactation for both pre- and postmenopausal women, while the relationship is less consistent for the latter. These results support an inverse association between breastfeeding and breast cancer risk.     

Risk factors for breast cancer: A case-control study of screen-detected breast cancer in Miyagi Prefecture, Japan

We examined the associations between reproductive factors and the risk of breast cancer on the basis of information from a total of 201,363 breast cancer screening program participants in Miyagi Prefecture, Japan, during 1987-1991. A case-control study method was applied on analysis. Data on 204 breast cancer cases identified and 810 screening year-, age- and screening area-matched normal controls were extracted. After adjustment for potential confounders, a trend of decreasing risk of breast cancer with increasing number of parity was observed (p for trend=0.03). Among parous women, lactation for the last child decreased the risk of breast cancer (odds ratio (OR) = 0.61, 95% confidence interval (95% CI) 0.39–0.94). These findings were consistent with those in clinical breast cancer reported previously. When cases were divided into two age groups, younger ( 49 y.o.) and older (50 y.o. ), family history of breast cancer among mother and sisters (OR=3.51, 95% CI 1.05–11.80), and lactation for the last child (OR=0.46, 95% CI 0.25–0.84) were associated with younger age breast cancer, whereas number of parity was associated with older age breast cancer (p for trend=0.03). The results by age group suggest that different mechanisms may exist in breast cancer developing at early and late onsets.     

Breast cancer risk factors and age at diagnosis: an Icelandic cohort study

An increasing number of studies indicates that the strength and even direction of association between breast cancer and established risk factors differ according to the woman's age when she develops the disease. This was studied in the setting of a population based cancer registry using a databank with information on age at menarche, parity, age at first birth, oral contraceptive (OC) use, lactation, height and weight. From a cohort of 80.219 women attending population-based cervical and breast cancer screening in Iceland, 1120 cases were identified, aged 26-90 years at diagnosis and 10,537 controls, individually matched to the cases on birth year and age when attending. Information given at last visit before diagnosis was used in the analysis, applying conditional logistic regression. Odds ratios and statistical strength of relationships varied according to age at diagnosis for age at first birth, number of births, duration of lactation, height and weight. The decreased risk associated with young age at first birth and increasing duration of breast feeding became less pronounced with advancing age at diagnosis. A reduced risk associated with an increasing number of births was not detected in women diagnosed under the age of 40. An increased risk associated with giving first birth after 30 years of age was mainly detected in women who had only given 1 birth and were diagnosed under the age of 40 (OR = 7.06 95% CI = 2.16-23.01). A positive association with height and especially with weight was confined to women diagnosed after the age of 55. The results confirm that age at diagnosis should be taken into account when studying the effects of breast cancer risk factors.     

Parity and breastfeeding are protective against breast cancer in Nigerian women

As the relation between reproductive factors and breast cancer risk has not been systematically studied in indigenous women of sub-Saharan Africa, we examined this in a case-control study in Nigeria. In-person interviews were conducted using structured questionnaires to collect detailed reproductive history in 819 breast cancer cases and 569 community controls between 1998 and 2006. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI). Compared with women with menarcheal age<17 years, the adjusted OR for women with menarcheal age>or=17 years was 0.72 (95% CI: 0.54-0.95, P=0.02). Parity was negatively associated with risk (P-trend=0.02) but age at first live birth was not significant (P=0.16). Importantly, breast cancer risk decreased by 7% for every 12 months of breastfeeding (P-trend=0.005). It is worth noting that the distribution of reproductive risk factors changed significantly from early to late birth cohorts in the direction of increasing breast cancer incidence. Our findings also highlight the heterogeneity of breast cancer aetiology across populations, and indicate the need for further studies among indigenous sub-Saharan women.     

Co-twin control and cohort analyses of body mass index and height in relation to breast, prostate, ovarian, corpus uteri, colon and rectal cancer among Swedish and Finnish twins

Associations between anthropometric measures and cancer have been studied previously, but relatively few studies have had the opportunity to control for genetic and early shared environmental factors. In this study, we analyzed 2 twin cohorts from Sweden born 1886-1925 (n = 21,870) and 1926-1958 (n = 30,279) and 1 from Finland born 1880-1958 (n = 25,882) including in total 78,031 twins, and studied the association between BMI and height and risk of prostate, breast, ovarian, corpus uteri, colon and rectal cancer. The cohorts were both analyzed through a co-twin control method and as traditional cohorts. In co-twin control analyses, older obese (BMI > or = 30 kg/m(2)) subjects (median age 56 years at baseline) were at higher risk of cancer of the corpus uteri (OR = 3.0; 95% CI 0.9-10.6), colon (OR = 1.9; 95% CI 0.8-4.5) and breast (OR = 2.5; 95% CI 1.3-4.2). For younger obese women (median age 30 years at baseline), an inverse tendency was observed for breast cancer (OR = 0.6; 95% CI 0.3-1.5, p for trend = 0.05). The tallest women had an increased risk of breast (OR = 1.8; 95% CI 1.3-2.7) and ovarian cancer (OR = 1.7; 95% CI 0.8-3.5). No consistent associations were found for prostate cancer either for BMI or height. There are some suggestions in our study that uncontrolled genetic or early shared environmental factors may affect risk estimates in studies of anthropometric measures and cancer risk, but do not explain observations of increased cancer risks related to BMI or height.     

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.     

Premenopausal levels of circulating insulin-like growth factor I and the risk of postmenopausal breast cancer

Increased levels of insulin-like growth factor I (IGF-I) may directly stimulate breast cell proliferation and promote growth and survival of transformed cells. Higher levels of IGF-I have been associated with increased risk of premenopausal breast cancer but not postmenopausal breast cancer. We investigated whether circulating levels of IGF-I prior to menopause are associated with breast cancer diagnosed after menopause in a population-based nested case-control study. Female cohort participants were enrolled in 1974 (n = 15,192) and 1989 (n = 18,724) and blood was drawn. Cases were women diagnosed with primary breast cancer at ages > or =50, of whom 152 were premenopausal at blood draw. One control was matched to each case on cohort participation, age, ethnic group, menopausal status and date of blood draw. Levels of IGF-I and IGF binding protein 3 (IGFBP-3) were measured using enzyme-linked immunoabsorbent assays. The association between IGF-I and breast cancer was determined using conditional logistic regression, adjusting for IGFBP-3. IGF-I levels decreased with age (p = 0.0001). Prior to age-stratification, IGF-I levels neither measured before nor after menopause were associated with postmenopausal breast cancer. After age-stratification, associations were suggested in the youngest premenopausal age group (upper vs. lowest third: odds ratio (OR) = 5.31, 95% confidence intervals (CI) = 0.85-33.13; p trend = 0.06) and oldest postmenopausal age group (upper vs. lowest third: OR = 3.41, 95% CI = 0.66-17.71; p trend = 0.13). The association between circulating levels of IGF-I and postmenopausal breast cancer risk may be modified by age. Increased levels of circulating IGF-I may be of particular interest in the younger premenopausal women and older postmenopausal women. Age-stratification should be undertaken in larger investigations of IGF-I levels as predictors of postmenopausal breast cancer.