Nadia Obi

Risk of different histological types of postmenopausal breast cancer by type and regimen of menopausal hormone therapy.

In a large population‐based case–control study in Germany, including 3,464 breast cancer cases aged 50–74 at diagnosis and 6,657 population based and frequency matched controls, we investigated the effects of menopausal hormone therapy (HT) by type, regimen, timing and progestagenic constituent on postmenopausal breast cancer risk overall and according to histological type. Data were collected by face‐to‐face interviews. Logistic and polytomous logistic regression analysis were used to estimate odds ratios (OR) and 95%‐confidence intervals (95% CI). Risk of invasive breast cancer was significantly elevated in current users (OR, 1.73, 95% CI, 1.55–1.94) and heterogeneous by histological type (p < 0.01), being more than 2‐fold higher for lobular and tubular than for ductal cancer. Risks for current users varied significantly by type and regimen of HT, with ORs per year of use of 1.05 (95% CI, 1.04–1.06) for continuous combined estrogen–progestagen, 1.03 (95% CI, 1.02–1.04) for cyclical EP and 1.01 (95% CI, 1.00–1.03) for estrogen‐only therapy. No statistically significant increase in risk was observed after 5 years of cessation of HT use for any histological type. Analyses of progestagenic content by regimen revealed a significantly higher risk for continuously administered norethisterone‐ or levonorgestrel‐derived progestagens than for continuously administered progesterone‐derived progestagens (OR, 2.27, 95% CI, 1.98–2.62 vs. 1.47, 95% CI, 1.12–1.93, respectively, p = 0.003), which may be explained by dose rather than type of progestagen. These data suggest that the risks associated with menopausal HT differ by type and regimen of HT and histological type of breast cancer and may vary by progestagenic component, depending on the effective dose.

Physical Activity and Postmenopausal Breast Cancer: Effect Modification by Breast Cancer Subtypes and Effective Periods in Life

Physical activity (PA) has been inversely associated with postmenopausal breast cancer risk. However, it is unclear how and in which life periods PA may be effective to reduce breast cancer risk. Moreover, the evidence is still not judged as ‘convincing’ as there is some heterogeneity among study results. Most studies regarded breast cancer as a single disease, at best separated by menopausal status. Yet, breast cancers are heterogeneous and likely have different etiologies. Therefore, we analyzed the association of PA with different breast cancer subtypes in 3,414 postmenopausal cases and 6,569 controls from a case-control study on breast cancer conducted 2002-2005 in Germany (MARIE study). PA in the age periods 30-49 and 50+ years was assessed, including leisure-time PA (sports, cycling, walking) and non-recreational PA (occupational and household activities). There was a significant protective effect of leisure-time PA for ER+/PR+ carcinomas (adjusted odds ratio = 0.71, 95% confidence interval: 0.60, 0.85; trend P = 0.0001), but no effect for ER-/PR- carcinomas. Moreover, looking at physical activity pattern over time, the effect of PA after menopause on reducing breast cancer risk was more pronounced than the effect of PA before menopause. Overall, effects of PA were independent from adult weight gain, body mass index, and energy intake. These findings suggest that leisure-time PA after menopause may reduce postmenopausal breast cancer risk at least in part via hormonal pathways and not solely by changing body composition. Inactive postmenopausal women should be encouraged to become physically active even later in life. (Cancer Epidemiol Biomarkers Prev 2008;17(12):3402–10)

Dietary patterns and survival in German postmenopausal breast cancer survivors

Background:Research on the association between dietary patterns and breast cancer survival is very limited.Methods:A prospective follow-up study was conducted in Germany, including 2522 postmenopausal breast cancer patients diagnosed in 2001–2005 with available food frequency questionnaire data. Vital status, causes of death, and recurrences were verified through the end of 2009. Principle component factor analysis was used to identify pre-diagnostic dietary patterns. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated with Cox proportional hazards models.Results:Two major dietary patterns were identified: ‘healthy’ (high intakes of vegetables, fruits, vegetable oil, sauces/condiments, and soups/bouillons) and ‘unhealthy’ (high intakes of red meat, processed meat, and deep-frying fat). Increasing consumption of an ‘unhealthy’ dietary pattern was associated with an increased risk of non-breast cancer mortality (highest vs lowest quartile: HR, 3.69; 95% CI, 1.66–8.17; P-trend <0.001). No associations with breast cancer-specific mortality and breast cancer recurrence were found. The ‘healthy’ dietary pattern was inversely associated with overall mortality (HR, 0.74; 95% CI, 0.47–1.15; P-trend=0.02) and breast cancer recurrence (HR, 0.71; 95% CI, 0.48–1.06; P-trend=0.02) in stage I–IIIa patients only.Conclusion:Increasing intake of an ‘unhealthy’ pre-diagnostic dietary pattern may increase the risk of non-breast cancer mortality, whereas increasing intake of a ‘healthy’ pattern may reduce the risk of overall mortality and breast cancer recurrence.

Association of pre-diagnosis physical activity with recurrence and mortality among women with breast cancer

Evidence is emerging that physical activity (PA) may improve overall survival after breast cancer diagnosis. However, the effect of PA on breast cancer recurrence and on cause‐specific mortality is less investigated. We assessed the association of pre‐diagnosis PA with recurrence, overall and cause‐specific survival in a prospective cohort study in Germany including 3,393 non‐metastatic breast cancer patients aged 50–74 years. Cox proportional hazards models were calculated adjusted for relevant prognostic factors. During a median follow‐up of 5.6 years, 367 patients deceased. Overall mortality was significantly inversely associated with pre‐diagnosis recreational PA. However, this effect was mainly attributed to deaths due to causes other than breast cancer. Multiple fractional polynomial analyses yielded a nonlinear association with markedly increased non‐breast cancer mortality for women who did not engage in any sports or cycling in the years before the breast cancer diagnosis with a hazard ratio (HR, none vs. any) of 1.71, 95% confidence interval (1.16, 2.52). There were no further risk reductions with increasing activity levels. The association with breast cancer‐specific mortality showed a similar dose‐response but was far less pronounced with HR (none vs. any) = 1.22 (0.91, 1.64). In contrast, regarding cancer recurrence the dose‐response was linear. However, this association was restricted to estrogen/progesterone receptor‐negative (ER−/PR−) cases (pinteraction = 0.033) with HR (highest vs. no recreational PA) = 0.53 (0.24, 1.16), ptrend = 0.0045. Thus, breast cancer patients with a physically inactive lifestyle pre‐diagnosis may decease prematurely irrespective of their cancer prognosis. Higher levels of exercise may reduce the risk of recurrence of ER−/PR− breast tumors.

Mortality and recurrence risk in relation to the use of lipid-lowering drugs in a prospective breast cancer patient cohort.

Lipid-lowering drugs are used for the prevention of cardiovascular diseases. Statins are the most commonly used lipid-lowering drugs. Evidence from preclinical and observational studies suggests that statins might improve the prognosis of breast cancer patients. We analyzed data from the German MARIEplus study, a large prospective population-based cohort of patients aged 50 and older, who were diagnosed with breast cancer between 2001 and 2005. For overall mortality, breast-cancer specific mortality, and non-breast-cancer mortality, we included 3189 patients with invasive breast cancer stage I–IV, and for recurrence risk 3024 patients with breast cancer stage I–III. We used Cox proportional hazards models to assess the association with self-reported lipid-lowering drug use at recruitment. We stratified by study region, tumor grade, and estrogen/progesterone receptor status, and adjusted for age, tumor size, nodal status, metastases (stage I–IV only), menopausal hormone treatment, mode of detection, radiotherapy, and smoking. Mortality analyses were additionally adjusted for cardiovascular disease, diabetes mellitus and body-mass index. During a median follow-up of 5.3 years, 404 of 3189 stage I–IV patients died, and 286 deaths were attributed to breast cancer. Self-reported use of lipid-lowering drugs was non-significantly associated with increased non-breast cancer mortality (Hazard ratio (HR) 1.49, 95% confidence interval (CI) 0.88–2.52) and increased overall mortality (HR 1.21, 95% CI 0.87–1.69) whereas no association with breast cancer-specific mortality was found (HR 1.04, 0.67–1.60). Restricted to stage I–III breast cancer patients, 387 recurrences occurred during a median follow-up of 5.4 years. We found lipid-lowering drug use to be non-significantly associated with a reduced risk of recurrence (HR 0.83, 95% CI 0.54–1.24) and of breast cancer-specific mortality (HR 0.89, 95% CI 0.52–1.49). Although compatible with previous findings of an improved prognosis associated with statin use, our results do not provide clear supportive evidence for an association with lipid-lowering drug use due to imprecise estimates.

The Use of Herbal Preparations to Alleviate Climacteric Disorders and Risk of Postmenopausal Breast Cancer in a German Case-Control Study

Background:The use of herbal preparations (HEP) to alleviate climacteric disorders is expected to increase as women seek alternatives to menopausal hormone therapy to avoid the associated breast cancer risk. Data are sparse on the long-term effects of HEP containing phytoestrogens and black cohosh on breast cancer risk. Methods: Within a German case-control study, associations between patterns of HEP use and incident breast cancer were investigated in 10,121 postmenopausal women (3,464 cases, 6,657 controls). Information on HEP use was collected in face-to-face interviews supported by a list of brand names. Multivariate logistic and polytomous regression analyses were done. Findings: Ever use of HEP (9.9%) was inversely associated with invasive breast cancer [odds ratio (OR), 0.74; 95% confidence interval (CI), 0.63-0.87] in a dose-dependent manner (OR, 0.96 per year of use; P = 0.03). Classes of HEP did not differ significantly (Pheterogeneity = 0.81). Risks for invasive ductal (OR, 0.72; 95% CI, 0.60-0.87) and combined lobular/mixed/tubular tumors (OR, 0.76; 95% CI, 0.58-1.01) were similarly reduced by any HEP use but not for in situ carcinomas (1.34; 95% CI, 0.86-2.09). There were no substantial differences in associations of HEP use by estrogen receptor status (ER+ OR, 0.74; 95% CI, 0.62-0.89; ER− OR, 0.68, 95% CI, 0.50-0.93) and progesterone receptor status of the tumor. Interpretation: Our findings support the hypothesis that HEP use protects from invasive breast cancer in postmenopausal women. Among conceivable modes of action, those independent of estrogen receptor–mediated pathways seem to be involved (i.e., cytotoxicity, apoptosis). (Cancer Epidemiol Biomarkers Prev 2009;18(8):2207–13)

Enterolactone concentrations and prognosis after postmenopausal breast cancer: Assessment of effect modification and meta‐analysis

We previously reported that high concentrations of enterolactone, a lignan metabolite, are associated with lower mortality in 1,140 breast cancer patients from Germany. Using an extended set of 2,182 patients aged 50–74 years at diagnosis (2001–2005) and prospectively followed up until 2009, we investigated whether the association with mortality differs by lifestyle factors and tumor characteristics. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using multivariable Cox regression. Potential differential effects by tumor characteristics and lifestyle factors were assessed and a meta‐analysis of five studies addressing lignan exposure and breast cancer prognosis was performed to summarize evidence. Median enterolactone concentrations were 17.4 (±30.5 standard deviation) and 22.9 nmol L−1 (±44.8), respectively, for 269 deceased and 1,913 patients still alive. High enterolactone concentrations were significantly associated with lower all‐cause mortality (per 10 nmol L−1: HR 0.94, 95% CI 0.90–0.98), breast cancer‐specific mortality (HR 0.94, 0.89–0.99), and distant disease‐free survival (HR 0.94, 0.90–0.98). Associations were found for stage 0–IIIA but not for stage IIIB–IV disease (phet = 0.01) and were stronger in patients with BMI <25 kg m−2 than those with BMI ≥25 (phet = 0.04). In patients with healthy lifestyle (BMI <25, nonsmoker, physically active), the inverse association with all‐cause mortality was still apparent (HR 0.92, 0.85–0.99). The meta‐analysis yielded significant associations both for all‐cause (HR 0.57, 0.42–0.78) and breast cancer‐specific mortality (HR 0.54, 0.39–0.75). Our findings show that high lignan exposure is associated with reduced mortality in breast cancer patients. The inverse association observed in this study cannot be entirely explained by a healthy lifestyle.

Menopausal Hormone Therapy and Risk of Clinical Breast Cancer Subtypes

Background: Breast cancer is a heterogeneous disease with subtypes that may vary in their etiologies. Menopausal hormone therapy has been associated more strongly with lobular and tubular than ductal histologic types and with tumors that are smaller, hormone receptor–positive, and of lower grade. At the same time, correlations have been observed between histology and clinical characteristics. To identify those tumor subtypes most strongly associated with hormone therapy use, it is necessary to disentangle these interrelationships. Methods: Based on 3,464 postmenopausal breast cancer cases and 6,657 controls from the population-based Mammary carcinoma Risk factor Investigation study, we used polytomous logistic regression to evaluate associations between hormone therapy use and risk of invasive breast cancer subtypes. We assessed variations in risk for selected tumor characteristics among histologic and hormone receptor subtypes, both overall and for specific hormone therapy regimens. Results: Lobular and mixed types showed less variation by prognostic factors than did ductal tumors. Current hormone therapy use had the strongest associations with prognostic variables in estrogen receptor (ER)-positive and/or progesterone receptor (PR)-positive ductal tumors and in lobular tumors regardless of ER/PR status, with little effect on ER/PR-negative ductal tumors. The observed associations varied minimally by hormone therapy type or regimen. Conclusion: Current hormone therapy use was associated with more favorable breast cancer characteristics for ductal tumors but had less effect on prognostic characteristics in women with lobular tumors. Both histologic type and estrogen receptor/progesterone receptor status seem to be important in explaining the role of hormone therapy in the etiology of breast cancer subtypes. (Cancer Epidemiol Biomarkers Prev 2009;18(4):1188–96)

Estrogen metabolite ratio: Is the 2-hydroxyestrone to 16α-hydroxyestrone ratio predictive for breast cancer?

Experimental studies have shown that two main estrogen metabolites hydroxylated by CYP1A1 and CYP1B1 in the breast differentially affect breast cell proliferation and carcinogenesis. Although 16α-hydroxyestrone (16αOHE1) exerts estrogenic activity through covalent estrogen receptor (ER) binding, 2-hydroxyestrone (2OHE1) presumably has antiestrogenic capabilities. The ratio of 2OHE1 to 16αOHE1 represents the relative dominance of one pathway over the other and is believed to be modifiable by diet. It was hypothesized that women with or at high risk of breast cancer have a lower estrogen metabolite ratio (EMR) compared with women without breast cancer. We conducted a systematic review on the EMR as a predictor for breast cancer. A total of nine studies (six prospective and three retrospective) matched our inclusion criteria, comprising 682 premenopausal cases (1027 controls) and 1189 postmenopausal cases (1888 controls). For the highest compared with the lowest quantile of urinary EMR, nonsignificant associations suggested at best a weak protective effect in premenopausal but not in postmenopausal breast cancer (range of odds ratios: 0.50–0.75 for premenopausal and 0.71–1.31 for postmenopausal). Circulating serum/plasma EMR was not associated with breast cancer risk. Associations were inconclusive for receptor subtypes of breast cancer. Uncontrolled factors known to be involved in breast carcinogenesis, such as 4-hydroxyestrone (4OHE1) concentration, may have confounded results for EMR. Results of the prospective studies do not support the hypothesis that EMR can be used as a predictive marker for breast cancer risk. Future research should concentrate on profiles of estrogen metabolites, including 4OHE1, to gain a more complete picture of the relative importance of single metabolites for breast cancer.

Circulating 25‐hydroxyvitamin D and postmenopausal breast cancer survival: Influence of tumor characteristics and lifestyle factors?

We previously reported that lower post‐diagnostic circulating 25‐hydroxyvitamin D [25(OH)D] concentrations were associated with higher risk of overall mortality and distant disease in stage I–IV postmenopausal breast cancer survivors. This association was now re‐examined in an extended dataset to investigate potential effect modification by tumor characteristics and lifestyle factors. A prospective cohort study was conducted in Germany including 2,177 incident stage I–IV postmenopausal breast cancer patients aged 50–74 years. Patients were diagnosed between 2001 and 2005 and median follow‐up time was 5.3 years. Cox proportional hazards models were stratified by age at diagnosis, study center and season of blood collection and adjusted for other prognostic factors. A meta‐analysis of studies on circulating 25(OH)D and mortality in breast cancer patients was performed to summarize evidence. Lower concentrations of 25(OH)D were significantly associated with higher risk of overall mortality [hazard ratio (HR) lowest vs. highest tertile = 1.86; 95% confidence interval (CI): 1.22, 2.82; p‐trend = 0.002] and distant disease (HR = 1.76; 95% CI: 1.24, 2.49; p‐trend = 0.003) in stage I–IIIa but not in stage IIIb–IV breast cancer patients. No significant interaction by lifestyle factors was observed (all p‐interaction > 0.05). The meta‐analysis yielded significant associations with overall and breast cancer‐specific mortality (lowest vs. highest quantile: HR = 1.52; 95% CI: 1.22, 1.88 and HR = 1.74; 95% CI: 1.23, 2.40, respectively). In conclusion, post‐diagnostic circulating 25(OH)D concentrations were associated with overall mortality and distant disease in stage I–IIIa postmenopausal breast cancer patients. This association was not strongly modified by lifestyle factors.