Metabolic syndrome and outcomes following early-stage breast cancer.

The prevalence of risk factors contributing to metabolic syndrome (MetS) is increasing, and numerous components of MetS are associated with increased primary breast cancer (BC) risk. However, less is known about the relationship of MetS to BC outcomes. The aim of this study was to evaluate whether MetS, characterized by increased weight, hypertension, low HDL-cholesterol, high triglycerides, and diabetes or impaired glucose tolerance, is associated with risk of second breast cancer events (SBCE) and BC-specific mortality. Retrospective cohort study of women diagnosed with incident early-stage (I-II) BC between 1990 and 2008, enrolled in an integrated health plan. Outcomes of interest were SBCE, defined as recurrence or second primary BC, and BC-specific mortality. We used multivariable Cox proportional hazards models to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI) for time-varying exposure to MetS components while accounting for potential confounders and competing risks. Among 4,216 women in the cohort, 26% had ≥3 MetS components and 13% developed SBCE during median follow-up of 6.3 years. Compared to women with no MetS components, presence of MetS (≥3 components) was associated with increased risk of SBCE (HR = 1.50, 95% CI 1.08-2.07) and BC-specific mortality (HR = 1.65, 95% CI 1.02-2.69). Of the individual components, only increased weight was associated with increased risk of SBCE (HR = 1.26, 95% CI 1.06-1.49). MetS is associated with modestly increased risk of SBCE and BC-specific mortality. Given the growing population of BC survivors, further research in larger and more diverse populations is warranted.

Recent oral contraceptive use by formulation and breast cancer risk among women 20 to 49 years of age.

Previous studies of oral contraceptives and breast cancer indicate that recent use slightly increases risk, but most studies relied on self-reported use and did not examine contemporary oral contraceptive formulations. This nested case-control study was among female enrollees in a large U.S. integrated health care delivery system. Cases were 1,102 women ages 20 to 49 years diagnosed with invasive breast cancer from 1990 to 2009. Controls were randomly sampled from enrollment records (n = 21,952) and matched to cases on age, year, enrollment length, and medical chart availability. Detailed oral contraceptive use information was ascertained from electronic pharmacy records and analyzed using conditional logistic regression, ORs, and 95% confidence intervals (CI). Recent oral contraceptive use (within the prior year) was associated with an increased breast cancer risk (OR, 1.5; 95% CI, 1.3-1.9) relative to never or former OC use. The association was stronger for estrogen receptor-positive (ER(+); OR, 1.7; 95% CI, 1.3-2.1) than estrogen receptor-negative (ER(-)) disease (OR, 1.2, 95% CI, 0.8-1.8), although not statistically significantly different (P = 0.15). Recent use of oral contraceptives involving high-dose estrogen (OR, 2.7; 95% CI, 1.1-6.2), ethynodiol diacetate (OR, 2.6; 95% CI, 1.4-4.7), or triphasic dosing with an average of 0.75 mg of norethindrone (OR, 3.1; 95% CI, 1.9-5.1; Pheterogeneity compared with using other oral contraceptives = 0.004) was associated with particularly elevated risks, whereas other types, including low-dose estrogen oral contraceptives, were not (OR, 1.0; 95% CI, 0.6-1.7). Our results suggest that recent use of contemporary oral contraceptives is associated with an increased breast cancer risk, which may vary by formulation. If confirmed, consideration of the breast cancer risk associated with different oral contraceptive types could impact discussions weighing recognized health benefits and potential risks.

Effect of systemic adjuvant treatment on risk for contralateral breast cancer in the Women's Environment, Cancer and Radiation Epidemiology Study.

BACKGROUND: Results from randomized trials indicate that treatment with tamoxifen or chemotherapy for primary breast cancer reduces the risk for contralateral breast cancer. However, less is known about how long the risk is reduced and the impact of factors such as age and menopausal status. METHODS: The study included 634 women with contralateral breast cancer (case patients) and 1158 women with unilateral breast cancer (control subjects) from the Women's Environment, Cancer and Radiation Epidemiology Study. The women were younger than age 55 when they were first diagnosed with breast cancer during 1985-1999. Rate ratios (RRs) and 95% confidence intervals (CIs) for contralateral breast cancer after treatment with chemotherapy or tamoxifen were assessed by multivariable adjusted conditional logistic regression analyses. RESULTS: Chemotherapy was associated with a lower risk for contralateral breast cancer (RR = 0.57, 95% CI = 0.42 to 0.75) than no chemotherapy. A statistically significant association between chemotherapy and reduced risk for contralateral breast cancer persisted up to 10 years after the first breast cancer diagnosis and was stronger among women who became postmenopausal within 1 year of the first breast cancer diagnosis (RR = 0.28, 95% CI = 0.11 to 0.76). Tamoxifen use was also associated with reduced risk for contralateral breast cancer (RR = 0.66, 95% CI = 0.50 to 0.88) compared with no use, and the association was statistically significant for 5 years after the first diagnosis. CONCLUSION: The associations between chemotherapy and tamoxifen treatment and reduced risk for contralateral breast cancer appear to continue for 10 and 5 years, respectively, after the initial breast cancer is diagnosed. Ovarian suppression may have a role in the association between chemotherapy and reduced risk for contralateral breast cancer.

Differences in breast cancer stage, treatment, and survival by race and ethnicity.

BACKGROUND: In the United States, black and Hispanic white women with breast cancer present with more advanced stages and have poorer survival rates than non-Hispanic whites, whereas Asians and Pacific Islanders do not. However, Asians and Pacific Islanders and Hispanic whites are heterogeneous populations, and few studies have evaluated breast cancer stage, treatments, and mortality rates for subgroups of these populations. METHODS: Using data from 11 population-based tumor registries that participate in the Surveillance, Epidemiology, and End Results Program, we conducted a retrospective cohort study to evaluate the relationship between race and ethnicity and breast cancer stage, treatments, and mortality rates. The cohort of 124,934 women diagnosed as having a first primary invasive breast carcinoma between January 1, 1992, and December 31, 1998, included 97,999 non-Hispanic whites, 10,560 blacks, 322 American Indians, 8834 Asians and Pacific Islanders, and 7219 Hispanic whites. RESULTS: Relative to non-Hispanic whites, blacks, American Indians, Hawaiians, Indians and Pakistanis, Mexicans, South and Central Americans, and Puerto Ricans had 1.4- to 3.6-fold greater risks of presenting with stage IV breast cancer. Blacks, Mexicans, and Puerto Ricans were 20% to 50% more likely to receive or elect a first course of surgical and radiation treatment not meeting the 2000 National Comprehensive Cancer Network standards. In addition, blacks, American Indians, Hawaiians, Vietnamese, Mexicans, South and Central Americans, and Puerto Ricans had 20% to 200% greater risks of mortality after a breast cancer diagnosis. CONCLUSIONS: Differences in breast cancer stage, treatments, and mortality rates are present by race and ethnicity. Breast cancer survival may be improved by targeting factors, particularly socioeconomic factors, that underlie these differences.