Oral contraceptive use by formulation and breast cancer risk by subtype in the Nurses' Health Study II: a prospective cohort study.

BACKGROUND: Oral contraceptive use has been associated with a higher breast cancer risk; however, evidence for the associations between different oral contraceptive formulations and breast cancer risk, especially by disease subtype, is limited. OBJECTIVE: This study aimed to evaluate the associations between oral contraceptive use by formulation and breast cancer risk by disease subtype. STUDY DESIGN: This prospective cohort study included 113,187 women from the Nurses' Health Study II with recalled information on oral contraceptive usage from 13 years of age to baseline (1989) and updated data on usage until 2009 collected via biennial questionnaires. A total of 5799 breast cancer cases were identified until the end of 2017. Multivariable Cox proportional hazards models estimated hazard ratios and 95% confidence intervals for the associations between oral contraceptive use and breast cancer risk overall and by estrogen and progesterone receptor and human epidermal growth factor receptor 2 status. Oral contraceptive use was evaluated by status of use (current, former, and never), duration of and time since last use independently and cross-classified, and formulation (ie, estrogen and progestin type). RESULTS: Current oral contraceptive use was associated with a higher risk for invasive breast cancer (hazard ratio, 1.31; 95% confidence interval, 1.09-1.58) when compared with never use, with stronger associations observed for longer durations of current use (>5 years: hazard ratio, 1.56; 95% confidence interval, 1.23-1.99; ≤5 years: hazard ratio, 1.19; 95% confidence interval, 0.95-1.49). Among former users with >5 years since cessation, the risk was similar to that of never users (eg, >5 to 10 years since cessation: hazard ratio, 0.99; 95% confidence interval, 0.88-1.11). Associations did not differ significantly by tumor subtype. In analyses by formulation, current use of formulations containing levonorgestrel in triphasic (hazard ratio, 2.83; 95% confidence interval, 1.98-4.03) and extended cycle regimens (hazard ratio, 3.49; 95% confidence interval, 1.28-9.53) and norgestrel in monophasic regimens (hazard ratio, 1.91; 95% confidence interval, 1.19-3.06), all combined with ethinyl estradiol, was associated with a higher breast cancer risk when compared with never oral contraceptive use. No association was observed for current use of the other progestin types evaluated (norethindrone, norethindrone acetate, ethynodiol diacetate, desogestrel, norgestimate, and drospirenone), however, sample sizes were relatively small for some of the subgroups, limiting these analyses. CONCLUSION: Current oral contraceptive use was associated with a higher risk for invasive breast cancer regardless of disease subtype, however, the risk in former users was comparable with never users 5 years after cessation. In analyses by progestin type, associations were observed for select formulations containing levonorgestrel and norgestrel. Assessment of the associations for newer progestin types (desogestrel, norgestimate, drospirenone) was limited by sample size, and further research on more recently introduced progestins is warranted.

Oral contraceptive use by formulation and endometrial cancer risk among women born in 1947-1964: The Nurses' Health Study II, a prospective cohort study.

Oral contraceptives (OCs) have been associated with long-term lower endometrial cancer risk; relatively little is known about associations with more recent OC formulations and associations with longer-term risk. A total of 107,069 women from the Nurses' Health Study II recalled OC use from age 13 to baseline (1989); biennial questionnaires updated data on OC use until 2009. OCs were classified by estrogen and progestin type, dose, and potency based on reported brand. 864 incident endometrial cancer cases were identified through 2017. Multivariable Cox proportional hazards models estimated hazard ratios (HR) and 95% confidence intervals [95% CI] for the association of OC use with endometrial cancer risk. OC use was associated with lower endometrial cancer risk (ever use, HR 0.77 [95% CI 0.65-0.91]; >10 years of use, 0.43 [0.32-0.58] vs. never OC use). Inverse associations for duration were evident regardless of time since last use. Longer durations (> 5 years) of ethinyl estradiol (0.52 [0.41-0.67]) and second-generation progestins (0.43 [0.30-0.61]), both versus never use, were more strongly associated with lower risk than mestranol (0.66 [0.50-0.88], p-het = 0.01) and first-generation progestins (0.62 [0.49-0.78], p-het = 0.03). Inverse associations were generally observed for cross-classified cumulative average estrogen and progestin dose and potency (< vs. ≥ median; ever use vs. never OC use), with the exception of high estrogen and low progestin dose. OCs were associated with lower endometrial cancer risk, independent of time since last use. Use of ethinyl estradiol and second-generation progestins were more strongly inversely associated with risk compared with older formulations.

Breast cancer survival in Brazil: How much health care access impact on cancer outcomes?

BACKGROUND: Breast cancer has a high incidence and increasing mortality in Southern Brazil. The present study evaluated clinical and sociodemographic characteristics, and their association with overall survival in a private cancer center. METHODS: 1113 breast cancer patients were included in this study. The association between survival and clinicopathological and sociodemographic characteristics was analyzed using Cox regression and Kaplan-Meyer curves. RESULTS: Median age at diagnosis was 52 years (SD 13.5). Most patients were diagnosed in stages 0 and I (62.7%), while only 1.3% had stage IV disease. Five- and 10-year overall survival were 93.5% and 83.8%, respectively. According to multivariate analysis, age at diagnosis (HR 1.05; CI95 1.03-1.06), staging (stage III: HR 4.04; CI95 1.34-12.19; stage IV: HR 9.61; CI95 2.17-42.50), high KI67 (HR 5.46; CI95 1.27-23.32) and distant recurrence (HR 7.28; CI95 4.79-11.06) were significantly associated with survival. Smoking status, years of education, BMI, and tumor biological status were not significantly associated with mortality. CONCLUSIONS: This cohort of Brazilian patients, who received timely and appropriate treatment, achieved outcomes that are comparable to those from high income countries. Breast cancer mortality seems dependent on the quality of health care available to patients.