Oral Contraceptives and Survival in Breast Cancer Patients Aged 20 to 54 Years

Effect of the use of prediagnosis hormones on breast cancer prognosis: MCC-Spain study

OBJECTIVE

To extend knowledge about the long-term use of hormones in hormone therapy or oral contraception as prognostic factors in breast cancer.

METHODS

The MCC-Spain project is a cohort of 1,685 women with incident breast cancer recruited in Spain. Recruitment was carried out between 2007 and 2010, and the follow-up finished in December 2017. The impact of hormone therapy or oral contraception on breast cancer prognosis was analyzed considering year of birth and menopausal status (1,095 women [65%] were postmenopausal). Hazard ratios (HRs) were estimated using Cox regression models. Death by any cause was considered as the event, and hormone therapy or oral contraception were analyzed as regressors.

RESULTS

Oral contraception use for less than 5 years shows an HR of 1.10 (95% CI, 0.75 to 1.62), whereas use for 5 or more years shows an HR of 1.46 (95% CI, 0.95 to 2.25), with a P trend of 0.01, showing a dose-dependent response. Regarding hormone therapy and restricting the analysis to postmenopausal women born between1940 and 1959, where most hormone therapy (consumption) is concentrated, the results did not show any trend.

CONCLUSION

Concerning oral contraception use, our results demonstrate that their use is related to poor prognosis in breast cancer. However, research in this field is limited and controversial, indicating the need for more research in this area. Regarding hormone therapy consumption, our results indicate no association with better prognosis, which contradicts what has previously been published.

Breast Cancer Risk Factors and Survival by Tumor Subtype: Pooled Analyses from the Breast Cancer Association Consortium

BACKGROUND

It is not known whether modifiable lifestyle factors that predict survival after invasive breast cancer differ by subtype.

METHODS

We analyzed data for 121,435 women diagnosed with breast cancer from 67 studies in the Breast Cancer Association Consortium with 16,890 deaths (8,554 breast cancer specific) over 10 years. Cox regression was used to estimate associations between risk factors and 10-year all-cause mortality and breast cancer-specific mortality overall, by estrogen receptor (ER) status, and by intrinsic-like subtype.

RESULTS

There was no evidence of heterogeneous associations between risk factors and mortality by subtype (P adj > 0.30). The strongest associations were between all-cause mortality and BMI ≥30 versus 18.5-25 kg/m2 [HR (95% confidence interval (CI), 1.19 (1.06-1.34)]; current versus never smoking [1.37 (1.27-1.47)], high versus low physical activity [0.43 (0.21-0.86)], age ≥30 years versus <20 years at first pregnancy [0.79 (0.72-0.86)]; >0-<5 years versus ≥10 years since last full-term birth [1.31 (1.11-1.55)]; ever versus never use of oral contraceptives [0.91 (0.87-0.96)]; ever versus never use of menopausal hormone therapy, including current estrogen-progestin therapy [0.61 (0.54-0.69)]. Similar associations with breast cancer mortality were weaker; for example, 1.11 (1.02-1.21) for current versus never smoking.

CONCLUSIONS

We confirm associations between modifiable lifestyle factors and 10-year all-cause mortality. There was no strong evidence that associations differed by ER status or intrinsic-like subtype.

IMPACT

Given the large dataset and lack of evidence that associations between modifiable risk factors and 10-year mortality differed by subtype, these associations could be cautiously used in prognostication models to inform patient-centered care.

A prospective investigation of oral contraceptive use and breast cancer mortality: findings from the Swedish women's lifestyle and health cohort

BACKGROUND

The association between oral contraceptive (OC) use and long-term mortality remains uncertain and previous studies have reported conflicting findings. We aim to assess the long-term impact of OC use on all-cause and cancer-specific mortality.

METHODS

Out of 49,259 participants, we analysed data on 2120 (4.3%) women diagnosed with first primary breast cancer between 1993 and 2012, in the Swedish Women's Lifestyle and Health Study. Kaplan-Meier plots were used to graph the hazard of mortality in association with oral contraceptives use, stage of disease and hormone receptors status at diagnosis. Cox proportional hazard model were used to estimate hazard ratios (HR) between OC use and all-cause mortality. The same association was studied for breast cancer-specific mortality by modelling the log cumulative mortality risk, adjusting for clinical stage at diagnosis, hormone receptor status, body mass index and smoking.

RESULTS

Among 2120 women with breast cancer, 1268 (84%) reported ever use of OC and 254 died within 10 years of diagnosis. The risk of death for OC ever-users relative to never-users was: HR = 1.13 (95% CI: 0.66-1.94) for all-cause mortality and HR = 1.29 (95% CI: 0.53-3.18) for breast cancer-specific mortality. A high percentage of women (42.9%) were diagnosed at early stage disease (stage I).

CONCLUSIONS

Among women with primary breast cancer, OC ever-users compared to never- users did not have a higher all-cause or breast cancer specific-mortality, after the adjustment of risk factors.

Association of Combined Estrogen-Progestogen and Progestogen-Only Contraceptives with the Development of Cancer

Combined estrogen-progestogen contraceptives (oral contraceptives or OCs) and progestogen-only contraceptives (POCs) are synthetic steroids that bind to steroid hormone receptors, which are widespread throughout the body. They have a profound effect on cellular physiology. Combined OCs have been classified by the International Agency for Research on Cancer (IARC) as Group 1 carcinogens, but their findings have not been updated recently. In order to update the information and better understand the impact that OCs and POCs have on the risk of development of cancers, a comprehensive literature search was undertaken, focusing on more recently published papers. In agreement with the IARC, the recent literature confirms an increased risk of breast cancer and cervical cancer with the use of OCs. The recent literature also confirms the IARC conclusion that OCs decrease the risk of ovarian and endometrial cancers. However, there is little support from recent studies for the IARC conclusion that OCs decrease the risk of colorectal cancer or increase the risk of liver cancer. For liver cancer, this may be due to the recent studies having been performed in areas where hepatitis is endemic. In one large observational study, POCs also appear to increase the overall risk of developing cancer. OCs and POCs appear to increase the overall risk of cancer when carefully performed studies with the least intrinsic bias are considered.

Summary

OCs have been classified as cancer-causing agents, especially leading to increases in breast cancer and cervical cancer. A review of the recent scientific literature was performed to see whether this still appears to be the case. The recent literature supports the cancer-causing role of OCs especially for breast cancer and cervical cancer. Studies also indicate that progesterone-only contraceptives (such as implants and vaginal rings) also can cause cancer. This is especially true for breast cancer and cervical cancer.

Do Breast Cancer Risk Factors Affect the Survival of Breast Cancer Patients in Southern Sri Lanka?

Background:

Breast cancer continues to be a major cause of morbidity among women in Sri Lanka. Possible effects of etiological risk factors on breast cancer specific survival (BCSS) of the disease is not clear. This study was designed to explore the impact of breast cancer risk factors on the BCSS of patients in Southern Sri Lanka.

Method:

This retro-prospective study included all breast cancer patients who had sought immunohistochemistry services at our unit from May 2006 to December 2012. A pre-tested, interviewer-administered questionnaire was used to gather information on risk factors. BCSS was estimated using the Kaplan-Meier model. Univariate Cox-regression analysis was performed with 95% confidence intervals using the SPSS statistical package.

Results:

A total of 944 breast cancer patients were included. Five year BCSS was 78.8%. There was a statistically significant difference between the patients who had a family history of breast cancer and no family history of any cancer in terms of the presence/absence of lymph node metastasis (p=0.011) and pathological stage (p=0.042). The majority of the premenopausal patients had associated DCIS (p<0.001) and large tumours (p=0.015) with positive lymph nodes (p=0.016). There was no statistically significant association between hormone receptor subtypes and hormone related risk factors. Univariate analysis revealed that breast cancer risk factors had no significant effect on the BCSS.

Conclusion:

Even though family history of breast cancer and premenopausal status are associated with poor prognostic features, they, in line with the other breast cancer risk factors, appear to have no significant effect on the BCSS of patients in Southern Sri Lanka.

Organochlorine insecticides DDT and chlordane in relation to survival following breast cancer

Organochlorine insecticides have been studied extensively in relation to breast cancer incidence, and results from two meta-analyses have been null for late-life residues, possibly due to measurement error. Whether these compounds influence survival remains to be fully explored. We examined associations between organochlorine insecticides [p,p'-DDT (dichlorodiphenyltrichloroethane), its primary metabolite, p,p'-DDE, and chlordane] assessed shortly after diagnosis and survival among women with breast cancer. A population-based sample of women diagnosed with a first primary invasive or in situ breast cancer in 1996-1997 and with available organochlorine blood measures (n = 633) were followed for vital status through 2011. After follow-up of 5 and 15 years, we identified 55 and 189 deaths, of which 36 and 74, respectively, were breast cancer-related. Using Cox regression models, we estimated the multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for lipid-adjusted organochlorine concentrations with all-cause and breast cancer-specific mortality. At 5 years after diagnosis, the highest tertile of DDT concentration was associated with all-cause (HR = 2.19; 95% CI: 1.02, 4.67) and breast cancer-specific (HR = 2.72; 95% CI: 1.04, 7.13) mortality. At 15 years, middle tertile concentrations of DDT (HR = 1.42; 95% CI 0.99, 2.06) and chlordane (HR = 1.42; 95% CI: 0.94, 2.12) were modestly associated with all-cause and breast cancer-specific mortality. Third tertile DDE concentrations were inversely associated with 15-year all-cause mortality (HR = 0.66; 95% CI: 0.44, 0.99). This is the first population-based study in the United States to show that DDT may adversely impact survival following breast cancer diagnosis. Further studies are warranted given the high breast cancer burden and the ubiquity of these chemicals.

Exposure to ethinyl estradiol prenatally and/or after sexual maturity induces endometriotic and precancerous lesions in uteri and ovaries of mice

Unrecognizable exposure to estrogenic substance may cause estrogen-dependent diseases, endometriosis and cancer. Pregnant mice (ICR/Jcl, CLEA) were exposed to 0.01 mg ethinyl estradiol (EE2 )/kg per day or vehicle (olive oil) through oral intubation from day 11 to 17 of gestation. They delivered their offspring and raised them. When the experimental female F1 mice were at 8 weeks of age, they were not exposed to EE2 or to the same dose of EE2 or to vehicle twice a week until 20 weeks of age. The control female F1 mice were exposed to the same dose of EE2 or vehicle alone, similarly. All mice were killed at 28 weeks of age. The resected uteri and ovaries were processed for microscopic examinations and for determination of the aromatase mRNA levels and aromatase protein through quantitative RT-PCR and Western blotting, respectively. Adenomyosis and adenocarcinomatous changes were significantly discernible in the EE2 -exposed uteri, and incidence of ectopic glands and serous cysts were significantly increased in the prenatally EE2 -exposed ovaries as compared with respective controls. Significant upregulation of the aromatase mRNA was seen in the prenatally EE2 -exposed uteri and in the EE2 -exposed ovaries. The aromatase protein was identified in all ovaries examined, and in EE2 -exposed uteri but not in controls and confirmed its localization in eutopic and ectopic glands, abnormally proliferated lesions and the lining of the cysts. Taken together, continuous EE2 exposure may cause endometriotic and precancerous lesions due to excessive estrogen synthesis in both target organs.

Oral contraceptive use and survival in women with invasive breast cancer

BACKGROUND

Oral contraceptives (OC) are widely used in the United States. Although the relation between OC use and breast cancer incidence has been widely studied, the few studies examining associations between OC use prior to breast cancer diagnosis and survival are inconsistent.

METHODS

Women with invasive breast cancer participating in the Women's Contraceptive and Reproductive Experiences (CARE) Study, a population-based case-control study (4565 women ages 35-64 years), and the California Teachers Study (CTS) cohort (3929 women ages 28-91 years) were followed for vital status. A total of 1,064 women died in the CARE Study (median follow-up, 8.6 years) and 523 died in the CTS (median follow-up, 6.1 years). Cox proportional hazards regression provided hazard rate ratio estimates [(relative risk, RR)] with 95% confidence intervals (CIs) for risk of death from any cause and from breast cancer.

RESULTS

No association was observed for any OC use prior to diagnosis and all-cause mortality [CARE Study: RR = 1.01 (95% CI = 0.86-1.19); CTS: RR = 0.84 (95% CI = 0.67-1.05)]. A decreased risk of all-cause mortality was observed in the CTS among women with more than 10 years of OC use (RR = 0.67, 95% CI = 0.47-0.96); however, no trend of decreasing risk with increasing OC duration was observed (P(trend) = 0.22), and no association was observed in the CARE study. No associations were observed for breast cancer-specific mortality.

CONCLUSIONS

OC use is not associated with all-cause or breast cancer-specific mortality among women with invasive breast cancer.

IMPACT

These 2 independent studies demonstrated no overall association between OC use and survival among women with breast cancer.

Oral contraceptive use and breast cancer: a prospective study of young women

BACKGROUND

Previous studies convincingly showed an increase in risk of breast cancer associated with current or recent use of oral contraceptives from the 1960s to 1980s. The relation of contemporary oral contraceptive formulations to breast cancer risk is less clear.

METHODS

We assessed lifetime oral contraceptive use and the specific formulations used among 116,608 female nurses ages 25 to 42 years at enrollment in 1989, and subsequently updated this information every 2 years. We related this information to risk of breast cancer up to June 1, 2001.

RESULTS

During 1,246,967 person-years of follow-up, 1,344 cases of invasive breast cancer were diagnosed. Past use of any oral contraceptive was not related to breast cancer risk [multivariate relative risk (RR), 1.12; 95% confidence interval 0.95-1.33]. Current use of any oral contraceptive was related to a marginally significant higher risk (multivariate RR, 1.33; 95% CI, 1.03-1.73). One specific formulation substantially accounted for the excess risk: the RR for current use of triphasic preparations with levonorgestrel as the progestin was 3.05 (95% CI, 2.00-4.66; P < 0.0001).

CONCLUSIONS

Current use of oral contraceptives carries an excess risk of breast cancer. Levonorgestrel used in triphasic preparations may account for much of this elevation in risk.

IMPACT

Different oral contraceptive formulations might convey different risks of breast cancer; ongoing monitoring of these associations is necessary as oral contraceptive formulations change.

Prediagnosis reproductive factors and all-cause mortality for women with breast cancer in the breast cancer family registry

Studies have examined the prognostic relevance of reproductive factors before breast cancer diagnosis, but most have been small and their overall findings inconclusive. Associations between reproductive risk factors and all-cause mortality after breast cancer diagnosis were assessed with the use of a population-based cohort of 3,107 women of White European ancestry with invasive breast cancer (1,130 from Melbourne and Sydney, Australia; 1,441 from Ontario, Canada; and 536 from Northern California, United States). During follow-up with a median of 8.5 years, 567 deaths occurred. At recruitment, questionnaire data were collected on oral contraceptive use, number of full-term pregnancies, age at first full-term pregnancy, time from last full-term pregnancy to breast cancer diagnosis, breastfeeding, age at menarche, and menopause and menopausal status at breast cancer diagnosis. Hazard ratios for all-cause mortality were estimated with the use of Cox proportional hazards models with and without adjustment for age at diagnosis, study center, education, and body mass index. Compared with nulliparous women, those who had a child up to 2 years, or between 2 and 5 years, before their breast cancer diagnosis were more likely to die. The unadjusted hazard ratio estimates were 2.75 [95% confidence interval (95% CI), 1.98-3.83; P < 0.001] and 2.20 (95% CI, 1.65-2.94; P < 0.001), respectively, and the adjusted estimates were 2.25 (95% CI, 1.59-3.18; P < 0.001) and 1.82 (95% CI, 1.35-2.46; P < 0.001), respectively. When evaluating the prognosis of women recently diagnosed with breast cancer, the time since last full-term pregnancy should be routinely considered along with other established host and tumor prognostic factors, but consideration of other reproductive factors may not be warranted.

Parity in relation to survival following breast cancer

AIM

The present study examines the association between parity and survival following breast cancer diagnosis.

METHODS

Medical records of 4453 women diagnosed with breast cancer in Malmö, Sweden, between 1961 and 1991 were analysed. All women were followed until 31 December 2003, using the Swedish Cause-of-Death Registry. Breast cancer specific mortality rate was calculated in different levels of parity. Corresponding relative risks, with 95% confidence intervals (CI), were obtained using Cox's proportional hazards analysis. All analyses were adjusted for potential prognostic factors and stratified for age, menopausal status and diagnostic period.

RESULTS

As compared to women with one child, nulliparity (RR 1.27: 95% CI 1.09-1.47), and high parity (four or more children) (1.49: 1.20-1.85) were positively associated with a high mortality from breast cancer. When adjusted for potential confounders, the association was only statistically significant for high parity (1.33: 1.07-1.66). In the analyses stratified on age and menopausal status, there was a similar positive association between high parity and breast cancer death in all strata, although only statistically significant among women older than 45 years of age or postmenopausal. Nulliparity was associated with breast cancer death in women that were younger than 45 years of age (1.28: 0.79-2.09) or premenopausal (1.30: 0.95-1.80), but these associations did not reach statistical significance. There was no association between nulliparity and breast cancer death in women older than 45 years of age or postmenopausal. All associations were similar in analyses stratified for diagnostic period.

CONCLUSION

Women with four or more children have a poor breast cancer survival as compared to women with one child.