Premenopausal Hysterectomy and Risk of Ovarian Cancer in African-American Women

Racial Differences in the Association of Endometriosis and Uterine Leiomyomas With the Risk of Ovarian Cancer

OBJECTIVE

To evaluate associations between endometriosis and uterine leiomyomas with ovarian cancer risk by race and the effect of hysterectomy on these associations.

METHODS

We used data from four case-control studies and two case-control studies nested within prospective cohorts in the OCWAA (Ovarian Cancer in Women of African Ancestry) consortium. The study population included 3,124 Black participants and 5,458 White participants, of whom 1,008 Black participants and 2,237 White participants had ovarian cancer. Logistic regression was used to calculate odds ratios (ORs) and 95% CIs for the associations of endometriosis and leiomyomas with ovarian cancer risk, by race, stratified by histotype and hysterectomy.

RESULTS

The prevalences of endometriosis and leiomyomas were 6.4% and 43.2% among Black participants and 7.0% and 21.5% among White participants, respectively. Endometriosis was associated with an increased risk of endometrioid and clear-cell ovarian cancer in both racial groups (eg, OR for endometrioid tumors for Black and White participants 7.06 [95% CI 3.86-12.91] and 2.17 [95% CI 1.36-3.45], respectively, Phetereogeneity =.003). The association between endometriosis and ovarian cancer risk in White participants was stronger in those without hysterectomy, but no difference was observed in Black participants (all Pinteraction ≥.05). Leiomyomas were associated with an elevated risk of ovarian cancer only in those without hysterectomy in both Black (OR 1.34, 95% CI 1.11-1.62) and White (OR 1.22, 95% CI 1.05-1.41) participants (all Pinteraction ≥.05).

CONCLUSIONS

Black and White participants with endometriosis had a higher risk of ovarian cancer, and hysterectomy modified this association among White participants. Leiomyomas were associated with an increased risk of ovarian cancer in both racial groups, with hysterectomy modifying the risk in both groups. Understanding how racial differences in access to care and treatment options (eg, hysterectomy) may help guide future risk reduction strategies.

Hysterectomy and risk of epithelial ovarian cancer by histologic type, endometriosis, and menopausal hormone therapy

BACKGROUND

This nationwide, register-based case-control study investigated the association between hysterectomy and risk of epithelial ovarian cancer according to histology and by history of endometriosis and menopausal hormone therapy (MHT) use.

METHODS

From the Danish Cancer Registry, all women registered with epithelial ovarian cancer at age 40-79 years during 1998-2016 were identified (n = 6738). Each case was sex- and age-matched to 15 population controls using risk-set sampling. Information on previous hysterectomy on benign indication and potential confounders was retrieved from nationwide registers. Conditional logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs) for the association between hysterectomy and ovarian cancer according to histology, endometriosis, and use of MHT.

RESULTS

Hysterectomy was not associated with risk of epithelial ovarian cancer overall (OR=0.99; 95% CI 0.91 -1.09) but was associated with reduced risk of clear cell ovarian cancer (OR=0.46; 95% CI 0.28-0.78). In stratified analyses, decreased ORs associated with hysterectomy were seen in women with endometriosis (OR=0.74; 95% CI 0.50-1.10) and in non-users of MHT (OR=0.87; 95% CI 0.76-1.01). In contrast, among long-term MHT users, hysterectomy was associated with increased odds for ovarian cancer (OR=1.20; 95% CI 1.03-1.39).

CONCLUSION

Hysterectomy was not associated with epithelial ovarian cancer overall but with reduced risk of clear cell ovarian cancer. Our findings may suggest a reduced risk of ovarian cancer after hysterectomy in women with endometriosis and in MHT non-users. Interestingly our data pointed to an increased ovarian cancer risk associated with hysterectomy among long-term users of MHT.

Endometriosis and menopausal hormone therapy impact the hysterectomy-ovarian cancer association

OBJECTIVE

To evaluate the association between hysterectomy and ovarian cancer, and to understand how hormone therapy (HT) use and endometriosis affect this association.

METHODS

We conducted a pooled analysis of self-reported data from 11 case-control studies in the Ovarian Cancer Association Consortium (OCAC). Women with (n = 5350) and without ovarian cancer (n = 7544) who never used HT or exclusively used either estrogen-only therapy (ET) or estrogen+progestin therapy (EPT) were included. Risk of invasive epithelial ovarian cancer adjusted for duration of ET and EPT use and stratified on history of endometriosis was determined using odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

Overall and among women without endometriosis, there was a positive association between ovarian cancer risk and hysterectomy (OR = 1.19, 95% CI 1.09-1.31 and OR = 1.20, 95% CI 1.09-1.32, respectively), but no association upon adjusting for duration of ET and EPT use (OR = 1.04, 95% CI 0.94-1.16 and OR = 1.06, 95% CI 0.95-1.18, respectively). Among women with a history of endometriosis, there was a slight inverse association between hysterectomy and ovarian cancer risk (OR = 0.93, 95% CI 0.69-1.26), but this association became stronger and statistically significant after adjusting for duration of ET and EPT use (OR = 0.69, 95% CI 0.48-0.99).

CONCLUSIONS

The hysterectomy-ovarian cancer association is complex and cannot be understood without considering duration of ET and EPT use and history of endometriosis. Failure to take these exposures into account in prior studies casts doubt on their conclusions. Overall, hysterectomy is not risk-reducing for ovarian cancer, however the inverse association among women with endometriosis warrants further investigation.

Racial Differences in Population Attributable Risk for Epithelial Ovarian Cancer in the OCWAA Consortium

BACKGROUND

The causes of racial disparities in epithelial ovarian cancer (EOC) incidence remain unclear. Differences in the prevalence of ovarian cancer risk factors may explain disparities in EOC incidence among African American (AA) and White women.

METHODS

We used data from 4 case-control studies and 3 case-control studies nested within prospective cohorts in the Ovarian Cancer in Women of African Ancestry Consortium to estimate race-specific associations of 10 known or suspected EOC risk factors using logistic regression. Using the Bruzzi method, race-specific population attributable risks (PAR) were estimated for each risk factor individually and collectively, including groupings of exposures (reproductive factors and modifiable factors). All statistical tests were 2-sided.

RESULTS

Among 3244 White EOC cases and 9638 controls and 1052 AA EOC cases and 2410 controls, AA women had a statistically significantly higher PAR (false discovery rate [FDR] P < .001) for first-degree family history of breast cancer (PAR = 10.1%, 95% confidence interval [CI] = 6.5% to 13.7%) compared with White women (PAR = 2.6%, 95% CI = 0.8% to 4.4%). After multiple test correction, AA women had a higher PAR than White women when evaluating all risk factors collectively (PAR = 61.6%, 95% CI = 48.6% to 71.3% vs PAR = 43.0%, 95% CI = 32.8% to 51.4%, respectively; FDR P = .06) and for modifiable exposures, including body mass index, oral contraceptives, aspirin, and body powder (PAR = 36.0%, 95% CI = 21.0% to 48.8% vs PAR = 13.8%, 95% CI = 4.5% to 21.8%, respectively; FDR P = .04).

CONCLUSIONS

Collectively, the selected risk factors accounted for slightly more of the risk among AA than White women, and interventions to reduce EOC incidence that are focused on multiple modifiable risk factors may be slightly more beneficial to AA women than White women at risk for EOC.

Racial/ethnic disparities in ovarian cancer research

Ovarian cancer is one of the most fatal cancers diagnosed in women in the United States (U.S.). Data from national databases, including the Surveillance Epidemiology and End Results (SEER) program, show racial/ethnic differences in risk and survival of epithelial ovarian cancer with higher incidence among white women yet worse survival among African-American women compared to other racial/ethnic groups. The reasons for these differences are not well understood, but are likely multi-factorial. Epidemiologic studies suggest there may be some risk factor differences across racial/ethnic groups that would explain differences in the incidence of this rare and heterogeneous disease. Likewise, although data suggest that socioeconomic factors and access to care contribute to the disparity in ovarian cancer survival among African-American women, there are likely other contributing factors that have not as of yet been identified. Small sample sizes of minority women from individual studies do not provide adequate power to evaluate fully the contributions of environmental, genetic, and clinical factors associated with ovarian cancer risk and survival within these groups. Pooling existing data from individual epidemiologic studies has made a valuable contribution; however, new data collection is warranted to further our understanding of the underpinnings of the disparities in ovarian cancer that may lead to prevention and improved survival across all racial/ethnic groups.

The Association Between Hysterectomy and Ovarian Cancer Risk: A Population-Based Record-Linkage Study

BACKGROUND

Recent studies have called into question the long-held belief that hysterectomy without oophorectomy protects against ovarian cancer. This population-based longitudinal record-linkage study aimed to explore this relationship, overall and by age at hysterectomy, time period, surgery type, and indication for hysterectomy.

METHODS

We followed the female adult Western Australian population (837 942 women) across a 27-year period using linked electoral, hospital, births, deaths, and cancer records. Surgery dates were determined from hospital records, and ovarian cancer diagnoses (n = 1640) were ascertained from cancer registry records. We used Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between hysterectomy and ovarian cancer incidence.

RESULTS

Hysterectomy without oophorectomy (n = 78 594) was not associated with risk of invasive ovarian cancer overall (HR = 0.98, 95% CI = 0.85 to 1.11) or with the most common serous subtype (HR = 1.05, 95% CI = 0.89 to 1.23). Estimates did not vary statistically significantly by age at procedure, time period, or surgical approach. However, among women with endometriosis (5.8%) or with fibroids (5.7%), hysterectomy was associated with substantially decreased ovarian cancer risk overall (HR = 0.17, 95% CI = 0.12 to 0.24, and HR = 0.27, 95% CI = 0.20 to 0.36, respectively) and across all subtypes.

CONCLUSIONS

Our results suggest that for most women, having a hysterectomy with ovarian conservation is not likely to substantially alter their risk of developing ovarian cancer. However, our results, if confirmed, suggest that ovarian cancer risk reduction could be considered as a possible benefit of hysterectomy when making decisions about surgical management of endometriosis or fibroids.

Racial/ethnic differences in the epidemiology of ovarian cancer: a pooled analysis of 12 case-control studies

Background

Ovarian cancer incidence differs substantially by race/ethnicity, but the reasons for this are not well understood. Data were pooled from the African American Cancer Epidemiology Study (AACES) and 11 case-control studies in the Ovarian Cancer Association Consortium (OCAC) to examine racial/ethnic differences in epidemiological characteristics with suspected involvement in epithelial ovarian cancer (EOC) aetiology.

Methods

We used multivariable logistic regression to estimate associations for 17 reproductive, hormonal and lifestyle characteristics and EOC risk by race/ethnicity among 10 924 women with invasive EOC (8918 Non-Hispanic Whites, 433 Hispanics, 911 Blacks, 662 Asian/Pacific Islanders) and 16 150 controls (13 619 Non-Hispanic Whites, 533 Hispanics, 1233 Blacks, 765 Asian/Pacific Islanders). Likelihood ratio tests were used to evaluate heterogeneity in the risk factor associations by race/ethnicity.

Results

We observed statistically significant racial/ethnic heterogeneity for hysterectomy and EOC risk (P = 0.008), where the largest odds ratio (OR) was observed in Black women [OR = 1.64, 95% confidence interval (CI) = 1.34-2.02] compared with other racial/ethnic groups. Although not statistically significant, the associations for parity, first-degree family history of ovarian or breast cancer, and endometriosis varied by race/ethnicity. Asian/Pacific Islanders had the greatest magnitude of association for parity (≥3 births: OR = 0.38, 95% CI = 0.28-0.54), and Black women had the largest ORs for family history (OR = 1.77, 95% CI = 1.42-2.21) and endometriosis (OR = 2.42, 95% CI = 1.65-3.55).

Conclusions

Although racial/ethnic heterogeneity was observed for hysterectomy, our findings support the validity of EOC risk factors across all racial/ethnic groups, and further suggest that any racial/ethnic population with a higher prevalence of a modifiable risk factor should be targeted to disseminate information about prevention.