A cohort study of 49 933 women with surgically verified endometriosis: Increased incidence of breast cancer below the age of 40

Association of Fibroids, Endometriosis, and Gynecologic Surgeries with Breast Cancer Incidence and Hormone Receptor Subtypes

BACKGROUND

Fibroids and endometriosis are sex hormone-mediated and exhibit cancer-like behavior. Breast cancer may be more common in women who have had these conditions, but the literature is conflicting and does not always address factors like hysterectomy/oophorectomy status, race/ethnicity, menopause, and hormone receptor subtypes.

METHODS

Data are from the Sister Study, a cohort of 50,884 U.S. women enrolled in 2003 to 2009 and followed through 2020. Cox proportional hazards models with time-varying exposures and covariates assessed the relationship of fibroids or endometriosis with breast cancer. Logistic regression examined the association with estrogen receptor (ER) status among cases.

RESULTS

Fibroids (19,932 cases) were positively associated with breast cancer [fully adjusted HR: 1.07; 95% confidence interval (CI): 1.01-1.14], notably among Black participants (HR: 1.34; 95% CI: 1.07-1.69) and women who had a hysterectomy (HR: 1.18; 95% CI: 1.05-1.31). Endometriosis (3,970 cases) was not associated with breast cancer (HR: 0.99; 95% CI: 0.91-1.08). Among 4,419 breast cancer cases, fibroids were positively associated with ER+ subtypes (OR: 1.34; 95% CI: 1.10-1.65), while endometriosis was negatively associated with ER+ subtypes (OR: 0.78; 95% CI: 0.61-1.01).

CONCLUSIONS

We observed a modest positive association between fibroids and breast cancer, particularly ER+ breast cancer. No relationship with endometriosis and breast cancer incidence was found.

IMPACT

Fibroids, even in those with a family history of breast cancer, might modify breast cancer risk stratification tools. Future studies should further assess this link and interrogate shared risk factors.

Causal effects of genetically predicted endometriosis on breast cancer: a two-sample Mendelian randomization study

This study used a Mendelian randomization (MR) approach to investigate the causal relationship between genetically predicted endometriosis (EMS) and breast cancer risk. A total of 122,977 cases and 105,974 controls were included in the analysis, with gene-level summary data obtained from the Breast Cancer Association Consortium (BCAC). An inverse variance-weighting approach was applied to assess the causal relationship between EMS and breast cancer risk, and weighted median and MR-Egger regression methods were used to evaluate pleiotropy. Results showed a causal relationship between EMS and a decreased risk of overall breast cancer (odds ratio [OR] 0.95; 95% CI 0.90-0.99, p = 0.02). Furthermore, EMS was associated with a lower risk for estrogen receptor (ER)-positive breast cancer in a subgroup analysis based on immunohistochemistry type (OR 0.91; 95% CI 0.86-0.97, p = 0.005). However, there was no causal association between ER-negative breast cancer and survival (OR 1.00; 95% CI 0.94-1.06, p = 0.89). Pleiotropy was not observed. These findings provide evidence of a relationship between EMS and reduced breast cancer risk in invasive breast cancer overall and specific tissue types, and support the results of a previous observational study. Further research is needed to elucidate the mechanisms underlying this association.

Association between breast diseases and symptomatic uterine fibroids by using South Korean National Health Insurance database

Both the uterus and breasts have sex hormone dependence, yet there are few studies on the association between breast disease and uterine fibroids (UFs). The purpose of this study was to investigate the incidence of benign breast disease (BBD), carcinoma in situ (CIS), and breast cancer (BC) in women treated for UFs compared to women who were not treated for UFs. This retrospective cohort study used national health insurance data from January 1st, 2011, to December 31st, 2020. We selected women between 20 and 50 years old who (1) were treated for UFs (UF group) or (2) visited medical institutions for personal health screening tests without UFs (control group). We analyzed independent variables such as age, socioeconomic status (SES), region, Charlson comorbidity index (CCI), delivery status, menopausal status, menopausal hormone therapy (MHT), endometriosis, hypertension (HTN), diabetes mellitus (DM), and dyslipidemia based on the first date of uterine myomectomy in the UF group and the first visiting date for health screening in the non-UF group. There were 190,583 and 439,940 participants in the UF and control groups, respectively. Compared with those of the control group, the RRs of BBD, CIS, and BC were increased in the UF group. The hazard ratios (HRs) of BBD, CIS, and BC in the UF group were 1.335 (95% confidence interval (CI) 1.299-1.372), 1.796 (95% CI 1.542-2.092), and 1.3 (95% CI 1.198-1.41), respectively. When we analyzed the risk of BC according to age at inclusion, UFs group had the increased risk of BCs in all age groups in comparison with control group. Women with low SES (HR 0.514, 95% CI 0.36-0.734) and living in rural areas (HR 0.889, 95% CI 0.822-0.962) had a lower risk of BC. Our study showed that women with UFs had a higher risk of BBD, CIS, and BC than those without UFs. This result suggests that women with UFs should be more conscious of BC than those without UFs. Therefore, doctors should consider recommending regular breast self-exams, mammography, or ultrasound for the early detection of BC in women with UFs.

Challenges and Considerations in Identifying the Origin of Peritoneal Carcinomatosis: A Case Report

Invasive lobular cancer (ILC) of the breast is the second most common type of invasive breast cancer. Clinical determination of the growth pattern of ILC of the breast is difficult. Furthermore, the ILC of the breast has a unique metastatic pattern that involves gastrointestinal and peritoneal sites. Our patient was initially misdiagnosed with left ovarian cancer based on the findings of positron emission tomography and computed tomography. Herein, we report a case of ILC of the breast presenting as peritoneal carcinomatosis. The ESMO Clinical Practice Guidelines for cancers of unknown primary sites were used in the diagnosis of the carcinoma of unknown primary origin. Image-guided biopsy and immunohistochemical staining are also useful in the diagnosis of these cancer types.

Genetic Contribution of Endometriosis to the Risk of Developing Hormone-Related Cancers

Endometriosis is a common gynecological disorder that has been associated with endometrial, breast and epithelial ovarian cancers in epidemiological studies. Since complex diseases are a result of multiple environmental and genetic factors, we hypothesized that the biological mechanism underlying their comorbidity might be explained, at least in part, by shared genetics. To assess their potential genetic relationship, we performed a two-sample mendelian randomization (2SMR) analysis on results from public genome-wide association studies (GWAS). This analysis confirmed previously reported genetic pleiotropy between endometriosis and endometrial cancer. We present robust evidence supporting a causal genetic association between endometriosis and ovarian cancer, particularly with the clear cell and endometrioid subtypes. Our study also identified genetic variants that could explain those associations, opening the door to further functional experiments. Overall, this work demonstrates the value of genomic analyses to support epidemiological data, and to identify targets of relevance in multiple disorders.

Genetic links between endometriosis and cancers in women

Endometriosis is a chronic disease occurring during the reproductive stage of women. Although there is only limited association between endometriosis and gynecological cancers with regard to clinical features, the molecular basis of the relationship between these diseases is unexplored. We conducted a systematic study by integrating literature-based evidence, gene expression and large-scale cancer genomics data in order to reveal any genetic relationships between endometriosis and cancers in women. We curated 984 endometriosis-related genes from 3270 PubMed articles and then conducted a meta-analysis of the two public gene expression profiles related to endometriosis which identified Differential Expression of Genes (DEGs). Following an overlapping analysis, we identified 39 key endometriosis-related genes common in both literature and DEG analysis. Finally, the functional analysis confirmed that all the 39 genes were associated with the vital processes of tumour formation and cancer progression and that two genes (PGR and ESR1) were common to four cancers of women. From network analysis, we identified a novel linker gene, C3AR1, which had not been implicated previously in endometriosis. The shared genetic mechanisms of endometriosis and cancers in women identified in this study provided possible new avenues of multiple disease management and treatments through early diagnosis.