Postmenopausal cancer risk after self‐reported endometriosis diagnosis in the Iowa Women's Health Study

Abstract

BACKGROUND Endometriosis, the presence of endometrial tissue outside the uterus, has an estimated prevalence between 4% and 10%. A recent study reported that women with a hospital discharge diagnosis of endometriosis were at increased risk of cancer at any site, breast cancer, ovarian cancer, and hematopoietic malignancies, especially non‐Hodgkin lymphoma (NHL). METHODS The authors examined whether self‐reported diagnosis of endometriosis was associated with increased risk of various cancers in the Iowa Women's Health Study. Incident cancer cases were identified from 1986 through 1998. Cox proportional hazards regression models were used to calculate relative risks and 95% confidence intervals for the particular cancers of interest. RESULTS Of 37,434 participants in this analysis, 3.8% reported a history of endometriosis at baseline in 1986. After 13 years of follow‐up, 1795 breast, 188 ovarian, and 243 NHL cases were detected in the cohort. Endometriosis was not associated with risk of all cancers combined (age‐adjusted relative risk [RR], 0.9; 95% confidence interval [CI], 0.7–1.2), breast carcinoma (RR, 1.0; 95% CI, 0.8–1.3), or ovarian carcinoma (RR, 0.8; 95% CI, 0.2–2.4). However, endometriosis was significantly associated with risk of NHL (age‐adjusted RR, 1.8; 95% CI, 1.0–3.0), especially diffuse NHL (RR, 3.2; 95% CI, 1.8–5.6). Multivariate adjustment had minimal effect on the point estimates of risk (NHL RR, 1.7; 95% CI, 0.97–2.7; diffuse NHL RR, 3.3; 95% CI, 1.9–5.9). Endometriosis was not associated with elevated risk of lung, urinary tract, endometrial, melanoma, or colorectal carcinomas (RRs, 1.2, 0.8, 1.2, 0.7, and 0.7, respectively). CONCLUSIONS These results corroborate a previously reported association between endometriosis and increased risk of NHL but not cancer at other sites. Cancer 2002;94:1612–18. © 2002 American Cancer Society. DOI 10.1002/cncr.10370

Endometriosis as a risk factor for Ovarian or Endometrial Cancer – Results of a hospital based case control study

“…A retrospective case-control study including 1399 patients did not show any association between endometrial cancer and endometriosis [59]. Previously reported data on endometriosis as a risk factor for endometrial cancer are inconclusive [37][38][39][40][41][42]. The studies mentioned have limited case numbers in comparison with the present study, which confirmed an increased risk.…”

A conditional mouse model for human MUC1-positive endometriosis shows the presence of anti-MUC1 antibodies and Foxp3+ regulatory T cells

“…The ectopic lesions often develop as invasive neoplasms and increasing evidence suggests that endometriosis might be a precursor of ovarian epithelial tumors (Brinton et al, 1997;Kobayashi et al, 2007;Melin et al, 2006;Nagle et al, 2008;Olson et al, 2002;Somigliana et al, 2006). Prevention strategies for ovarian cancer, the most lethal gynecologic malignancy, are a research priority, and early identification and treatment of precursor lesions is essential for long-term survival.…”

Endometriosis and cancer: is there a connection?

“…It is not clear from the available studies whether endometriosis is associated with an increased risk of breast cancer. [10][11][12][13] An unexpected reduced incidence of cervical cancer was seen in a National Swedish cancer registry study. 14 Alternative explanations to a causal one are an increased number of referrals to gynaecologists for endometriosis and more regular performance of cervical smears.…”

“…A definitive link has yet to be made. Similarly, inconclusive, but intriguing, associations have been made between endometriosis and nonHodgkin's lymphoma, 10,11 and melanoma. 11,13 Further work is needed to confirm or refute these findings, particularly as many previous studies included only a small number of subjects.…”