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The Study

A woman has a 1:70 risk of being diagnosed with ovarian cancer in her life.[1]

Early-stagedisease is usually asymptomatic, and unfortunately, there are no effective screening tools.

Ovarian cancer, therefore, is often diagnosed at an advanced stage, when treatments have limited

efficacy.

There are several theories regarding the etiology of ovarian cancer.[2-4]

Certain reproductive

factors (early menarche, late menopause, low parity, infertility) are associated with increasedrisk. The most widely accepted theory explains the origin of ovarian cancer by the repeated

epithelial trauma accompanying ovulations. The surface trauma is followed by repair, during

which mutations could occur, resulting in malignant transformation.

The gonadotropin theory attributes a role to elevated levels of gonadotropins in inducing

malignant changes. Another theory posits a role of androgen hormones in the induction ofovarian cancer. Some groups consider ovarian cancer to be the result of inflammatory changes,

which can be induced by endometriosis.

[5]

Ovarian cancer and fallopian tube cancer often coexist; this raises the possibility that these

epithelial cancers originate from the tube. Carriers of certain mutations (BRCA1and BRCA2) are

also at a higher risk of developing ovarian cancer.

Infertile women are often nulliparous or have low parity, may have abnormally elevated

gonadotropin/androgen levels, and usually require stimulation that will induce multipleovulations as part of their treatment. In addition, many of them are affected by endometriosis. It

is not surprising, then, that many researchers have shown an interest in a potential link between

ovarian cancer and various aspects of infertility and its treatment.

The OMEGA Project Group aimed to investigate the late effects of hormones. This current

subgroup analysis evaluated the risk for ovarian cancer among women with endometriosis. Over19,000 women who had undergone in vitro fertilization (IVF) were enrolled in the OMEGA

study between 1980 and 1995. The controls included 6604 women with a diagnosis of infertility

who had not received IVF treatment. Data were collected from questionnaires, by checking

medical records, and by linking to a histology database and cancer registry.

Researchers enrolled 2851 women with histologically or surgically confirmed endometriosis and

806 women self-reporting endometriosis as the cause of infertility. Controls included 5247women without any evidence for endometriosis. During the analysis, age, contraceptive pill use,

parity, and IVF exposure were controlled for. The median follow-up was 15.2 years.

The main analysis included cases in which endometriosis had been diagnosed before the

diagnosis of ovarian tumor was made. Twenty-six cases (16 cancers and 10 borderline tumors)

were diagnosed in the endometriosis group, and 5 (2 cancers and 3 borderline tumors) werediagnosed in the control group (hazard ratio [HR], 8.2; 95% confidence interval [CI], 3.1-21.6).

The risk remained similar after adjustments were made for age, oral contraceptive use, parity,

and IVF treatment. Women who were exposed to oral contraceptives for more than 5 years had

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only a nonsignificant elevation in ovarian cancer risk (HR, 2.7; 95% CI, 0.7-10.4). In contrast,

those with less than 5 years of oral contraceptive use were at an increased risk (HR, 6.8; 95% CI,

2.3-20.5).

Viewpoint

This study found an increased risk for ovarian cancer among infertile women with endometriosis.

Endometriosis can be diagnosed in about 10%-15% of women and in 30%-40% of the infertile

population.[6]

Therefore, a 3- to 8-fold increased risk, even if based on relatively few cases, issignificant.

Many groups looked for an association between ovarian cancer and fertility treatment. The

results so far have been mostly reassuring. Compared with the general population, a slightlyincreased risk was seen among those with infertility who had been exposed to treatment, but the

risk was primarily limited to nulliparous women. Within the infertile cohort, the use of

gonadotropins typically was not associated with an increased risk compared with those not

exposed.

[7-9]

Most studies suffer from methodological issues, such as lack of controlling forconfounding variables, short follow-up, a limited number of cancer cases, and incomplete data

collection.

Endometriosis is known to be associated with inflammatory changes that could induce malignantchanges. Endometriosis is often associated with infertility and nulliparity could further increase

the risk. One of the strengths of the current study is that most endometriosis cases were

confirmed by operative or histology reports. Women who self-reported endometriosis without

surgical confirmation were also enrolled, but excluding them from the analysis would not havesignificantly changed the direction of the associations.

Contraceptive pills are often used to manage the various problems associated with endometriosis.In this study, women who took oral contraceptives for more than 5 years were at lower risk of

developing ovarian cancer. Oral contraceptive use is known to be associated with an up to 50%

risk reduction for ovarian cancer.[10]

It appears that a similar beneficial effect can be seen amongthose with endometriosis. This benefit should further be explored.

Many women with endometriosis require surgery to manage their symptoms; this may involveovarian surgery, or potentially, oophorectomy. This certainly would have a significant impact on

their future ability to conceive. On the basis of the findings of the current study, infertile women

with endometriosis are at an increased risk for ovarian cancer. One could consider elective

oocyte or embryo cryopreservation to allow them to maintain fertility, should radical surgery be

needed to manage their symptoms.

Abstract

http://www.medscape.com/medline/abstract/24014607http://www.medscape.com/medline/abstract/24014607http://www.medscape.com/medline/abstract/24014607