Sex and Gender-based Analysis of this topic
There are 3 main types of ovarian cancer: (1) epithelial cell cancer, which starts in the cells covering the outer surface of the ovary; (2) germ cell tumours which starts in the egg cells within the ovary (generally occur in younger women, even children); and (3) stromal tumours which start in the connective tissue cells that hold the ovary together . Epithelial cell cancer is the most common type of ovarian cancer. It is estimated that in 2009, there will be 2,500 new diagnoses and 1,750 deaths due to ovarian cancer in Canada. In Canada, the probability of a woman developing ovarian cancer is 1 in 71, while the probability of a woman dying from ovarian cancer is 1 in 87 . Because there is no reliable ovarian cancer screening test, most women are at an advanced stage of the disease at the time of diagnosis , which may be why it is the fifth leading cause of cancer deaths in Canadian women .
There are a number of risk factors for ovarian cancer . In addition to having a family history of cancer (colon, uterine, pancreatic), approximately 5-10% of women with ovarian cancer have a family member who also has the disease. The risk increases if: one first-degree relative (mother, sister, daughter) has been diagnosed with ovarian cancer especially before the age of 50 or before menopause; two or more first-degree relatives diagnosed with ovarian cancer; or a combination of first- and second-degree relatives diagnosed with ovarian cancer. These risks apply to the woman’s paternal or maternal relatives. Although breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2) were first identified for their role in the development of breast cancer, these genes have also been linked to ovarian cancer. For example, women with BRCA1 mutations have a lifetime risk of 35-50% of developing ovarian cancer and more likely to occur before the age of 50, while women with BRCA2 mutations have a lifetime risk of 10-30% and is more likely to occur after the age of 60.
Other ovarian cancer associations include: a personal history of breast cancer ; women who began menstruating at a young age and/or reached menopause relatively late ; and women who have never been pregnant. However, researchers are unclear if this is due to hormones or a protective effect of pregnancy or damage to the epithelial cells of the ovary with each ovulation . Other potential risk factors include smoking and a body mass index (BMI) of more than 30.
Women who have taken oral contraceptives compared to women who have used other forms of contraception and women who have had many children are at a lower risk of developing ovarian cancer . Tubal ligation may decrease ovarian cancer risk [5,6]. Oral contraceptives are recommended to women who are BRCA 1 or 2 carriers due to the decreased number of ovulations.
Ovarian cancer is often not diagnosed because of the broad range of symptoms (irritable bowel syndrome, gastritis, depression, stress, urinary tract infection, constipation, nausea, bloating, indigestion, infertility, changes to menstruation patterns) . One study found that although the majority of women had at least one of the aforementioned symptoms of ovarian cancer, 25% of these women were first diagnosed with stress and/or depression .
Although it is not known why, women from developed countries are more likely to develop ovarian cancer . Women with Eastern European ancestry, such as women of Ashkenazi Jewish descent, are more likely to carry BRCA1 and BRCA2 genes; approximately 1 in 40 Ashkenaki Jewish women carry a BRCA gene mutation compared to 1 in 500 women in the general population . Among women aged 15 through 29 years, ovarian cancer represents 4% of cases (compared to 19% thyroid, 9% cervix, 7% breast) . French Canadian women are at a significantly higher lifetime risk for developing young age of onset breast and ovarian cancer due to recurrent mutations in their BRCA1 and BRCA2 genes .
Ovarian cancer surveillance data is limited. This may be due to the lack of good screening techniques and/or symptomology that is not often recognized when women first present with ovarian cancer. In addition, Canadian data on ovarian cancer is limited. For example, Canadian Cancer Statistics do not provide pan-Canadian statistics of ovarian cancer like they do for breast cancer. The Public Health Agency of Canada’s Centre for Chronic Disease Prevention and Control lists breast, cervical, and lung cancer as the key cancers of interest.