Ovarian Cancer |
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DescriptionAn in-depth report on the causes, diagnosis, treatment, and prevention of ovarian cancer. |
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CausesAbout 25,580 new cases of ovarian cancer are expected in 2004. Evidence suggests that the incidence of ovarian cancer is declining. The average age for the onset of ovarian cancer is about 60, although ovarian cancer can develop in women from the age of 20 to 90. The lifetime risk of ovarian cancer in women with no family history of the disease is approximately one in 70 (1.4%). Women with a history of ovarian cancer in one first-degree relative have an overall risk of 5% of developing the disease, but it may be higher in women with specific genetic factors. The majority of women with ovarian cancer have no family history of the disease, however, meaning that genetic inheritance is not the only risk factor. Genetic mutations causing abnormal cell growth and differentiation are the basis for all cancer. The great majority of genetic defects that cause cancer are due to unknown causes. Most likely overexposure to environmental assaults or errors that occur during cell division play a role in many cases. The Role of Hormones and Ovarian StimulationA number of circumstances that create hormonal changes may increase the risk of ovarian cancer. Number of Ovulations. Risk of ovarian cancer is directly related to the number of times a woman ovulates, which is indicated by the total number of menstrual periods she has had. A lower number of ovulations occur when the menstrual periods are shut off (as in pregnancy), so the risk of developing ovarian cancer is reduced. The following women have a lower risk for ovarian cancer:
Some researchers theorize that ovarian cancer develops in women with a higher number of ovulations because of persistent damage to the epithelial cells as the egg passes through during ovulation. Researchers postulate that the recurring cell division needed to heal these tiny wounds to the ovaries, month after month and year after year, creates opportunities for errors in cell reproduction that lead to the formation of cancerous cells. Therefore, the more ovulations, the more risk of ovarian cancer. Ovulation temporarily ceases during pregnancy, breast-feeding, and birth control pill use. Gonadotropins and Fertility Drugs. Gonadotropins are hormones produced in the pituitary gland that stimulate the ovaries to secrete estrogen and cause the follicles to produce and release eggs.
In a few studies, elevated levels of gonadotropins have been associated with an increased risk for ovarian cancer. These hormones are the basis for many fertility drugs, including human menopausal gonadotropin (Pergonal, Repronal, Metrodin) and clomiphene (Clomid, Serophene). Although there has been concern about an increased risk for ovarian cancers in women, a growing body of evidence is finding no higher risk from the drugs themselves. Instead, evidence suggest that ovarian cancers are most likely caused by factors contributing to the infertility -- not the agents used to treat it. Hormone Replacement Therapy (HRT). Although some studies have reported a weak increased risk for certain ovarian cancers in women taking HRT, others have found no association either with short- or long-term use of HRT. Inherited Genetic FactorsFamily history plays a role in between 5% and 10% of women who have ovarian cancer. Certain genes are being investigated and identified that are responsible for some of these cases. Depending on the particularly genetic type, the lifetime risk for ovarian cancer in women who carry these genes ranges from 16% to 65%. BRCA1 and 2 Genes. Inherited mutations in genes known as BRCA1 or BRCA2 are now believed to be responsible for 30% to 50% of breast cancers, ovarian cancers, or both in patients with a strong family history of these cancers. According to some studies, the risk each carries appears to be as follows:
The mutated genes are linked to an even higher risk for developing breast cancer. These mutations are present in only about 0.5 of the US or UK population overall but occur in about 2.5% of all Jewish women of Eastern European (Ashkenazi) descent. This prevalence in a relatively large population makes mutations to BRCA1 and BRCA2 the most common serious genetic disease known in any population group. These mutations are not restricted to the Ashkenazi population and may occur in women of any ethnicity, including women of Asian and African descent. The BRCA mutations can be passed down to the daughter by either the mother or the father. It should be noted that these mutations may occur in 5% to 10% of ovarian cancer patients who have no family history of breast or ovarian cancer. A number of studies have suggested that women with BRCA-mutated ovarian cancers tend to have better survival rates than others. Other Genetic Mutations. Women who carry the hereditary nonpolyposis colorectal cancer (HNPCC) gene have about a 9% chance of developing ovarian cancer.
Sporadic Genetic FactorsMost ovarian cancers are the result of genetic mutations that are not inherited but occur from environmental or other factors that cause damage to genetic material over time. Such genetic changes are referred to as sporadic (as opposed to inherited). Genetic alterations that have been observed in ovarian cancers involve the p53 tumor suppressor gene, the HER2/neu gene, and the PIC3KA gene. Ethnic FactorsSome research indicates that ovarian cancer occurs more often in North America and Northern Europe and among middle to upper socioeconomic class women from highly industrialized countries. Ovarian cancer is also much more common in Caucasian women than in African American women. Japan has a low, but rising, number of ovarian cancer cases. One study observed that when Japanese women immigrate to the United States, they and their daughters have an incidence of ovarian cancer that approaches that of Caucasian women, although another study did not support such findings. Other FactorsEndometriosis. Women with endometriosis may have some higher risk for ovarian cancer. It should be noted that endometriosis is very common and ovarian cancer is not, so the risk is still very low. Some research suggests that ovarian cancer associated with endometriosis may differ from most ovarian cancer cases, and, in fact, have a better outlook.
Fat Intake. Fats have been under scrutiny for some time. posing some higher risk for ovarian cancer. A 2001 analysis of eight observational studies reported an association between a high intake in animal fats and a greater risk. However, other studies on this subject have found no correlation between fat intake and ovarian cancer. In any case, both positive and negative studies are only suggestive and should not be considered to be conclusive, although they may lead to better research. Lactose Intolerance. Women who have an impaired ability to digest lactose, an enzyme found in dairy products, particularly milk, may be at increased risk for ovarian cancer. Galactose, an enzyme involved with this disorder, appears to be toxic to the ovaries and may be responsible for this effect. It should be strongly noted, however, that lactose intolerance is very common and ovarian cancer is uncommon. If such a risk exists in women with this digestive disorder, it still very small. Talcum Powder and Feminine Deodorants. Some reports suggest that the use of talcum powder used near the genital area may increase the risk for ovarian cancer, although this is controversial. |
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