Ovarian cancer is the leading cause of death due to a gynecological tumor—the overall survival rate is less than 40% within five years of diagnosis. A new review published in Ovarian Cancer Prevention has identified several risk factors and potential clinical and surgical strategies for prevention of the disease.
Investigators from the Research Institute of Oncology at the Universidade Federal do Triangulo Mineiro in Brazil reviewed nearly 100 articles to gain a better understanding of the etiology and other aspects of ovarian cancer.
Epithelial-stromal tumors account for 90% of all primary ovarian cancer tumors and can be classified as either Type I or Type II. Type I are slow-growing tumors that can develop from precursor lesions and include borderline serous tumors, low grade serous carcinomas, mucinous carcinoma, endometrioid carcinomas, and clear cell carcinomas.
Type II tumors are highly aggressive with most being diagnosed at an advanced stage. They include high-grade serous carcinomas, malignant mixed mesodermal tumors (carcinosarcomas), and undifferentiated tumors.
The sensitivity and specificity of ovarian cancer screening methods is low, so traditional approaches such as gynecological examination, ultrasonography, and monitoring of a panel of systemic tumor markers offer the best chance for early diagnosis.
The total number of lifetime menstrual cycles has also been associated with ovarian cancer risk, as ovulation increases levels of inflammatory agents that can lead to mutations in DNA. To that end, the most consistent risk factors for the disease are related to reproductive history such as nulliparity, early menarche, and late menopause.
Approximately 5% to 10% of cases can be attributed to genetic defects—primarily mutations in BRCA1 and BRCA2. Ovarian carcinomas associated with mutations in the BRCA gene are also considerably more aggressive than sporadic tumors. However, sensitivity to platinum-based treatments is high, and patients with the BRCA1 mutation have a more favorable prognosis.
In this review, hidden cancers were found in 4% to 17% of samples obtained from prophylactic bilateral salpingo-oophorectomies performed in patients with BRCA1 and BRCA2 mutations, with 57% to 100% of the cancers located in the distal portion of the fallopian tubes.
Therefore, women with BRCA1 or BRCA2 mutations are often advised to consider prophylactic bilateral salpingo-oophorectomy surgery after they no longer want to become pregnant. The surgery is not without drawbacks; salpingo-oophorectomy induces a sudden onset of menopause in premenopausal women along with the associated symptoms and risks, including hot flashes and sleep disturbances, as well as increased risk for osteoporosis, and ischemic heart disease.
A number of lifestyle choices and modifiable factors have also been associated with ovarian cancer, including smoking, alcohol consumption, physical exercise, and diet.
The incidence of mucinous ovarian epithelial tumors in women with a history of smoking is much higher than the other histological subtypes, and it is higher than that of women who have never smoked. Although the correlation between smoking and overall survival has not been fully elucidated, it is thought that the association between smoking and patient survival differs according to the tumor stage at the time of diagnosis.
Studies that have investigated the effects of alcohol consumption on the incidence and survival of patients with ovarian cancer are inconsistent; however, epidemiological studies have reported a direct correlation between alcohol consumption and an increased risk of developing ovarian cancer. This correlation was dependent on the amount and duration of exposure.
Being overweight is also associated with an increased risk of ovarian cancer. While the effects of physical exercise on ovarian cancer have not been specifically evaluated, a higher incidence of ovarian cancer was observed in a study of sedentary women who report chronic inactivity and low intensity exercise. Whether ovarian cancer and diet are linked is currently under evaluation.
Currently, the jury is out regarding a relationship between the intake of high-fat diets and ovarian cancer, as data are limited and inconsistent. Eating starchy foods and a diet with a high glycemic index and glycemic load has been linked to an increased risk of ovarian cancer, although this has not been confirmed.
Carcinogenic heterocyclic amines and nitrous compounds are also present in red and processed meats. These components could eventually lead to accelerated tumor development, so a diet of limited red and processed meats and an increased intake of poultry and fish could reduce the risk of developing ovarian cancer.
In general, clinical data regarding the intake of natural products or herbs appear to be positive, although most studies have not included randomized clinical trials. Derivatives from plants and anticancer agents both block cell proliferation and induce apoptosis. Currently, more than half of the drugs available for treatment are derived from natural products.
In one study analyzed in the review, data from The Ovarian Cancer Association Consortium evaluated survival of ovarian cancer patients with a history of hypertension or diabetes. The results demonstrated that diabetes influenced the prognosis of ovarian cancer patients, affected treatment, and increased the risk of death in these patients.
Significant associations of mortality for hypertension were not observed. In addition, use of beta-blockers, oral antidiabetic drugs, and insulin was associated with increased mortality.
“Prevention of ovarian cancer remains a challenge due to our limited knowledge of its causes, difficulties associated with the modification of several established risk factors, and limited availability of early detection techniques,” the authors concluded. “It is crucial to understand the role of additional factors related to the prognosis of ovarian cancer, including factors that are potentially modifiable and may contribute to change the progression of ovarian cancer and improve survival.”
To read more about this study, click here.