Ovarian cancer is the leading cause of death from gynecologic cancer in the United States. It generally affects women aged 40-65 years.
The ovary is composed of epithelial cells along the surface, germ (egg-producing) cells, and surrounding connective tissue. Each of these cell types has the potential for malignant transformation. In addition, breast and gastrointestinal cancers commonly metastasize to the ovaries. The most common ovarian malignancy is epithelial carcinoma (over 90% of cases), which is the focus of this chapter.
In the early stages, ovarian cancer usually causes subtle and nonspecific symptoms that rarely prompt a woman to seek medical attention. These may include fatigue, abdominal pain and bloating, urinary frequency, post-menopausal vaginal bleeding, anorexia, and early satiety. A common presentation is the finding of an adnexal mass on pelvic exam or imaging.
More advanced cases may present with a malignant pleural effusion or bowel obstruction.
Family history. Genetic predisposition is the strongest risk factor for ovarian cancer. Women who have relatives with ovarian cancer have an approximately 3-fold increased risk, with multiple affected relatives further raising the risk.
Specific hereditary cancer syndromes, including Lynch syndrome and the BRCA gene mutations, also increase ovarian cancer risk. Women with a BRCA1 or BRCA2 mutation have a 25%-45% lifetime risk of ovarian malignancy, with BRCA1 generally presenting a higher risk.
Age. Most ovarian cancers occur in women over 50 years, with the highest risk for those over 60.
Race. White women have higher rates of ovarian cancer than black women.
Reproductive factors. Early menarche, late menopause, infertility, and nulliparity have all been associated with increased risk of ovarian cancer.
Diet. See Nutritional Considerations below.
Patients with signs and/or symptoms of ovarian cancer should be evaluated with pelvic imaging, typically a CT scan of the abdomen and pelvis.
If a suspicious mass is found, most women should undergo surgical biopsy to determine a histologic diagnosis. Less commonly, the diagnosis is made from fluid obtained from thoracentesis or paracentesis, or from tissue obtained by image-guided biopsy.
The preferred treatment depends on histology and surgical tumor staging, using the tumor, nodes, metastasis (TNM) classification system:
- Stage I is limited to the ovary or ovaries.
- Stage II includes pelvic extension.
- Stage III includes extra-pelvic peritoneal spread and/or inguinal or retroperitoneal lymph node involvement.
- Stage IV involves distant metastases.
In early stages, treatment involves surgical resection, along with abdominal hysterectomy, bilateral salpingo-oophorectomy, omentectomy, and selective lymphadenectomy. With more advanced disease, surgical removal and postoperative chemotherapy are indicated.
Epidemiologic investigations have revealed important clues to etiological factors in ovarian cancer. Ovarian cancer mortality in the Mediterranean region and in Asia has been associated with consumption of meat, milk, and animal fat. In contrast, evidence suggests that ovarian cancer risk may be significantly reduced through higher intake of soy products and certain kinds of vegetables.
The following factors are under investigation for possible roles in reducing ovarian cancer risk:
Avoiding or reducing meat, eggs, and other sources of saturated fat. The NIH-AARP study found that women consuming the highest amount of animal fat had a 30% higher risk for ovarian cancer when compared with those in the lowest intake group. Similarly, an analysis of data from the EPIC and Netherlands Cohort studies found that a high (compared with low) intake of saturated fat was associated with an approximately 20% increase in risk for ovarian cancer. Various food sources of saturated fat have been implicated, including meat, , eggs, and whole milk. A meta-analysis of egg consumption found that American women in the highest intake group had a nearly 40% greater risk when compared with those eating the fewest eggs.
Animal fat and meat influence estrogen activity and increase blood concentrations of insulin-like growth factor-1 (IGF-1), a polypeptide implicated in several cancers, including ovarian cancer.
Avoiding milk. Studies of dairy products and ovarian cancer risk have produced conflicting results and are a subject of some controversy. Although some studies have not revealed a relationship, a meta-analysis of prospective study data concluded that each glass of milk consumed daily raised the risk for ovarian cancer by 13%, on average. In addition, a pooled analysis of 12 prospective cohort studies including 553,217 women concluded that consumption of 3 dairy servings per day was associated with a 20% increased risk for this cancer, compared with 1 serving per day. More recently, a study of lactose intolerant women (i.e. who avoid or minimize consumption of dairy products) concluded that the risk for ovarian cancer was significantly lower in these individuals than in milk consumers.
Dairy products are the largest source of saturated fat in the US diet. However, saturated fat may not be the only explanation for the association between dairy consumption and ovarian cancer. Even consumption of small amounts of skim or low-fat milk (1 or more servings daily) has been associated with an increased risk for ovarian cancer. This has been attributed to galactose-related oocyte toxicity and/or elevation of gonadotropin concentrations. , Milk consumption also elevates IGF-1 blood concentrations. Some researchers have suggested this is due to the fact that cow’s milk contains IGF-1 that is identical to the growth factor produced by humans. However, milk’s macronutrients also stimulate IGF-1 production within the human body, which is likely a greater contributor to blood IGF-1 concentrations than any direct effect of the IGF-1 ingested from milk.
Soy products. A 2014 meta-analysis found that higher (compared with lower) intake of soy products is associated with a roughly 50% lower risk for ovarian cancer, while a 2016 meta-analysis estimated a 33% lower risk.
Increased fruit and vegetable intake. The intake of higher amounts of cruciferous vegetables is inversely related to ovarian cancer incidence, with an 11% lower risk compared to those with the lowest intakes.
Diet and Survival after Ovarian Cancer Diagnosis
The Women’s Health Initiative (WHI) found that women with ovarian cancer whose diets were most healthful, based on the Healthy Eating Index (HEI-2005), had an almost 25% lower risk for all-cause mortality, when compared with those whose diets were least healthful.
A number of reviews have found significantly poorer survival in women who were obese either in early adulthood or 5 years prior to diagnosis.
Genetic testing, when indicated.
Weight loss, as appropriate. See Obesity chapter.
What to Tell the Family
Risk of developing ovarian cancer, or of succumbing to it, may be reduced through healthy diet and lifestyle practices, along with timely screening and early intervention. Family members may support the patient and improve their own health by adopting the same changes. Smoking cessation and maintenance of a healthy weight should be encouraged.
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