Ovarian cancer incidence and mortality have declined significantly over the past few decades, but eliminating racial disparities in treatment and improving prevention and early detection could help save even more women.
Lindsey A. Torre, MSPH
Ovarian cancer incidence and mortality have declined significantly over the past few decades, but eliminating racial disparities in treatment and improving prevention and early detection could help save even more women, according to an American Cancer Society (ACS) analysis of related statistics.1
From 1985 to 2014, the incidence rate declined 29%, from 16.6 to 11.8 per 100,000 individuals. From 1976 to 2015, ovarian cancer mortality declined by 33%, from 10.0 to 6.7 per 100,000. Despite these gains, “fewer than one-half of women survive beyond 5 years after diagnosis because of the predominance of aggressive high-grade serous carcinomas and the absence of specific early symptoms and effective early detection strategies,” the report said.
Lead author Lindsey A. Torre, MSPH, a Surveillance and Health Services Research scientist with ACS, and her team reviewed population-based data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results registry, the National Center for Health Statistics, and the Centers for Disease Control and Prevention’s National Program of Cancer Registries. Torre et al calculated long-term incidence trends using data representing 9% of the US population.
In an interview, Torre told OncologyLive® that the drop in mortality was largely due to the decline in incidence. The decreased use of hormone replacement therapy among white women and increased use of birth control, especially among women younger than 65 years, help explain reduced incidence, which has dropped continuously since at least 1975.
Using oral contraceptives for 5 to 9 years was associated with a 35% reduced risk of ovarian cancer. The protective effect diminishes over time but lasts at least 30 years after the final dose. Tubal ligation and oophorectomy also contribute to lower risk. Treatment improvements also have influenced the declines in incidence and mortality but have not been available to all, Torre said. “There are disparities in who has access to those advances, with non-Hispanic blacks having markedly lower survival than non-Hispanic whites,” she said.
Among black women, the 5-year causespecific survival for serous carcinoma, the most common form of ovarian cancer, is 36%, compared with 47% to 48% for non-Hispanic whites, Asians/ Pacific Islanders, and Hispanic women. Torre and her team found that survival was poorest among black women at every stage of the disease.
Furthermore, although 5-year survival for epithelial ovarian cancer improved from 40% for white women who received diagnoses from 1992 to 1994 to 47% for those who received diagnoses from 2007 to 2013, it remained roughly 35% for black women. Comorbidities and inferior access to optimal debulking surgery and intraperitoneal chemotherapy are possible contributors to the worse outcomes.
“Non-Hispanic black women have the secondlowest incidence rate and the second-highest mortality rate. That doesn’t make any sense,” Torre said. “It’s thought to be because of disparities in access to treatment—specifically, in receiving optimal treatment. We’re at an opportunity point. We’re understanding the disease better, and there are effective treatments that just need to be applied more equitably.”The ACS estimates that there will be 22,240 new ovarian cancer diagnoses and 14,070 disease-specific deaths in the United States this year. Ovarian cancer represents just 2.5% of all cancers among women but 5% of cancer deaths. For women with local disease, the 5-year relative survival rate is 93%, but many ovarian cancers are diagnosed in hard-to-treat advanced stages, providing hope for improving survival with better prevention and early detection.
Many efforts are under way to improve early detection, and so far in 2018, there have been 2 FDA approvals of oncologic drugs for treatment of ovarian cancer.2 In June, the FDA approved an expanded indication for bevacizumab (Avastin) for epithelial ovarian, fallopian tube, or primary peritoneal cancer. The drug, which starves tumor cells of blood, was approved in combination with carboplatin and paclitaxel, followed by bevacizumab, for stage III or IV disease after initial resection.
In April, the PARP inhibitor rucaparib (Rubraca) was approved for maintenance treatment of recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer. The drug was indicated for patients who have complete or partial response to platinum-based chemotherapy.
On average, the lifetime risk of developing ovarian cancer is 1.3%. Incidence rates were highest among non-Hispanic white women (12.0 per 100,000), 30% greater than for black women (9.4 per 100,000) and Asians/Pacific Islanders (9.2 per 100,000).
Epithelial cancers account for 90% of ovarian cancers across all racial and ethnic groups. Serous carcinoma, the most prevalent epithelial subtype, is most common among women aged 70 to 79 years. More common in younger women are the endometrioid (50-54 years), clear cell (50-59), and mucinous (55-59) subtypes.
The incidence of serous carcinoma (5.2 per 100,000) and endometrioid carcinoma (1.1 per 100,000) is highest among non-Hispanic white women. Serous carcinoma occurs at the rate of 3.4 per 100,000 among Asians/Pacific Islanders and black women. Asians/Pacific Islanders receive diagnoses of endometrioid carcinoma at the same rate as white women and have the highest rate of clear cell carcinoma (1.0 per 100,000). Serous carcinomas are associated with poor survival and tend to be aggressive, which is one reason they typically are detected at an advanced stage—51% at stage III and 29% at stage IV. Other subtypes are diagnosed at stage I 58% to 64% of the time. As a result, the 5-year cause-specific survival for serous carcinoma is just 43%, compared with 82% for endometrioid, 71% for mucinous, and 66% for cell carcinomas.
Ovarian cancer mortality is highest among white women (7.9 per 100,000), followed by black women (6.6 per 100,000) and Asians/ Pacific Islanders (4.4 per 100,000).
Family history remains the strongest risk factor associated with ovarian cancer. Women with a first-degree relative who has a history of ovarian cancer have an approximately 50% greater likelihood of developing invasive epithelial disease. Having a first-degree relative with a history of breast cancer increases the risk by 10%.
Inherited mutations that confer elevated risk, most often in the BRCA1 and BRCA2 genes, are responsible for an estimated 18% of epithelial ovarian cancers—particularly, highgrade serous carcinomas.
Using menopausal hormones increases the risk of ovarian cancer by 20% compared with never using them. The risk increases to 40% among current users or women who discontinued within 5 years.
In 2002, Jacques E. Rossouw, MD, and colleagues published results in JAMA showing that menopausal hormone replacement therapy was significantly associated with increased risk of breast and endometrial cancers.3 Torre et al found that since 2000, the incidence rate has declined annually by 3.7% for endometrioid carcinoma and by 1.0% for serous carcinoma.1 That could be due in part to declining use of menopausal hormone therapy, which is specifically associated with those subtypes.
In contrast, the risk of invasive epithelial disease drops by about 20% with the first childbirth, and each additional childbirth reduces the risk by about 10%.
There is no recommended screening test for ovarian cancer, and the US Preventive Services Task Force advises against screening for women at average risk. However, Torre said, women with a family history of breast or ovarian cancer should discuss genetic counseling with their physicians. BRCA1/2 mutations account for almost 40% of ovarian cancers in women with a family history, she added.
Symptoms of ovarian cancer include back pain, pelvic or abdominal pain, abdominal distention, difficulty eating or feeling full quickly, vomiting, indigestion, changes in bowel habits, and changes in urinary urgency or frequency— vague symptoms that are often associated with less serious maladies such as indigestion, Torres acknowledged. “If [a woman] experiences these symptoms, she does need to seek medical attention,” she said. “But that’s one of the difficulties with ovarian cancer. Often there aren’t any pointed symptoms until the disease is advanced.”