Chapter 9: Risk Assessment and Clinical Management – Ovarian Cancer

DISEASE SPECIFIC CANCER EPIDEMIOLOGY AND RISK FACTORS

Ovarian cancer is the second most common gynecologic malignancy and the most common cause of death from gynecologic cancer in the United States with 22,240 new cases and 14,000 deaths annually.¹ It is the fifth leading cause of cancer death in women after cancers of the breast, lung, and endometrium. Based on the National Cancer Database Surveillance, Epidemiology, and End Results (SEER) data from 2011 to 2015, the lifetime risk of developing ovarian cancer is 1.3%, and the median age at diagnosis is 63. The number of new cases and deaths are reported to be 11.6 and 7.2 per 100,000 women per year, respectively.²

The high mortality rate of ovarian cancer is due to the fact that most of the patients present with advanced stage disease and screening tests to diagnose early stage disease are still far from ideal. The majority of these neoplasms originate from coelemic epithelium (95%), high-grade serous carcinoma being the most common histologic subtype (75%).³ Other histologic epithelial subtypes include clear cell, endometrioid, mucinous, Brenner and undifferentiated carcinomas. High-grade serous carcinomas are closely related to fallopian tube and peritoneal carcinomas because of the extreme similarities in histologic features and clinical behaviors. Recent evidence supports that the majority of high-grade serous tumors that have been classified as ovarian (and some peritoneal) cancers actually arise in the fimbrial portion of the fallopian tubes.⁴ Due to this close proximity of origin, the primary site of these cancers may not always be determined, possibly leading to underestimation of annual incidence rates of primary fallopian tube (3.3 per 1,000,000)⁵ and peritoneal carcinomas (2.7 per 1,000,000).⁶

Certain risk factors are implicated in the etiology of ovarian cancer and based on these factors, women may be categorized into two groups. The high-risk group includes individuals with hereditary cancer syndromes and certain inherited genetic mutations that significantly increase the risk of ovarian cancer. The average-risk group reflects the general population without any of these hereditary cancer syndromes or mutations. At this point, it is important to distinguish a family history of ovarian cancer from familial hereditary ovarian cancer syndrome, as nearly one-third of women with hereditary ovarian carcinoma have no close relatives with cancer.⁷ Also the attributed risks are different; one first-degree relative with ovarian cancer increases the lifetime probability of developing it from 1.4 to 5%,⁸ whereas this risk is much higher, up to 46%, in a patient with a BRCA1 mutation.^9,10 These well-established risk factors that are used to modify individual risks are summarized in Table 9.1.