Noteworthy Numbers: Ovarian Cancer

TON - September 2018, Vol 11, No 4

Ovarian cancer affects the glands found in women that produce eggs, known as ova, for reproduction. The American Cancer Society estimates that 22,240 women will be diagnosed with new cases of ovarian cancer in 2018, and 14,070 women will die from the disease during the same year.1,2 Ovarian cancer primarily occurs in older women; approximately 50% of women diagnosed with the disease are aged 63 years or older. The rate at which women are diagnosed with ovarian cancer has been gradually declining over the past 20 years.2 According to a recently published report by the American Cancer Society, the incidence rate of ovarian cancer declined by 29% from 1985 (16.6 per 100,000) to 2014 (11.8 per 100,000), and the death rate associated with the disease declined by 33% between 1976 (10.0 per 100,000) and 2015 (67 per 100,000).3

The ovaries comprise 3 cell types, each capable of developing into a different tumor type. Epithelial cells make up the outer surface of each ovary, and tumors that start from these cells represent the overwhelming majority (85%-90%) of malignant ovarian cancers.4 This type of ovarian cancer typically occurs in postmeno­pausal women.5

Germ cells, which produce eggs within the ovary, are the source for approximately 5% of all ovarian cancers. Although germ cell tumors may occur in women of any age, they tend to develop most often in women in their early 20s.5

Stromal cells make up the connective tissue that holds the ovary together and produce the hormones estrogen and progesterone. Approximately 5% of all ovarian cancers develop within stromal cells.5 More than 50% of stromal tumors are found in women aged 50 years or older.4

Ovarian cancer cell tissues are given a grade based on how much they look like normal cell tissue. Grade 1 ovarian carcinomas resemble normal tissue and tend to have an overall better prognosis, whereas grade 3 ovarian carcinomas do not resemble normal cell tissue and are associated with an overall worse prognosis. Ovarian carcinomas are also assigned a tumor type, based on how fast the cancer cells grow and how quickly they respond to treatment. Type I ovarian tumors cause fewer symptoms and grow slowly, whereas type II tumors tend to spread faster to other parts of the body and do not respond well to chemotherapy.4

The 2018 estimate of 5-year relative survival for women with ovarian cancer significantly improves depending on disease stage at the time of diagnosis. The National Cancer Institute’s SEER registries cite a 5-year survival rate of 47% for ovarian cancer overall. For patients with localized, regional, and distant tumors, the 5-year survival rates are 93%, 73%, and 29%, respectively.1

References

  1. Cancer Statistics Center. 2018 estimates. https://cancerstatisticscenter.cancer.org. Accessed August 2, 2018.
  2. American Cancer Society. Key statistics for ovarian cancer. www.cancer.org/cancer/ovarian-cancer/about/key-statistics.html. Accessed August 15, 2018.
  3. Torre LA, Trabert B, DeSantis CE, et al. Ovarian cancer statistics, 2018. CA Cancer J Clin. 2018;68:284-296.
  4. American Cancer Society. What is ovarian cancer? Updated April 11, 2018. www.cancer.org/cancer/ovarian-cancer/about/what-is-ovarian-cancer.html. Accessed July 30, 2018.
  5. Ovarian Cancer Research Fund Alliance. Types of ovarian cancer. https://ocrfa.org/patients/about-ovarian-cancer/types-ovarian-cancer/. Accessed July 30, 2018.
Last modified: October 26, 2018