Ovarian cancer refers to malignant growth arising from different parts of the ovaries.
The ovaries are part of a woman’s reproductive system, where the eggs are developed. Most (90%) ovarian cancers are classified as "epithelial" and arise from the surface (epithelium) of the ovary. Other types (10%) arise from the precursors to egg cells (germ cell tumour) or supporting cells (sex cord/stromal).
Ovarian cancer is the fifth commonest cancer among women in Singapore. According to the Singapore Cancer Registry, in the period 2014-2018, 379 cases were diagnosed yearly. It is the second most common female genital tract cancer.
Epithelial ovarian cancer usually affects older women although it can also happen to younger women. Germ cell cancers of the ovary occur more frequently in younger women.
Among female genital tract cancers, epithelial ovarian cancers are the most difficult to prevent or cure because they rarely have early symptoms or signs. Symptoms tend to develop only when the cancer is advanced. These symptoms include abdominal swelling and discomfort, bloating or wind, pain, change in bowel or urinary habits.
While there is no known way to prevent epithelial ovarian cancer, but research has shown that these things may lower a woman’s chance of getting it:
Risk factors associated with ovarian cancer include:
Ovarian cancer is known to run in some families where family members may have increased risk of getting ovarian, breast and prostate cancer (e.g. BRCA gene abnormalities) or increased risk of getting endometrial cancer, colorectal cancer in addition to ovarian cancer (Lynch syndrome). These patients account for 15% of all women who have ovarian cancer. The lifetime risk in women with a BRCA1 gene mutation is 40-60%, and the lifetime risk in women with a BRCA2 gene mutation is 20-35%.
Although a marker in the blood, called CA 125, is raised in about 80% of patients with epithelial ovarian cancers, it is not always accurate and not adequate for diagnosis of ovarian cancer. It is also raised in non-cancerous conditions, such as endometriosis and appendicitis. The result of elevated CA-125 must therefore be interpreted in the light of other clinical findings. Pelvic ultrasound can help to detect abnormal ovarian cysts. CT scans of the chest, abdomen and pelvis and chest x-rays are also useful in detecting whether are areas of the body is affected. Ultimately an operation or biopsy is required to prove that the organs affected are cancerous and originate from the ovaries.
To determine the actual extent of the cancer, surgical exploration or staging is required. During the procedure, the doctor will examine the peritoneum, which is the inner lining of the abdomen. Fluid within the abdomen is sent for assessment which involves analysis under a microscope. Besides determining the stage of the cancer, the aim of surgery is to remove as much of the cancer as possible. Often this includes removing ovaries, the fallopian tubes, the uterus and its surrounding lymphatics.
Additional treatment following surgery will be determined by the stage of the disease, the grade (aggressiveness) of the disease and the subtype of cancer.
For very early stage disease and non-aggressive types, further treatment may not be required. For the more advanced and aggressive types of cancers, chemotherapy is the treatment of choice.
Occasionally, patients with advanced epithelial ovarian cancer may be unsuitable for surgery in the first instance. In such cases, pre-operative chemotherapy may be given to shrink or control the cancer before surgery.
There are newer targeted drugs which can be used to treat selected cases of epithelial ovarian cancer in the appropriate disease settings, including intravenous (given by drip) Bevacizumab and oral Olaparib.
Ovarian cancer in the early stage can potentially be cured while those in the late stage of the cancer, permanent cure may be difficult.
Is there a screening test for ovarian cancer?There is currently no widely accepted and effective screening test for ovarian cancer. However, if there is a strong family of history of breast or ovarian cancer, it may be appropriate for that woman to go for genetic counseling and testing.
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