Ovarian cancer is the 2nd most common women’s genital cancer following cervical cancer. The incidence is approximately 5.9 persons per one hundred thousand women per year. Statistics of the International Cancer Research Office in 2012 showed that 2,689 Thai women are diagnosed with ovarian cancer each year, with 1,431 deaths occurring per year, or 53%. Thus, ovarian cancer is a cancer with a high mortality rate compared with cancer in other organs, as diagnosis at the early stage is somewhat difficult. More than 70% of patients are in severe metastasis at the time of diagnosis, which usually presents with poor treatment results.
Causes and risk factors of ovarian cancer
Causes of ovarian cancer are not clearly known. There is a correlation to family history of ovarian cancer and breast cancer. Ovarian cancer is more commonly found in unmarried women or married women with no children or who are infertile, whereas women with multiple children or who take birth control pills have decreased risk. Furthermore, ovarian cancer can be found in women who are obese or are heavy alcohol consumers. Risk of ovarian cancer will decrease in breastfeeding women and women undergoing sterilization or hysterectomy.
Ovarian cancer symptoms
Patients with early stage ovarian cancer do not present with any abnormalities. A lump or mass may be found in some patients or they may feel the lower abdomen enlarged. Symptoms of suspected ovarian cancer include bloating, burping frequently, indigestion or lots of gas in the stomach and not feeling better even after taking antacid. They should see a doctor for examination or ultrasound. Abdominal bloating usually comes from high fluid content or having a tumor in the abdomen. Some patients may have nausea, vomiting, constipation, increased urination frequency, or abnormal vaginal bleeding.
Prevention and screening
High risk women with family history of ovarian cancer should receive advice regarding prevention. Unmarried married women or those who do not yet want children should regularly take oral contraceptives. In women with enough children, ovary removal is recommended; however, risks of peritoneal cancer still exist, since cells also develop from the epithelium lining of the ovary.
To date, screening of ovarian cancer has not sufficiently effective. It is mostly recommended in women at high risk of ovarian cancer. Screening methods include:
- Vaginal examination annually.
- Vaginal ultrasound to determine size and characteristic of ovaries as well as ovarian blood supply.
- Blood test to measure a substance produced from ovaries, i.e. CA125, which may increase in patients with some types of ovarian cancers and may in normal range in some types of ovarian cancer. CA125 also increases in cancers other than ovarian cancer, e.g. peritonitis, endometriosis, ovarian cyst, pregnancy and menstruation, etc.
Treatment of ovarian cancer depends on cancer stage and patient’s requirement to have children. In patients who are young and only have ovarian cancer on one side and in an early stage can receive a conservative treatment to reserve the chance to have children by only removing one ovary along with surgery to examine metastasis of peritoneal cancer. Chemotherapy may also be considered in some circumstances. In patients with advanced ovarian cancer, the treatment is to remove ovaries by surgery as much as possible, following with chemotherapy and targeted therapy accordingly.
Treatment response depends on cancer stage, quantity of cancer cells in the abdomen, and types of cancer. Overall survival rate at 5 years of all stages ovarian cancer is approximately 45-50%. In the event of early stage ovarian cancer, overall survival rate at 5 years is as high as 80-90%, whereas overall survival rate at 5 years in patients with advanced cancer is decreased to 10-20%.