Ovarian cancer

Definition 

Ovarian cancer is a malignant disease affecting the ovaries (egg-producing organs) of women. It is one of the most common causes of  cancer deaths in females and has an incidence of about 1,4 percent of the population. The average age at diagnosis is mid-50s.

Causes and risk factors

The cause of ovarian cancer is unknown, but it is thought that constant ovulation with subsequent healing of the burst egg follicle is responsible. Each ovulation, needing cell renewal to heal the ovary gives a possible opportunity for a malignant change. Some factors which are considered protective, by reducing the number of ovulations, are:

• Having many pregnancies
• Use of the contraceptive pill
• Tubal ligation and hysterectomy
• Breastfeeding

Factors increasing the risk of ovarian cancer are:

• Early onset of puberty
• Late menopause
• Cigarette smoking
• Obesity
• Infertility (but not infertility treatment)
• Family history of breast/ovarian cancer
• Genetic: certain genes : BRCA1 and BRCA2

The link with diet, exercise, talc/asbestos exposure and mumps remain unproven.

Symptoms, signs and spread

In the early stages there are no specific symptoms for ovarian cancer, which means it may go undetected at the stage when it is the most curable. General symptoms are:

• Vague abdominal discomfort and symptoms like bloating, mild nausea and lack of appetite
• Menstrual irregularities
• Painful intercourse
• Urinary frequency

Examination may show a mass in the abdomen with signs of fluid in the belly (ascites).

Spread is to the rest of the abdomen and lymph nodes by lymph channels, or by blood to other organs, such as liver, lung, diaphragm, bone and brain.

Diagnosis

Any suspicion of ovarian cancer must immediately be investigated.

Ultrasound of the abdomen is the most useful first step to confirm that the suspicious mass is in the ovary, and show any fluid present.

CT or MRI scans will show any malignant spread in the belly. If these are found, scans of the liver, bones and brain may be done as well.

Some tumours of the bowel and breast spread to the ovaries, so these primary tumour sources must be excluded by mammograms, endoscopy or other studies.

Blood tests to measure CA 125 in postmenopausal women is a useful indicator, and can also be used to monitor progress with treatment. A full blood count and liver and kidney function tests are also needed.

Open surgery or laparascopy is done (unless patient circumstances prevent it) to:

1. Obtain tissue samples for confirmation
2. Remove as much tumour as possible
3. Assess spread

Most surgeries will include hysterectomy and tubal removal.

Treatment

The start of treatment is the diagnostic and debulking surgery, which may include removal of any visible spread to other organs such as liver or bladder.

Post-operative treatment is by chemotherapy mainly, and is monitored by measuring the CA125 levels.

Outcome

This depends largely on the stage at which the disease is first diagnosed. Younger patients with early-stage disease, less aggressive tumours, and maximal tumour removal at surgery do best. The five-year survival rates vary from 89.3 percent for stage I patients with tumour limited to the ovaries, to 13.4 percent for stage IV, which has distant spread.

Prevention

There is no known prevention, and there are no effective screening tests. Patients with positive family histories or known to carry the BRCA gene should have regular pelvic examinations, with further tests at the discretion of their doctors.

Dr A G Hall

Reviewed by Dr David Eedes, Oncologist, March 2011