Ovarian cancer is the sixth most common cancer in Singaporean women. 

It is the second most common female genital tract cancer (after uterine cancer), according to the Singapore Cancer Registry Annual Report 2021.

A woman’s chance of getting ovarian cancer may not seem very alarming – about 1 in 71 – up to 80 per cent of cases are only diagnosed at an advanced stage due to a lack of early symptoms. 

However, diagnosing ovarian cancer at an early stage is crucial as it is associated with a cure rate of up to 90 per cent. But once the disease has spread beyond the ovary, the 5-year survival rate drops to as low as 20 to 25 per cent (for stage 4).

Causes of ovarian cancer

Women have two ovaries, one on each side of the womb, which produce eggs and female hormones during a woman’s reproductive life.

According to the gynaecological cancer team from the Depa​rtment of Obstetrics & Gynaecology at Singapore General Hospital (SGH), a member of the SingHealth group, ovarian cancer occurs when ovarian cells begin to grow in an uncontrolled manner and produce tumours in one or both ovaries.

One in 10 ovarian cancers is caused by an inherited faulty gene.​ Your risk of getting the disease is increased four-fold if your sister or mother has it. 

Furthermore, ovarian cancer is known to run in families with a history of breast cancer, uterine and colorectal cancer. There are means to test for such mutations to help counsel patients on prevention.

Risk factors for ovarian cancer

Factors that increase risk of ovarian cancer include:

  • Older age – Ovarian cancer is most often diagnosed in women aged 50 years and above. However, younger women can get it too.

  • Had other cancers – Women who have had breast cancer, colorectal cancer (colon cancer), cancer of the uterus (uterine cancer).

  • Family history of ovarian cancer – Women who have inherited gene mutations (of breast cancer genes BRCA1 or BRCA2)

  • Endometriosis – Women who have a painful disorder where the womb lining (or endometrium) is found outside the womb.

  • Never being pregnant – Women who have never had children or been pregnant.

6 Ways to lower risk of ovarian cancer

There is no known way to prevent ovarian cancer, but the following factors may reduce risk:

  1. Avoid obesity – Excess body fat increases the risk of ovarian cancer. Eating healthily and engaging in regular exercise, especially during one’s teenage years, may play a preventive role.

  2. Have regular health assessments – This is especially so for women at high risk such as those with a family history of ovarian cancer, or who are carrying the breast cancer gene 1 (BRCA 1) or breast cancer gene 2 (BRCA 2).

  3. Oral contraception – Taking birth control pills can lower the risk of ovarian cancer. But this must be balanced against the slight increase in breast cancer risk. Discuss with your doctor if this is suitable for you.

  4. Having children, and breastfeeding them – Each full-term pregnancy reduces the risk of ovarian cancer. Breastfeeding may help to lower the risk even further.

  5. Tubal ligation or surgical removal of the uterus (hysterectomy) - These procedures are usually performed for medical reasons and not specifically to reduce the risk of ovarian cancer.

  6. Risk-reducing surgery for individuals with breast cancer gene (BRCA) mutations - this involves removal of the fallopian tubes and ovaries.

As some of the above measures involve surgery and may carry serious risks or side effects, they cannot be recommended for every woman. It is best to discuss appropriate ways to reduce your individual risk of ovarian cancer with your doctor.

Ovarian cancer symptoms

Early-stage ovarian cancer may not cause any noticeable symptoms.

Symptoms are usually attributed to other more common conditions and may only be noticed when the cancerous tumour has become quite large. Symptoms include:

  • Constant discomfort or a feeling of ‘pressure’ in the lower abdomen (pelvic area)

  • Persistent bloating in the abdomen

  • Abdominal swelling

  • Quickly feeling full when eating

  • Increased urinary frequency

  • Changes in bowel habits, such as constipation or diarrhoea

Make an appointment with your doctor if you have any signs or symptoms that worry you.

3 Types of ovarian cancer

There are different types of ovarian cancer classified by the type of cell from which it originates:

  • Epithelial ovarian cancer: This is the most common, making up 85 to 90 per cent of ovarian cancers. It develops from one of the cells that surround the exterior of each ovary. Epithelial ovarian cancer tends to affect older women.

  • Germ cell ovarian cancer: These tumours occur in the egg-producing cells of the ovary and generally occur in younger women.

  • Stromal ovarian cancer: These start from cells that hold the ovary together and produce female hormones.

Treatment for ovarian cancer

According to the team, treating ovarian cancer generally involves surgery.

The type of surgery will depend on the stage and type of cancer. In the early stage of ovarian cancer, surgery may be the only treatment that is needed. 

However, in the advanced stages of the disease, a combination of surgery and chemotherapy is usually required.

Surgery for ovarian cancer

Surgery for ovarian cancer has two main goals. The first is to stage the cancer and determine how far it has spread from the ovary. As the treatment for ovarian cancer is different at different stages, proper staging is vital for effective treatment. The four stages of ovarian cancer are:

  • ​​Stage 1: The tumour is limited to one or both ovaries and can be found on the surface of the ovary.

  • Stage 2: The tumour has invaded one or both ovaries and extended to the pelvic region but not to the abdomen.

  • Stage 3: The tumour has extended to the abdominal organs.

  • Stage 4: The cancer has spread to the lungs, liver or lymph nodes in the neck.

The second goal is to remove as much of the tumour as possible. This is known as debulking. Successful debulking surgery gives the patient a better outlook.

If the cancer is diagnosed at a very early stage where it’s confined to just one of the ovaries, only the affected ovary and adjoining fallopian tube need to be removed. With the unaffected ovary and womb left behind, you may still be able to have children in the future.

In most cases where the cancer has spread to the omentum (an apron of fat covering the abdominal contents), surgery will include removal of both ovaries, the uterus (womb), the fallopian tubes, nearby lymph nodes and the omentum. 

As a result, the patient begins her menopause immediately and is no longer able to conceive.

Chemotherapy for ovarian cancer

Chemotherapy involves injecting drugs into the bloodstream to reach all areas of the body with the aim of killing cancer cells that may have spread. A majority of women with ovarian cancer will require chemotherapy after surgery; however, it can also be given before surgery.

Treatment usually involves 6 courses of chemotherapy with each course given 3-4 weeks apart or alternatively a weekly regime for 3 weeks with a week break between courses.

Even after completion of chemotherapy, follow-up examinations are recommended every three months for the first two years and subsequently, every four to six months in the following years.

Ref: H24 (ed)

Check out other women's cancer articles:

Top 10 Cancers in Singapore (for Men and Women)

Breast Cancer: What Puts You at Risk?

Breast Cancer Screening: Your Best Protection

Tips to Keep Your Breasts Healthy

Endometrial Cancer: Risk Factors, Symptoms, Treatment and Prevention

Ovarian Cancer: What Puts You at Risk?

Cervical Cancer: Symptoms, Screening and How to Prevent

Cancer Diet: Top Foods to Eat and Avoid When Undergoing Treatment