Ovarian Cancer
Ovarian cancer facts:
- What is ovarian cancer?
- How common is ovarian cancer?
- What are the risk factors for ovarian cancer?
- What are the symptoms of ovarian cancer?
- How is ovarian cancer diagnosed?
- Types of Ovarian Cancer
- How does ovarian cancer spread?
- How is Ovarian Cancer treated?
- What is the survival rate for ovarian cancer?
- What is the role of a gynaecological oncologist?
References:
The Australian Cancer Network and National Breast Cancer Centre. Clinical practice guidelines for the management of women with epithelial ovarian cancer. 2004 National Breast Cancer Centre, Camperdown, NSW.Berek JS & Hacker NF. Practical Gynecologic Oncology, 2005.
What is ovarian cancer?
The ovaries are part of the female reproductive system and are located on either side of the uterus, or womb. They are almond shaped and approximately two to four centimetres in diameter.The role of the ovaries is to produce ova, or eggs, as well as the hormones that are involved in the menstrual cycle and fertility.
While cells in our body usually grow in a controlled and organised fashion, when they grow abnormally, they form a growth or a tumour, which can be benign or malignant. Benign tumours are not cancerous and do not spread uncontrollably, but a malignant tumour, also known as a cancer or carcinoma, will continue to spread through the body unless it is treated. Ovarian cancer is a malignant tumour of the ovary.
How common is ovarian cancer?
Ovarian cancer is the fourth most common cancer affecting women. Every year approximately 400 women in Victoria are diagnosed, most of them with an advanced stage of the disease. This means one in 90 women have a chance of developing ovarian cancer in their lifetime, equal to a lifetime risk of 1.1%. Nine out of ten cases occur in women over the age of 40.
Although it is less common than breast cancer (which affects one in 13 women), because it is usually diagnosed in its advanced stages, proportionally more women die from ovarian cancer.
While advances have been made in survival rates for breast cancer, there have been no recent breakthroughs in ovarian cancer, and survival rates have barely improved.
What are the risk factors for ovarian cancer?
The cause of ovarian cancer is not known, but some women are at greater risk. A risk factor increases the chance of developing ovarian cancer.
Age
Most women develop ovarian cancer after menopause and 50% are older than 65.
Lifestyle Factors
- Caucasian women in industrialised countries with a higher standard of living have a higher risk
- Dietary factors such as the consumption of meat, whole milk and animal fat have been associated with an increased risk in some studies; others have not found this connection.
- The evidence suggests a small to moderate positive relation between an increased Body Mass Index (BMI) and occurrence of ovarian cancer
Ovulatory factors
Women who ovulate less appear to be somewhat protected. Ovulation is the process by which an egg that has matured in the ovary is released for fertilisation by sperm.
Risk factors therefore include:
- Having few or no children
- Having started periods at an early age
- Having your first child after the age of 30
- Menopause occurring after the age of 50
The use of the combined oral contraceptive pill and breastfeeding lowers the risk slightly. Conditions that interfere with normal ovulation e.g. polycystic ovarian syndrome also lower the risk slightly.
Genetic factors
- Between 5 and 10% of cases of ovarian cancer are believed to be attributable to hereditary factors
- Most hereditary ovarian cancer is associated with mutations in the BRCA1 gene. A smaller proportion of inherited disease has been traced to another gene, BRCA2.
- Hereditary nonpolyposis colorectal cancer (HNPCC) syndrome involves a high rate of ovarian cancers and other malignancies of the gastrointestinal and genitourinary system.
- Women with one first degree relative (mother, aunt or sister) diagnosed with ovarian cancer and no confirmed family history have a lifetime risk of ovarian cancer which is at most moderately above the average for the general population; more than 97% of women in this group will not develop ovarian cancer.
- Women with two or more first-degree relatives diagnosed with ovarian cancer or who have other risk factors like Ashkenazi Jewish ancestry have a potentially high risk of developing ovarian cancer and perhaps other cancers, such as breast cancer. But although the risk may be more than 3 times higher than the population average, the majority of women in this group will not develop ovarian cancer.
However, 95% of all ovarian cancer occurs in women without these risk factors and many women who have risk factors do not develop ovarian cancer.
What are the symptoms of ovarian cancer?
Most women diagnosed with ovarian cancer are already in advanced stages of the disease. Unfortunately, there is a marked difference in survival rates if ovarian cancer is detected early.
Early stage ovarian cancer may not have obvious symptoms but the following may occur:
- Vague abdominal pain or pressure
- Feeling of abdominal fullness, gas, nausea, indigestion - different to your normal sensations
- Sudden abdominal swelling, weight gain or bloating
- Persistent changes in bowel or bladder patterns
- Low backache or cramps
- Abnormal vaginal bleeding
- Pain during intercourse
- Unexplained weight loss
The majority of women who experience one or two of these early symptoms do not have cancer. However, it is important that you seek medical advice if the symptoms are unusual or persist.
How is ovarian cancer diagnosed?
There is no simple or effective screening test for ovarian cancer. A conclusive diagnosis cannot be made until the tissue is looked at under a microscope following biopsy or surgery. Prior to this though, a diagnosis can be assisted by:
- Physical examination:
A general check up of the body which will include an internal pelvic examination and perhaps a Pap smear. - Blood tests:
A full blood count may be done and a measure of the blood protein CA 125, which is often raised in women with ovarian cancer. Other special 'tumour markers' may also be tested for, but some tumours will not have elevations of these markers and the type of marker depends on the type of tumour. - Imaging tests:
A chest and/or abdominal x-rays and an ultrasound scan of the lower abdomen is usually done. Ultrasound scanning cannot give a definite diagnosis though. A CAT scan may see if the cancer has spread to other parts of the body, but this cannot definitely diagnose ovarian cancer either. - Biopsy:
This is sometimes done during the operation. A sample of tissue is sent to the laboratory to be looked at under the microscope to confirm or exclude the diagnosis.
Types of Ovarian Cancer
Although they all affect the ovaries, there are different types of ovarian cancer. When a diagnosis is made, the type of cancer is identified. The types are:
- Epithelial
Epithelial ovarian cancers are derived from cells covering the surface of the ovary and comprise over 90% of ovarian cancers. Epithelial ovarian cancer is further divided into subtypes being serous, mucinous, endometrioid, clear cell, and undifferentiated. Epithelial ovarian cancers can also be divided into grades depending on how abnormal the cancer looks under the microscope. - Germ cell
Germ cell ovarian cancers arise from the eggs within the ovary and can also be classified into several subtypes. Germ cell cancers are uncommon, and tend to occur in women less than 30 years of age. Generally this type responds well to treatment, and young women may still have children afterwards if only one ovary is affected. - Sex-cord stromal
Sex-cord stromal ovarian cancers originate from the tissue that releases female hormones. These are uncommon and can occur at any age. They respond well to treatment and young women may still have children if only one ovary is affected. - Borderline
Borderline ovarian cancers are a group of epithelial cancers that are not as aggressive or malignant as the others. They generally have a better outcome, whether diagnosed early or late.
The treatment and likely outcome for a particular type of ovarian cancer will vary with each individual case and needs to be discussed with a gynaecological oncologist.
How does ovarian cancer spread?
Ovarian cancer spreads to other parts of the body by shedding cancerous cells which may then attach to the abdominal lining and continue to grow. Cancerous (malignant) cells can also implant on:
- The liver
- The omentum, which is the curtain of fatty tissue that hangs from the stomach and intestines
- The bladder
- The diaphragm, situated under the lungs
Ovarian cancer may spread via the lymph glands which are part of the immune system and often swell when our bodies are fighting an infection. These glands are all over the body, but it is those in the pelvis, around the aorta and in the groin and neck that are usually affected with ovarian cancer.
Another way of spreading is via the bloodstream or through the diaphragm, affecting the lungs and causing fluid to collect.
The stages of ovarian cancer
Ovarian cancer can be classified into four 'stages', depending on the extent of spread of the disease. This requires an operation to obtain some samples of tissue, which is then examined under a microscope.
- Stage I: cancer is limited to the ovaries only.
- Stage II: one or both ovaries are affected, as well as other pelvic tissues.
- Stage III: involves one or both ovaries; the cancer is in the abdominal cavity but outside the pelvis, or there is cancer in the lymph nodes in the pelvis, or around the aorta or in the groin.
- Stage IV: involves one or both ovaries with spread to distant organs, such as the liver or diaphragm.
How is Ovarian Cancer treated?
Surgery
Unfortunately, by the time ovarian cancer is diagnosed, the disease is usually well advanced. This means that often there are significant deposits of tumour outside the pelvis, perhaps on the surface of the bowel, and a large deposit of tumour is frequently found in the fatty apron, known as the 'omentum', which hangs down from the large bowel. Small deposits of tumour that look like boiled grains of white rice are often seen over wide areas of the internal abdomen.
In the pelvis, in advanced stage ovarian cancer, the ovaries and uterus are often stuck to the surface of the large bowel and bladder. Removal of these tumour deposits offers a patient the advantage that the chemotherapy which will follow is more likely to be effective than if the deposits are not removed. This maximum surgery is known as radical debulking surgery, the aim of which is to remove as much tumour as possible, leaving tumour deposits of less than 1cm in diameter in any one location. This gives chemotherapy the best chance of having a significant effect and gives the patient a possible complete remission from their cancer.
A small percentage of patients will have cancer that is confined to the ovary, in which case conservative surgery may be possible. This is especially desirable in young women wishing to preserve their fertility. In this situation it is important to identify whether there is any spread of cancer outside the ovary, which involves searching for hidden deposits of tumour.
It is very important to discover whether there is any disease outside the ovary to establish whether recurrence is likely. Thorough staging (see 'The Stages of Ovarian Cancer' under 'How Does Ovarian Cancer Spread?') will enable patients who require further treatment to receive timely chemotherapy to try and afford a long-term cure. Patients who have been found to have the cancer isolated to a single ovary and have had the appropriate surgery may remain fertile and long-term survival should be greater than 90%.
Chemotherapy
Chemotherapy for ovarian cancer has shown only small incremental improvement in survival over the past thirty years. In the middle 1970s Cisplatin chemotherapy became available and improved response rates quite dramatically, giving approximately 70% of patients a significant reduction in their tumour size, compared to patients treated with the previous treatment schedule.
Since the early 1990s platinum (Carboplatin/Cisplatin) has been combined with taxanes (Paclitaxel/Taxotere) and a combination of these drugs is now regarded as the best first line chemotherapy. Some patients who are unable to receive combination chemotherapy due to co-existing illnesses may be offered single agent platinum based chemotherapy, which is well tolerated, even in elderly patients.
About 70% of patients will achieve a significant response to first line chemotherapy and 50% or more will have no evidence of cancer at the completion of their chemotherapy. Response rates are measured both by a physical examination, CT scans etc, as well as measuring the tumour markers in the blood. Tumour markers are proteins, which are released by tumours and can be measured in the blood to evaluate response to treatment and can be helpful in diagnosis of ovarian tumours.
There are a number of other drugs used for patients with ovarian cancer, mainly when the disease recurs. These include Topotecan, Liposomal doxorubicin, Gemcitabine, Etoposide or Tamoxifen. Occasionally patients will be offered new drugs as part of a clinical trial.
Side Effects of Chemotherapy
The main reason why patients feel anxious about receiving chemotherapy is the fear of side effects such as hair loss, nausea and vomiting, bowel disturbances and the effects that the chemotherapy has on peripheral nerves and bone marrow. These side effects may cause numbness and tingling in the hands and feet.
What is the survival rate for ovarian cancer?
Every woman with ovarian cancer is treated as an individual case, depending on the stage of the disease and other personal factors, and so it is difficult to give a general prognosis.
If the cancer is diagnosed and treated early, between 80-100% of patients will survive for more than five years. Approximately 20% of women diagnosed at later stages will survive for more than five years. This figure, however, is improving all the time with better treatment. See 'How is Ovarian Cancer Treated?' for further discussion about survival rates.
What is the role of a gynaecological oncologist?
Gynaecological Oncologists are specialists in Obstetrics and Gynaecology, who are competent in the comprehensive management of patients with gynaecological cancer. They have obtained the subspecialist qualification of 'Certification in Gynaecologic Oncology' and must be recertified every three years.
Requirements of a Gynaecologic Oncology Unit (RACOG Guidelines 1994)
Cancer cases
- Workload must be a minimum of 200 new cases of invasive gynaecologic malignancy per year.
Staff
- Two consultants holding the CGO, one of whom is the Director.
- A gynaecologic pathologist.
- Appropriate liaison with a Medical Oncologist and Radiation Oncologist with expertise in gynaecologic malignancy.
- At least one identifiable Gynaecologic Oncology Nurse Appropriate Service managing preinvasive disease.
Facilities
- Designated bed space.
- Access to relevant diagnostic modalities including - CT Scan, nuclear medicine, MRI, ultrasound and FNA cytology.
- Facilities for high dependency care.
- Appropriate facilities for assessment and follow-up.
- Access to radiotherapy services.
Activities
- Cancer registry and data collection.
- Regular Tumour Board / Clinico-pathology meetings.
- Written and agreed treatment procedures.
- Participation in clinical trials.
- Clinical and basic research in gynaecologic cancer.
- Undergraduate and postgraduate education.
