Ovarian Cancer Overview
Ovarian cancer is the fourth leading cause of cancer death in New Zealand women.
It is a growth of abnormal malignant cells that begins in the tissue of the ovaries (women’s reproductive glands that produce eggs).
Cancer that spreads to the ovaries but originates at another site is not considered ovarian cancer. Ovarian tumors can be benign (noncancerous) or malignant (cancerous). Although abnormal, cells of benign tumors do not metastasize (spread to other parts of the body). Malignant cancer cells in the ovaries can metastasize in two ways: directly to other organs in the pelvis and abdomen (the more common way), through the bloodstream or lymph nodes to other parts of the body.
It's not known for certain what causes ovarian cancer, but it is thought that the cancer starts when the cells on the surface of the ovary do not repair themselves after ovulation. Cancer can occur in the ovary at any age, although the most common type of ovarian cancer (epithelial) tends to occur in post menopausal women. 90% of cases occur in those over the age of 45.
Types of Ovarian Cancer
Different types of ovarian cancer are classified according to the type of cell from which they start.
Epithelial tumors – About 90 percent of ovarian cancers develop in the epithelium, the thin layer of tissue that covers the ovaries. This form of ovarian cancer generally occurs in postmenopausal women.
Germ cell carcinoma tumors –Making up about five percent of ovarian cancer cases, this type begins in the cells that form eggs. While germ cell carcinoma can occur in women of any age, it tends to be found most often in women in their early 20s. Six main kinds of germ cell carcinoma exist, but the three most common types are: teratomas, dysgerminomas, and endodermal sinus tumors. Many tumors that arise in the germ cells are benign.
Stromal carcinoma tumors – Ovarian stromal carcinoma accounts for about five percent of ovarian cancer cases. It develops in the connective tissue cells that hold the ovary together and those that produce the female hormones estrogen and progesterone. The two most common types are granulosa cell tumors and sertoli-leydig cell tumors. Unlike with epithelial ovarian carcinoma, 70 percent of stromal carcinoma cases are diagnosed in Stage I.
Stages of Ovarian Cancer
The stages of ovarian cancer are determined by how far the cancer has spread. The stage of ovarian cancer at diagnosis is the most important indicator of prognosis.
Stage I – Cancer is limited to one or both ovaries.
IA – Cancer is limited to one ovary and the tumor is confined to the inside of the ovary. No ascites containing malignant cells is present, and the surface of the tumor has not ruptured.
IB – Cancer is limited to both ovaries without any tumors on the ovaries’ outer surfaces. No ascites containing malignant cells is present, and the surface of the tumor has not ruptured.
IC – The tumor is classified as either Stage IA or IB and one or more of the following conditions exist:
- a tumor on the outer surface of one or both ovaries;
- at least one ruptured tumor;
- ascites or abdominal peritoneal washings containing malignant cells.
Stage II – The tumor involves one or both ovaries and extends to other pelvic structures.
IIA – The cancer has extended to and/or involves the uterus and/or the fallopian tubes
IIB – The cancer has extended to the bladder or rectum.
IIC – The tumor is classified as either Stage IIA or IIB and one or more of the following conditions exist:
- a tumor on the outer surface of one or both ovaries;
- at least one ruptured tumor;
- ascites containing malignant cells or abdominal(peritoneal) washings containing malignant cell
Stage III – The tumor involves one or both ovaries, and one or both of the following exist:
- The cancer has spread beyond the pelvis to the lining of the abdomen;
- The cancer has spread to the lymph nodes. The tumor is limited to the true pelvis but with histologically-proven malignant extension to the small bowel or omentum (peritoneum fold).
IIIA – The tumor is in one or both of the ovaries. While surgeons cannot see cancer in the abdomen, and the cancer has not spread to the lymph nodes, biopsies checked under a microscope reveal tiny deposits of cancer in the abdominal (peritoneal) surfaces.
IIIB – The tumor is in one or both ovaries, and deposits of cancer are present in the abdomen that are large enough for the surgeon to see but do not exceed two cm in diameter. The cancer has not spread to the lymph nodes.
IIIC – The tumor is visible in one or both ovaries, and one or both of the following conditions exists:
- the cancer has spread to lymph nodes;
- the deposits of cancer exceed two cm in diameter and are found in the abdomen.
Stage IV- Growth of the cancer involves one or both ovaries and distant metastases to the liver or lungs have occurred. Finding ovarian cancer cells in the excess fluid accumulated around the lungs (pleural fluid) also shows evidence of stage IV.
Ovarian cancer is often referred to as the 'silent cancer'. This is because the symptoms can be mistaken for more common and less serious health concerns making diagnosis difficult. It is also not uncommon to have no symptoms until the later stages of the disease.
It is very important to consult your Doctor if you experience one or more of the following symptoms for two weeks or more -
- increased abdominal size
- persistent bloating
- difficulty eating and/or feeling full quickly
- change in bowel habits
- extreme tiredness
- back pain
As you can see these are quite common. The acronym B.E.A.T. has been adotped globally to help women remember these symptoms and educate others.
B = Bloating that is persistent and doesn't come and go
E = eating less and feeling fuller
A = abdominal pain
T = tell your Doctor
Most cases of ovarian cancer occur for unknown reasons, but about 1 in 10 cases are thought to be caused by a faulty gene (ie BRCA1 or BRCA2) inherited from either parent. Below is the approximate increased risk associated with the BRCA gene mutation.
Source: National Cancer Institute www.cancer.gov
Other risk factors include -
- an increase in age. Women of all ages have a risk of developing ovarian cancer, however 85% of all cases in New Zealand occur in women over the age of 45.
- the risk increases for women who have a first degree relative (i.e mother, daughter, sister) who has had ovarian cancer.
- cancers occuring at an earlier age ie <45 years
- women of North American, North European, or Ashkenazi Jewish heritage have an increased risk.
- women who have never had children and have not taken the contraceptive pill (this is because it is thought that having children and/or taking the contraceptive pill gives the ovaries a 'rest').
- women who have taken estrogen only hormone replacement therapy (HRT) after menopause
- recent studies have also shown that postmenopausal women who are obese are also at risk
The treatment for ovarian cancer typically involves a combination of surgery and chemotherapy. These treatments are generally carried out by specialist teams. Gynaecological Oncologists are best euqipped to carry out this surgery. They are fully supported by Medical Oncologoists who specialise in the management of ovarian cancer. This joint approach is believed to produce the best outomes.
The surgical approach involves the removal of the uterus (hysterectomy) and both ovaries as well as much of the cancer from elsewhere that can be safely removed. There is a view held by some that removing the fallopian tubes is also advantageous (research is starting to indicate that ovarian cancer can start in the fallopian tubes). There is a direct correlation between the small size of the deposits that remain after surgery and eventual outcome or cure rates. A course of chemotherapy enhance what the surgery has already achieved and in recent years very effective chemotherapy agents have been developed for use in ovarian cancers.
In spite of modern treatments, the overall survival figures for ovarian cancer remain disappointing. For all stages there is about a 50% chance of a five year survival. For stages three and four however the figure drops to around 20% even with good managment, whereas with stage one disesase the five year survival is close to 100%.
Unfotunately no reliable screenging tests have yet been found.
The much debated CA125 elevation (blood test) has been found to detect 50% of patients with stage one ovarian cancer and 60% of patients with stage two disease. So although helpful, there will still be false negatives and this method cannot be relied on as a pure screening tool.