OVARIAN CANCER- a patient's guide
WHAT IS IT?
Ovarian cancer is not a common cancer, accounting for only 4% of all cases of cancer in the western world. About 1.5% of women will be diagnosed with this disease at some time in their lives. What makes this a difficult cancer, is that by the time most women present to their doctor with symptoms, the disease has often spread and become advanced, and is therefore very difficult to cure.
There are 3 main types of ovarian cancer. The most common type (about 90%) is epithelial ovarian cancer, which arises from the lining cells of the ovary. The next most common are germ cell tumours which arise from the egg producing cells. Stromal tumours are the rarest; these derive from the hormone producing cells which fill the ovary.
The information in the following paragraphs relates only to the common epithelial type, a short section at the end outlines germ cell tumours.
- Most ovarian cancers have no identifiable cause, in particular there are no lifestyle or dietary factors which are known to cause these cancers.
- The strongest risk factor that has been identified is a family history of ovarian and breast cancer - however less than 10% of all patients who have ovarian cancer have this hereditary variety. For those that do, the most common problem is a mutation (error) in a gene called BRCA 1 or, less often BRCA 2.
- Women who have the BRCA gene mutation probably have about a 20-30% chance of developing ovarian cancer, and also about a 50% chance of developing breast cancer.
- Women with this gene abnormality seem to develop ovarian cancer at an earlier age (average 48 years) than other patients without the abnormal gene, who on average develop this cancer in their mid 60s.
- Use of the oral contraceptive pill is thought to offer some protection against the development of ovarian cancer.
- Ovarian cancer is unfortunately usually diagnosed once the disease is already advanced. This is because the symptoms can be very vague, and in fact some women have very few or no symptoms at all.
- The most common symptoms are abdominal or pelvic discomfort and bloating.
- Abnormal bleeding from the vagina may occur, and some women notice abnormalities in passing urine or in their bowel motions.
- The best, first examination for any woman with these symptoms is a doctor's examination of the abdomen and a pelvic (internal) examination.
- An ultrasound scan or CT scan of the pelvis and abdomen is the next step. These scans can show a mass, but can only give a rough idea as to whether any mass seen is likely to be benign or malignant (cancer).
- If the scans are suspicious, then a referral is made to a gynaecological surgeon. He or she will then usually discuss an operation to remove the mass.
- If it appears as though this mass is an ovarian cancer during the operation, in most cases, both ovaries, the uterus and fallopian tubes are removed together with the omentum (a fatty membrane covering the internal organs).
- The diagnosis is confirmed once the pathologist has examined under the microscope all the tissue that was removed at operation.
There is a blood test called CA-125, which is used in the management of ovarian cancer.Unfortunately the CA-125 is not always useful in helping to make a diagnosis of ovarian cancer, as only 80% of women with advanced ovarian cancer have an abnormally high level of CA125 in their blood, and the CA12-5 is high (abnormal) in only a small percentage of women with early stage ovarian cancer.
It can also be elevated in benign conditions like endometriosis and even with normal menstruation.
- As with all other cancers, ovarian cancer is 'staged', which is a way of describing how far a tumour has spread at the time of diagnosis.
- The stage of the cancer is then used by the specialists to help make the right decisions regarding treatment, and it also gives a rough guide to the prognosis.
- The stage of the cancer is determined by :
1) What the surgeon finds at the initial operation
2) What the pathologist who examines the tumour tissue and other samples (biospsies) sees under the microscope.
For ovarian cancer;
Stage 1 means the tumour is confined to the ovary.
Stage 2 means the tumour has extended onto surrounding tissues and organs in the pelvis such as the uterus.
Stage 3 is the stage that most women have at diagnosis. Stage 3 means that the tumour has spread outside the pelvis (the lower part of the abdomen) and into the main part of the abdomen. What the surgeon usually finds are several nodules of tumour attached to the surface of the bowel and other organs and their anchoring membranes, and in the omentum which often harbours the bulk of the cancer cells from an ovarian cancer.
Stage 4 ovarian cancer means there is evidence of cancer in the liver or outside the abdomen, usually in the outer lining of the lung.
It is important to know that the staging system only describes cancers when they are first diagnosed, and is not used if the cancer recurs.
Surgery is the first treatment for ovarian cancer for most women. Surgeons will try, if they can, to remove all evidence of cancer that they find inside the abdomen. As ovarian cancer spreads to the uterus, tubes and omentum easily, these organs are almost always all removed at the initial operation when ovarian cancer is suspected.
Unfortunately it is not always possible for the surgeon to remove all of the cancer. In some patients, tumour tissue may be in areas too difficult to access and small deposits may be left behind. In other patients, the disease is too widespread to operate safely initially, and the surgeon may then consult with the medical oncologist (cancer physician) about treatment with chemotherapy before surgery, in an effort to shrink the cancer enough to make an operation possible.
Whether chemotherapy is advisable after surgery depends on the spread of the tumour seen at the time of the operation and what the cancer looks like under the microscope. Women will be referred to discuss chemotherapy with a Medical Oncologist (Physician specialising in cancer) if there is a question about needing chemotherapy. Chemotherapy is recommended in most women after surgery for ovarian cancer.
For those women who have not been able to have all (or any) of their tumour removed by surgery, chemotherapy is offered to try to shrink the cancer, and prolong the time to when it returns and causes problems. It is only able to cure the cancer in a very small number of these women.
Most of those women who have all visible evidence of their tumour removed are also advised to have chemotherapy. This is because there are often cancer cells left behind that are invisible to the naked eye (microscopic cells), and these can grow again. The aim of chemotherapy is to reduce the numbers of the remaining microscopic cells, to delay them regrowing and the cancer returning. In some cases chemotherapy may even kill all the remaining cancer cells and prevent recurrence altogether (ie a cure).
In a minority of women the surgeon and the oncologist are satisfied that the tumour appears to have been confined to the ovary, and the appearances of the tumour tissue seen under the microscope suggest that the chances that there is microscopic spread of cells is very small. Chemotherapy may not be necessary in these women as they are likely to have been cured without the need for further treatment.
Chemotherapy usually involves treatment with a platin drug (carboplatin ) plus or minus another drug called paclitaxel (Taxol) every 3-4 weeks for 5-6 months. Advances in anti-nausea medications mean that nowadays the most significant side effect for most women on chemotherapy is tiredness.
Radiotherapy is not routinely used in the initial treatment of ovarian cancer. It can be very useful in the later stages however, for example in the control of symptoms of pain or bleeding, or blockage of the rectum.
If the cancer is caught in stage 1, the prognosis is generally very good, with over 70 to over 90% of patients surviving 5 years. With stage 2 about 60%, and stage 3 about 30% of women survive beyond 5 years, and a smaller number with stage 4 disease.
There is a great deal of research ongoing in ovarian cancer. While the most interesting avenues being explored include gene therapy and immunotherapy, at this stage they are many years away from being of any practical use. The most immediately promising research underway is looking to combine newer chemotherapy drugs with the 'gold standard' drugs that are currently used, in an attempt to improve response and length of survival. Some of the newer drugs under investigation include gemcitabine, topotecan, etoposide and encapsulated doxorubicin (Caelyx or Doxil). If any of these combinations are proven to be better than the current gold standard, then they will be introduced as the new standard treatment. It is likely to be at least several years before enough data is collected to recommend a change to the current recommendations.
GERM CELL OVARIAN TUMOURS
These rare tumours, which account for less than 5% of ovarian cancers, are very different from common epithelial ovarian cancers. They generally arise in younger women (in their 20s), and are most often diagnosed in the early stages. Surgical treatment is different in that the surgeon will try to preserve the uterus and unaffected ovary, as most women with this diagnosis are of childbearing age. There are several types of germ cell tumours, and the treatment recommendation will depend on how the cancer looks under the microscope (ie the type and grade). Treatment is usually chemotherapy. The prognosis for these types of tumours is generally excellent.
The Cancer Society, Auckland ph 09 524 0023 or free phone 0800 800 42