Surgery is the first treatment for ovarian cancer for most women. Surgeons will try to remove all evidence of cancer that they find inside the abdomen. Chemotherapy may be recommended after surgery if there is evidence that the cancer has spread beyond the ovary or if there is a risk that it may have. If the cancer hasn’t spread beyond the ovary the risk of their being tiny amounts of disease left behind is assessed by looking under the microscope at the cancer that has been removed.

In the majority of women with ovarian cancer, by the time the cancer is diagnosed the disease has spread over the surface of other organs in the abdomen. The surgeon may be able to remove all visible cancer, however there are often cancer cells left behind that are invisible to the naked eye (microscopic cells). For this reason, chemotherapy is usually recommended if the disease has was found to have spread beyond the ovary at the time of the operation. The aim of chemotherapy is to reduce the numbers of the remaining microscopic cells, to delay them re-growing and the cancer returning. In some cases chemotherapy may even kill all the remaining cancer cells and prevent recurrence altogether.

In situations where the cancer is contained within the ovary, and has not begun to spread (early ovarian cancer) there may still be microscopic cancer cells that the surgeon cannot see. This is more likely if the cancer is of a higher grade. The grade of the cancer describes how fast growing it is and is determined by looking at the cancer cells under a microscope. Cells that look similar to the normal cells are said to be low grade and slow growing. Cancer cells that look very abnormal are high grade and faster growing. Recent research has shown that giving chemotherapy after surgery for early ovarian cancer can help to improve the outcome and prevent the cancer from returning.

If the tumour appears to be confined to the ovary and is of a low grade, chemotherapy may not be necessary. These women are likely to have been cured with surgery alone and without the need for further treatment.