What Is Ovarian Cancer? Ovarian cancer is cancer that begins in the cells that constitute the ovaries, including surface epithelial cells, germ cells, and the sex cord-stromal cells. Cancer cells that metastasize from other organ sites to the ovary (most commonly breast or colon cancers) are not then considered ovarian cancer.
According to the American Cancer Society, ovarian cancer accounts for 4 percent of all cancers among women and ranks fifth as a cause of their deaths from cancer. The American Cancer Society statistics for ovarian cancer estimate that there will be 25,580 new cases and 16,090 deaths in 2004. The death rate for this disease has not changed much in the last 50 years.
Unfortunately, almost 70 percent of women with the common epithelial ovarian cancer are not diagnosed until the disease is advanced in stage?i.e., has spread to the upper abdomen (stage III) or beyond (stage IV). The 5-year survival rate for these women is only 15 to 20 percent, whereas the 5-year survival rate for stage I disease patients approaches 90 percent and for stage II disease patients approaches 70 percent.
There are many types of tumors that can start in the ovaries. Some are benign, or noncancerous, and the patient can be cured by surgically removing one ovary or the part of the ovary containing the tumor. Some are malignant or cancerous. The treatment options and the outcome for the patient depend on the type of ovarian cancer and how far it has spread before it is diagnosed.
Symptoms: Often no symptoms are evident in the early stages of the disease. When symptoms appear, they may include:
- Gas, nausea, indigestion that does not go away
- Frequent urination
- Unexplained change in bowel habits
- Abnormal postmenopausal bleeding
- Weight gain or loss
- Pain during intercourse
- Abdominal swelling and/or pain, bloating or a feeling of fullness. Ovarian cancer may spread to the sac inside the abdomen that holds the intestines, uterus and ovaries - causing fluid to accumulate and the abdomen to swell.
- Shortness of breath caused by the spread of the disease to the muscle under the lung. Fluid buildup in the area makes it difficult for the patient to breathe.
Ovarian tumors are named according to the type of cells the tumor started from and whether the tumor is benign or cancerous.
The three main types of ovarian tumors are:
Epithelial ovarian tumors develop from the cells that cover the outer surface of the ovary. Most epithelial ovarian tumors are benign. There are several types of benign epithelial tumors, including serous adenomas, mucinous adenomas, and Brenner tumors. Cancerous epithelial tumors are carcinomas. These are the most common and most deadly of all types of ovarian cancers. There are some ovarian epithelial tumors whose appearance under the microscope does not clearly identify them as cancerous; these are called borderline tumors or tumors of low malignant potential (LMP tumors). Epithelial ovarian carcinomas (EOC's) account for 85 to 90 percent of all cancers of the ovaries. It is this group of cancers we refer to as "ovarian cancer" throughout the remainder of this report. It is this group of cancers we must expand our knowledge about in order to conquer its ravages.
The cells that make up EOC have several forms that can be recognized under the microscope. They are known as serous, mucinous, endometrioid, and clear cell types. Undifferentiated EOC's lack distinguishing features of any of these four subtypes and tend to grow and spread more quickly.
In addition to their classification by cell type, EOC's are given a grade and stage. The grade is on a scale of 1, 2, or 3. Grade 1 EOC more closely resembles normal tissue and tends to have a better prognosis than Grade 3 EOC, which looks less like normal tissue and usually implies a worse outlook than Grade 1 EOC.
The stage of the tumor can be ascertained during surgery, when it can be determined how far the tumor has spread from where it started in the ovary. The following are the various stages of ovarian cancer:
Stage I?Growth of the cancer is limited to the ovary or ovaries.
Germ Cell Tumors
Stage IA?Growth is limited to one ovary and the tumor is confined to the inside of the ovary. There is no cancer on the outer surface of the ovary. There are no ascites present containing malignant cells. The capsule is intact.
Stage IB?Growth is limited to both ovaries without any tumor on their outer surfaces. There are no ascites present containing malignant cells. The capsule is intact.
Stage IC?The tumor is classified as either Stage IA or IB and one or more of the following are present: (1) tumor is present on the outer surface of one or both ovaries; (2) the capsule has ruptured; and (3) there are ascites containing malignant cells or with positive peritoneal washings.
Stage II?Growth of the cancer involves one or both ovaries with pelvic extension.
Stage IIA?The cancer has extended to and/or involves the uterus or the fallopian tubes, or both.
Stage IIB?The cancer has extended to other pelvic organs.
Stage IIC?The tumor is classified as either Stage IIA or IIB and one or more of the following are present: (1) tumor is present on the outer surface of one or both ovaries;
(2) the capsule has ruptured; and (3) there are ascites containing malignant cells or with positive peritoneal washings.
Stage III?Growth of the cancer involves one or both ovaries, and one or both of the following are present: (1) the cancer has spread beyond the pelvis to the lining of the abdomen; and (2) the cancer has spread to lymph nodes. The tumor is limited to the true pelvis but with histologically proven malignant extension to the small bowel or
Stage IIIA?During the staging operation, the practitioner can see cancer involving one or both of the ovaries, but no cancer is grossly visible in the abdomen and it has not spread to lymph nodes. However, when biopsies are checked under a microscope, very small deposits of cancer are found in the abdominal peritoneal surfaces.
Stage 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 not exceeding 2 cm in diameter. The cancer has not spread to the lymph nodes.
Stage IIIC?The tumor is in one or both ovaries, and one or both of the following is present: (1) the cancer has spread to lymph nodes; and/or (2) the deposits of cancer exceed 2 cm in diameter and are found in the abdomen.
Stage IV This is the most advanced stage of ovarian cancer. Growth of the cancer involves one or both ovaries and distant metastases (spread of the cancer to organs located outside of the peritoneal cavity) have occurred. Finding ovarian cancer cells in pleural fluid (from the cavity which surrounds the lungs) is also evidence of stage IV disease.
Ovarian germ cell tumors develop from the cells that produce the ova or eggs. Most germ cell tumors are benign, although some are cancerous and may be life threatening. The most common germ cell malignancies are maturing teratomas, dysgerminomas, and endodermal sinus tumors. Germ cell malignancies occur most often in teenagers and women in their twenties. Prior to the modern era of combination chemotherapy, the most aggressive of these tumors, the GNP abnormal sinus tumor, was associated with a 1-year disease-free survival of only 10 to 19 percent. This occurred despite the fact that 70 percent of these tumors were diagnosed as stage I disease. Today, 90 percent of patients with ovarian germ cell malignancies can be cured and fertility preserved. We hope, ultimately, to achieve similar results in our strategic research planning for epithelial ovarian cancer.
Ovarian stromal tumors develop from connective tissue cells that hold the ovary together and those that produce the female hormones, estrogen and progesterone. The most common types among this rare class of ovarian tumors are granulosa-theca tumors and Sertoli-Leydig cell tumors. These tumors are quite rare and are usually considered low-grade cancers, with approximately 70 percent presenting as stage I disease.
These statistics, and the information regarding tumor stage and grade, demonstrate that there is a critical need to establish an agenda for more research into the areas of basic and translational research, genetic susceptibility and prevention, diagnostic imaging, screening and diagnosis, and therapy. These could hold the most promise for future discoveries that will lead to improved prevention, detection, and treatment of ovarian cancer, particularly the common epithelial cancers.