Ovarian cancer is malignant tumor that can form in different parts of the ovary. The cancer can begin in the cells that line the surface of the ovary (epithelial carcinoma of the ovary), in the cells that produce ova (germ cell tumor of the ovary) or the cells of the connective tissue that link the different elements of the ovary (stromal tumor of the ovary). However, most malignant ovarian tumors are epithelial carcinomas. The cancer can affect one or both ovaries.
The ovaries are two small oval organs of the internal female reproductive system. They are located in the lower abdomen on either side of the uterus, near the end of the fallopian tubes. Their two main functions are to secrete hormones (estrogen and progesterone for example) and ensure ovulation. Each month, in women of childbearing age, an ovary releases an egg. Once released, the egg is moved from one of the fallopian tubes to the uterus, where it can be fertilized by sperm and develop into a fetus. If the egg is not fertilized, it will be expelled with menstrual flow. To accomplish these important functions, the ovarian cells work harmoniously before dying to be replaced by new-born cells.
Types of Ovarian Cancer
There are three main types of ovarian cancer, according to the type of cells in the ovary where the cancer originates.
Ovarian epithelial cancer – also known as surface epithelial-stromal tumor, ovarian epithelial carcinoma begin in the cells located on the outer surface of the ovary; it is the most common type of ovarian cancer, representing nearly 80% of ovarian malignancies.
Ovarian germ cell tumors– these forms of ovarian cancer are more common among young women and girls; they are account for less 12% of ovarian cancers. Ovarian germ cell tumors develops in the cells that produce eggs; they are less common than epithelial ovarian cancer but usually more aggressive.
Stromal Tumors of the Ovary – these cancers develop in the connective tissue cells that hold various elements of the ovary together; it accounts for nearly 8% of ovarian cancers. Stromal tumors are less common than epithelial.
Ovarian Cancer Statistics
Each woman has about 1.7 percent chance of developing ovarian cancer in her lifetime. According to the World Health Organization (WHO), there are more than 204,000 new cases of ovarian cancer each year worldwide; the tumor is responsible for around 4% of all cancers diagnosed in women. In the U.S. alone, it is estimated that 21.550 women were diagnosed with ovarian cancer in 2009.
Ovarian cancer is the leading cause of death from gynecological cancers after breast cancer. Every woman has about 1 percent chance of dying from ovarian cancer in her lifetime. According to the National Cancer Institute, about 14.600 women died of cancer of the ovary in the United States in 2009.
The peak incidence of ovarian cancer is seen after menopause. From 2002-2006, the median age at diagnosis for cancer of the ovary was 63 years of age; percentages and ages at diagnosis were approximately:
- 3% under age 20;
- 5% between 20 and 34;
- 4% between 35 and 44;
- 9% between 45 and 54;
- 3% between 55 and 64;
- 9% between 65 and 74;
- 0% between 75 and 84;
- 6% 85+ years of age.
Ovarian Cancer Causes
Ovarian cancer occurs when part of the normal cells of the ovaries begin to transform and divide in an uncontrolled manner to become malignant. In some women, this division does not lead to a malignant tumor; their immune system fights the disease and prevents the cancer from developing. For others, however, their immune system is not able to destroy those belligerent cells; their numbers continue to increase to form a malignant tumor. The tumor is initially well defined; it produces no symptoms. Over time, however, cancer cells invade surrounding tissue to destroy them gradually. Cancer cells can also use the lymphatic system or bloodstream to reach parts of the body far distant from their point of departure to form new tumors; this condition is called metastatic ovarian cancer.
Scientists do not know for sure the causes of ovarian cancer; there are however, many suspected factors. Although it exists many, the only risk factor to develop cancer of the ovary clearly highlighted is family history of the cancer. In most families, the increased risk is due to genetic predisposition to ovarian cancer.
Ovarian Cancer Risk Factors
Ovarian cancer is multifactorial disease; it is not attributable to a unique factor but many; the most common include:
- Ethnicity– cancer of the ovary is more common in certain ethnic groups, especially among Ashkenazi Jews (those of Eastern European descent).
- Inherited gene mutations– research in Obstetrics and Gynecology have discovered two genes, BRCA1 and BRCA2, which may be responsible for the occurrence of a form of ovarian cancer called hereditary ovarian cancer.
- Absence of pregnancy– if you never been pregnant, you are at Increased risk of becoming an ovarian cancer victim.
- Age– ovarian cancer occurs mostly after menopause, it does not mean that if you are a premenopausal woman you cannot have the disease.
- Obesity –if you are obese, you are ata greater risk of ovarian cancer than women who are not.
- History of certain Caners– if you have a personal history of breast cancer, cancer of the uterus or colorectal cancer, your risk of developing ovarian cancer is higher comparably to other women.
- Family history– if you have family history of ovarian cancer or breast cancer, you are at higher risk comparably to women do not; in fact your risk of ovarian cancer increases by 10 to 15 percent, according to the American Cancer Society (ACS).
- Hormone replacement therapy (HRT)– use of menopausal hormone replacement therapy containing estrogen only slightly increases your risk of ovarian cancer. The risk is even higher if you take the therapy for more than five years.
- Infertility– if you have never been able to carry a pregnancy to full term, you are at higher risk of ovarian cancer. In addition, certain medications such as clomiphene (Clomid, Serophene), used in the treatment of infertility, has been suspected as carcinogenic, but this theory has not been fully confirmed by the medical elite.
- Medications –a synthetic steroid derived from ethisterone called danazol, used to treat endometriosis and for the prevention of attacks of angioedema, is suspected to be linked to an increased risk of ovarian cancer; however, more studies are needed to confirm this.
Ovarian Cancer Symptoms
An ovarian cancer may develop in your body for a long period of time before producing symptoms. In fact, early in the disease, its symptoms are often nonspecific and may be easily taken for other disorders such as digestive problems and bladder disorders.
This makes it early diagnosis of ovarian cancer difficult. Thus, the tumor is often detected late, when it extends to adjacent organs: fallopian tubes, uterus and other organs / distant tissues such as abdomen, liver and intestine. In general, symptoms associated with ovarian cancer are:
- severe fatigue
- abdominal discomfort
- back pain
- loss of appetite
- weight loss or gain
- frequent urination
- pelvic pain
- pain during intercourse (dyspareunia)
- abnormal vaginal bleeding
- bowel disorders such as indigestion, gas or bloating
- nausea and vomiting
- Increased abdominal size.