Not all tumors in the ovary are cancer. Ovarian tumors are classified as benign (non-cancerous), borderline or malignant (cancerous). Most epithelial ovarian tumors are benign and do not spread or cause cancer. There are many types of benign tumors such as serous cystadenomas, mucinous cystadenomas, and Brenner tumors.
Borderline epithelial ovarian cancer or low malignant potential tumors (LMP) are different from typical ovarian cancers because they do not grow into the supporting tissue of the ovary (stromal)—it is a disease in which abnormal cells form in the tissue covering the ovary. These abnormal cells could become cancer, but usually do not, and usually remain in the ovary. When disease is found in one ovary, the other ovary should also be checked carefully for signs of disease.
These tend to occur in younger women, and are less threatening than most ovarian cancers. These tumors account for 15% of all epithelial ovarian cancers, and nearly 75% are diagnosed at Stage 1. These tumors are recognized as distinct from the malignant invasive carcinomas described below because their prognosis and treatment is markedly different.
Borderline epithelial ovarian cancer may not cause early signs or symptoms. If signs or symptoms do occur, they may include the following:
- Pain or swelling in the abdomen.
- Pain in the pelvis.
- Gastrointestinal problems, such as gas, bloating, or constipation.
The prognosis and treatment options depend on the following:
- The stage of the disease (whether it affects part of the ovary, involves the whole ovary, or has spread to other places in the body);
- What type of cells make up the tumor;
- The size of the tumor;
- The patient’s general health.
Patients diagnosed with ovarian low malignant potential tumors have a good prognosis, especially when the tumor is found early.
The less common endometrioid tumor of low malignant potential is not typically regarded as malignant because it seldom, if ever, metastasizes. Malignant transformation can, however, occur and may be associated with a similar tumor outside of the ovary; such tumors are the result of either a second primary or rupture of the primary endometrial tumor.