Types of Ovarian Cancer
In most ovarian cancers, the tumor begins on the surface layer of cells inside the ovary. The medical term for this surface layer is epithelium. The most common type of ovarian cancer is epithelial. Ninety percent of ovarian cancer tumors are epithelial and it is this type of cancer that talcum powder cancer risk studies have investigated.
Epithelial ovarian cancers are further subdivided into the following main subtypes:
- High-grade serous
- Clear cell
- Low-grade serous
High-Grade Serous Ovarian Cancer
The word “serous” comes from “serum,” a clear fluid that is one component of blood. Here the word refers to a fluid that is secreted by the thin double layer of epithelial cells—the serous membrane—that lines the ovaries. Many organs of the body have serous membranes.
Cancerous cells are graded after being examined under a microscope. Generally speaking, high grade cancers are more abnormal looking. They grow and spread faster than lower grade cancers, which look more like normal cells.
Seventy percent of all ovarian cancers are high grade serous cancers. Most cancers of this type are now known to originate in the fallopian tubes, though some may originate in the ovary itself. This has critical implications for the link between talcum powder [link to talcum powder subpage] and ovarian cancer, as the fallopian tubes connect the uterus to the ovaries. This offers a pathway by which talc powder can migrate from the vagina to the fallopian tubes and ovaries and cause cancer. In fact, researchers have found talc particles in ovarian cancer tumors. By the time they are detected, serous cancers are usually in the advanced stages of their development and the outcomes are generally poor.
Clear Cell Ovarian Cancer
This type of cancer is called clear cell because the inside of the cell looks clear when viewed under a microscope. Clear cell cancer is the second most common form of ovarian cancer representing an estimated 4% to 14% of ovarian cancers. Five-year survival rates (the percentage of patients who are still alive after five years) for this type of cancer are excellent if detected early, but may be worse than rates for serous cancers in the later stages of development.
Endometrioid Ovarian Cancer
These cancers make up about 2% to 4% of ovarian cancers. They are generally low-grade and are detected at early stages (meaning the cancer has not spread and the tumor is relatively small).
Mucinous Ovarian Cancer
This type of cancer represents only about 4% of ovarian cancers. It gets its name from the tumor, which is filled with mucus. Mucinous ovarian cancer does not respond well to chemotherapy.
Low-Grade Serous Ovarian Cancer
This type of cancer is the least common. It is slow growing, but it is commonly diagnosed at advanced stages and is very resistant to chemotherapy.
“We believe the observations made here present a good case for talc carcinogenicity…”
– Researchers in the Department of Obstetrics and Gynecology, Brigham and Women’s Hospital, Boston, MA and Department of Epidemiology, Harvard School of Public Health, Boston. Their study, “The Association Between Talc Use and Ovarian Cancer,” was published in May 2016 issue of Epidemiology