Is ovarian cancer a misnomer?

December 7, 2021
Posted in Blogs
December 7, 2021 Aditi Bhatt

Ovarian cancer is the 4th most common of all the cancers that occur exclusively in women. It’s the 8th most common cancer in women. About 3,00,000 women are diagnosed with ovarian cancer every year across the world. One/two in every 10,000 women will develop ovarian cancer during her lifetime but more than half the women who are diagnosed with it die due to ovarian cancer within five years of diagnosis.

Ovarian cancer is a silent killer. In the early stages, it does not produce any signs of symptoms and nearly 80% of the cancers are diagnosed in the third or the fourth stage. Even the progression from early to advanced disease is very rapid. Thus, screening is not useful in ovarian cancer.
Till the last decade, it was believed that the ovaries are the sole origin of ovarian cancer. There is another counterpart that is very rare and arises from the peritoneum, being referred to as primary peritoneal serous carcinoma. The ovaries have 3 types of cells. The cells covering the surface are called epithelial cells and these cells give rise to the majority of ovarian cancers. The other cells are the germ cells (that produce eggs) and stromal cells or the supportive cells that provide the framework in which the germs cells rest. Tumors arising from these two types of cells are very rare. The tumors arising from the epithelial cells are called epithelial ovarian cancer (EOC). Alongside each ovary lies a fallopian tube (a narrow channel that connects the peritoneal cavity to the inside of the uterus). These tubes also carry eggs from the ovaries to the uterus.
The fallopian tubes are also lined by cells similar to the ovarian epithelial cells.
The ends of the fallopian tubes have multiple projections or fimbriae that are lined by the ovarian epithelium.

Recent research has shown that it is this epithelium lining the fallopian tubes that gives rise to ovarian cancer in a large proportion of patients. The cancer is preceded by precancerous lesions or growths that are known as STIC (serous tubal intraepithelial carcinoma). STICs have been found in the fallopian tubes of patients without cancer and those with cancer both. The incidence in women with BRCA mutations but no ovarian cancer was reported to be 2% in one study and nearly 50% in all women with ovarian cancer irrespective of the BRCA mutation status. It is difficult to say what proportion of all ovarian cancers arise from the fallopian tubes as many times the ovarian tumors are large and the fallopian tube is already involved by the tumor making it impossible to determine if the tumor arose from the ovary or the tube. Genetic tests performed on STICs showed that they had the same genetic mutations or abnormalities as those seen in ovarian cancer. This is a very important and interesting development in the prevention of ovarian cancer.

5-10% of all women develop ovarian cancer due to mutations in the BRCA 1 or 2 genes which can be passed from one family member to another. Women with these mutations have a 60-70% risk of developing ovarian cancer during their lifetime which is many-fold higher than that with other risk factors like contraceptives (risk of 1.3%). One of the effective ways of preventing ovarian cancer is to remove both the ovaries and fallopian tubes by performing a surgery. This is a very effective method of preventing ovarian cancer in women with high-risk of developing it. However, removing the ovaries also induces menopause and all the side-effects that come with it. The most concerning side effects are osteoporosis (brittle bones) and the increased risk of heart disease. Since most of the ovarian cancers arise from the fallopian tubes, removal of the tubes alone that has minimal or no side-effects could be a better alternative to removing the tubes and ovaries both. Two studies (one in Denmark and the other in Sweden) stated that removal of the tubes reduces the risk of getting ovarian cancer by 50%. There is a clinical trial being carried out in Denmark to determine if removal of the tubes alone is enough to reduce the risk of developing ovarian cancer. For women who do not have BRCA mutations or a strong family history of ovarian cancer, removal of the tubes could be performed during gynecological surgeries performed for non-cancerous conditions. Pregnancy is possible after such a surgery with assisted reproductive technology.

If we were to twist Shakespeare’s famous quote, it would read, ‘A rose by any other name, still has thorns’. And similarly an ovarian cancer arising from the tube or the ovary is still a deadly disease. Nevertheless, this research has lit a lamp of hope for a future treatment that could prevent ovarian cancer with minimal side-effects.