What is choriocarcinoma?
Choriocarcinoma is the cancer of the uterus which originates from the tissues that would have otherwise developed as the placenta during pregnancy. This type of cancer develops from the germ cells that would have originally turned into egg. The cancer can spread to other organs of the body and can cause deleterious effects. This is a type of gestational trophoblastic disease (GTD). Choriocarcinoma can develop immediately after conception, during pregnancy and even after abortion. It is a rare form of cancer affecting about 1 in every 40,000 pregnant women.
There are many different types of tumors that can affect the female organs and the uterus specifically. Some of these are malignant (cancerous) and some benign (non-cancerous). It can start from certain types of tissue within the uterus (primary) or spread from elsewhere in the body to lodge in the uterus (secondary or metastatic). Choriocarcinoma is one type of cancer of the uterus that has many predisposing factors. These include :
Malignant transformation of the trophoblast
During pregnancy the trophoblastic cells form the placenta, which provides nutrition to the developing fetus. In instances, when it fails to do so, the trophoblastic cells undergo transformation and form a grape-like water-filled mass. This happens in a condition known as a hydatidiform mole. Remnants of the mole when removed may still remain in the uterus which may lead to malignancy of the trophoblastic tissues causing choriocarcinoma.
Absent Chorionic Villous
The chorionic villi (singular ~ villous) are small hair like structures that attaches the placenta to the uterus during pregnancy. When the trophoblastic cells of the uterus undergo malignant transformation they cause improper development of the villous. The tissues therefore form watery bunch-like structures which are incapable of sustaining the developing fetus.
Trophoblastic cells invade the myometrium and blood vessels
The trophoblastic cells due to their abnormal growth gradually begin to attack the smooth muscles of the uterine wall (myometrium) and their blood vessels. The abnormal growth of cells continues and they start affecting the entire uterus. Beginning from the outer region of the uterus the cancer rapidly spreads to the uterus and the organs of the body.
Age of the women
Pregnant women aged 40 years and above have higher chances of developing choriocarcinoma as compared to younger women.
Miscarriage or abortion
Pregnant women who have undergone miscarriage in the past or abortion are at a higher risk of developing choriocarcinoma.
Choriocarcinoma is a rare form of cancer and is curable if diagnosed in early stages. Pregnant women who developo this type of cancer may or may not have a healthy fetus. The major causative factor behind choriocarcinoma is a hydatidiform mole. If the mole was successfully removed then the chances of developing cancer is much lower but not zero. In instances when traces of the mole remain even after removal, the tissues from the mole continue to grow and become malignant in nature. Statistics have revealed that about 50% of the women who had a hydatidiform mole developed choriocarcinoma in later stages.
A genital tumor or ectopic pregnancy can also trigger the development of choriocarcinoma. Ectopic pregnancy is a condition, wherein the embryo develops outside the uterus, and chances of survival of the fetus is very low. However, these conditions are less common causes of choriocarcinoma.
Symptoms of choriocarcinoma include:
- Nausea or vomiting
- Irregular or continuous vaginal bleeding
- Ovarian cysts
- Abdominal swelling
- Pain in the lower part of the abdomen
- Uneven swelling of the uterus
- Elevated HCG levels that do not come back to normal post pregnancy
- Presence of lump in the vagina
- Abnormal nipple discharge
- No reduction in the size of uterus after delivery
- Excessive bleeding postpartum
Choriocarcinoma can also spread to the other parts of the body. The major areas to be affected other than uterus is the lungs and brain and symptoms of a cancer in these parts of the body will therefore be present as well.
A preliminary internal pelvic examination is carried out to confirm the presence of the tumor. Several blood tests follow to determine,
- Levels of HCG
- Total blood count
- Live and kidney functioning
The hormone HCG (Human Chrionic Gonadotrophin) is present during pregnancy but should subside after childbirth or with a miscarriage or abortion. The elevated levels of this hormone after pregnancy, miscarriage or abortion is indicative of cancer. The extent of spread of the cancer is determined with the help of magnetic resonance imaging (MRI), X-rays and computed tomography (CT) scan. The tumors are never biopsied prior to treatment as they are chances of heavy bleeding post biopsy.
One of the most debilitating effects of choriocarcinoma is the recurrence of cancer several months after complete removal of the malignant tumor. Since the tumor is malignant in nature, it may never be completely eliminated from the body especially when diagnosed at a late stage. Therefore it can show signs of reccurrence after a short period of time. A choriocarcinoma may recur even after 3 years.
Other complications include:
- Urinary tract infection (UTI)
- Uterine enlargement
- Intermenstrual bleeding
Side effects of chemotherapy and radiation therapy for choroiocarcinoma may also be a cause a host of symptoms.
Early diagnosis always helps in treatment of cancer in its early stages and this shall also arrest its spread to the other parts of the body. Surgery followed by chemotherapy is the main resort for treating choriocarcinoma. Surgical removal of tumors can cause mild bleeding and discomfort for a day or two, but the patient can soon recommence their normal activities. Hysterectomy, removal of uterus, is carried out in rare cases as this type of cancer shows excellent response to chemotherapy drugs. However, in case of excessive bleeding and if the age of patients is above 40 years, it can call for hysterectomy.
The process of chemotherapy basically involves the use of drugs that target the cancer cells and destroys them. The drugs are either taken orally or are directly injected into the blood stream. The success rate for curing choriocarcinoma through chemotherapy is about 90 to 95% but depends on the stage of the cancer. Radiation therapy may be required in cases when the cancer has spread to other sites. In these cases, surgical removal of even the entire uterus will not stop the cancer.