Ovarian germ cell tumors

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Introduction0:00–0:25

With germ cell ovarian cancer, germ cell refers to the precursor cells that develop into eggs, ovarian refers to ovary of which there are two that sit on either side of the uterus which is where the germ cells live.
So, a germ cell ovarian cancer refers to situations where these precursor germ cells become cancerous and form tumors. During fetal development, the entire body derives from three layers, called germ layers, the ectoderm, mesoderm, and endoderm.

Physiology0:25–1:47

These germ layers are made of germ cells, and the germ cells migrate out and differentiate into all of the different types of tissues, for example some ectodermal germ cells become cells of the brain and spinal cord, some mesodermal form bone and muscle, and some endodermal cells become cells in the gastrointestinal tract.
Some very special germ cells, though, stay as germ cells - meaning that unlike the cells that differentiate, these germ cells retain their ability to turn into other cells types.
They’re like ancient little shape-shifters. Normally, during development these germ cells head to the ovary in women or testicle in men where they remain for decades, eventually developing into eggs or sperm, respectively.
Now, if those germ cells in the ovaries start to divide uncontrollably, it can either form a benign tumor which means that it does not invade nearby tissue or spread to other parts of the body, or it can be a malignant tumor which means that it can both invade and spread to other tissues.
Compared with benign tumor cells, malignant tumor cells have key features like not having a clearly defined border or like a slightly less organized nuclei.
Now, there are four types of germ cell tumors and each type is named after the type of cell that these pluripotent germ cells develop into.

Pathophysiology1:47–4:07

The first, are teratomas, terato means monster and oma is a tumor. So teratomas are monster tumors, and they are called that because they contain all different types of tissues, including hair, eyes, teeth, bone and neurons - kind of like a Frankenstein that’s got bits of this and that stitched together.
Now, there are two types of teratomas, the first are mature cystic teratomas, which are the most common ovarian tumors in young women and are formed from tissue that comes from any of the three germ layers.
One example, is a struma ovarii tumor which is made up of only thyroid tissue and can release thyroid hormone which leads to hyperthyroidism.
The other type are immature teratomas, and they develop specifically from neuroectoderm cells - which come from the ectoderm layer.
Immature teratomas tend to be malignant and metastasize quickly. The second subtype is a yolk sac tumor, also called an endodermal sinus tumor, and it’s made of germ cells that differentiate into yolk sac tissue.
These are the most common germ cell tumor in children, and the tumors can be very aggressive. Under the microscope, they form Schiller-Duval bodies which are rings of cells around a central blood vessel.
The third subtype is a choriocarcinoma and it’s made of germ cells that turn into syncytiotrophoblast cells which are the ones that help form the placenta.
These tumors are usually small, bleed easily, and often spread beyond the ovaries. The syncytiotrophoblast cells secrete high levels of the hormone β-hCG, and that can cause ovarian cysts to form.
The fourth subtype is a dysgerminoma and it’s made of germ cells that turn into oocytes, which is the normal pattern, but then they start to grow uncontrollably.
It turns out that these are the most common malignant types of ovarian tumors. Under the microscope, the germ cells have a central nuclei surrounded by a clear cytoplasm.

Causes and risk factors4:07–5:26

So, during ovulation the follicle ruptures and releases an egg which inadvertently leads to epithelial cell damage. To fix that damage the epithelial cells have to undergo cell division to replace and heal the tissue.
Each time cells divide, there is a chance of a mutation and the possibility of tumor formation. So this means that with more ovulatory cycles there’s an increased risk of tumor formation.
So things that are associated with a decreased risk of ovarian cancer include things that reduce the number of ovulatory cycles like pregnancy, breastfeeding, and oral contraceptive use.
On the flip side, some things that are associated with an increased risk include certain medical conditions like endometriosis and polycystic ovarian syndrome.
There are also genetic risk factors like having the BRCA-1 or BRCA-2 mutation, which are both autosomal dominant mutations, which in addition to ovarian cancer, carry with them an increased risk of breast cancer.
There’s also hereditary nonpolyposis colorectal cancer, also known as Lynch syndrome, which increases the risk of developing a number of cancers, including ovarian cancer.

Symptoms5:26–6:10

Generally speaking, symptoms of ovarian cancers can be subtle and nonspecific. Common early symptoms can include abdominal distension, bloating, as well as abdominal or pelvic pain, which can come from an ovarian torsion - where the ovary gets twisted.
Occasionally, ovarian tumors can cause ascites, abdominal masses, bowel obstruction, or dyspareunia, which is pain during sexual intercourse.
A classic finding is a Sister Mary Joseph nodule which happens when the cancer metastasis to the umbilicus. This finding is often linked with a few types of cancer - one of which is ovarian cancer.

Diagnosis6:10–6:36

Diagnosis of ovarian cancer typically involves looking for specific tumor markers like B-hCG, as well as having a transvaginal ultrasound.
Tumor biopsies are done to figure out whether a growth is benign or malignant, and imaging with a CT or MRI scan can be done to look for evidence of metastasis.

Treatment6:36–7:09

Treatment of ovarian cancer typically involves chemotherapy, surgery, and sometimes radiotherapy. Surgery might be enough for malignant tumors confined to the ovary, whereas chemotherapy might be needed for disease that has spread.
Carbohydrate antigen 125, called CA 125, is a protein produced by various types of ovarian tumors, so tracking levels of this biomarker in the blood can help monitor response to therapy and potential relapse.
All right, as a quick recap: germ cell ovarian cancers come from pluripotent germ cells that normally develop into sperm or egg.

Review7:09–8:53

The four major types of germ cell tumors are: fetal teratomas, both mature cystic and immature teratomas; yolk sac tumors, or endodermal sinus tumor, choriocarcinoma or placental tissue tumors or and finally dysgerminomas or oocyte tumors.
A well known risk factor for ovarian cancers is the cumulative amount of time a woman spends in ovulation, with protective factors being pregnancy, breastfeeding, and oral contraceptive use.