Embryonal tumours are a type of cancer that develops from embryonic (or foetal) cells in the central nervous system (CNS). The CNS is responsible for all sensory and motor functions in the body, and is composed of the brain and the spinal cord.
Embryonic cells are the cells that humans develop from after fertilisation. Normally, these cells in the embryo differentiate into a specific cell type (such as blood cells and organ tissues) before the eighth week of pregnancy. However, in some cases embryonic cells may be present after birth. They are usually harmless, but in rare instances they may become cancerous.
Embryonal tumours are most commonly found in babies and children under nine years of age. However, they can develop at any age.
Types of Embryonal Tumours
There are six different types of embryonal tumours in the CNS.
Medulloblastomas
Medulloblastomas are the most common type of embryonal tumour, and are the most common type of childhood brain cancer. These tumours often develop in the lower back portion of the brain, known as the cerebellum. The cerebellum is responsible for muscle coordination, posture, balance and movement. This type of tumour is most common in children between the ages of three and nine, with male children having a slightly higher incidence than female children. While many medulloblastomas can be aggressive with a tendency to spread through the cerebrospinal fluid (CSF) surrounding the brain and spinal cord, these tumours can have a good prognosisto predict how a disease/condition may progress and what the outcome might be when caught early.
Embryonal Tumours with Multilayered Rosettes (ETMRs)
Embryonal tumours with multilayered rosettes (EMTRs) are a rare subtype of embryonal tumours that generally occurs in children under three years old. These tumours often begin in the largest portion of the brain, known as the cerebrum, however it can develop in other parts. The cerebrum is primarily responsible for thinking and voluntary movement. Unfortunately, ETMRs are very aggressive, and may not have as good of a prognosis as other embryonal tumours.
Medulloepitheliomas
Medulloepitheliomas are a rare subtype of embryonal tumours that generally develop in children under the age of nine. These types of tumours can develop anywhere in the CNS, including the brain, spinal cord, or nerves located just outside of the spinal column, as well as the eye. Unfortunately, Medulloepitheliomas are very aggressive, and may not have as good of a prognosis as other embryonal tumours.
Atypical Teratoid/Rhabdoid Tumours
Atypical teratoid rhabdoid tumours (ATRTs) are a very rare subtype of embryonal tumours that generally develop in children under three years of age. In most cases, these tumours develop in the cerebellum or brainstem, however they can develop in other parts of the CNS. The cerebellum is the lower back portion of the brain that is responsible for muscle coordination, posture, balance and movement. The brainstem, which is located next to the cerebellum, is responsible for controlling breathing, heart rate, and the nerves and muscles used for seeing, hearing, walking, talking and eating. Unfortunately, ATRTs are very aggressive, and may not have as good of a prognosis as other embryonal tumours.
CNS Neuroblastomas
Neuroblastomas of the CNS are a very rare subtype of embryonal tumours that generally occurs in children under 10 years old, with the average age of diagnosis of 18 months. These tumours develop in the nerve tissue of the cerebrum, or in the layers of tissue that cover the brain and spinal cord, known as the meninges. The meninges have three layers, and acts to protect the CNS. While CNS neuroblastomas can be aggressive, they can have a good prognosis when caught early.
For more information on neuroblastomas, please refer to the Rare Cancers Australia Neuroblastoma page.
CNS Ganglioneuroblastomas
Ganglioneuroblastomas of the CNS are a subtype of CNS neuroblastomas that have both benignnot cancerous, can grow but will not spread to other body parts (non-cancerous) and malignant (cancerous) parts of the tumour. They usually develop in the meninges of the brain and spinal cord, and can have a good prognosis when caught early.
For more information on ganglioneuroblastomas, please refer to the Rare Cancers Australia Neuroblastic Tumours page.
Some of the information regarding the types of embryonal tumours was obtained from the Childhood Medulloblastoma and Other Central Nervous System Embryonal Tumours Treatment (PDQ) page published by the National Cancer Institute.
Treatment
If an embryonal tumour is detected, it will be staged and graded based on size, metastasis, and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.
Cancers can be staged using the TNM staging system:
- T (tumour) indicates the size and depth of the tumour.
- N (node) indicates whether the cancer has spread to nearby lymph nodessmall bean-shaped structures that filters harmful substances from lymph fluid.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0-IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advancedat a late stage, far along or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
Once your tumour has been staged and graded, your doctor may recommend genetic testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment is dependent on several factors, including location, age, stage of disease and overall health.
Treatment options for embryonal tumours may include:
- Surgery, potentially including:
- Brain surgery to remove as much of the tumour as possible.
- Shunt insertiona procedure to relieve build-up of cerebrospinal fluid (CSF) in the brain.
- Chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells.
- Radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells.
- Targeted therapymedication that targets specific molecular features of cancer cells, potentially including signal transduction inhibitors.
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
Some of the information regarding treatment was obtained from the Childhood Medulloblastoma and Other Central Nervous System Embryonal Tumours Treatment (PDQ) page published by the National Cancer Institute.
Risk factors
While the cause of embryonal tumours remains unknown, there are several inherited conditions that may increase the risk of developing this disease, including:
- Turcot syndrome.
- Rubinstein-Taybi syndrome.
- Nevoid basal cell carcinoma (Gorlin) syndrome.
- Li-Fraumeni syndrome.
- Fanconi anaemia.
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Some of the information regarding risk factors was obtained from the Childhood Medulloblastoma and Other Central Nervous System Embryonal Tumours Treatment (PDQ) page published by the National Cancer Institute.
Symptoms
Symptoms of embryonal tumours may vary between the different subtypes and different age groups.
Children with embryonal tumours may experience the following symptoms:
- Difficulties with balancing and coordination and/or walking.
- Slowed speech.
- Headache, especially in the morning.
- Headache that only goes away after vomiting.
- General weakness and fatigue.
- Seizures.
- Diplopiaseeing two images of a single object, also known as double vision and/or other eye problems.
- Nausea and/or vomiting.
In addition to this, infants and/or young children may also experience:
- Irritability.
- Slowed growth.
- Changes in eating habits.
- Delayed developmental milestones, such as sitting up, walking and talking.
Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.
Diagnosis
If your doctor suspects you have an embryonal tumour, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Neurological examinationan assessment of sensory and motor functions, such as vision, balance and coordination.
- Imaging tests, potentially including:
- MRI (magnetic resonance imaging)a type of medical imaging that uses radiowaves, a strong magnet and computer technology to create detailed images of the body.
- CT (computed tomography) scana type of medical imaging that uses x-rays and computer technology to create detailed images of the body.
- Blood teststesting done to measure the levels of certain substances in the blood.
- Lumbar puncturea procedure that involves inserting a needle between two vertebrae in the lower spine and extracting a sample of cerebrospinal fluid (CSF) for analysis.
- Biopsyremoval of a section of tissue to analyse for cancer cells.