General Information
A tumor is an abnormal clustering of cells. If it is a brain tumor these cells are located in the brain. Though cancer and tumors are often used interchangeable, this is a common misconception. The word cancer is derived from latin where it means crab because like a crab cancer is irregularly shaped and "grabs on and won't let go" [1]. Cancer is a threatening type of tumor also called malignant tumor that can spread and damage other parts of the body. This leads to the classification of tumors into benign and malignant tumors:
- Benign Tumors: Generally speaking benign tumors are less lifethreatening than malignant tumors, because they dont contain cancerous cells. Furthermore benign tumors do rarely spread to tissue around them and have a low growth rate. However, they can still cause severe issues even leading to death by pressing on nearby tissue. If that is the case an operation is necessary.
- Malignant Tumors: Being able to spread aggressively, malignant tumors invade other cells to gain access to their blood and nutrient supply which cancer cells need to survive. They have a varying growth rate. The treatment depends on the size and the location of the tumor.
Malignant Brain Tumors are further divided into primary and secondary or metastatic brain tumors.
- Primary: The tumor originates in the brain as a result of a random cell transforming and changing its behaviour. Usually primary tumors tend to stay in the brain and are the uncommon form.
- Secondary: The cancer cells originate in another part of the body with lung, breast, colon, skind and kidney being the most common and spread to the brain in a process called metastasis. These type of brain tumors occur the most.
Specific Types
Since there are more than 120 different types of brain tumors, this section describes 3 of the most common ones. To get more general information about tumor grading refer to Tumor Grading.
WHO 2016 classification of tumors of the central nervous system
Meningiomas arise from the meninges, the layers of tissue covering the brain and the spinal cord. Most Meningiomas are considered benign, though they can compress surrounding brain tissues if they grow. They account for 34 percent of all brain tumors and occur twice as much in women as in men. The cause might be related to an abnormal chromosone 22, which is normally involved in fighting tumor growth. Around 40 to 80 percent of meningiomas possess this chromosome. Meningiomas are divided into three gradings.
I - Benign Meningioma
II - Atypical Meningioma
III - Malignant (Anaplastic) Meningioma
Astrocytoma [5]
Astrocymota arise from star shaped cells, the so called astrocytes, which are a subtype of gliomas (gliomas account for 25% of all primary tumors). Gliomas are a general term for tumors that arise from the supportive tissue of the brain. Astrocytoma can appear in various part of the brain and the nervous system with the exact cause being unknown.They are graded on a scale from I to IV depending on how abnormal the cells look.
- I - Pylocytic Astrocytoma: usually stay in the place where they started and do not spread, are considered the most benign ones
- II - Diffuse Astrocytoma: invade nearby tissue at a slow pace
- III - Anaplastic Astrocytoma: rare tumor that requires more agressive treatment
- IV - Astrocytoma Grade IV: is divided into secondary and primary, with primary as the more common one
A special type of astrocytoma are glioblastomas which 60-75% of all astrocytomas. Glioblastomas are considered highly malignant, because they grow rapidly being supported by the blood vessels. Usually glioblastomas contain a mixture of different cells.
Oligodendrogliomas are another subtype of gliomas developing from glial cells that make up the supportive tissue of the brain called oligodendrocytes (10-15% of all gliomas). They can occur in the cerebral hemisphere though most frequenty they are found in the frontal or temporal lobe.Under the microscope these tumors seem to have" short arms" or a fried egg form. They occur in 2 to 4 percent of tumor cases sometimes in children. As in meningiomas chromosomal abnormalites might play a role. Oligodendrogliomas are divided into two gradings (Grade II, Grade III).
Kommentar
Unbekannter Benutzer (ga47xoj) sagt:
16. Mai 2017Feedback from Group 3:
The page is very informative. You can also add some more types of tumors.
Good work