Overview 

Choroid plexus carcinoma (CPC) is a very rare type of brain cancer that mainly occurs in children but can also present itself in adults. These tumours are considered to be aggressive and malignant, meaning they are highly infectious and can invade nearby tissue and spread to other areas of the body. As it is a highly invasive disease, understanding the causes and symptoms of the condition can help inform you about how the condition can affect your health. 

What are Choroid Plexus Tumours (CPT)? 

These tumours are caused by uncontrolled, abnormal growth of cells in the choroid plexus, a type of brain tissue. This specialised tissue lines the fluid-filled cavities (ventricles) of the brain and has two main functions. The first is to produce and regulate the composition of your cerebrospinal fluid (CSF), a clear colourless fluid that protects the brain and spinal cord.¹ The other function is to act as a barrier that separates the blood and CSF in the brain, helping preserve the brain environment and ensuring its health and well-being. Hence, the choroid plexus is vital in ensuring successful brain development and protecting the brain from harmful pathogens. In the presence of a tumour, however, these typical functions of the choroid plexus are greatly diminished. 

Types of Choroid Plexus Tumours  

CPTs are grouped into three grades depending on their different characteristics. For example, these types of tumours can be either benign (slow-growing/non-cancerous) or malignant (highly infectious/cancerous). These tumours can come in three different ‘grades’ based on how they look under the microscope. The Centre of Cancer Research and the World Health Organisation (WHO) uses the following grading system to differentiate between the three types of choroid plexus tumours:^2,3

• Grade 1: These choroid plexus tumours are referred to as choroid plexus papillomas (CPP) which are benign tumours
• Grade 2: Mid-grade tumours known as, atypical choroid plexus papillomas, are benign as well. However, in contrast to grade 1 CPPs, grade 2 CPPs have a greater chance of recurrence even after being surgically removed
• Grade 3: Tumours of this degree are referred to as choroid plexus carcinoma (CPC) and are malignant. Due to their malignancy, they are highly infectious, fast-growing, and are more likely to spread to other regions of your central nervous system. 

Age 

The risk of developing choroid plexus carcinoma (CPC) varies with age. CPC primarily affects children, constituting 80% of all CPC cases.⁴ While CPC can occur in adults, it is relatively rare and much less common. Among paediatric (children) brain tumours, CPC comprises 1-4% of all brain tumours, with 10-20% of cases manifesting within the child's first year of life.⁴

Causes of CPCs  

Cancer is a complex disease that is rooted in genetic changes (mutations) that disrupt the normal functioning of cells. A wide range of mutations can occur in any cancer. These mutations typically target the cell life cycle, often accelerating the proliferation and secretion of malignant tumour cells to other regions of the brain. 

Genetics 

The causes of CPC are not fully understood, but several factors have been implicated. For instance, approximately 50% of CPC cases have been shown to have mutations in the TP53 gene.⁵ Normally, TP53 acts as a "stop" signal for cell growth, preventing cells from growing uncontrollably and forming tumours. However, people with mutations in their TP53 gene produce a non-functioning TP53 protein that loses its ability to regulate cell growth effectively. As a result, cells can grow and spread more easily, leading to the development of more aggressive or malignant forms of cancer, such as CPC.

When scientists looked at the complete set of genes in samples from patients with CPC, they found recurrent TP53 mutations in cases of CPTs in children.⁶ However, they also found adults with CPT have mutations in the TERT gene which encodes for a protein involved in chromosome stability.⁶ Chromosomes are like instruction manuals for our bodies. They contain all the genetic information needed to build and maintain us. Without our chromosomes, our cells wouldn't know what to do, nor would our body work properly. Hence having proteins like TERT monitoring the structural integrity of our chromosomes is highly important and necessary for our health. 

Other researchers have observed that individuals with CPC also have either additional copies of chromosomes (specifically chromosomes 1, 2, 4, 10, 12, and 20) or losing chromosomes (specifically chromosomes 5, 6, 9, 16, 18, 19, and 22).^7,8 The specific genes are yet to be determined, highlighting the need for more research on the genetic causes of CPC. However, the addition or loss of so many genes is highly detrimental as too much or too little of something can cause many problems in our bodies. 

Because of these characteristics, CPC may be more challenging to treat effectively. Doctors may face difficulties in devising the most suitable treatment plan due to the tumour's aggressive nature and increased likelihood of spreading.

Are CPCs Hereditary? 

Cancer is not usually inherited from your family genetics, however, some types of cancer can be influenced by them. In the context of CPC, it’s rare for specific mutations to be inherited from a family's genes to increase the risk of developing the condition (Centre of Cancer Research). However, it has been observed that individuals with Li Fraumeni syndrome (LFS) have a 36% association with CPC as both conditions have mutations within the TP53 gene.^9,10 The mutations in LFS are known as germline mutations which are genetic alterations we inherit from our parents and are passed down from generation to generation. However, not all people with LFS develop CTC and not all people with CTC have mutations within their TP53 genes. Overall, further research needs to be conducted to evaluate whether CTC is hereditary or not. 

Symptoms of CPCs 

The symptoms of CPC depend on the size, the location, and the tumour’s rate of growth within the choroid plexus. People with CPTs may have a condition known as Hydrocephalus. This is a build-up of excess fluid (normally CSF) which can cause an increased pressure in the brain. The tumour can alter the production of CSF (as it is within the choroid plexus) and also cause other symptoms due to its mass and location. 

The main symptoms are as follows (Brain Tumour Research & MayoClinic): 

• Headaches or migraines
• Nausea or vomiting
• Irritability
• Seizures
• Issues with your eyes such as blurry vision, abnormal eye movement, or double vision
• Trouble with walking 
• Confusion
• Memory problems 

It’s important to note that these symptoms can also be caused by other conditions, so it is essential to consult a healthcare professional for an accurate diagnosis if you’re experiencing any of these symptoms, especially if they are persistent or worsening over time. 

Summary 

Choroid plexus carcinoma (CPC) is a rare and aggressive brain cancer that primarily affects children, but can also occur in adults. CPCs are highly infectious and can spread to other areas of the body. They arise from abnormal cell growth in the choroid plexus, a brain tissue responsible for producing cerebrospinal fluid (CSF) and maintaining brain health. These tumours are classified into three grades based on their characteristics: choroid plexus papillomas (Grade 1), atypical choroid plexus papillomas (Grade 2), and choroid plexus carcinomas (Grade 3), with the latter being the most malignant.

Genetic mutations, particularly in genes like TP53 and TERT, are implicated in CPC development. These mutations disrupt normal cell growth control mechanisms, leading to uncontrolled tumour growth. Additionally, changes in chromosome numbers and structures contribute to CPC progression. Although CPC is not usually inherited, rare genetic syndromes like Li Fraumeni syndrome (LFS) can increase the risk of developing the disease. Symptoms of CPC vary depending on tumour size and location but commonly include headaches, nausea, vomiting, seizures, vision problems, and difficulties with walking or memory.

Given the complexity of CPC and its aggressive nature, effective treatment can be challenging. Doctors may encounter difficulties in devising suitable treatment plans due to the tumour's propensity for recurrence and spreading. Therefore, ongoing research is essential to improve our understanding of CPC and develop more effective treatments.