What Is A Metastatic Spinal Tumour?

Introduction 

Did you know that cancer could affect bones? In fact, the third most common site that cancers spread to is bone. Of those, around 70% affect the spine - and are known as metastatic spinal tumours.¹ Metastatic spinal tumours (MSTs) are cancers that start elsewhere and spread to or around the spine or spinal cord.¹ Being diagnosed or having a family member being diagnosed with such a condition could be stressful, to say the least. This article will provide a quick overview so you can wrap your head around the diagnosis and the potential risks and benefits of its various treatment options. 

Understanding metastatic spinal tumours 

What are tumours? 

Tumours are abnormal clumps of cells that could form in many places in the body. The reason they start could be a bit complicated, but we’ll summarise it. Cells have a life cycle, where they eventually die so that other new ones can be created. Tumours happen when some cells do not die as quickly as they should, causing a build-up of cells.       

Benign tumours are tumours that stay in their place and do not move anywhere. Malignant tumours grow faster than benign ones and could spread to other body parts. There are some other scientific differences between them, but these are the main ones you should know about. 

For more detailed answers about the differences between tumours in general and a general overview of cancer, follow this link.

Differentiating between primary spinal tumours and metastatic spinal tumours 

There is a subtle difference between primary spinal tumours and MSTs. Primary spinal tumours are abnormal masses originating within the spine, whilst metastatic spinal tumours are abnormal masses originating elsewhere and spreading to the spine. 90% of masses found in or around the spine or spinal cord are MSTs. This article’s focus is on MSTs and not primary spinal tumours. 

Where do metastatic spinal tumours come from? 

Metastatic Spinal Tumours could originate from anywhere in the body, but the most common sites are breast (21%), lung (19%), prostate gland (7.5%), kidney (5%), gastrointestinal tract (4.5%), and thyroid gland (2.5%).² These are also the sites from which the tumour could spread relatively early in the disease process.² They are most commonly spread from their point of origin to the spine via blood circulation, usually through this specific network of veins called the Batson plexus.²

Types of spinal tumours 

There are many kinds of spinal tumours, depending on where the tumour originated and where the mass is in or around the spine or spinal cord. The tumour/s could be extradural, intradural extramedullary, and intradural intramedullary. These terms refer to where the tumours are in or around the spine. More than 95% of spinal metastatic tumours are extradural.² For more in-depth information about these types, see our other article, “Spinal Cancer Treatment”. 

Symptoms and diagnosis of metastatic spinal tumours 

Signs and symptoms of metastatic spinal tumours

People may have different symptoms depending on the type of tumour/s they have. However, they also share many symptoms. The most prominent and common one is back pain. It often starts at night and could wake people up.^1,2 As the disease progresses, this pain could occur during any part of the day and spread to parts of the arms or legs. If the metastases invade the soft tissue that helps stabilise the spine, the spine could become unstable and cause pain in certain positions.^1,2 This could also cause a change in posture, leading to kyphosis or more commonly known as a hunchback. People with MSTs may also complain of tingling in the arms or legs.^1,2

In serious cases, it can lead to a problem called spinal cord compression. It's not very common, affecting about 1 out of 10,000 patients. When this happens, it requires immediate attention from doctors. The symptoms are rather severe and can include weakness (in 60%-85% of cases), changes in feeling like numbness around the hips and buttocks, and problems with controlling bowel and bladder. If left untreated, spinal cord compression can worsen and cause paralysis, loss of feeling, and more issues with bowel and bladder function.²

Diagnosis of metastatic spinal tumours 

While this article simplifies metastatic spinal tumours, diagnosing it is complex and requires several tools.^1,2,3 Studies show that diagnosing metastatic spinal tumours should be done through X-ray, bone scanning, magnetic resonance imaging (MRI), and possibly a biopsy - when MST is clinically suspected.² 

Firstly, the doctors will want a plain X-ray of the spine, as it is a quick and money-saving way to try and locate the masses.³ However, more is needed as it will only show tumours of a specific size and give limited information about the origin of the tumour and how much it has invaded the spine or spinal cord.³ Therefore, doctors may also use an MRI scan of the entire spine.^2,3 MRI will give them more information on where the tumour is, how big it is, whether it invaded any soft tissue, and if spinal cord compression is present.^2,3

Doctors may also use PET scans and bone scintigraphy (a type of bone scan).^2,3 These scans give valuable information about the cancer's staging, where it has spread elsewhere in the body and to other bones, and how active it is.^2,3 Studies even show that bone scintigraphy is the most efficient way to detect metastases in the whole body.³

Doctors may also use biopsies when evaluating the tumour if they are still uncertain about its danger or the type of cells the tumour is made from.⁴ A biopsy is a sample of the tumour itself. With a tumour sample, they may look at it under a microscope and determine what it’s made from and how likely it is to invade other tissues.⁴ Such information is essential because it can significantly change how they want to treat it. There are two ways they might take the biopsy:

• The first is doing it surgically and opening up a part of the back to get to the tumour.
• The second is inserting a needle through the skin, using a CT scanner to guide them to the tumour, and taking a sample using that needle.^4,5 While the latter option is safer and less invasive, it might not yield enough tissue to properly show the characteristics of the tissue, especially if the tumour lies within the bone.⁵ Therefore, whether or not your medical team will want a biopsy and which technique they want to use to obtain it will depend on your specific case

Treatment of metastatic spinal cancers

Around 10-20% of people diagnosed with metastatic spinal cancer manage to survive two years after the metastases are diagnosed.⁴  An interdisciplinary team is needed to successfully treat people with metastatic spinal cancers.^4,6,7 Surgeons, oncologists, and other specialists are needed to make decisions about treating MSTs. Below is a quick overview of the different treatment options. 

I must also emphasise that a well-rounded team is needed to treat people with MSTs. This may include physiotherapists to help with range of motion, occupational therapists to help with their ability to manage daily activities, and social support groups to aid with emotional and psychological impacts. Each of these facets is important in increasing the quality of life of people with MSTs and takes much pressure off patients and their loved ones.

Stereotactic spine radiosurgery (SRS)

Radiation therapy uses high-energy waves to shrink tumours.⁷ Stereotactic spine radiosurgery is a cutting-edge treatment that uses advanced technology to deliver a powerful radiation dose directly to the tumour/s. It targets the tumour using narrow radiation beams with pinpoint accuracy, maximising its radiation dose while protecting nearby healthy tissues from exposure.⁷ This precise and selective radiation often leads to effective pain and tumour control.^6,7 The best part is that the treatment can be given in one or more outpatient sessions.⁶ However, it can take a while for the benefits of radiation therapy to kick in. Also, some tumours are resistant to radiation, which can limit its effectiveness.^6,7 On the other hand, some recent studies show that it may even treat these previously thought to be radioresistant metastases.^6,7 

Systemic therapy

Systemic therapies, like chemotherapy and targeted therapies, treat the whole body and can be very useful in managing spinal tumours that have spread.⁶ These treatments are especially good for treating many tumours at once and tumours that respond well to specific drugs.⁶ However, they can also have serious side effects and might not work for all tumours.⁶

Palliative care

Palliative care is a special kind of care designed to improve the quality of life for patients with serious illnesses. Instead of aiming to cure the disease, palliative care focuses on managing symptoms and making patients comfortable. This is particularly useful for people whose risks of undergoing treatment outweigh their benefits.²

Surgery

Surgery can be used to remove these tumours, which can provide immediate relief from symptoms like pain and problems with movement.^4,6 However, surgery can be a major process and might not be suitable for everyone, particularly those already very sick from cancer. It should also be known that surgery is often a palliative treatment for metastatic spinal tumours rather than a curative one.⁶

Summary

In summary, metastatic spinal tumours are a type of cancer that has spread to or around the spine or spinal cord. There are different types of them, depending on where they are, where they came from, and how far they have invaded. Multiple diagnostic procedures are used to identify them and uncover essential information to inform how they should be managed. Every treatment option has its own set of benefits and drawbacks. Doctors consider many factors, including the patient's overall health and the type of tumour, before deciding on the best treatment approach.