Overview of Palliative Radiation Therapy For Bone Metastases
Metastases refers to a process where cancer spreads from its original site to other parts of the body. The bone is often a place where many types of cancer can spread. This happens in around 280,000 new cases every year in the US. The types of cancer which are most likely to spread to the bone are breast, prostate, and lung cancers, as well as thyroid cancer, melanoma, colorectal cancer, and to some extent, bladder and kidney cancers. Multiple myeloma, a blood cancer, has the most likelihood to cause bone lesions or psychic changes to the bone.
When cancer spreads to the bone, it can cause structural damage leading to significant pain, potential fractures, and a decreased quality of life overall. The cancer can spread to any part of the bone but it’s most commonly found in three main areas: the arms and legs, pelvis, and spine. The spine is the most common site, specifically the midsection or thoracic area, followed by the lumbosacral spine (lower back), and then the cervical spine (neck area). In terms of the arms and legs, it’s most commonly found in the leg bones.
The main goal of treating bone metastases is to prevent further damage to the skeleton and to improve the patient’s symptoms. Surgical treatments are generally considered for patients who have an estimated life expectancy of more than 6 weeks. For patients with a life expectancy of 3 to 12 months, doctors might suggest less invasive surgeries. If the patient is expected to live 12 months or more, doctors may opt to surgically remove the metastatic lesions, for better outcomes. If a patient does not qualify for surgical treatment, then palliative radiation therapy may be used, which is designed to relieve pain and improve quality of life rather than curing the disease.
Anatomy and Physiology of Palliative Radiation Therapy For Bone Metastases
The health of our bones is managed by a continual process of renewal. This cycle involves bone-making cells, called osteoblasts, which deposit new bone, and bone-absorbing cells, known as osteoclasts, which remove old bone. The activity of the osteoclasts is influenced by hormones like parathyroid hormone and calcitonin, and these cells also release certain enzymes and acids that assist with bone creation and breakdown.
Certain cases of cancer result in “bone metastasis”, which means that cancer cells have spread from the original (primary) tumor to the bones. This spreading is due to the growth of the primary cancer, which allows for the formation of new blood vessels (neovascularization). Some of these cancer cells then detach and invade nearby tissues before entering the bloodstream. Once in the bloodstream, surviving cells can reach the bone marrow, which is the soft, spongy center of the bone.
In the bone marrow, these cancer cells avoid detection by the body’s immune system and continue to grow, stimulating more osteoclast activity and thus more bone resorption (removal of bone). The cancer cells themselves can also release a bunch of different growth factors that promote the production of more osteoclasts.
A side-effect of bone metastasis is pain. This is partially due to an increase in inflammatory cells at the site of the cancer. Other sources of the discomfort can be infiltration of the nerve root (which is where nerves originate in the spinal cord), tiny breaks in the bone, pulling of the periosteum (the outer surface of the bone), increased pressure within the bone, muscle spasm, or pressure on surrounding nerves.
Why do People Need Palliative Radiation Therapy For Bone Metastases
The main purpose of palliative radiation therapy is to reduce pain. Usually, after undergoing this treatment, around 60% of patients can expect relief from their pain in approximately 2 to 3 weeks. This treatment is often used for the following reasons:
- When pain from cancer spreading to the bones (bone metastases) is too intense to manage with pills or liquid medicine
- When cancer has spread to the spine, putting pressure on the spinal cord (a condition called malignant spinal cord compression)
- To prevent fractures that might happen because the cancer has weakened the bones (pathologic fractures)
When a Person Should Avoid Palliative Radiation Therapy For Bone Metastases
There are a few reasons why someone might not be able to have radiotherapy, which is a common treatment for many different types of cancer:
If they have had certain diseases in the past that affect their digestive system (like inflammatory bowel disease) or their connective tissues (like collagen vascular disease), it might not be safe for them to have radiotherapy. It’s also not safe for pregnant people or those with inherited conditions that could lead to more cancers (like Down syndrome), Fanconi anemia, Gorlin syndrome, Cockayne syndrome, Gardner syndrome, Usher syndrome, Ataxia-telangiectasia, and Nijmegen breakage syndrome.
Apart from that, anyone who has radiotherapy needs to be able to stay still for short periods while the treatment is happening. This is because the radiotherapy machine has to be aimed very carefully to make sure it targets only the cancer cells and as few healthy cells as possible.
Patients also need to be able to understand and agree to the treatment (this is known as giving ‘informed consent’) and follow instructions from the safety of another room where the radiation technicians will be. Lastly, they need to be able to come back for regular check-ups to see how well the treatment is working and whether it’s causing any side effects.
Who is needed to perform Palliative Radiation Therapy For Bone Metastases?
When planning treatment with radiation therapy, a team of specialists work together to make sure you get the best possible care. Here’s who they are:
* Radiation oncologists: These are experienced doctors who specialize in using radiation to treat different types of cancer. They decide if radiation therapy is the right treatment for you.
* Dosimetrists: They are licensed healthcare experts who figure out how to give the strongest possible treatment of radiation to the specific area where it’s needed, while also trying to make sure it causes as few side effects as possible.
* Medical physicists: These are professionals trained in the use of radiation for medical treatment. They work alongside the dosimetrists to design a treatment plan that will focus the radiation very accurately to treat the cancer, whilst also minimizing damage to healthy tissue. They double-check that the treatment plan is carried out correctly with several quality assurance measures before the patient receives the therapy.
* Radiation therapists: These are licensed therapists who operate the machines that deliver the radiation treatment.
Also, there are radiation oncology nurses and support staff. They help with setting up the simulation, arranging appointments, and taking care of the patient’s needs during treatment.
How is Palliative Radiation Therapy For Bone Metastases performed
Radiotherapy is a treatment method that uses high-energy x-rays to target and destroy certain growths or lesions in the body. You receive this treatment in a dedicated center with special equipment. When preparing for radiotherapy, you will go through a process called simulation. This involves figuring out the best position for you to lie in during treatment so that the x-rays can effectively reach the target area. You need to be comfortable because you will have to stay in the same position for all your treatments, which usually last 15 to 30 minutes. If you’re being treated for something in your upper neck, head, or chest area, you might have to wear a tight mask or piece of clothing.
The high-energy beams used in treatment cause damage to the DNA of cells, causing them to die. If you’re receiving treatment with the goal of curing your condition, you’ll likely receive small daily doses known as fractions. Breaking the treatment down into these smaller chunks helps to protect healthy tissue around the target area and reduces the chances of lasting side effects. If you’re receiving treatment to manage symptoms of a chronic or severe condition, the doses might be lower and the focus will mainly be on reducing your discomfort.
There are two main techniques used in radiotherapy. One is called 3-dimensional conformal radiation therapy (3-DCRT), and the other is stereotactic body radiation (SBRT). The 3-DCRT method uses a detailed scan of the target area to guide the radiation, carefully avoiding important nearby organs. On the other hand, SBRT delivers a higher dose of radiation directly to the target area with extreme precision, minimizing the impact on nearby structures. SBRT is not as commonly used as 3-DCRT, but it could be more useful in certain situations, like treating bone metastases that are resistant to radiation, for instance.
One important aspect with these treatments is the course of treatment. Where suitable, doctors recommend a single strong dose of radiation for palliative pain relief of bone metastases. This is often preferable to a treatment schedule broken down into smaller doses, as it reduces costs and is more convenient for you. However, one-time strong dose tends to result in a higher chance of needing to retreat the same painful site as compared to a series of smaller doses.
Depending on each individual’s condition, surgery may sometimes be needed before starting radiation treatment. For patients with bone metastases, there are a few techniques that can sometimes be used, such as embolization to decrease the blood supply to bone lesions and thermal ablation to cause rapid temperature changes in cells and damage them. There are also options of injecting a strengthening compound into bones weakened by cancer growth, something known as cementoplasty.
In summary, radiotherapy is a carefully planned and executed treatment approach that aims to maximize its effects on target lesions while minimizing negative impacts on surrounding healthy tissue. While the treatment itself gets done in a relatively short period of time, the preparation, consultation, and possible need for alternative or supplementary treatments are likely to require more time and commitment.
Possible Complications of Palliative Radiation Therapy For Bone Metastases
The side effects of radiation therapy can vary depending on the treated area and the dosage used. Fatigue is often the most common side effect after treatment, affecting about 35% of patients. Pain could increase in the first week of treatment, however, this usually goes away within three days. The usage of a medicine called dexamethasone can help manage this increased pain.
Radiation of the spine can sometimes cause stomach issues like nausea, diarrhea, or abdominal discomfort. Patients feeling nauseous can take certain drugs called 5-HT3 antagonists; these are designed to relieve nausea symptoms both before and after treatment. To manage the effects of diarrhea, other medications like loperamide and hyoscine butylbromide may be used.
Usually, these side effects gradually improve and resolve within 4 to 6 weeks after completing the therapy. Long-term side effects are not that common.
There might be times when radiation needs to be repeated if the patient doesn’t respond adequately or if they experience returning pain. After the first therapy, up to 40% of patients might not find relief, and half of the patients see a return of pain within a year. There isn’t a universally accepted guideline for when to repeat the radiation treatment. It’s crucial to have regular check-ups with the specialist who provides the radiation treatment (the radiation oncologist) after several rounds of irradiation.
What Else Should I Know About Palliative Radiation Therapy For Bone Metastases?
As people with cancer are living longer, the use of palliative radiotherapy, a form of treatment that uses high-energy waves to destroy or damage cancer cells, has become more common. To effectively apply this treatment, a well-coordinated interprofessional team is essential. It’s crucial to pick the right patients for this treatment to minimize complications, avoid damage to nearby body parts, and enhance the patient’s overall quality of life.
Doctors caring for cancer patients need to fully understand the benefits of palliative radiotherapy when talking about care plans with patients who can no longer undergo systemic therapy, drug treatments that reach and affect cells all over the body, or surgery. It’s very important to educate patients about the role of palliative therapy. Patients should know that the goal of this treatment is to improve their comfort and quality of life, not necessarily to improve their chances of survival.
Like any other medical treatment, palliative radiotherapy may have side effects. However, it’s generally tolerated well by most patients and can be personalized to ensure each patient can follow through with their individual treatment plans.
