Everything You Need to Know About Bone Cancer: Overview, Causes, Types, Signs and Symptoms, Diagnosis, Stages, and Treatment

The skeleton makes up the most compact tissue in the body. However, contrary to what many people think, it is still a tissue, and it is composed of cells, just like the rest of the organism.

Your bones make up the body’s primary framework, but most of them are hollow or have a porous structure on the inside. The outside is very hard, and it is known as cortical bone. It is covered by a fibrous layer known as the periosteum. The interior is more fragile, and it is known as trabecular bone. It contains a cavity where the bone marrow is located.

Another structure attached to the bone is the cartilage. It is a bone-like tissue with a soft surface that usually serves as a cushion in our joints.

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If we take the bone to the microscope, we will see two different cells. Osteoblasts are bone-creating cells and form new layers of fresh bone. Osteoclasts have potent enzymes to destroy old bone tissue that needs to be renewed. So, your bones are very active, and these cells are supported by many others every day. Bone cancer can develop in any of these cells.

Overview

Bone cancer is not the most common malignant disease. It is actually very rare, and most cases of malignancy in the bone are due to bone metastasis, not bone cancer. The difference is that bone cancer starts in the bone. Bone metastasis begins elsewhere and spreads to the bone.

In adults, bone cancer is quite rare. Only 0.2% of cancers are actually bone cancers. It is called sarcoma, which is the name given to any cancer that develops in the connective tissue (the bones, the fatty tissue, the blood vessels, and other soft or fibrous tissues).

Causes

As noted above, bone cancer is rare, and that makes it particularly difficult to study. However, the same principle applies to bone cancer as in the rest of cancers in the body. This type is also a multifactorial disease. Different factors play a role, and there is not a single cause of the illness. Instead, we can point out various risk factors. They are particular situations that increase your personal risk of bone cancer.

They are:

Genetic disorders: If you have a mutation in specific genes, bone cancer can be more likely. Some of these genes are known as tumor suppressors. When they are not functional, they won’t fulfill their role, and a tumor will start growing.
Family history: Osteosarcoma, one type of bone cancer, typically runs in families. So, if you had a family member with bone cancer, there’s a chance of sharing the same genes that led to the disease.
Paget disease and other conditions: Certain conditions predispose to bone cancer, and one of the most important is Paget disease. This is a pre-cancerous condition where excessive bone tissue develops. It can turn into bone cancer in 1% of cases.
Radiation: If you have been subject to radiation, the chance of developing bone cancer is slightly higher. This does not mean that you will get cancer after an X-ray. We’re talking about very large doses and often repeated exposure. Being close to radioactive areas and materials can also lead to bone cancer formation.
Bone marrow transplantation: Some patients who received bone marrow transplantation develop osteosarcoma after a few years. Thus, the chance is a bit higher in these patients.

In any case, the exact cause is not known. The above are only risk factors found in the population in general. However, it is generally accepted that bone cancer results from DNA mutations, which can be inherited or acquired.

Types of bone cancer

The bone tissue has different cells, as noted above. Thus, there are different types of bone cancer depending on where it develops and how. The main types are as follows:

Osteosarcoma: It is the most common type of bone cancer (still, bone cancer incidence remains quite rare). This type of cancer starts in bone cells, usually before age 30 years. It is more common in males, and typically appears in large bones of the legs and arms. It may also develop in the pelvis.
Chondrosarcoma: It is technically cartilage cancer, but cartilage can be considered a bone-like structure. This is the second most common type of bone cancer, and it usually develops in young adults and middle-aged adults. It is more common in women, and it is more common in articulations of the legs and arms. However, it can also develop in the larynx, trachea, or the chest wall.
Ewing tumor: This is the third most common type of bone cancer. It mostly develops in teenagers and children, and it becomes rare after age 30 years. It is associated with genetic mutations, and it is more common in white people. This type of tumor can run in families.
Malignant fibrous histiocytoma: This is also a possibility in bone tissue, although very rare. It mainly affects the arms and legs of middle-aged adults. This type is easily spread to other tissues, especially the lungs.
Other types of bone cancer: Still, other rare types of bone cancer can be found, such as chordomas in the base of the skull, fibrosarcomas in the jaw, or giant cell tumors, which develop benignant and malignant tumors. In some cases, the well-known non-Hodgkin lymphoma starts in the bone tissue instead of the lymph nodes.

Signs and symptoms

Pain: Bone pain is the most common symptom in bone cancer. It can be intermittent at first, usually worse at night and during walking. As the tumor keeps growing, the pain remains constant and becomes worse.
Swelling: The area around the bone tumor may start to swell, but this depends on where it is located. You could feel a lump sometimes when it is superficial. If bone cancer is located somewhere near the throat, you could feel difficulty swallowing or breathing.
Bone fractures: They are known as pathological fractures because bone tissue becomes fragile and breaks with a mild or moderate impact that would not affect healthy bones. Fractures can be small and difficult to notice, but patients describe a sudden onset of severe bone pain.
Numbness: In some cases, the bone tumor becomes large and starts pressing on the passing nerves. If that is your case, you can start feeling tingling or numbness in the legs, arms, or an area related to the location of bone cancer.
Weight loss: Similar to other types of cancer, bone cancer consumes a lot of resources and causes a negative calorie balance. These patients may lose weight without making any dietary or exercise modifications.
Metastasis symptoms: After bone cancer spreads to other tissues, it starts causing additional symptoms. For example, it could spread to the lungs and cause severe breathing difficulties.

Diagnosis

Finding bone cancer early and before the consequences would be ideal. However, it is not always possible. There are currently no specific tests that help us screen patients for bone cancer. Thus, signs and symptoms are particularly important to detect the disease in an early course.

If you have suspicious signs and symptoms of bone cancer, your doctor may need to run a few tests to evaluate your bones. They are imaging tests and blood tests, mainly. However, and depending on your case, the doctor may also require a biopsy. This is a procedure in which he takes a sample of the tumor and takes it to a microscope.

The diagnosis of bone cancer requires a combination of signs and symptoms, a physical exam, and tests. Several diseases could be causing an image or a symptom, but doctors will have a clear view if they consider every aspect of your condition. The most important tests are as follows:

X-Rays: They will probably be the first imaging tests you will need. Bone cancer is evident in X-rays, primarily when the tumor is fully grown. The affected tissue looks somewhat ragged and not as solid as healthy bone. In some cases, your doctor may point out a hole in the center of the tumor. This imaging test is also useful to evaluate your lungs and whether or not they are taken by the disease.
CT scan: This imaging test is usually done to stage bone cancer when doctors have already diagnosed the disease. It is useful to evaluate your soft tissues and see whether cancer has spread to other organs, especially the lymph nodes, the liver, and the lungs.
MRI scan: They are sometimes required to evaluate the spinal cord and the brain. They will also help doctors outline the extent of the bone tumor more accurately.
Radionuclide bone scans: These tests are helpful to detect small spreads of the primary bone tumor. It shows if cancer is starting to metastasize to another bone. Metastasis areas look like black or gray areas.
PET scan: This is a very special test that uses a type of sugar with a mildly radioactive atom. Cancer cells take up the radioactive sugar, and a PET scan detects cancer right away due to its fast metabolism. This test can be helpful to differentiate between benign and malignant tumors.
Biopsy: It is a procedure in which your doctor will take a sample of the affected bone and evaluate the tissue under the microscope. This procedure is also useful when doctors are unsure if bone cancer is a primary bone tumor or metastasis that comes from elsewhere. There are different types of biopsy, such as needle biopsy or surgical biopsies. They are used depending on the type of tumor the patient has.

Stages

Cancer stages are important tools to measure the extent and severity of cancer. It also estimates how far it has reached and if other organs are taken by the disease. Based on the stage, doctors can also decide how to treat bone cancer.

The staging system of bone cancer goes from 1 to 4 (I to IV). A higher stage means that cancer is more advanced. So, stage I means that cancer is only found in the bone, and stage IV means that it has spread to other tissues.

Staging can be determined by a standardized system known as TNM, which stands for Tumor, Nodes, and Metastasis.

T measures the tumor and how large it is. Doctors will try to find out if there is only one tumor or several spots.
N measures the lymph nodes and if they are taken. This is the first stage of cancer spread, but it is not the same as metastasis.
M measures metastasis to distant organs. When other organs are already taken by cancer, the disease is very serious regardless of how large the tumor is and how many lymph nodes are taken.

After a biopsy is taken, we can also determine the grade of cancer by looking at the cells and evaluating how different they look from healthy cells. Bone cancer can be graded from 1 to 3. So, we have low-grade cancer (G1) when it is very similar to healthy cells, middle-grade cancer (G2) when it is starting to look very different, and high-grade cancer (G3) when the tissue has lost every major characteristic. The more differentiated it is, the more aggressive it will be.

Treatment

Treating bone cancer can take several pathways depending on the stage and the patient’s health. They are basically:

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Surgical treatment: It is often the main treatment of bone cancer. In many cases, doctors take out the tumor and do a biopsy at the same time. When the disease is advanced, surgical treatment may require cutting off a limb. In any case, the goal is removing cancer cells and the apparently healthy tissue that is around.
Radiation therapy: This type of treatment uses external beam radiation to kill cancer. It may also damage nearby healthy tissues. This type of therapy is more useful in cancers that cannot be treated by surgery. It can also be recommended after surgery to make sure that there’s no trace of cancer cells left.
Chemotherapy: This therapy uses drugs in the bloodstream to kill cancer, wherever they are. However, these substances can also affect healthy tissues and have several side effects. This type can be used when the disease has spread to other tissues.
Targeted therapy: This type of treatment makes use of the genetic understanding of cancer to trigger cell destruction targeted in cancer cells only. There’s a lot of research going on to figure out metabolic pathways only found in cancer cells to exploit them and destroy cancer without affecting other tissues.