Bone Cancer is considered rare but latest bone sarcoma treatment options has made the survival rates for bone cancer significantly better than in the past. A key step to treatment is first to understand the types of Sarcoma and its prognosis and the part of the body that is affected. We discuss this in detail below.
To understand bone cancer, it helps to know a little about how normal bone tissue works. The supporting framework of your body is made up of your bones. Most bones are hollow; the outer part is a network of fibrous tissue known as matrix where calcium salts are laid down. The outer layer is made of compact bone (cortical) that protects the spongy bone (trabecular) inside. A layer of fibrous tissue called periosteum covers the outside of the bone. Hollow bones have a space called the medullary cavity and it contains soft tissues called bone marrow. Endosteum is the tissue lining the medullary cavity. At either end of the bone, there is a softer bone-like tissue known as cartilage.
WHAT IS CARTILAGE?
It is softer than bones but firmer than most tissues. It is made of fibrous tissue matrix combined with a gel-like substance that doesn’t contain much calcium. Most bones start out as cartilages and as the body lays calcium onto the cartilage, they become bones. After the bone has been formed, some cartilage remains at the ends to serve as a cushion between the bones. Cartilage along with ligaments and other tissues connect bones to form a joint. Cartilage is mainly found at the end of some bones as a part of a joint in adults. It can also be seen at the point in the chest where the ribs meet the sternum (breastbone) and in parts of the face. The windpipe and voice box and the outer part of the ear also contain cartilage. Bone is hard and strong. Some bones are able to support up to twelve thousand pound per square inch. To break the femur (thigh bone), it takes up to one thousand eight hundred pounds of pressure. The bone contains two kinds of cells:
- Osteoblast: Cells that lay down new bones
- Osteoclast: Cells that dissolve old bones
Bones don’t look like they change much. However, the truth is, they are highly active. New bones are always forming throughout the body while old bones are dissolved. Some bone marrows are only fatty tissue while others are a mixture of fat cells and blood-forming cells. Blood-forming cells create red blood cells, white blood cells and blood platelets. Other cells in the marrow are plasma cells, fibroblasts and reticuloendothelial cells. Cancer can develop in any of these tissues.
IS BONE CANCER COMMON?
It is an uncommon type of cancer that starts in the bones. It can occur in any bone in the body. However, it commonly affects long bones that make up arms and legs. There are a few types of bone cancer. Some occur primarily in children while others affect mostly adults. Bone cancer does not include cancers that started in other part of the body and has spread to the bone. Those cancers are named after the area where it first occurred such as breast cancer that has metastasized to the bone.
WHAT ARE THE DIFFERENT TYPES OF BONE CANCER?
Depending on where the cancer started, bone cancer can be broken down into different types. The most common types are:
- Osteosarcoma: Starts in bone cells and normally occurs in children and young adults in the bones of the leg or arm
- Chondrosarcoma: Starts in cartilage cells and normally occurs in the pelvis, legs or arms in middle-aged or older adults
- Ewing’s sarcoma: It is unclear where this cancer occurs but the tumors are commonly found in the pelvis, legs or arms of children and young adults
SYMPTOMS OF BONE SARCOMAS
The signs and symptoms of bone cancer include:
- Pain in bones
- Affected area is swollen and tender
- Broken bone
- Unintended weight loss
TREATMENT OPTIONS AVAILABLE FOR BONE SARCOMAS
The type of bone cancer, stage of cancer, overall health and your preferences will determine your treatment options. Your doctor will guide you in choosing the best treatment option for your cancer as different bone cancers respond to different treatments. Some treatments involve:
- Surgery and chemotherapy
- Surgery, chemotherapy and radiation therapy
The goal is to remove the entire bone cancer. Most of the time, this involves using special techniques to remove the tumor in one single piece with a rim of healthy tissue that surrounds it. The different types of surgery include:
- Surgery to remove the cancer but spare the limb: The surgeon may be able to remove the entire bone cancer and spare the limb if the bone cancer can be separated from the nerves and tissues. The surgeon will then replace the lost bone with some bone from another part of your body, material from a bone bank or a special metal prosthesis.
- Surgery for cancer that does not affect the limbs: The surgeon may be able to remove the bone and some surrounding tissue if the cancer did not occur in the arms and legs such as cancer in a rib. Bone cancer can be removed while preserving as much bone as possible in areas such as the spine. Lost bone can be replaced with bones from another part of the body, a material from bone bank or special metal prosthesis.
- Surgery to remove a limb: Large bone cancers or those that are located in a complicated position may require surgery to remove part of or all of a limb. Other treatments have been developed, making this procedure less common. After the surgery, you’ll likely be fitted with an artificial limb and go through training using your new limb to learn to do everyday tasks.
This is a drug treatment that uses chemicals to destroy cancer cells. It is normally administered through a vein. The medication will then travel throughout your body. Patients with bone cancer that has spread beyond the bone to other areas of the body can be treated with chemotherapy as well.
High-powered energy beams are used to kill cancer cells. You will be required to lie on a table while a special machine moves around you aiming energy beams at precise points on your body during therapy. Radiation therapy is often combined with chemotherapy are frequently given before an operation. The chances of an amputation will decrease when combined treatment is received. After surgery, radiation therapy may be used to kill remaining cancer cells. People with bone cancer that can’t be removed may also be treated with radiation therapy. It can also help to control signs and symptoms in patients with advanced bone cancer.
DIAGNOSING BONE SARCOMAS
- History taking and physical examination: Your doctor will ask you questions about your overall health, symptoms you have and family medical history, as those, who have a family history of cancers are assumed to be more predisposed to have the same condition. Then your doctor will perform a physical examination of your body to look for any visible symptoms.
- X-rays: This screening test will be able to show most bone cancers. The bone at the site of the cancer may appear ragged rather than solid. Bone cancer may also show up as a hole in the bone. There may be a tumor around the defect in the bone that might extend to nearby tissues such as fat or muscle. Your doctor will be able to tell if it’s malignant from the way it looks on the X-ray. However, a biopsy is the only absolute method to determine if it’s bone cancer. Chest X-ray is also often performed to check if the cancer has spread to the lungs.
- Computed tomography (CT) scans: A CT scanner looks like a big donut with a narrow table in the middle. You will be required to lie down on the table. It may take a little longer than regular X-ray. This procedure takes detailed, cross-sectional images of your body as the machine rotates around you. The machine is used to create multiple images of your body that is being examined. A computer is then used to produce an image of a part of your body.
It is helpful in staging cancer and help to tell if your bone cancer has spread to lymph nodes and other organs to check if metastatic cancer is present. You may be asked to drink one or two pints of contrast agent before the procedure. This will help to make the images of the lining of the stomach and intestine to appear clearer. You may also receive an intravenous line where a different kind of contract dye is injected. This dye helps to outline the structures in your body. The side effects of the injection include:
- Flushing that may last for hours to days
Some people who are allergic to the dye can get hives from the injection. More serious but rare side effects are:
- Trouble breathing
- Low blood pressure
Medication may be given to prevent and treat these allergic reactions. If you have experienced any allergic reactions to any contrast material previously or if you are allergic to shellfish, be sure to let your doctor know. CT scans can also be used to guide a biopsy needle into a suspected metastasis. This procedure is known a CT-guided needle biopsy where the patient will remain on the scanning table while a radiologist will advance a biopsy needle to the suspected site. The scans are repeated until the needle is within the mass.
- Magnetic resonance imaging (MRI) scans: Radio waves and strong magnets are used instead of X-rays. Energy from the radio waves is absorbed and released in a pattern formed by the type of tissue and by certain diseases. A computer will then translate the patterns into a detailed image of parts of the body. A contrast material called gadolinium is sometimes injected into your veins to see the tumor better.
This scan is often the best test for outlining a bone tumor as well as the brain and spinal cord. They may be a little more uncomfortable than CT scans. They take longer (up to an hour) and you will be placed inside a tube. The machine makes a thumping noise that may be disturbing to some people. Some centres provide headphones with music to block the noise out.
- Radionuclide bone scans: This helps to check if the cancer has spread to other bones. It is able to find metastases earlier than regular X-rays. It can also check how much damage the primary cancer has caused in the bone. The patients receive an injection that contains technetium diphosphonate. Radioactivity used is very low and causes no long-term side effects. Diseased bone cells attract this substance throughout the entire skeleton. Areas of diseased bones will appear as dense, grey to black spots (hot spots). These areas may represent metastatic cancer is present. However, arthritis, infections or other bone diseases can also cause a similar pattern. The cancer care team may use other tests or bone biopsies to confirm the condition.
- Positron emission tomography (PET or PET) scans: This procedure uses glucose (sugar) that contains radioactive atom and a special camera to detect radioactivity that is absorbed by the cancer cells. Cancer cells absorb a lot of the radioactive sugar due to the high rate of metabolism. PET scan helps to look for cancer throughout the body and can help to tell if a tumor is malignant or benign. It is combined with CT scans to better detect certain kinds of cancer.
- Biopsy: A tissue sample taken from a tumor is looked at under a microscope. This is the only absolute way to confirm cancer and that it is not any other bone disease. If cancer is present, it can help to tell if the cancer started in the bone or somewhere else.
There are several types of biopsies used to diagnose bone cancer and it is important to go with a surgeon who is experienced to conduct the procedure. Your surgeon will pick the biopsy method based on whether your tumor looks malignant or benign and what type the tumor is most likely. Certain kinds of bone tumors can be detected by needle biopsy samples, while larger samples are often needed to diagnose other types. Removal of the entire tumor at the time of biopsy will also influence the choice of biopsy chosen. The wrong method may sometimes make it hard for the surgeon to remove the entire cancer later without having to remove a part of or all of a limb containing the tumor. It may also cause the cancer to spread.
- Needle biopsy: The two types of needle biopsies are fine needle aspiration biopsy and core needle biopsy. Both uses local anaesthesia to numb the area for the biopsy.
- Fine needle aspiration: A thin needle attached to a syringe is used to withdraw a small amount of fluid and some cells from the tumor. Your doctor may sometimes be able to aim the needle by feeling the tumor or the area that is near the surface of the body. The doctor may use a CT scan for guidance if the tumor is too deep and can’t be felt. This is known as a CT guided needle biopsy and is mostly done by an interventional radiologist.
- Core biopsy needle: A larger needle is used to remove a small cylinder of tissue. Most experts think that this procedure is better than fine needle aspiration when it comes to diagnosing primary bone cancer.
- Surgical bone biopsy: Also known as incisional biopsy, a small piece of tissue is removed during this procedure. A surgeon will cut through your skin to reach the tumor. When the entire tumor is removed, it is known as an excisional biopsy. This is normally done with patients under general anaesthesia or using a nerve block (numbs a large area). It is important that the surgeon who conducted the biopsy is also the surgeon who later removes your cancer.