What is Bone Cancer?
Normal bone tissue:
To understand bone cancer, it is helpful to know a little about normal bone tissue.Bones form the structure that supports your entire body. Most bones are hollow. The hard outer layer is composed of compact (cortical) bone, which covers the spongy (trabecular) inner bone of less density. A fibrous tissue known as periosteum covers the outer part of the bones. The hollow bones contain a space called the medullary cavity that contains the soft, spongy tissue called bone marrow (discussed below). The tissue that lines the medullary canal is called the endosteum.
At each end of the bones, there is an area formed by a softer type of tissue, similar to the bone called cartilage. Cartilage is softer than bone but firmer than most tissues. The cartilage is made up of a matrix of fibrous tissue mixed with a gelatinous substance that does not contain much calcium. Most bones start being cartilage. Then, the body deposits calcium in the cartilage to form bone. Once the bone is formed, cartilage may remain at the ends to act as a cushion between the bones. This cartilage, together with ligaments and other tissues, connects the bones to form a joint. In adults, cartilage is found mainly at the ends of some bones that are part of a joint.
The cartilage can also be seen in the thorax, where the ribs join the sternum and in certain areas of the face. Other structures that contain cartilage are the trachea, the larynx and the outer part of the ears.
The bones are very hard and resistant. Some bones can withstand up to 12,000 pounds of pressure per square inch. It is necessary to exert a pressure of between 1,200 and 1,800 pounds to break the femur (thigh bone).
The bones themselves contain two types of cells.
- The osteoblast is the cell that deposits new bone
- The osteoclast is the cell that disintegrates the old bone
In some bones, the bone marrow is only fatty tissue. In other bones, the bone marrow is a mixture of fat cells and blood-forming cells. Blood forming cells produce red blood cells, white blood cells, and platelets. There are also other types of cells in the bone marrow, such as plasma cells and fibroblasts.
Any of these bone cells can become cancer.
Types of Bone Tumors:
Non-Cancerous Bone Tumors
Some tumors that begin in the bone are benign (not cancer). Benign tumors do not spread to other tissues or other organs, and do not usually pose a risk to life. Often, they can be cured with surgery. Some types of benign bone tumors are:
- Osteoid osteoma
- Osteoblastoma
- Osteochondroma
- Enchondroma
- Chondromyxoid fibroma
Bone Metastases
Most of the time when a person with cancer is informed that they have bone cancer, the doctor refers to cancer that has spread to the bones from elsewhere. This is called metastatic cancer, and it can occur in many different types of advanced cancer, such as breast cancer, prostate cancer, and lung cancer. When cancer cells in the bone are seen under a microscope, they look the same as the tissue they come from.Therefore, if a person has lung cancer that has spread to the bones, the cancer cells present in the bone look like lung cancer cells and will continue to behave as such. They do not look like bone cancer cells or behave like these, even if they are in the bones. Since these cancer cells continue to behave like lung cancer cells, they should be treated with drugs that act against lung cancer.
Blood cancers
Other types of cancer that are sometimes called "bone cancer" have their origin in the blood-forming cells of the bone marrow, not in the bone itself.Multiple myelomas are the most common cancer that originates in the bone marrow and causes bone tumors. Another cancer that originates from the bone marrow is leukemia. Sometimes lymphomas, which most often originate in the lymph nodes, can originate in the bone marrow. These blood cancers are not discussed in this article.
Bone cancers
True (or primary) bone tumors originate in the bone itself and are called sarcomas. These are malignant tumors, which means they are cancerous.Sarcomas originate in the bones, muscles, fibrous tissue, blood vessels, fatty tissue and also in other tissues. They can develop in any part of the body. Detailed information on these tumors is provided below.
Malignant bone tumors:
There are many different types of primary bone cancers. The name assigned to them is a function of the part of the bone or adjacent tissue affected and the type of cells that make up the tumor. Some are quite uncommon.Osteosarcoma
Osteosarcoma (also called osteogenic sarcoma) is the most common primary bone cancer. It originates in bone cells. Most often it affects young people between 10 and 30 years of age, but about 10% of cases of osteosarcoma occur in people between 60 and 79 years. It is rare in middle-aged people and is more common in men than in women. These tumors develop more frequently in the bones of the arms, legs or pelvis.
Chondrosarcoma
Chondrosarcoma originates in cartilage cells and is the second most common primary bone cancer. It is rare to see this cancer in people under 20 years of age, but after that age, the risk of chondrosarcoma is increased until the person turns approximately 75 years old. Women develop this cancer as often as men.
Chondrosarcomas can start anywhere where there is cartilage. Most are formed in bones, such as the pelvis, legs or arms. Sometimes chondrosarcoma can begin in the trachea, larynx and chest wall. Other places may be the scapula (shoulder blade), ribs or skull.
Benign tumors (not cancer) are more common in cartilage than malignant tumors. These are known as enchondromas. Another type of benign cartilage tumor is a bone projection covered by cartilage, which is called osteochondroma. Rarely do these benign tumors turn into cancer. People who have many of these tumors have a slightly higher chance of getting cancer, but this is not common.
Chondrosarcomas are classified by grade, which measures how fast they grow. The pathologist (a doctor specially trained to examine and diagnose tissue samples with a microscope) is the one who assigns the grade. The lower the grade, the slower cancer grows. When cancer grows slowly, the chances of it spreading are lower. Therefore, the prospects are better. Most chondrosarcomas are low grade (grade I) or intermediate (grade II). High-grade chondrosarcomas (grade III), which are the most likely to spread, are less common.
Some chondrosarcomas have distinctive features that can be observed with a microscope. These subtypes of chondrosarcoma often have a different prognosis:
- Dedifferentiated chondrosarcomas begin as common chondrosarcomas, but then some parts of the tumor become cells such as those of a high-grade sarcoma (such as high-grade malignant fibrohistiocytoma osteosarcoma or fibrosarcoma). This type of chondrosarcoma is usually formed in older patients and is more aggressive than usual chondrosarcoma.
- Chondrosarcomas of clear cells are rare and grow slowly. They rarely spread to other parts of the body, unless they have reappeared several times in the original location.
- Mesenchymal chondrosarcomas can grow rapidly, they are sensitive to treatment with radiation and chemotherapy.
Ewing's tumor
Ewing's tumor is the third most common type of primary bone cancer, and the second most common type in children, adolescents, and young adults. It is uncommon to see this cancer in adults over 30 years. This cancer (also known as Ewing's sarcoma) was named after the doctor who first described it in 1921, Dr. James Ewing. Most Ewing tumors develop in the bones, but they can originate in other tissues and organs. The sites where this cancer most commonly develops are the pelvis, the chest wall (for example, the ribs or shoulder blades), and the long bones of the legs or arms. Ewing tumors occur more frequently in white people and are very rare in black and Asian Americans.
Malignant Fibrohistiocytoma
Malignant fibrohistiocytoma (MFH) originates more frequently in soft tissues (connective tissues, such as ligaments, tendons, fat, and muscle); It is uncommon in the bones. This cancer is also known as undifferentiated pleomorphic sarcoma, especially when it originates in soft tissues. When MFH occurs in the bones, it usually affects the legs (usually around the knees) or the arms. This type of cancer occurs more frequently in older or middle-aged adults and is quite uncommon in children. Usually, MFH tends to grow locally, but it can spread to distant sites, such as the lungs.
Fibrosarcoma
It is another type of cancer that develops more frequently in soft tissues than in bones. Usually, fibrosarcoma occurs in middle-aged and elderly adults. The most affected bones are those of the legs, arms, and jaw
Giant cell bone tumor
This type of primary bone tumor is benign (not cancer) and malignant. The benign form is the most common. Typically, giant cell bone tumors affect the legs (usually near the knees) or the arms of young and middle-aged adults. They usually do not spread to remote sites, but tend to reappear at the place where they originated after surgery. (It is called local recurrence). This can happen many times. With each recurrence, the chances of the tumor spreading to other parts of the body increase. Rarely, a malignant tumor of giant cell bone spreads to other parts of the body without first resorting locally.
Chordoma
Usually, this primary bone tumor occurs at the base of the skull and in the bones of the spine. This cancer most often in adults over 30 years of age. It is approximately twice as frequent in men than in women. Chordomas usually grow slowly and often do not spread to other parts of the body. They often return in the same area, if not completely removed. The most common areas of tumor spread are lymph nodes, lungs, and liver.
Other types of cancer that form in the bones:
Other types of bone cancer can be detected, but they do not start in bone cells. These types are not treated as primary bone cancers.Non-Hodgkin lymphomas
Usually, non-Hodgkin lymphoma develops in the lymph nodes, but sometimes it originates in the bone. Non-Hodgkin primary bone lymphoma is usually an extended disease since many bones are usually affected. The prognosis is similar to that of other non-Hodgkin lymphomas of the same subtype and at the same stage. Primary bone lymphoma receives the same treatment as lymphomas that originate in the lymph nodes; It is not treated as a primary bone sarcoma. For more information, see Non-Hodgkin lymphoma.Multiple myelomas
Multiple myelomas almost always form in the bones, but it is not primary bone cancer since it originates in the plasma cells of the bone marrow (the soft inner part of some bones). Although it causes bone destruction, it is not bone cancer, nor is leukemia. It is treated as an extended disease. Sometimes, myeloma can first be found as a single tumor (called plasmacytoma) in a single bone, but most of the time it will spread to the marrow of other bones. See Multiple Myeloma.Signs and symptoms of bone cancer:
Pain
The most common sign of bone cancer is a pain in the affected bone. At first, the pain is not constant. It can become worse at night or when the bone is used (for example, pain in the leg when walking). As cancer grows, the pain will be constant, and it can get worse with activity.
Swelling
The swelling in the area of pain may not occur until several weeks later. Sometimes, a lump or mass may be felt, depending on where the tumor is.
Cancers in the bones of the neck can cause a lump or mass in the back of the throat that can cause problems swallowing or make breathing difficult.
Fractures
Bone cancer can weaken the bone in which it is formed, but most of the time the bones do not fracture (break). The person who suffers a fracture next to or through the site of the bone tumor usually describes a sudden severe pain in a bone that he had felt in pain for a few months.
Other symptoms
Cancer in the bones of the spine can press on the nerves, causing numbness and tingling or even weakness.
Cancer can cause weight loss and exhaustion. If cancer spreads to the internal organs, it can also cause other symptoms. For example, if cancer spreads to the lungs, it can cause breathing problems.
More often, these symptoms are caused by conditions other than cancer, such as injuries or arthritis. Even so, if these problems last for a long time for no apparent reason, you should consult your doctor.
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