Bone Cancer: Causes, Symptoms, and Treatments
Bone cancer describes a malignant tumor of the bone that destroys healthy bone tissue. Not all bone tumors are malignant, in fact, non-malignant (benign) tumors are more common than malignant ones.
Bone cancer is divided into primary and secondary bone cancer: primary bone cancer first forms in the cells of the bone and secondary bone cancer starts elsewhere in the body, eventually spreading to bones.
The National Cancer Institute, United States, estimates that by the end of 2016, there will have been 3,300 new cases and 1,490 deaths from cancer of the bones and joints.
Survival rates vary depending on a variety of factors, including the type and stage of the cancer. According to the University of Rochester Medical Centre, United Kingdom, for all bone cancers combined, the 5-year survival rate is around 70 percent.
Fast facts on bone cancer
Here are some key points about bone cancer. More detail and supporting information is in the main article.
- Benign bone tumors are more common than malignant bone tumors
- There are a number of different bone cancer types
- Early symptoms might include pain in the affected area
- A range of diagnostic tests can help diagnose bone cancer
- Radiotherapy, chemotherapy, and surgery can all be used to treat bone cancer
Types of bone cancer
Below are some of the more common types of bone cancer:
Primary bone cancers
Bone cancer can be classed as primary or secondary.
Primary bone cancers are either benign tumors or cancers.
Benign tumors can be due to developmental changes, trauma, infections, inflammation, or abnormal tissue growth (neoplastic); they are more common in people under the age of 30.
Examples of benign bone tumors include osteoma, osteoid osteoma, osteochondroma, osteoblastoma, enchondroma, giant cell tumor of bone, aneurysmal bone cyst, and fibrous dysplasia of bone.
Examples of malignant primary bone tumors include osteosarcoma, chondrosarcoma, Ewing's sarcoma, malignant fibrous histiocytoma, fibrosarcoma, and other sarcomas.
Multiple myeloma is a blood cancer that may include one or more bone tumors. Certain bone cancers are found in specific bones, for instance, teratomas and germ cell tumors are frequently located in the tailbone.
Osteosarcoma is the most common type of bone cancer. It usually develops in children and young adults. After leukemia and brain tumors, osteosarcoma is the third most common cancer among teens in the U.K. and U.S.
Ewing sarcoma usually develops in the pelvis, shin bone, or thigh bone. It most commonly affects teenagers and young adults.
Chondrosarcoma usually develops in adults. It starts in the cartilage cells and moves on to the bone.
The outlook for a patient with malignant bone cancer depends mainly on whether it has metastasized (spread to other parts of the body). If the cancer is localized (has not spread), prognosis is usually good.
Symptoms of bone cancer
The patient initially experiences pain in the affected area. Over time, the pain gets worse and continuous. In some cases, the pain is subtle, and the patient may not see a doctor for several months.
The progression of pain with Ewing sarcoma tends to be faster than in most other bone cancers. Typically, bone cancer pain is deep, nagging, and has a permanent character.
- There may also be swelling in the affected area
- Often the bone will weaken, resulting in a significantly higher risk of fracture
- The patient may find he/she loses weight unintentionally
- A mass (lump) may be felt in the affected area
- Although much less common, the patient might also experience fever, chills, and/or night sweats
Causes of bone cancer
Nobody knows what the causes of bone cancer are. Patients with chronic (long-term) inflammatory diseases, such as Paget's disease are at a significantly higher risk of developing bone cancer later on in life. However, nobody can explain why one person gets bone cancer while another one does not. It is not contagious - you cannot catch it from someone else.
The following groups of people may be at a higher risk of developing bone cancer:
- Being a child or very young adult - most cases of bone cancer occur in children or young adults aged up to 20
- Patients who have received radiation therapy (radiotherapy)
- People with a history of Paget's disease
- People with a close relative (parent or sibling) who has/had bone cancer
- Individuals with hereditary retinoblastoma - a type of eye cancer that most commonly affects very young children
- People with Li-Fraumeni syndrome - a rare genetic condition
- Babies born with an umbilical hernia
Diagnosis of bone cancer
A doctor may order a blood test to rule out other possible causes of the patient's symptoms. The patient will then be
referred to a bone specialist (orthopedic surgeon).
The following diagnostic tests may be ordered:
A number of tests might be ordered to diagnose bone cancer.
- Bone scan: a liquid which contains radioactive material is injected into a vein. This material collects in the bone, especially in abnormal areas, and is detected by a scanner.
- CT scan: these are commonly used to see whether the bone cancer has spread and where it has spread to.
- MRI scan: the device uses a magnetic field and radio waves to create detailed images of the body, which in this case, would be a specific bone or part of a bone.
- Positron emission tomography (PET): a PET scan uses radiation, or nuclear medicine imaging, to produce 3-D, color images of the functional processes within the human body.
- X-rays: this type of scan can detect any damage that the cancer may have caused to the bone. It may also detect new bone cells that have started to form around the tumor. An X-ray does not provide enough data for a definitive diagnosis but can help the surgeon decide whether further tests are needed.
- Bone biopsy - a sample of bone tissue is extracted and examined for cancer cells. This is the most reliable way to diagnose bone cancer. A core needle biopsy involves inserting a long, thin needle into the bone and removing a sample; an open biopsy involves making an incision in the target bone area and surgically removing a sample of tissue.
Staging the bone cancer
Bone cancer has different stages which describe its level of advancement.
- Stage 1 - the cancer has not spread out of the bone. The cancer is not an aggressive one
- Stage 2 - same as stage 1, but it is an aggressive cancer
- Stage 3 - tumors exist in at least two places in the same bone
- Stage 4 - the cancer has spread to other parts of the body
Treatment of bone cancer
The type of treatment for bone cancer depends on several factors, including what type of bone cancer it is, where it is located, how aggressive it is, and whether it is localized or has spread. There are three approaches to treating bone cancer:
- Radiotherapy (radiation therapy)
The aim of surgery is to remove the tumor, all of it if possible, and some of the bone tissue that surrounds it. If some of the cancer is left behind after surgically removing the tumor, it may continue to grow and eventually spread.
Limb-sparing surgery, also known as limb salvage surgery means that surgical intervention occurs without having to amputate the limb. The surgeon may take some bone from another part of the body to replace lost bone (bone graft), or an artificial bone may be put in. In some cases, however, amputation of a limb may be necessary.
Radiation therapy is also known as radiotherapy, radiation oncology, and XRT. Radiotherapy is commonly used in the treatment of many cancer types. It involves the use of beams of high-energy X-rays or particles (radiation) to destroy cancer cells. Radiotherapy works by damaging the DNA inside the tumor cells, destroying their ability to reproduce.
Radiotherapy can be used for different reasons:
- Total cure - to cure the patient by completely destroying the tumor.
- To alleviate symptoms - radiotherapy is often used to relieve pain in more advanced cancers.
- Neoadjuvant radiotherapy (before surgery) - if a tumor is large, radiotherapy can shrink it, making it easier and less harmful to then surgically remove it.
- Adjuvant radiotherapy - given after surgery. The aim is to eliminate the cancer cells that remained behind.
- Combination therapy (radiotherapy combined with another type of therapy) - in some cases, chemoradiation - radiotherapy combined with chemotherapy - is more effective.
Chemotherapy involves the use of chemicals (medication) to treat disease. More specifically, it usually refers to the destruction of cancer cells. Cytotoxic medication prevents cancer cells from dividing and growing. In general, chemotherapy has five possible goals:
- Total remission - to cure the patient. In some cases, chemotherapy alone can get rid of the cancer completely.
- Combination therapy - chemotherapy can help other therapies, such as radiotherapy or surgery have more effective results.
- Delay/prevent recurrence - chemotherapy, when used to prevent the return of a cancer is most often used after a tumor has been removed surgically.
- Slow down cancer progression - used mainly when the cancer is in its advanced stages and a cure is unlikely. Chemotherapy can slow down the advancement of the cancer.
- To relieve symptoms - also more frequently used for patients with advanced cancer.
Written by Christian Nordqvist