Osteosarcoma is one of the cancers in the group of sarcomas. Sarcomas are cancers that develop in tissues that connect and support different parts of the body such as bones, muscles, cartilages, fats and blood vessels.
Osteosarcoma is the cancer that start in the bones. Osteosarcoma normally develop from developing bones and specifically from immature bone cells. When talking about osteosarcoma, we mean primary bone cancer (cancer originating from bones) and not secondary cancer (start from other parts of the body and metastasize to the bones).
Although osteosarcoma can develop from any bone in the body, most common bones that are involved include distal part of femur (near knee joint), proximal part of tibia (near knee joint), proximal part of humerus (near shoulder), pelvis and skull and jaw. Most osteosarcomas occur in children and young adults (10-30 years age). Teens are the most commonly affected age group, but osteosarcoma can occur at any age.
Types of osteosarcoma
There are several different types of osteosarcoma, including osteoblastic, fibroblastic and chondroblastic osteosarcoma. There are also rare subtypes, such as parosteal, periosteal, telangiectatic and small cell osteosarcoma.
Risk factors for osteosarcoma
When dealing with cancer, a risk factor is anything that increase your chance of developing cancer. Some people develop cancer despite not having (exposed to) any risk factor we know while those exposed to risk factors do not develop the disease.
Although what exactly causes osteosarcoma is unknown, several factors are strongly linked to the development of osteosarcoma. These factors include the following;
• Genetic factors. Those with certain genetic factors are more prone to development of this type of cancer. These include the following;
• Li-fraumen syndrome. Condition associated with mutation of p53 gene which is responsible for destroying abnormal cells in the body.
• Mutation of RB gene. Those children with retinoblastoma have increased risk of developing osteosarcoma.
• Werner syndrome. Disorder associated with mutation of WNR gene
• Paget disease. Genetic inheritance may trigger Paget disease which is a disease of bone that disrupts the normal cycle of bone renewal causing bones to become weakened and deformed. Common to those older than 50 years.
• Rothmund-Thomson syndrome. Associated with inheritance of mutated REQL4. This syndrome is associated with bone defects (short height), hypogonadism and skin dysplasia.
• Age. Osteosarcoma affect those at the age where there is rapid growth. Hence during this period, there will be high generation of bone cells for growth. This rapid growth increase your chance of developing osteosarcoma.
• History of radiation treatment. People with the history of radiation therapy treatment at early stage of their life are linked to possibility of developing osteosarcoma to those bones that where irradiated.
• Gender. Statistics shows that, men (boys) are more affected than women (girls).
To prevent something, you need first to know what causes it. Since we do not know what causes osteosarcoma, currently there is no way of preventing it. Also currently are no ways of even reducing the risk of developing osteosarcoma because most of the risk factors like age, gender and genetic predisposition cannot be avoided.
Early detection and screening
Screening is the process of running some tests to someone with no signs or symptoms of a certain disease so as to test presence or absence of that disease. Screening tests have proven to be helpful in early detection of various cancers which result to improved treatment outcome.
For osteosarcoma there is no widely recommended screening tests for this type of cancer. Still, most of osteosarcomas, are detected while they are at early stage (before they spread to other organs). Symptoms such as bone pain or swelling often prompt a visit to a doctor.
But those with an increased risk of developing the disease, like those with genetic changes that increase possibility of developing osteosarcoma, they are advised to contact their doctor for possible close monitoring of their development.
Signs and symptoms of osteosarcoma
Most of osteosarcoma cases are detected while still at an early stage (not spread) due to signs and symptoms that influence people to go and seek medical help. Signs and symptoms of osteosarcoma depend on the bone in which tumor has developed. Sometimes the signs and symptoms may not be caused by cancer but by other medical condition. Signs and symptoms of osteosarcoma include the following;
• Bone pain. Cancer developed inside the bones is likely to cause some pain. Normally this type of bone pain gets worse at night.
• Swelling. Tumor inside bones can cause swelling that if it grows large enough can easily be felt. Location of swelling will depend on the bones affected. For example swelling at knee joint.
• Bone fracture. Osteosarcoma makes bones weak and break easily. One can break his/her bone even due to minor fall or accident.
Diagnosis of osteosarcoma
Medical diagnosis simply means identification of nature of an illness by elimination of the symptoms. Normally people don`t go to hospital knowing they have cancer but during diagnostic procedures is when doctors detect the disease.
Following suspicion of the disease, doctors normally run combination of tests to determine whether there are cancerous cells in the body or not and if there are cancer cells, how far have they spread. Along with thorough medical history and physical examination, doctors normally use combination of the following tests to diagnose cancer.
Laboratory tests. Laboratory tests are important in ruling out other conditions and confirming diagnosis. For cancer diagnosis laboratory tests normally include blood tests, urine tests, tumor markers and other body fluids tests.
• Blood tests. Blood tests help to reveal level of different substances in the blood which will help doctors to know if there is anything wrong in the body. From blood tests doctors can see complete blood count which indicates number, size and maturity of blood cells. Also from the blood tests doctors can analyze if kidney and liver are working properly.
• Urine tests. Urine tests (urinalysis) involve laboratory examination of urine to check presence of blood, proteins, and other substances such as drugs. For instance, blood in the urine may be an indication of benign condition, infection or other health problem.
• Tumor markers. These are biomarkers (proteins) that can be produced by both cancer cells and normal body cells in response to cancer. Tumor markers are released into the blood or urine. Although studies are still conducted to determine role of these markers in diagnosing cancer because sometimes people with benign condition will have elevated level of these proteins. Also not all tumors have their markers and some markers are not specific to one type of tumor.
• Other body fluids. Despite being rarely used, sometimes body fluids can be tested in the lab during diagnosis of cancer. For instance, the use of cerebral spinal fluid (CSF) and pleural fluid. CSF is used in diagnosis of brain tumors while pleural fluid for lung cancer.
Diagnostic imagings involve tests that create pictures of inside the body that help the doctor to see if there is tumor or not. There are several imaging tests used in cancer diagnosis depending on the type and location of cancer suspected. These imaging tests include;
• Computed tomography (CT) scan. CT scan machine is a donut-shaped scanner that uses x-rays to create series of pictures of body organs from different angles. This machine is linked to a computer where those series of pictures taken will be combined to create a 3D- image of inside the body. During the scanning process patient will lie still on the table which will slide into the scanner. In order to get a clear image, sometimes the doctor will inject the patient with a contrast material before scanning. From the images the doctor will be able to differentiate between healthy and unhealthy tissues.
• Magnetic resonance imaging (MRI). MRI is an imaging technique that uses powerful magnet and radio waves to take series of pictures of body organs and create a 3D image in a computer linked to a machine. Just like in CT, during MRI procedure the patient will lie on a table that will slide into a long round chamber. Also during this procedure, the doctor may inject the patient with a contrast material for clear image view.
• X-ray. This is an imaging technique that is uses low dose of radiation to create pictures of inside your body. Technician will position the patient and direct the x-ray beam to the intended part of the body.
• Ultrasound. Ultrasound is a diagnostic imaging procedure that uses high energy sound waves to produce images of organs inside the body. During the examination, a patient will lie on the table while the technician will slowly move a device called transducer on the skin over the part of the body that is being examined.
• PET scan. Positron emission tomography (PET) scan is an imaging test that uses radioactive glucose to create 3-D images of areas inside the body. Radioactive glucose is used for this test because cancer cells tend to absorb more glucose than normal body cells, so the scan will show which areas of the body has more glucose than others. Before the scan, doctor will inject the patient with tracer called radioactive glucose then during imaging the patient will be asked to lie on the table that will be moving back and forth through the scanner.
• Bone scan. Bone scan is used to examine bones. When it comes to cancer, bone scan is used for diagnosis of bone cancer or cancer that has metastasized into the bones. Before the test, patient will be injected with small amount of radioactive material that tends to collect more on abnormal parts of the bones. Then pictures that will be taken by a scan will indicate the distribution of those radioactive materials in the bones throughout the body.
Biopsy is a diagnostic procedure that involves removing a tissue sample from the body and examines it under microscope in the laboratory. Examination in the laboratory is normally done by a pathologist who will check if the cells in the tissue are cancerous or not. In most cancer cases, biopsy is considered to be the confirmatory test. Depending on the location and type of cancer, biopsy can be obtained in different ways. Some of them include;
• Using needle. By using a thin needle, doctors can draw same tissue or fluid for examination under microscope. This method can be used to draw some fluid (spinal tap), bone marrow (bone marrow aspiration), blood or small amount of tumor from the suspected organ such as liver and breast (fine needle aspiration).
• Surgery. Abnormal tissue samples are obtained while the doctor is performing the surgery. Tissues are then sent to the lab for examination during the surgery. If the surgeon removes just a portion of abnormal area, it is called incisional biopsy while when the entire tumor (abnormal site) is removed it is called excisional biopsy.
• Using endoscope. Endoscope is a thin, lighted tube with a camera (focusing telescope) at the end. It is used for viewing inside the body through natural openings like mouth and anus. During an examination if the doctor sees any abnormal tissue, then endoscope can also be used to take sample for that tissue. There are different kinds of endoscopy exams depending on the site of the body being examined. Some of the exams include colonoscopy (for rectum and colon), bronchoscopy (for trachea, bronchi and lungs) and esophagogastroduodenoscopy EGD (for esophagus, stomach and duodenum)
In addition to physical examination, diagnosis of osteosarcoma normally involves the use of X-ray, CT-scan, MRI scan, bone scan and biopsy which in most cases it is used as confirmatory test.
Staging of osteosarcoma
Staging is a standard way of describing the size and extent of spread of cancer. Staging simplifies communication among doctors worldwide. Doctors use diagnostic results to determine stage of the disease. So without diagnostic results, it is not possible to determine stage of cancer. Knowing stage of cancer, enable doctors to know which treatment option will give better outcome.
The conventional staging used for other solid tumors is not appropriate for skeletal tumors, because these tumors rarely involve lymph nodes or regional spread. Enneking system (musculoskeletal tumor society staging system (MSTS)) is commonly used for staging of these kind of cancers including osteosarcoma.
This system stage cancer by basing on grade of cancer as either low or high grade tumor, whether tumor is at intracompatimental or extracompatimental and if tumor has metastasized to distant organs.
• Low grade tumor. This is basically depending on the appearance of cells under microscope. For low grade tumor, tumor cells resemble to normal cells. These tumors grow and spread slowly.
• High grade tumor. Tumor cells appear different to normal cells. These tumors grow and spread quickly.
• Intracompartimental. Tumor is still within the bone
• Extracompartmental. Tumor has spread to nearby tissues.
• Metastasis. Either tumor has spread to distant organs or not.
Stage IA. Tumor is of low grade, intracompartimental and has not spread to distant organs.
Stage IB. Tumor is of low grade, extracompartimenta and has not spread to distant organs.
Stage IIA. Tumor is of high grade, intracompartmental and has not spread to distant organs.
Stage IIB. Tumor is of high grade, extracompartimental and has not spread to distant organs.
Stage III. Tumor is of any grade, intracompartmental or extracompartmental and has spread
Treatment of osteosarcoma
Following cancer diagnosis, the doctor will break the news and it is normally not very easy to accept that it is cancer. The doctor will be there to help the patient process the news and to help the patient in taking the next steps.
After the patient receives and processes the news that he/she has cancer, one of the most important steps that will follow is decision making. The doctor will present to the patient (relatives/parents/guardians) with all the possible treatment options and explain what they mean. Then with the help of the doctor, the patient (relatives/parents/guardian) will have to choose which treatment option is good depending on benefits of such option.
Despite all the information given by the doctor, sometimes the patient may still be unsatisfied with what he/she has been told. In such situation, the patient is free and advised to seek a second opinion. Second opinion is the opinion that the patient may seek from another specialist (doctor) regarding his/her health problem and in this case it is cancer. Second opinion may include confirmation of the diagnosis, more clarification on your primary doctor recommendations or even reassurances that all the options have been explored.
In addition to standard care treatment options, sometimes there are those new treatments or drugs or combination of treatments that have not been approved yet to be used as standard care treatments for a particular cancer (disease) but have shown some promising results that they may help. These type of treatments are called clinical trials.
If there are some clinical trials for your case, the doctor may present to the patient or the patient may ask if there are any clinical trials for the particular cancer case. Over the years, have improved treatments and led to better outcomes to people diagnosed with various diseases including cancer. If you have decided to take part in clinical trial, you can also withdraw at any time
Treatment of osteosarcoma requires a team of doctors, nurses and other health care professionals to work together. This team is called multidisciplinary team. Osteosarcoma may be treated by using three treatment options (surgery, chemotherapy and radiotherapy). These options may be used as single treatment option or in combination different options.
Surgery is the treatment option that involve removing the tumor through operation. Surgery is performed by a specialized doctor called orthopedic oncologist. Treatment of osteosarcoma by using surgery is a complex process and will depend on the location of the disease. Nowadays improvements have been made in surgery for bone cancer. For example in the past, it was often necessary to remove (amputate) the affected limb if osteosarcoma was found.
Nowadays it’s possible just to remove the affected part of the bone and some of the healthy tissue around it. The bone is then replaced with a specially designed metal replacement (prosthesis) or a bone graft (bone taken from another part of the body). If the cancer affects a bone in or near a joint, the whole joint can often be replaced with an artificial one. These operations are known as limb-sparing surgery
However it`s no always possible to use bone sparing surgery. This will entirely depend on the nature of spread of the disease around nearby tissues.
Side effects of surgery
Side effect will depend on location and extent of surgery. Most common side effects include excessive bleeding, pain, reaction from anesthesia and risk of infection. Most of these side effects can be relieved by medication.
Chemotherapy is the treatment of cancer that involve the use of medications to kill cancer cells. This treatment option is given by a specialized doctor called medical oncologist. Chemotherapy is an important treatment for most people with osteosarcoma as it can greatly improve the results of surgical treatment.
It is usually given before surgery in order to shrink large tumors. This is called neo adjuvant chemotherapy. Chemotherapy can also be given after surgery in order to destroy any remaining cancer cells and to stop the sarcoma from spreading outside the bone. This is called adjuvant chemotherapy.
Side effects of chemotherapy
Some of the possible side effects of chemotherapy includes; hair loss, loss of appetite, nausea and vomiting, fatigue, diarrhea, mouth sores, increased risk of infection and easily bruising and bleeding.
Radiation therapy is the use of high energy x-ray or other radiation particles to kill cancer cells. This treatment is given by a specialized doctor known as radiation oncologist.
Radiation therapy may be used after surgery to kill the remaining cancer cells after surgery or may sometimes be used as the only treatment option when surgery will not benefit the patient.
Side effects of radiation therapy
Side effects of radiation therapy will depend on the location (site) of disease and radiation dose used. These may include skin reactions, hair loss, feeling tired (fatigue), nausea and diarrhea.
Most of these side effects may go away on their own following completion of treatment. When the side effects becomes too severe, they can be relieved by using medications.