Orthopedic oncology is a subspecialty of Orthopedics which deals with diagnosis and treatment of individuals, both children and adults, with tumors and tumor like conditions of the musculoskeletal system, sarcomas or cancers spread to bone from other locations in the body as well as other problems that occur alongside these cancers.
Bone Tumors
Bone tumors develop when cells within a bone divide uncontrollably and as a result a mass of abnormal tissue is formed.
Bone tumors can affect any bone in the body and develop in any part of the bone from the surface to the center of the bone (bone marrow). A growing bone tumor destroys healthy tissue and weakens bone, making it more vulnerable to fracture.
The cause of most bone tumors remains unknown.
Symptoms
Patients with a bone tumor will often experience pain in the area of the tumor. The pain is generally described as dull and aching, may worsen at night, and may sometimes increase with activity.
Other symptoms of a bone tumor can include fever and night sweats.
Many patients will not have any symptoms, but will note a painless mass instead.
Although bone tumors are not caused by trauma, an injury can sometimes cause a tumor to start hurting. Injury can also cause a bone that is weakened by a tumor to fracture, or break. This may be severely painful.
Occasionally, benign tumors may be discovered incidentally when an x-ray is taken for another reason, such as a sprained ankle or knee injury.
Types of Bone Tumors
Benign tumors are usually not life-threatening and, in most cases, will not spread to other parts of the body. Depending upon the type of tumor, treatment options are wide-ranging—from simple observation to surgery to remove the tumor.
Some bone tumors are cancerous (malignant). Malignant bone tumors can metastasize—or cause cancer cells to spread throughout the body. In almost all cases, treatment for malignant tumors involves a combination of chemotherapy, radiation, and surgery.
Benign Bone Tumors
Benign tumors are more common than malignant tumors of the bones. These are a few common types of benign bone tumors:
Osteochondroma
Results from over growth of cartilage at the ends of bone near growth plates. Usually affects long bones of legs, can also occur in pelvis and shoulder region. It is more common in people in their 20s.
Giant cell tumor
Giant cell tumor is a benign tumor with a potential for aggressive behavior. It expands and damages the bone locally. In rare cases it can also metastasize.
Osteoid osteoma
It is a small tumor, usually less than 1.5cm. Affects long bones, often the thigh bone. It presents with pain which worsens at night. Occurs commonly in early adulthood.
Osteoblastoma
Osteoblastoma is closely related to osteoid osteoma but differs in its ability to grow larger than 2.0 cm in diameter and its aggressive behavior in bone. This type of tumor occurs in spine and long bones in young adults.
Enchondroma
Benign cartilaginous neoplasm that is usually solitary lesions in intramedullary bone. Mostly appear in bones of the hand and feet. It often has no symptoms. It is the most common type of hand tumor.
Malignant Bone Tumors
When a bone tumor is cancerous, it is either a primary bone cancer or a secondary bone cancer. A primary bone cancer actually begins in bone while a secondary bone cancer begins somewhere else in the body and then spreads to bone. Secondary bone cancer is also called metastatic bone disease.
Metastatic Bone tumors
Metastatic tumors are not considered as primary bone cancers as their cell type and behavior is same as the primary tumor from which they have originated.
Cancers that commonly spread to the bone include:
Breast
Lung
Thyroid
Renal
Prostate
Primary Bone Sarcomas
Most common type of bone cancers include
Osteosarcoma
Osteosarcoma occurs in up to five people per million each year, with most cases in teenagers and children. Most tumors develop around the knee in either the thigh bone or shinbone. Other common locations include the hip and shoulder. Osteosarcoma is typically treated with chemotherapy and surgery.
Ewing’s sarcoma
Ewing’s sarcoma typically occurs in patients between the age of 5 and 20. The most common locations are upper and lower leg, pelvis, upper arm, and ribs. Ewing’s sarcoma is usually treated with chemotherapy and either surgery or radiation therapy.
Chondrosarcoma
Chondrosarcoma is a malignant tumor formed by cartilage-producing cells. Typical age of presentation is between 40 and 70. Affects the hip, pelvis, or shoulder area. In most cases, surgery is the only treatment for chondrosarcoma.
Multiple myeloma
Multiple myeloma is a malignant tumor of bone marrow. Incidence of Multiple myeloma is approximately six people per 100,000 every year. Most cases are seen between the ages of 50 and 70. Multiple myeloma is typically treated with chemotherapy, radiation therapy and, occasionally, surgery.
Diagnosis
Infections, stress fractures, and other non-tumor conditions can all closely resemble tumors. Daignosis of a bone tumor requires a thorough evaluation followed by a number of tests.
Medical History
As part of the examination, a complete medical history is taken. Information about general health, medications, and current symptoms is noted. The doctor also takes family history of any tumor or cancer.
Physical Examination
A thorough physical examination is done, focusing on the tumor mass. Doctors look for:
Swelling or tenderness in the area of the tumor
Changes in the overlying skin
The presence of a mass
Any effect the tumor might have on nearby joints
In certain cases, doctors examine other parts of the body to rule out cancers that can spread to bone.
Tests
Radiology
X-rays provide images of dense structures such as bone. Most bone tumors are initially diagnosed on x-ray. Different tumors look different on x-ray. Some dissolve bone and others cause additional bone to form. Some do both.
Other imaging studies. For further evaluation of the tumor a magnetic resonance imaging (MRI), computed tomography (CT), or bone scan may be performed.
Biopsy
A biopsy is mostly necessary to confirm the diagnosis of a bone tumor. A sample of tissue is taken from the tumor, examined under a microscope and analyzed by a pathologist.
Biopsy is taken by two basic methods:
Needle biopsy
This procedure is done under local anesthesia. A needle is inserted into the tumor to remove some tissue. This procedure can be done in the doctor’s office. In certain cases, the needle biopsy is performed by a radiologist under radiological guidance like x-ray, CT scan, or MRI scan.
Open biopsy
An open biopsy is performed in an operating room under general anesthesia. A small incision is made in an area corresponding to the planned definitive surgery incision and some tumor tissue is removed.
Other tests
Tests like blood and/or urine may be done to help confirm the diagnosis of a bone tumor or exclude other conditions.
Approach
Patients are handled by a multi-disciplinary team comprising of Orthopedic Oncologist, General surgical Oncologist, Medical oncologist, Radiation oncologist, radiologist, pathologist, Plastic surgeon and other specialties as needed in individual cases.
Staging
Staging pertains to malignant tumors (cancers). This process helps determine how widespread a cancer may be. It will show whether the cancer has spread and how far. The treatment and prognosis for bone cancers depend on the cancer’s stage when the patient is first diagnosed.
AJCC Staging System
The American Joint Commission on Cancer (AJCC) system is used to stage all bone cancers. It combines 4 factors to determine stage that go by the initials T, N, M, and G. T stands for features of tumor (its size and if it is in more than one spot on the bone), N stands for spread to lymph nodes, M is for metastasis (spread) to distant organs, and G is for the tumor’s grade. The grade of a tumor is based on how abnormal the cells look when seen under a microscope. The higher the number, the more abnormal the cells appeared. Higher grade cancers tend to grow and spread more quickly than lower grade tumors.
This information about the tumor, lymph nodes, metastasis, and grade is combined in a process called stage grouping. The stage is then described in Roman numerals from I to IV (1-4).
T stages of bone cancer
TX: Primary tumor can’t be measured
T0: No evidence of the tumor
T1: Tumor is 8 cm (around 3 inches) or less
T2: Tumor is larger than 8 cm
T3: Tumor is in more than one place on the same bone
N stages of bone cancer
N0: The cancer has not spread to the lymph nodes near the tumor
N1: The cancer has spread to nearby lymph nodes
M stages of bone cancer
M0: The cancer has not spread anywhere outside of the bone or nearby lymph nodes
M1: Distant metastasis (the cancer has spread)
Grades of bone cancer
G1-G2: Low grade
G3-G4: High grade
TNM stage grouping
After the T, N, and M stages and the grade of the bone cancer have been determined, the information is combined and expressed as an overall stage. The process of assigning a stage number is called stage grouping. To determine the grouped stage of a cancer using the AJCC system, find the stage number below that contains the T, N, and M stages, and the proper grade.
Stage I: All stage I tumors are low grade and have not yet spread outside of the bone.
Stage IA: T1, N0, M0, G1-G2: The tumor is 8 cm or less.
Stage IB: T2 or T3, N0, M0, G1-G2: The tumor is either larger than 8 cm or it is in more than one place on the same bone.
Stage II: Stage II tumors have not spread outside the bone (like stage I) but are high grade.
Stage III: T3, N0, M0, G3-G4: Stage III tumors have not spread outside the bone but are in more than one place on the same bone. They are high grade.
Stage IV: Stage IV tumors have spread outside of the bone they started in. They can be any grade.
Even though the AJCC staging system is widely accepted and used for most cancers, bone cancer specialists tend to simplify the stages into localized and metastatic. Localized includes stages I, II, and III, while metastatic is the same as stage IV.
Treatment Options
Non-Surgical Treatment
Benign Tumors
If the tumor is benign, only close monitoring of the tumor may be recommend to see if it changes. During this time, periodic follow-ups would be required with x-rays or other tests.
Some benign tumors can be treated effectively with medication. Some will disappear over time. This is particularly true for certain benign tumors that occur in children, such as osteoid osteoma.
Malignant Tumors
If the tumor is malignant, treatment will include a team of doctors from the above mentioned specialties working together to provide care. Each case of tumor is discussed in the tumor board, which recommends and gives options for the best line of treatment based on latest available scientific evidence. The goal of treatment is to cure the cancer while maintaining function, as best as possible, in the part of the body affected by the tumor.
Treatment depends upon several factors, including the stage of the disease. If the cancer is localized, cancer cells are contained to the tumor and the immediate surrounding area. When the cancer has reached a metastatic stage, it has spread elsewhere in the body and may be more extensive and harder to cure.
Several treatment modalities may be combined to treat malignant bone tumors:
Radiation therapy
Radiation therapy uses high-dose x-rays to kill cancer cells and shrink tumors. This method only treats the cancer in the area of the beam. It does not affect cancer elsewhere in the body.
Chemotherapy.
Chemotherapy is used to kill tumor cells when they have spread into the bloodstream but cannot yet be detected on tests and scans. Used for tumors that have a very higher chance of metastasis. Chemotherapy is usually given intravenously.
Generally, malignant tumors are removed by surgery. Often, radiation therapy and chemotherapy are used in combination with surgery (Adjuvant). In certain cases chemotherapy is given before surgery also (Neo-Adjuvant).
Surgical Treatment
Benign Tumors
In certain cases surgical excision of the benign tumors is recommend; occasionally other surgical techniques are also utilized to reduce the risk of fracture and disability. Some benign tumors may recur after surgery, even repeatedly, after appropriate treatment due to the nature of disease. Rarely, certain benign tumors can metastasize or become cancerous.
Malignant Tumors
Limb salvage surgery
In this type of surgery the cancerous section of bone is excised but nearby muscles, tendons, nerves, and blood vessels are kept intact where possible. The surgeon makes and attempt to take out the tumor and a portion of healthy tissue around it. The excised bone is replaced and is reconstructed with metallic implants (prosthesis), bone from elsewhere in your body (auto graft), or bone from a donor (allo graft). The main focus of this type of procedure is to safely remove the tumor and to preserve the maximum function possible.
Amputation
Amputation is surgery to remove all or part of a limb that is affected by the tumor. It is usually used when a tumor is large and/or nerves and blood vessels are involved. A prosthetic limb is later provided that can aid function after amputation.
Recovery / Post Treatment
The length and complexity of recovery in all cases depends upon the type of tumor as well as the type of treatment / procedure performed.
When the initial treatment finishes, further tests may be ordered like x-rays and other imaging studies to confirm that the tumor has been treated adequately.
After this, the patient continues to see team for regular follow-up visits and tests every few months. Even though the tumor has been treated, it is important to monitor the patient for any signs of recurrence. Tumors that come back can pose serious problems so it is important to detect them early.