Bone cancer

Definition

Bone cancer, or osteosarcoma, is a malignant tumor originating from bone tissue. It is characterized by a tendency to rapid course and early metastasis. In the initial stages, it is manifested by localized pain, similar to the pain of rheumatism. Later, there is swelling and limitation of movement in the nearby joint. Pain becomes sharp and unbearable. Metastases arise. Pathology is diagnosed based on anamnesis, the results of examination, radiography, CT, MRI, and other studies. Treatment includes surgery to remove the tumor in combination with preoperative and postoperative chemotherapy. 

General information

Osteosarcoma is a malignant neoplasm arising from bone elements. This tumor is characterized by early metastasis and a rapid course. Previously, the prognosis of this disease was very unfavorable. Five-year survival was observed in less than 10% of cases. Due to the emergence of new treatment methods, the chances of patients have increased significantly. Today, more than 70% of patients with localized osteosarcoma and 80-90% with chemotherapy-sensitive tumors survive five years after diagnosis.

According to experts in clinical oncology, osteosarcoma is more common in younger patients. More than two-thirds of all cases of the disease occur at the age of 10-40. At the same time, men suffer twice as often as women. The peak of morbidity falls on the period of rapid growth: 10-14 years in girls and 15-19 years in boys. After 50 years of age, this tumor is sporadic.

Causes of osteosarcoma

The reasons for the development of the disease have not yet been elucidated. However, there are several circumstances where the risk of its occurrence increases. These include radiation therapy and chemotherapy previously performed for another cancer. The trauma itself (bruise or fracture) does not affect the likelihood of tumor formation. Nevertheless, in several cases, it is a rather severe traumatic injury (pathological fracture) or unusual pain in the affected area, persisting for a long time after the contusion, that causes a visit to a traumatologist and the subsequent detection of osteosarcoma. In some cases, osteosarcoma develops on the background of chronic osteomyelitis. The risk of tumor formation also increases with Paget’s disease.

Classification

When osteosarcoma is diagnosed, staging is performed to assess the extent of the process. All osteosarcomas are divided into two large groups based on their prevalence:

• Localized sarcomas. There are tumor cells only at the site of its original localization or surrounding tissues.
• Metastatic sarcomas. Metastatic involvement of other organs is detected.

It is assumed that 80% of patients have micrometastases that are so small that they are not detected by additional tests. In addition, multifocal sarcoma, in which tumors occur simultaneously in several (two or more) bones, is distinguished.

Osteosarcoma, like other malignant tumors, in some cases returns after treatment. A new tumor may arise either at the site of the previous tumor or in another part of the body (in the area of metastases). Such a condition is called recurrence. Recurrence in osteosarcoma most often develops 2-3 years after treatment and is found in the lungs. In the future, recurrences are also possible, but the probability of their development decreases.

Symptoms of osteosarcoma

The disease begins gradually. At first, the patient is bothered by dull, vague pains occurring near the joint. They may resemble the pain syndrome in rheumatic myalgias, arthralgias, myositis, or periarthritis. There is no effusion (fluid) in the joint. The tumor gradually grows, nearby tissues become involved, and the pain increases. The affected part of the bone increases in volume, the soft tissues above it become swollen, and phlebectasias (a network of small dilated veins) appear on the skin. Contracture is formed in the adjacent joint. When osteosarcoma is localized on the bones of the lower limb, lameness develops. Palpation of the affected area is sharply painful.

After a while, the pains become intolerable and sleep-depriving. They appear both on exertion and at rest and are not relieved by conventional analgesics. Osteosarcoma proliferates, spreading to neighboring tissues, sprouting muscle, and filling the medullary canal. Tumor cells spread with the bloodstream, “settling” in various organs and forming metastases. The brain and lungs are most often affected.

Diagnosis

The diagnosis of osteosarcoma is made based on clinical data and instrumental and laboratory findings. The oncologist questions the patient, paying attention to the gradual onset and vague pain near the joint and the intensification of these pains over time. Swelling in the area of the lesion in the initial stages is identified in only 25% of patients. Phlebectasias occur in later stages and are also not observed in all patients. Therefore, the absence of these symptoms cannot be a reason to exclude a malignant neoplasm.

The final diagnosis is established based on the results of additional tests: radiography, bone scanning, and biopsy of tissue taken from the affected area. Computed tomography and radiography are performed to detect metastases in other organs.

In the initial stage, radiographs show osteoporosis and blurred contours of the tumor. Subsequently, a bone tissue defect is detected. Examination of biopsy specimens reveals sarcomatous connective tissue cells, some of which form osteoid and atypical bone cells. Severe disturbances of bone structure are detected. In many cases, osteogenesis (bone formation) is poorly expressed and observed only on osteosarcoma’s periphery. Osteosarcoma is differentiated with giant-cell tumors, cartilage exostoses, eosinophilic granuloma, and chondrosarcoma.

Treatment of osteosarcoma

Treatment tactics are chosen considering the location of osteosarcoma, stage of the disease, age of the patient, general condition, recurrences, etc. Treatment of osteosarcoma is carried out in the oncology department and includes three stages:

• Preoperative chemotherapy to shrink the primary tumor and suppress small metastases. Ifosfamide, methotrexate, etoposide, and platinum drugs (cisplatin, carboplatin) are used.
• Surgical treatment to remove the tumor. In the past, amputations and disarticulations were performed for osteosarcomas. Nowadays, in most cases, a sparing organ-preserving operation is performed – segmental resection of the affected area with its replacement with an implant made of metal, plastic, the patient’s own bone, or cadaveric bone. Amputation is necessary only when the size of osteosarcoma is large, pathologic fracture, soft tissue, or neurovascular bundle sprouting. Surgery can remove not only the primary tumor but also large metastases in the lungs. If lymph nodes are affected, they are also surgically removed (lymphadenectomy). 
• Postoperative chemotherapy to finally suppress malignant cells that may have remained in the area of metastasis or the site of the primary tumor.

Radiation therapy for osteosarcoma is ineffective and is performed only if there are absolute contraindications to surgery.

All these treatment options are available in more than 790 hospitals worldwide (https://doctor.global/results/diseases/bone-cancer). For example, Surgery for bone cancer can be performed in 23 clinics across Turkey for an approximate price of $5.5 K (https://doctor.global/results/asia/turkey/all-cities/all-specializations/procedures/surgery-for-bone-cancer). 

Prognosis and prevention

Prognosis in osteosarcoma depends on certain factors both before and after treatment. Factors affecting prognosis beforetreatment for osteosarcoma:

• The size and location of the tumor.
• Stage of osteosarcoma (localized tumor, presence of metastases in other organs).
• The age and general health of the patient.

After treatment, the prognosis is determined by the effectiveness of chemotherapy and the outcome of surgery. The prognosis is more optimistic in cases of significant reduction of the sites and primary focus after chemotherapy and in cases of complete removal of the tumor.

In the past, osteosarcoma was one of the malignant tumors with the worst prognosis. Even if severe mutilation, amputation, and disarticulation of limbs were performed during treatment, the five-year survival rate did not exceed 5-10%. Due to the emergence of new treatment methods and the use of effective organ-preserving operations, the chances of patients with a favorable outcome have increased significantly, even in the presence of lung metastases. The five-year survival rate in localized osteosarcoma nowadays is more than 70%, and in the group with osteogenic sarcomas sensitive to chemotherapy, this figure is even higher – 80-90%.