Bone cancer

Generality

A bone tumor is any neoplasm, benign or malignant, that originates from a cell of bone tissue or cartilage tissue.

The main benign bone tumors include: osteochondroma, unicameral non-ossifying fibroma, osteoclastoma, enchondroma and fibrous dysplasia.

Ewing's sarcoma

Among the most important malignant bone tumors, on the other hand, are osteosarcoma, Ewing's sarcoma, chondrosarcoma and all secondary bone tumors.

The symptoms of a bone tumor depend on the nature of the neoplasm: in general, benign bone tumors are asymptomatic, while malignant ones are symptomatic.

A benign bone tumor tends to resolve spontaneously; the use of treatments takes place only in certain circumstances.

A malignant bone tumor, on the other hand, is a condition that requires specific therapies, including: surgery to remove the tumor mass, radiotherapy and chemotherapy.

Short review of what a tumor is

In medicine, the terms tumor and neoplasia identify a mass of very active cells, able to divide and grow uncontrollably.

• We speak of a benign tumor when the growth of cell mass is not infiltrative (that is, it does not invade the surrounding tissues) and even metastasizing.
• There is talk of a malignant tumor when the abnormal cell mass has the ability to grow very quickly and to spread to the surrounding tissues and the rest of the body.

  The terms malignant tumor, cancer and malignant neoplasia are to be considered synonymous.

What is bone cancer?

A bone tumor, or bone tumor, is any neoplasm that originates from a cell of a bone tissue or from a cell of cartilaginous tissue.

It is important to remind readers that this definition applies only and exclusively to primary type bone tumors .

In fact, there are also secondary bone tumors, which derive from the metastases spread by malignant neoplasms located in other organs or tissues of the human body.

According to some statistical surveys, secondary bone tumors are 50-100 times more common than primary bone tumors.

Types

A bone tumor can be benign or malignant.

Benign bone tumors

The main examples of benign bone tumors are:

• Osteochondroma . Representing 35-40% of all benign cases of bone cancer, osteochondroma is the most common benign bone tumor in humans.

  It mainly affects adolescents and young adults under the age of 20.

  The most affected anatomical districts are the initial or terminal ends of the long bones that make up the upper and lower limbs. For example, tumor masses typical of an osteochondroma tend to form in the terminal extremity of the femur, in the initial end of the tibia or in the initial end of the humerus.

  From a histological analysis of an osteochondroma it can result that, in the tumor mass, cells typical of a bone tissue and cells typical of a cartilaginous tissue are present.

  A person with osteochondroma can develop one or more tumor masses.

• The unicameral non-ossifying fibroma . The presence of a unicameral non-ossifying fibroma coincides with the formation of a simple solitary cyst.

  Usually, the aforementioned cyst is formed in the lower limbs, in particular the legs.

  The subjects most at risk of unicameral non-ossifying fibroma are children and adolescents.

• Osteoclastoma, or giant cell tumor . This generally benign tumor is characterized by the presence of multinucleated giant cells, which resemble osteoclasts (NB: hence the name osteoclastoma).

  The most affected anatomical districts are the ends of the long bones that form the skeleton of the lower limbs; however, the wrists, arms and pelvis are also possible sites of an osteoclastoma.

  Osteoclastoma is particularly prevalent among women aged 20 to 40 years.

• The encondroma . The enchondroma is a benign tumor that develops from the cartilage present in the bone marrow. Its presence is characterized by the formation of a cartilaginous cyst.

  The enchondroma can affect people of all ages; however, statistics in hand, is more widespread in the population aged between 10 and 20 years.

  The possible sites of onset of an enchondroma include: the bones of the hand, the femur, the tibia and the humerus.

  Often, the presence of an encondroma is associated with Ollier syndrome or Maffucci syndrome.

• Fibrous dysplasia . Fibrous dysplasia is a particular neoplastic disease, the result of a genetic mutation that causes the formation of fibrous tissue instead of the normal bone tissue.

  Bones affected by fibrous dysplasia become more fragile, so they are more prone to fractures or deformations.

  The most affected skeletal areas are the bones of the skull and the long bones of the legs and arms.

  In general, fibrous dysplasia is an uncommon tumor; in most cases, patients are teenagers or young adults.

• Aneurysmal bone cyst . This benign bone tumor is quite rare; its presence coincides with the formation of a blood-filled bone cyst. The blood inside the bone cyst results from an abnormality in the blood vessels.

  The aneurysmal bone cysts can arise in any bone of the human skeleton, however they are more frequent in: legs, arms, pelvis and spine.

Malignant bone tumors

The main examples of malignant bone cancer, however, are:

• Osteosarcoma . It is the most common primary malignant bone cancer in the human population. It mainly affects children and adolescents.

  Any skeletal district of the human body can develop osteosarcoma; however, in most cases, this dangerous neoplasm occurs at the lower end of the femur or at the upper end of the tibia.

  Osteosarcoma is a malignant tumor characterized by a very high rate of growth: this involves its rapid spread to other parts of the body.

• Ewing's sarcoma . Less common than osteosarcoma, this primary malignant bone tumor affects mainly adolescents and young adults.

  The most affected skeletal districts are: the long bones of the upper and lower limbs (humerus, femur and tibia), the bones of the pelvis, the ribs and the clavicles.

  According to some statistical surveys, Ewing's sarcoma would represent 16% of all malignant neoplasms of primary bone.

  In Italy, every year less than 100 people become ill with Ewing's sarcoma.

• Chondrosarcoma . Less common in both osteosarcoma and Ewing's sarcoma, chondrosarcoma is a malignant tumor that originates from the cartilage located at the ends of some bones of the human skeleton.

  Among the most common sites of chondrosarcoma are cartilaginous tissues of: femur, pelvis, scapula, humerus and ribs.

  The subjects most at risk of chondrosarcoma are middle-aged and elderly individuals.

• All secondary bone tumors . The main neoplasms, which, following a process of metastasization, can give rise to secondary bone cancer, are: prostate cancer, breast cancer, lung carcinoma, kidney carcinoma and carcinoma of the thyroid.

  Among the various types of secondary bone tumors, multiple myeloma deserves special mention.

Causes

Most cancers - including bone cancer - arise due to genetic DNA mutations that alter cellular processes of growth, division and death. The tumor cells, in fact, grow and divide in an anomalous way, with a rhythm higher than normal, so that, for these reasons, the experts tend to define them with the terminology of " mad cells ".

WHAT MAKES THE ORIGINAL MUTATIONS OF A BONE CANCER?

The doctors have not yet identified the precise causes of bone cancer; however, they noted that some particular circumstances represent an important factor favoring the mutational processes, responsible for the neoplasm in question.

The main risk factors for bone cancer include:

• The presence of certain genetic-inherited conditions, including, for example, Li Fraumeni's syndrome, hereditary multiple exostosis, Maffucci's syndrome etc;
• A past history of exposure to ionizing radiation . It may be an environmental exposure (eg: nuclear disasters) or a subsequent exposure to a radiotherapy cycle (eg: people with a tumor who have had to undergo radiotherapy treatment);
• A previous anti-cancer drug treatment . Physicians have noted that there is a certain relationship between cancer drug treatments and the onset of bone cancer;
• A past history of bone fractures . Statistical data in hand, a fair number of bone cancer patients have been victims of major bone injuries in the past.

It is important to point out that, in many episodes of bone cancer, there are no clearly definable risk factors.

Symptoms, signs and complications

In the case of bone cancer, the presence of symptoms depends on the nature of the tumor: in general, malignant bone tumors are symptomatic, whereas benign bone tumors tend to be asymptomatic. Clearly, there are always exceptions.

TYPICAL SYMPTOMS OF A MALICNO BONE CANCER

The typical symptom of a malignant bone tumor is pain in the bone or affected bone.

Generally, it is a deaf painful sensation, occasional at the beginning, severe and constant at an advanced stage. It is quite common for patients to experience a worsening of the aforementioned painful sensation when they get tired with some activity or when they wake up from sleep at night.

Other fairly common clinical manifestations of malignant bone tumors are:

• The fragility of the bones affected by the neoplasm: these, in fact, become extremely susceptible to fractures (pathological fractures);
• The presence of swelling at the bone or bones affected by the tumor;
• The fever;
• Episodes of night sweats;
• Lameness, if the bone tumor involves one of the two lower limbs.

POSSIBLE SYMPTOMS OF A BENIGNO BONE CANCER

As stated, benign bone tumors have a tendency to be asymptomatic.

However, in some circumstances, they can determine the onset of:

• Small bumps, detectable to the touch and responsible for a swollen area;
• Mild pain where the prominence resides;
• Tingling or numbness near the affected bone. This is due to the fact that the bulge compresses the neighboring nerves.

COMPLICATIONS OF THE TUMORS OF THE MALIGNANT BONES

A bone cancer at an advanced stage is a malignant tumor capable of spreading its cancer cells to organs and tissues distant from the place of origin (lungs and liver are the most common sites).

The cells that a tumor disperses in other anatomical districts of the body are called metastases .

COMPLICATIONS OF THE TUMORS OF THE BENIGNIAN BONES

Sometimes, benign bone tumors become malignant neoplasms.

Diagnosis

Numerous conditions - including fractures and bone infections - can mimic the presence of a bone tumor and make the diagnosis of the latter so complex.

To be sure of the presence of a bone tumor, doctors must resort to: a thorough physical examination, a detailed medical history, blood tests, urinalysis, diagnostic imaging tests and a tumor biopsy.

OBJECTIVE AND ANAMNESIS EXAMINATION

The objective examination is the set of diagnostic maneuvers, carried out by the doctor, to verify the presence or absence, in the patient, of signs indicative of an abnormal condition.

• In case of suspected bone cancer, one of the most common diagnostic maneuvers is to feel the protuberance and evaluate its consistency and pain.

The medical history, on the other hand, is the collection and critical study of symptoms and facts of medical interest, reported by the patient or his family members (NB: family members are involved, above all, when the patient is small).

• In case of suspected bone cancer, a past event of ionizing radiation is a matter of great medical interest.

BLOOD ANALYSIS AND URINE EXAMINATION

Substances that are absent in healthy people are present in the blood and urine of a person with a malignant tumor. For example, in the urine of a malignant patient, there may be proteins in the malignant bones, which are completely absent in the urine of a healthy person; similarly, in the blood of a bone cancer patient there may be large amounts of alkaline phosphatase, an enzyme present in low amounts in the blood of healthy individuals.

Figure: two Ewing's sarcomas seen with a nuclear magnetic resonance. On the left, the affected bone is the femur; on the right, however, the affected bone is the humerus.

DIAGNOSTICS FOR IMAGES

The diagnostic imaging examinations serve mainly to identify the exact position of the tumor mass.

The diagnostic imaging tests useful for bone cancer include:

• X-rays;
• Nuclear magnetic resonance (RMN);
• CT Scan (or Computerized Axial Tomography);
• PET (or Positron Emission Tomography);
• Angiography.

TUMOR BIOPSY

A tumor biopsy consists of the collection and histological analysis, in the laboratory, of a sample of cells from the tumor mass.

It is the most suitable test to define the main characteristics of a bone tumor, from histology to the cells of origin, passing through the degree of malignancy, staging, etc.

Performed under local or general anesthesia, the removal of cells from a bone tumor can occur in at least two different ways: by means of a needle (needle biopsy) or by means of a scalpel ("open" biopsy).

To learn more about this topic, readers can consult the article here.

What are staging and the degree of a malignant tumor?

The staging of a malignant tumor includes all that information, collected during biopsy, which concerns the size of the tumor mass, its infiltrating power and its metastasizing capacities. There are 4 main stages of staging (or stages): stage 1 is the least severe, stage 4 is the most severe.

The degree of a malignant tumor, on the other hand, includes all those data that emerged during the biopsy, which concern the extent of transformation of malignant tumor cells, compared to their healthy counterparts. There are 4 degrees of increasing gravity: therefore, grade 1 is the least serious, while grade 4 is the most serious.

Therapy

The treatment of bone cancer varies depending on whether the neoplasm is benign or malignant.

TREATMENT OF A TUMOR TO THE BENIGNO BONES

Generally, a benign bone tumor does not require any special treatment; if it is required it is because the tumor mass has reached considerable dimensions, becoming symptomatic, or because the tumor mass has assumed a malignant nature.

In the aforementioned unfortunate situations, therapy is usually surgical.

TREATMENT OF A CANCER TO THE MALICNO BONES

The choice of the best therapy for malignant bone cancer depends on several factors, including: staging and degree of the tumor (presence of metastases, progression of the disease, etc.), the type of bone cancer, the general state of health of the patient, the age of the patient and the affected areas of the body.

Currently, the possible treatments of a bone tumor are: surgery to remove the tumor mass, radiotherapy and chemotherapy.

• Surgical removal surgery . The goal of surgical treatment is to remove the tumor mass in its entirety. Unfortunately, the total removal of tumors from malignant bones is not always possible, especially if the aforementioned neoplasms are at an advanced stage and have affected neighboring and distant tissues.

  Removal of the tumor involves the removal of part of the affected bone. To remedy this, doctors must therefore arrange to install a metal prosthesis, in place of the removed bone portion.

  When a bone tumor is particularly severe and resides on a limb, surgery may involve amputation of the affected limb. Fortunately, surgical amputation is an increasingly less practiced solution, as medical surgery is making steady progress.

• Radiotherapy . Radiation therapy involves exposing the tumor mass to a certain dose of high-energy ionizing radiation (X-rays), which are intended to destroy neoplastic cells.

  In the case of bone cancer, radiotherapy can represent: a treatment to be combined with surgery, a pre-surgical treatment (adjuvant radiotherapy) or a post-surgical treatment (neoadjuvant radiotherapy).

• Chemotherapy . Chemotherapy consists of the administration of drugs capable of killing rapidly growing cells, including cancer ones.

  In the case of bone cancer, chemotherapy may represent: a pre-surgical treatment (adjuvant chemotherapy), a post-surgical treatment (neoadjuvant chemotherapy) or a treatment for a bone tumor characterized by metastasis.

Prognosis

Every discussion on the prognosis of a bone tumor varies depending on whether the neoplasm is benign or malignant.

Benign bone cancer episodes are, as a rule, not serious and resolvable clinical conditions with excellent results; therefore they generally have a positive prognosis. The only exceptions concern those benign neoplasms that have turned into malignant neoplasms.

Malignant bone tumors, on the other hand, are conditions of a certain clinical relevance, which may have a poor prognosis if:

• Diagnosis and treatment are late;
• The tumor mass is located at a point that is difficult to reach by the surgeon. This prevents surgical removal;
• The patient's state of health is not optimal or the patient is very old;
• The tumor mass is particularly aggressive and has spread metastases to various parts of the human body.

Clearly, an early diagnosis and treatment, a tumor mass located at a point easily accessible by the surgeon, a healthy and / or young patient and, lastly, a malignant malignant bone tumor, are all situations that make the prognosis positive .