What Are The Types Of Sarcomas?

Introduction

Saa-kow-muh is how to pronounce sarcoma. How a collective subtypes of cancer produce sarcoma types. Why is it important to get familiar with those subtypes?

Definition of Sarcoma

Sarcoma is cancer originating from the connective tissues. For example, tissues can be muscle, fat and connective bone tissue like tendons, joints and blood vessels.

Importance of knowing different types of Sarcomas

There are 70 types of sarcomas. Sarcoma identification is important to tailor and prescribe the right prescription to treat sarcoma cancers. 

The location of the cancer is inserted with the suffix “sarcoma”. For instance, if we break down the term angiosarcoma; ‘angio’ describes blood disease, the cancer found in the lining of the blood vessels is called angiosarcoma.

The rate of sarcoma cancer depends on where the cancer is located, some cancers have 10% and others have 40% change of diagnoses. Therefore, knowing the sarcoma types is beneficial to not delay the diagnosis. 

Classification of sarcoma

When an individual is diagnosed with sarcoma, the healthcare professional will classify the type based on the location (histological type) of the tumour. It can either be considered bone sarcoma or soft tissue sarcoma.

Sarcoma tumours overall are classified by knowing their primary site.¹ 

Then the tumour is evaluated on whether it is malignant or benign. Based on the connective tissue cancer type, the terminology differs. As an example fat is a connective tissue; the tissue can be lipoma or liposarcoma reflecting on being malignant and benign characteristics.¹ 

From the classification chart of sarcoma, we can see that for each type of sarcoma, we notice the term differs and so does the treatment and surgery¹. 

Cell differentiation is monitored. Normally healthy cells in the histology image show cells travelling towards the surface of the skin (inner ectoderm to outer ectoderm) and replace old cells with healthy cells. However, sarcoma produces irregular cell production.¹ 

Two main types of Sarcoma

The classification divides sarcoma into bone sarcoma and soft tissue sarcoma. 

Bone sarcoma

The reason for bone sarcoma to be one of the primary classifications has to do with targeting bone cells. Bone sarcoma is diagnosed at a younger age around early twenties and infant age. 

Soft tissue sarcoma

Soft tissue is the other classification, the cancer begins in the muscle and moves to the rest of the connective tissue area. Soft tissue sarcoma is common from 35 years old onwards. 

An example of a soft tissue sarcoma tumour is angiosarcoma. 

Bone sarcoma

Definition and location of bone sarcoma

Bone sarcoma refers to the cancer in the bone’s connective tissue. Bone sarcoma types are osteosarcoma, chondrosarcoma, chordoma, Ewing's sarcoma and fibrosarcoma. 

Metastatic bone sarcoma refers to the cancer that has spread from the bone’s connective tissue to other organs within close proximity like the lungs, kidneys, breast and prostate regions.  

Types of bone sarcoma

Let’s get a deep dive into the types of bone sarcoma. Bone sarcoma grows in the bone’s connective tissue precisely attacking the bone cells, and bone cartilage, tumour growth in the skull and spine area, cancer on the tibia’s bone and tumours found on ligaments and muscles. 

Osteosarcoma

This cancer develops from the actual bone cells. The cancer cells during the initial stages resemble the regular bone cells (osteoblast cells) leading to the growth of the tumour. These tumours later create immature, irregular, diseased bone which is later on diagnosed as osteosarcoma.  

Osteosarcoma is a bone tumour that adheres to long bones like on the arms and legs. The cancer grows as the bone grows so if the cancer patient still has time to grow (in terms of height) so does the cancer.

Osteosarcoma can be classified as low-grade, intermediate grade and high-grade based on the growth rate of the tumour and its metastasis status (travelling cancer). 

The survival rate for osteosarcoma is 70%, osteosarcoma occurs in individuals that are less than 25 years old. The cancer cells prefer to target the bone cells and develop in bone cells that are still in the growing stage no matter the gender.

Other factors like radiation treatment, taking anti-cancer drugs without proper prescription, gene alteration in the RB1 gene and experiencing syndromes like Li-Fraumei syndrome, Werner syndrome, Paget disease, Hereditary retinoblastoma, Rothmund-Thomson syndrome etc can increase your risk of developing osteosarcoma. 

Chondrosarcoma

Chondrosarcoma is a bone sarcoma that develops in cartilage and this type of sarcoma is rare. It has a survival rate of 60 to 70%. Chondrosarcoma tissue starts as benign tumour (non-cancerous) at first and progresses into a malignant invasive tumour.   

Chondrosarcoma can develop in the pelvis cartilage, shoulder, hip and spine. This rare type of tumour grows slowly so the signs and symptoms are not experienced or visible in the initial stages. The cause of chondrosarcoma still remains unclear. 

Chondrosarcoma types are: 

• Clear cell chondrosarcoma: Found in the joints of AMABs (those assigned male at birth)
• Dedifferentiated chondrosarcoma: a low to intermediate-grade conventional cartilage tumour found alongside a high-grade non-cartilaginous sarcoma, seen commonly in older patients
• Mesenchymal chondrosarcoma: the tumour grows rapidly in young adults

Ewing sarcoma

Ewing sarcoma is a rare tumour developing in the tibia bone. The sarcoma typically occurs in teenagers but is also seen in young kids and young adults. It usually affects the bone but sometimes they can also affect the soft tissues nearby. Ewing sarcoma is diagnosed as 1% in children and 2% in adolescents. The survival rate is 75%.   

Ewing sarcoma can develop in the abdomen, limbs and chest. The sarcoma can metastasize to the lung and other areas that are near the cancerous bone. The patients usually experience swelling in their legs due to cancer. 

Spindle cell sarcoma

Spindle cell sarcoma are cancers that occur in the long bones. It affects any sex and age of the patient, the description of spindle cell sarcoma can be much more invasive even breaking the surface of the skin barrier.² 

Regular follow-up is essential as the tumour can allow other opportunistic factors like an ulcer to form at the same site of the tumour.² 

Spindle cell sarcoma is monitored by conducting X-rays and biopsies. The lump can grow out of the skin as far as 9 cm in diameter and only surgical intervention can reduce the lump along with medication.² 

Soft tissue sarcoma

There are over 50 types of soft tissue sarcoma and the diagnosis is sometimes misled on where the cancer location developed from. The treatment depends on the size of the tumour as they progressively becomes abnormal. 

Definition and location of soft tissue sarcoma

Soft tissue sarcoma originates in soft tissue. For instance, the muscle is a soft tissue as well as fat, blood vessels, nerves and tendons. Soft tissue sarcomas are more likely to develop in young children. 

Types of soft tissue sarcoma

Soft tissue sarcoma are all derived from mesenchymal cells. The cancer prefers extremities so soft tissue sarcoma is usually present on the upper and lower back of the limb.³ Similar to bone sarcoma, soft tissue sarcoma is also diagnosed by its location and by its description.³ 

Leiomyosarcoma

Leiomyosarcoma is a rare tumour that occurs in the smooth muscle which means that cancer can occur in the uterus, digestive system and blood vessels.⁴

The grading of the tumour is based on the TNM grading system. 

The tumour is classified into different stages based on the size of the tumour as 

• T1 where the cancer is 5 cm
• T2 the cancer is between 5-10 cm
• T3 the cancer is between 10-15 cm
• T4 the cancer is over 15 cm 

The other stages of grading leiomyosarcoma are node staging and metastasis staging. This is based on the invasion into the lymph nodes or any distant organs respectively.⁴

The tumour staging and grading depends on the type of soft tissue sarcomas as there are 50 types of them and the lump size differs.⁴  

Liposarcoma

Liposarcoma is a type of soft tissue cancer that targets fat cells, the lipoblast tumour occurs in the leg, arm, belly and other areas in the body consisting of fat cells.⁵ 

Cancerous fat cells multiply rapidly, the cell cycle keeps on producing abnormal tumour cells which eventually get rid of healthy cells and even spread by metastasis. No symptoms were reported except for the lump followed by experienced pain and edema.⁵ 

Liposarcoma also follows the TNM grading to monitor the tumour to make decisions and take the best approach regarding the surgery.⁵

Synovial sarcoma

Synovial sarcoma is found in the joint where it consists of soft tissue, the cancer cells can be seen on the back of the leg and near the knee area, the ankle and the shoulder. The cancer grows slowly delaying the diagnosis. 

The tumour is malignant and starts to produce more cancerous cells that can be diagnosed around the age of 30 and the tumour is mostly predominant in AFABs.  

The difference between the other soft tissue sarcoma and synovial sarcoma is that the synovial sarcoma occurs due to changes in the chromosome while other soft disorders sarcoma are inherited.  

Malignant peripheral nerve sheath tumour

The malignant peripheral nerve sheath tumour, unlike the other soft tissue discussed, is a tumour that occurs in the nerves associated with transmitting electrical signals to the brain. The tumour is found where the nerve is protected by a soft tissue where the nerve sheath tumour is induced. 

Schwann tissue cells, endoneurium and perineurium are the tissue layers that protect nerves and the cells that are more prone to cancer development.   

Malignant peripheral nerve sheath tumours are classified into two types which are schwannomas that affect the vestibular nerve (a paired nerve) located in the inner ear area and neurofibromas tumours. Both are benign tumours and can be malignant⁶. 

Neurofibromas appear when there is a deletion (an absence of a segment in the DNA) within the NF1 gene and form a mutation. The tumour is diagnosed when the tumour is plexiform type (appearing as a large nerve or described as a bag of worms).⁶    

Diagnosis and treatment of sarcoma

Now that we have discussed the different types of sarcomas and established how the sarcomas are classified as bone sarcoma or soft tissue sarcoma, let’s go through the diagnosis process and the tailored treatments. 

Diagnostic tests for sarcoma

Bone sarcoma is diagnosed by conducting physical exams, image analysis and tissue biopsy to help determine the cancer’s origin.⁷ 

Sadly, some bone sarcomas take a long time to get diagnosed as the cancer growing process takes a long.⁷ Similarly, soft tissue sarcoma diagnosis is also delayed as the abnormal mass takes time to develop and appear.³

Your healthcare provider will conduct a physical exam to check for lumps. Your healthcare provider will order imaging analysis and biopsies to further confirm the lump. The Ultrasound scan is used to measure the size and the depth of the tumour with which a biopsy is taken from the cancer. Cancer is diagnosed by MRI followed by a CT scan.³

Treatment options for sarcoma

• Surgery is the common tool used to remove any cancer mass. Based on where the cancer is located the need for surgery is decided. Some cancers will be fit to go through the neoadjuvant therapy to simply shrink the tumour³ 
• Chemotherapy is also viewed as a treatment option for different types of sarcomas. Chemotherapy works best in Ewing sarcoma and osteosarcoma tumours
• Cytotoxic drugs are prescribed after being diagnosed with sarcoma leading to metastasis³
• Radiation therapy treatment is said to be efficient for soft tissue sarcomas and metastasis, especially when soft tissue sarcoma is diagnosed as a high-grade³
• Chemotherapy, radiotherapy and surgery can be used to treat bone sarcoma as well 

Importance of early detection and treatment

Early detection of sarcoma whether bone or soft tissue sarcoma plays an important role in improving the treatment outcome and increasing the chances of survival. If you experience drastic weight loss suddenly, fatigue, extreme pain, lumps or swelling that lasts longer, please visit your healthcare provider immediately.  

Summary

Sarcoma is a connective tissue tumour that originates from the bone or soft tissue. There are over 70 types of sarcomas and the treatment depends on their location and size. Sarcoma types should be investigated to provide an appropriate treatment tailored to sarcoma cancer which is why knowing sarcoma’s type is recommended. Please visit your healthcare provider if you experience drastic weight loss suddenly, fatigue, extreme pain, lumps or swelling that lasts longer.