Introduction

Liposarcoma is a rare type of cancer that originates in fat cells. It is a form of soft tissue sarcoma, found deep in fat tissues within the abdomen, arms, and legs, especially the thighs and behind the knees, although it can occur anywhere in the body. 

It is caused by genetic mutations that lead to the uncontrollable growth of fat cells and the formation of tumours; however, the exact mutations leading to liposarcoma remain unclear. Risk factors such as ageing and exposure to radiation and carcinogens may increase your chance of developing the condition.¹ 

Liposarcoma is usually spotted by a lump that persistently grows and causes swelling, and in some cases, loss of appetite and weakness or pain at the affected site. The size and location of a tumour can directly influence the symptoms presented, and although the main symptoms are often shared across the different subtypes of the condition, some types are more common than others and vary in the rate of tumour growth, spread, aggressiveness and recurrence.¹

Why epidemiology matters

Early detection is crucial in improving the progression and long-term outlook of liposarcomas as well as the success of treatment options like surgery, radiotherapy and chemotherapy. Yet, understanding the risk factors of the condition, who it affects, and the spread across populations, known as the epidemiology, is crucial in informing diagnosis, screening and public health strategies. This article takes a closer look at the patterns of occurrence of liposarcoma and trends across age groups and gender. 

Incidence of liposarcoma

The incidence of a condition refers to how often it is diagnosed in a given population over a specific time. Measuring the incidence allows researchers, doctors and public health professionals to track and interpret how common a condition is and how this changes over time.

Sarcomas can occur anywhere in the body, and can be classified as either soft tissue or bone sarcoma, with many subtypes within each classification depending on the type of soft tissue or bone affected by cancer. About 80% of sarcomas affect the soft tissue, and liposarcoma is one of the most common types, accounting for about 20% of all soft tissue sarcomas worldwide.²

Liposarcoma is a rare type of soft tissue cancer, with an incidence of about 7 in every 100,000 people each year.² The condition makes up only 1% of adult cancers, but is more common in children, affecting about 15% of child cancer diagnoses.²

Incidence by age, gender and subtype

The World Health Organisation (WHO) classifies liposarcoma into five main subtypes based on the frequency, typical features and patterns, and tumour locations of each type.^2,3 The subtypes differ slightly in the age groups they affect, but all subtypes are usually diagnosed more often in middle-aged people born male (AMAB) than those born as female (AFAB).

Well-differentiated liposarcoma (WLDS), also called Atypical lipomatous tumour (ATL):

• The most common subtype, making up about 31-50% of all liposarcomas²
• This is a slow-growing, often painless subtype found in the limbs, especially deep in the inner thigh, abdomen, or head and neck region. It often resembles a benign fatty tumour (lipoma), and generally does not spread to other parts of the body
• It most commonly affects adults born male over the age of 50, with most people diagnosed around the age of 65

Dedifferentiated liposarcoma (DDLS):

• This subtype accounts for up to 20% of cases; however, it is less common^2,3
• This is a fast-growing, aggressive tumour that mutates and develops from pre-existing WLDS. It is often found in the retroperitoneum and has the greatest chance of spreading to other parts of the body and recurring, with metastasis occurring in about 10% of cases
• It most commonly affects adults born male over the age of 50, and most are diagnosed around the age of 68

Myxoid liposarcoma (MLS):

• The second most common subtype accounts for about 30% of all liposarcomas. ^2,3
• This type of tumour often occurs in the limbs, particularly in the thighs and legs, and is more likely to metastasise to nearby soft tissues like muscles and skin, and to the bones and lungs. It is unique in that it originates from immature fat cells called lipoblasts and is characterised by the appearance of round cells.
• It most commonly affects adults born male around age 50, and most are diagnosed around the age of 46.

Pleomorphic liposarcoma (PLS):

• A rare and more aggressive subtype, accounting for about 7% of cases²
• This is a fast-growing tumour that has a high chance of metastasis and recurrence, often spreading to the lungs, and also originates from lipoblasts. It is the least common subtype and is usually found in the arms, legs and sometimes the retroperitoneum
• It is most commonly diagnosed in adults born male, typically between the ages of 54 and 70

Myxoid pleomorphic liposarcoma (MPL):

• An extremely rare and very aggressive subtype, only recently defined by WHO in 2020⁴
• This type of tumour is very uncommon and is still undergoing research. It differs from other subtypes as it originates in the chest area (mediastinum) and shows both myxoid features from lipoblasts and many abnormal, fast-growing cells under the microscope
• Unlike other subtypes, MPL usually affects children and young adults under the age of 30, and more commonly affects those born as females than males⁴ 

Global patterns of liposarcoma

About 4,300 cases of soft tissue sarcomas are diagnosed each year in England, according to Cancer Research UK, with a 5% yearly increase in cases recorded between 2017 and 2019. National data published by Sarcoma UK shows that liposarcoma accounts for about 12% of all soft tissue sarcomas, with an average of 454 cases being diagnosed each year. WLDS has been recorded to be the most common type of liposarcoma diagnosed in England.⁵

In the United States, about 13,500 soft tissue sarcomas were estimated to be recorded in 2023, and the number of liposarcoma cases has been slowly increasing over time.² Data recorded in the US National Cancer Registry between 2001 and 2016 showed an overall 19% rise in liposarcoma cases regardless of subtype, with an average 1.43% increase per year.² Another study following over 12,000 cases in the US and Canada confirmed liposarcoma as one of the most frequent soft tissue sarcomas, with considerable variation in presentation and prognosis between different subtypes.⁶ WLDS was the most common subtype, followed by myxoid and dedifferentiated liposarcoma.⁶

Whilst research has studied the frequency of soft tissue sarcomas across different regions, data has shown that they remain rare and account for a small percentage of all cancers diagnosed. For instance, the annual incidence rates in 2023 were recorded to be around 2.91 per 100,000 people in China and 4 to 5 per 100,000 people across Europe.⁷ 

The rarity of soft tissue sarcomas means that data on the incidence of liposarcomas in other parts of the world, especially by subtype, is limited. Existing research mainly highlights the condition’s common features, such as tumour formation mainly in the limbs, and WLDS being the most frequent type with the best prognosis. Broader research into the incidence of liposarcomas and subtypes across specific regions is needed to further analyse global epidemiological patterns. 

Age distribution of liposarcoma

Liposarcoma is a rare cancer that typically affects adults between 35 and 70, and whilst it can occur at any age, it is most commonly diagnosed in those around the age of 50.^1. As the global population ages and lifestyles change, soft tissue sarcomas are becoming increasingly common, especially in middle-aged and older adults. 

However, some subtypes, such as MPL, are seen more often in younger adults and children. Liposarcomas are generally uncommon in children and only represent about 2% of all childhood soft tissue sarcomas.⁸ Malignant subtypes are rarely seen in children, possibly due to differences in the way tumours develop and mutate.¹ However, the majority of research has been studied in adults and data on liposarcoma in children is limited, making it difficult to draw parallels and determine conclusive links between the features, outcomes and treatment approaches of the condition in adults and children.⁸

Gender patterns of liposarcoma

Liposarcomas are more common in adults born male than in those born female. The ratio of males to females affected can be about 2:1, meaning roughly double the population born as males are diagnosed with liposarcomas compared to females. 

This gender difference is more prominent in childhood cases of soft tissue sarcomas. Research shows a stronger male dominance that may be due to biological differences, such as in hormones and genetics, and this is also seen in other types of cancer, such as in the lungs and colorectal cancer.⁹ However, further research is required to better understand gender differences in liposarcoma and how this can affect the development and treatment of the condition.

Factors influencing epidemiological patterns

There are currently no widely accepted risk factors associated with the development of liposarcoma.² However, the condition has been linked to genetic syndromes such as Li-Fraumeni Syndrome, a family history of cancer, lowered immunity due to viral infections such as HIV/AIDS or immunosuppressants, and environmental exposures of radiation and certain chemicals that can cause genetic mutations. 

Geographic and socioeconomic factors also influence epidemiological patterns, with less economically developed countries facing limited access to resources and education, which can result in a lack of accurate diagnoses or adequate treatment options. Public health strategies should focus on improving awareness and education of liposarcomas as well as improving access to disease screening and specialised healthcare.

Summary 

Liposarcoma is a rare type of cancer that arises in the soft tissue and is characterised into different subtypes, each with its features and patterns of development. It is vital to consult your doctor if you are concerned about your health or notice any symptoms of liposarcoma. 

Understanding who the condition affects and how frequent it is across different ages and genders is crucial in improving awareness and outcomes. An early diagnosis, support from specialist doctors, patient support groups and access to appropriate therapies are also key in supporting the best possible care. Together, these approaches can help improve quality of life, especially as a timely diagnosis of the condition can result in more effective treatment.