Sarcoma is a rare cancer that develops in the connective tissues: muscle, bone, nerves, cartilage, tendons, blood vessels and the fatty and fibrous tissues.

Retroperitoneal sarcomas occur in the retroperitoneum. This is an area behind the peritoneum, the lining of the abdominal space that covers the abdominal organs. The retroperitoneum is deep in the abdomen and pelvis, behind the abdominal lining, where organs such as the major blood vessels, kidneys, pancreas and bladder are located.

The main types of sarcoma that occur in the retroperitoneum are:

Signs and symptoms

Symptoms of retroperitoneal sarcoma can vary depending on the size and location of your tumour. They may include:

  • A noticeable lump in the abdomen 
  • Increase in abdominal girth
  • Dull pain in the abdomen or back
  • Intense abdominal pain with bleeding

Other rare symptoms include early satiety (meaning feeling full after eating a small amount of food), weight loss, hernia or anaemia. 

Types of diagnostic scans

A diagnosis of retroperitoneal sarcoma may start with a visit to your GP who will then refer you to a specialist doctor. Some retroperitoneal sarcomas are discovered through investigations for another medical condition or are diagnosed after surgery for a different problem. 

A specialist doctor will diagnose sarcoma through a series of tests. These may include:

  • Physical examination – looking at and feeling any lump
  • A scan – taking pictures of the inside of the body using ultrasound, x-ray, CT, EUS, PET or MRI
  • A biopsy – taking and testing a tissue sample

Types of diagnostic scans and tests


A scan that uses sound waves to create images from within the body.


The Computer Tomography (CT) scan takes a number of x-rays to make a 3D image of an affected area.


Magnetic Resonance Imaging (MRI) uses magnets to create an image of the tissues of the body.


Examination of a tissue sample by a pathologist under a microscope to identify disease.

Blood test

Laboratory analysis of a blood sample.


Understanding the diagnosis

The diagnosis of a retroperitoneal sarcoma is mostly made from a needle biopsy and analysis of tissue by a pathologist. A diagnosis of retroperitoneal sarcoma should be confirmed by a specialist sarcoma pathologist who will identify the type of sarcoma and grade of the tumour. This will help your sarcoma specialist advise you on the best course of treatment for you.

Identifying the stage and grade of a cancer means your doctor can advise on the best course of treatment for you. It also describes the cancer in a common language which is useful when your doctor is discussing your case with other doctors or healthcare professionals. The stage of cancer is measured by how much it has grown or spread. This can be seen on the results of your scans or tests. The results from a biopsy can tell what grade the cancer is. 


  • Low-grade means the cancer cells are slow-growing, look quite similar to normal cells, are less aggressive, and are less likely to spread
  • Intermediate-grade means the cancer cells are growing slightly faster and look more abnormal
  • High-grade means cancer cells are fast growing, look very abnormal, are more aggressive and are more likely to spread


Most sarcomas are staged by looking at:

  • The size and grade of the tumour
  • Whether the tumour is deep in the body or superficial. This means closer to the surface.
  • Whether it has spread to another part of the body 

Most retroperitoneal sarcomas are more than 5cm in size and deep in the body. This makes the grade of the cancer a more important factor when finding out the stage of your cancer. 

  • Stage 1 means the cancer is low grade, small (less than 5cm) and has not spread to other parts of the body
  • Stage 2 means the cancer is of any grade, usually larger than stage one but has not spread to other parts of the body
  • Stage 3 means a high grade cancer that has not spread to other parts of the body
  • Stage 4 means a cancer of any grade or size that has spread to any other part of the body


Depending on where you live in the UK, you should be referred to a specialist sarcoma team for diagnosis and treatment.

In England and Wales, the National Institute for Health and Care Excellence (NICE) recommends that anyone with sarcoma should be referred to a specialist sarcoma team. In Northern Ireland, retroperitoneal sarcoma is diagnosed and treated across a number of hospitals in Belfast. People in Scotland should be referred to the Scottish Sarcoma Service for treatment.  

Your case will be managed by a team of experts from a wide range of health care professions called a multidisciplinary team (MDT). Your MDT will include your key worker or sarcoma clinical nurse specialist, surgeon and other healthcare professionals involved in your care. They will support you throughout your treatment to ensure you get the right treatment as and when you need it.

Types of treatment

The treatment for retroperitoneal sarcoma is highly individualised and depends on the size and location of your tumour. The main types of treatment are: 


Surgery is the main treatment for this type of sarcoma. The surgeon will remove the tumour and will aim to take out an area of normal tissue around it too; this is known as taking a margin. As retroperitoneal sarcomas can sometimes touch or press on surrounding organs, the surgeon will aim to remove the tumour along with any organs next to it ‘en bloc’ meaning, as a whole. This is to ensure they remove all cancer cells including those that are not clearly visible. 

Depending on the size and location of your tumour, the surgery you have may take away part of or whole organs such as the kidney, colon (bowel), pancreas, spleen or bladder which can have implications on your quality of life. Your surgeon will explain to you if this is required and the implications of removing the organ attached or next to your tumour. A small number of people will need a colostomy or urostomy following surgery.

The treatment you receive should take into account your individual situation and your doctor or clinical nurse specialist should talk you through all possible treatment alternatives. You should also have the opportunity to ask any questions you may have regarding the future implications of your surgery. 

Surgery for retroperitoneal sarcoma can be complex and only a small number of surgeons in the UK are specialists in this type of surgery. Your surgeon should also be a core or extended member of your sarcoma MDT. The quality of surgery received is critical to a patient’s outcome so it is important that the surgeon operating on you has sufficient expertise in operating on sarcomas that occur in the retroperitoneum. Surgeons with this expertise include gastrointestinal surgeons. 


This treatment uses high-energy radiation beams to destroy cancer cells. 

In some cases, radiotherapy to the tumour can be used before surgery to reduce the chance of the cancer returning. It can also be used after surgery to kill off any local cancer cells. It is not always possible to use radiotherapy to treat retroperitoneal sarcoma. If the tumour is located near to an organ and there is a risk that the organ will be damaged by the radiation, then this treatment is not used. 

There are currently research studies being carried out to investigate the exact role of radiotherapy for retroperitoneal sarcomas. 


This treatment uses anti-cancer drugs to destroy cancer cells. In some sarcomas which are sensitive to chemotherapy (Ewing’s sarcoma, synovial sarcoma and rhabdomyosarcoma) it is used to try and shrink a large tumour so it is safe to be operated on. Sometimes the tumour completely disappears when treated by chemotherapy. In this case, radiotherapy is used to kill off any local cancer cells that remain in the area of the tumour. 

Chemotherapy is sometimes used in the treatment of leiomyosarcoma after surgery to prevent the cancer coming back. Chemotherapy is also used to treat leiomyosarcomas that have spread to other parts of the body.

Liposarcoma is not sensitive to chemotherapy and therefore it is not used to treat retroperitoneal sarcomas of this sub-type.

Surgery to remove a retroperitoneal sarcoma may not always be possible. The location of the tumour and the state of your health may make major surgery too risky for your survival. If this is the case then there are other options available. These include, radiotherapy without surgery, and observation. You may also be offered best supportive care. This is care that aims to help you live as well as possible with the effects of sarcoma. It could include social, physiological or spiritual support as well as access to dietary services, physiotherapy and occupational therapy.

Clinical trials

You may be offered an opportunity to take part in a study to investigate new diagnosis methods, drugs or treatments. Some studies also look at the care and well-being of patients. Your doctor or nurse can give you more information on opportunities for you to take part in a clinical trial.

After treatment

After treatment, you will have regular follow-up appointments for several years. You should receive a follow-up schedule from your sarcoma clinical nurse specialist. The usual practice will include:

  • A chance to discuss symptoms
  • An examination to look for any signs of the sarcoma returning. This may include an MRI or ultrasound if required after examination
  • A chest x-ray to rule out any secondary cancers occurring in the lungs


Retroperitoneal sarcoma can reappear in the same area after the treatment for a previous tumour; this is called a local recurrence.

Retroperitoneal sarcoma can come back near the site of your first tumour or spread through to the abdomen. If the sarcoma does reappear, it is important to get treated as quickly as possible. It is useful to check for recurrences yourself through self-examination: your doctor or sarcoma clinical nurse specialist can tell you what to look for.

If you are worried about your sarcoma returning, contact your doctor or nurse; they may decide to bring forward the date of your follow up appointment to investigate your concerns.

What if my cancer spreads to another part of my body?

A recurrence of sarcoma may be accompanied by cancer in other parts of the body. This is called metastasis or secondary cancer. In retroperitoneal sarcoma patients, secondary cancer may appear in the lungs, which is why a chest x-ray is taken at follow-up appointments.

Treatment for secondary cancer may involve surgery, radiotherapy or chemotherapy as appropriate; your treatment will be assessed on an individual basis.