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Rare and less common cancers


A cancer diagnosis is a life-changing event, but when you have been diagnosed with a rare or less common cancer, it can be especially challenging.

Rare and less common cancers are harder to identify than more common cancers, and as a result, are more likely to be diagnosed at a later stage, potentially making them more difficult to treat.

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There are many different types of rare and less common cancers including Kaposi Sarcoma, endocrine cancer, thymus cancer, peritoneal cancer, and eye cancer such as retinoblastoma.

A range of organisations provide information and support specifically for people affected by a rare or less common cancer. You may find the following helpful:

Australian organisations
International organisations

As these organisations are based overseas, some treatments and services may be different to those available in Australia.

Specific rare and less common cancers

What makes a cancer rare?

A cancer is considered rare or less common (RLC) when it only affects a small number of people. There are many different types of RLC cancers. They can start in many different parts of the body and from different types of cells.

Some may originate in a part of the body, such as the bowel, where other more common cancers arise, but from a different type of cell to the more common cancer, making it rare. A cancer might be common in one sex but rare in the other, for example breast cancer in men is rare.

A cancer might be rare because it is found in an unusual part of the body for that type of cancer. For example, melanoma is a common type of skin cancer, but melanoma that starts in the eye is very rare.

A cancer might be rare as it is a subtype of a more common cancer. For example, lymphoma is a common cancer but there are some subtypes that are rare such as some T-cell lymphomas.

Cancers are considered rare if they affect a child or a teenager. Cancer only affects a very small number of children and teenagers so any cancer that is found in a child is rare. 

How common are rare cancers?

A cancer is considered rare if it affects fewer than 6 people per 100,000 each year and less common if it affects fewer than 12 people per 100,000 each year.

In Australia, around 145,000 people are diagnosed with cancer each year. RLC cancers account for around 52,000 of these cancers, which is about one-third of all cancer diagnoses.

RLC cancers account for half of all cancer deaths in Australia and 7 per cent of all diseases. Over the last 20 years, while the incidence rate for common cancers has increased, death rates have decreased significantly. This is a result of better screening, early detection and advancements in treatment.

The difficulty of diagnosis

RLC cancers are often difficult to diagnose for several reasons:

  • Symptoms may be like those caused by more common conditions. Often the doctor will explore the more common reason first, leading to a delay of a diagnosis.
  • Some symptoms are unusual and as a result are less well known to doctors than symptoms of more common cancers.
  • Sometimes cancer develops in a person who is not expected to get cancer, especially in children and adolescents. Doctors will often look for other causes for their symptoms first.
  • You may need to have several tests and see more than one specialist before you get a diagnosis. Often doctors and pathologists don’t have enough information on rarer cancers and people may receive an initial incorrect diagnosis.
  • The pathologist may need to do several tests on your biopsy or blood sample or may have to send the sample to a specialist laboratory for testing. This can all result in a delayed diagnosis.

Health professionals

The health professionals you will see depend on the type of cancer you have. Your specialist may discuss your treatment options with other health professionals who specialise in different aspects of your care, at what is known as a multidisciplinary team (MDT) meeting.

Some rare cancers are subtypes of more common cancers and are managed by the MDT for that type of cancer.


Rare and less common cancers can be difficult to diagnose, and you will often have to have more tests than people with more common cancers.

The first test you may have is a physical examination to check for lumps, enlarged organs, or to look for other signs of cancer. If your doctor thinks you might have cancer, they will arrange for you to have further tests.

Further tests

To diagnose most cancers, doctors will need to remove a sample of tissue from the affected area and have the cells examined under a microscope by a pathologist. This is called a biopsy.

For blood cancers such as leukaemia and lymphoma, and some other cancers, you will have blood tests to measure your blood count, tumour markers (chemicals produced by cancer cells) and to check if you have an infection. You may also have a urine test to check for blood and bacteria.

If tests show that you may have cancer, you may have an ultrasound, endoscopy or CT, PET and MRI scans to learn more about the cancer, whether it has spread and plan treatment.


Understanding Rare and Less Common Cancers

Download our Understanding Rare and Less Common Cancers booklet to learn more

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Expert content reviewers:

Dr Dani Bullen, Clinical Psychologist, Peter MacCallum Cancer Centre, VIC; Sally Carveth, Cancer Support Consultant, Cancer Council NSW; Tracey Gardner, Senior Psychologist, Cancer Council Queensland, QLD; Dr Anna Hughes, Liaison Psychiatrist and Senior Staff Specialist, Canberra Health Services, ACT Health, ACT; Caitriona Nienaber, 13 11 20 Consultant, Cancer Council WA; Wayne Reynolds, Consumer; Dr Charlotte Tottman, Clinical Psychologist, Allied Consultant Psychologists and Flinders University, SA; Ann Marie Weber, Consumer; Shirley Witko, Senior Social Worker, Sir Charles Gairdner Hospital, WA. 

Page last updated:

The information on this webpage was adapted from Understanding Rare and Less Common Cancers - A guide for people with cancer, their families and friends (2021 edition). This webpage was last updated in September 2021. 

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