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Rare Cancers, Cancer Subtypes, and Precancers

It can be hard to find information about rare cancers and precancers, especially when they have more than one name. The list below has links to more information on many rare cancers. You’ll also learn about finding clinical trials of newer treatments for rare cancers.

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What is a rare cancer?

A rare cancer is any cancer that only happens in a very small number of people compared to other cancers.

The National Cancer Institute defines a rare cancer as one that affects fewer than 15 out of 100,000 people per year. In other words, this is less than roughly 52,000 people diagnosed each year in the US.

Many types of cancer are rare.

Why information might be hard to find

Some cancers are so rare that only a small number of people are diagnosed with them each year. Clinical trials are the main way doctors learn how to treat any cancer. But because so few people have these rare cancers, they might not have been studied in clinical trials.

As a result, doctors and researchers don’t know much about these rare cancers. There is less information available, and that information might be harder to find.

Instead, much of the information about these cancers comes from case studies. In a case study, doctors share the experience of one patient so others can learn from it.

For help finding information on these cancers, see the links included in the rare cancers list below.

Where to get treatment for a rare cancer

Some doctors might never have taken care of anyone with your type of rare cancer. You might need to travel to find a doctor or cancer center that has experience treating it. Larger cancer centers or hospitals are also more likely to have clinical trials you might be able to take part in.

To learn more about deciding where to get treatment, see Choosing a Cancer Center or Hospital and Choosing a Cancer Doctor.

What is the difference between a rare cancer, a cancer subtype, and a precancer?

The information on this page includes rare cancers as well as cancer subtypes and precancers. These are terms used to describe different conditions.

  • A rare cancer is a cancer that only happens in a small number of people.
  • A cancer subtype is a specific kind of a more common cancer. For example, inflammatory breast cancer is a rare subtype of breast cancer that causes different symptoms. A cancer subtype can have features that are different from its more common counterpart. It might also be treated differently.
  • Precancers are groups of cells with abnormal features. They are not cancer, but they might lead to cancer in the future. Some precancers might be treated, while others might not.

It can be hard to find information about some cancer subtypes and precancers. Many of these are included in the rare cancers list below, along with links to more information.

How to find clinical trials for rare cancers

Clinical trials can sometimes help people with rare cancers to get access to newer treatments. They can be helpful at any point during your cancer care journey. They can also help doctors learn more about rare cancers. There are several steps you can take to help find a clinical trial for a rare cancer.

Look for a cancer center that studies your cancer

​Larger cancer centers or hospitals are more likely to have clinical trials you might be able to take part in. ACS has information that can help you choose a cancer center or hospital or choose a cancer doctor.

Ask about biomarker testing

Sometimes clinical trials enroll people with many different types of cancers that share certain gene changes or other specific features. Getting biomarker testing might help you find out if you are a candidate for these types of trials. Ask your healthcare team if biomarker testing could be right for you.

Search the National Institutes of Health database

The National Institutes of Health lists the clinical trials taking place in the United States. You can search this database at clinicaltrials.gov.

Use a clinical trials matching service

Matching services like ACS ACTS (Access to Clinical Trials & Support) help people with cancer find clinical trials that might work for them.

ACS Acts patient talks to provider in room

ACS ACTS: Access to Clinical Trials and Support

We understand the challenges of finding the right clinical trial and navigating your treatment options. ACS ACTS is here to empower you every step of the way, from clinical trials matching to connecting you with community resources.

Learn More About ACS ACTS

List of rare cancers, cancer subtypes, and precancers

This list includes rare cancers and precancerous conditions, as well as where to find more information about them. The list also includes some other conditions that are not cancer but are related to cancer in some way.

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A

B

C

D

  • Dermatofibrosarcoma protuberans: A type of soft tissue tumor that starts in the deep layers of the skin.
  • Desmoid tumor (aggressive fibromatosis; desmoid fibromatosis): A type of locally invasive soft tissue tumor.
  • Desmoplastic small round cell tumor: A type of soft tissue sarcoma.
  • Dysgerminoma: A subtype of germ cell tumor that starts in the ovaries.

E

F

G

H

I

J

None listed.

K

L

M

N

  • NUT carcinoma (NUT midline carcinoma): A type of cancer that can grow anywhere in the body. See the National Cancer Institute.

O

P

R

S

T

U

V

W, X

None listed.

Y, Z

  • Yolk sac tumor (endodermal sinus tumor; infantile embryonal cancer): A subtype of germ cell tumor that most often starts in the ovaries or testicles.

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More resources

You may be able to find more information on your rare cancer, cancer subtype, or precancer at:

Are There Clinical Trials for Rare Cancers?

Some rare cancers may have genetic changes that are being studied in clinical trials. Learn more about these trials and who’s eligible for them.
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The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

Last Revised: November 10, 2026

American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.

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