Rare cancers are those that affect fewer than 40,000 people per year in the U.S. As a group, they make up just over a quarter of all cancers. Because rates of cancer in children are very low, all children’s cancers are considered rare. A quarter of all cancer deaths each year are due to rare cancers. Although new treatments are always being developed, finding new treatments for rare cancers is very hard for many reasons. The MyPART network was started to make it easier to find treatments for rare cancers.

Why are rare cancers challenging?

Rare cancers are challenging for patients, doctors, and scientists.

For patients:

• It often takes a long time from the time you think something is wrong to the time when doctors know that you have a rare cancer and what kind of cancer it is.
• It is hard to find doctors who know a lot about your cancer and how to treat it.
• It is hard to know what to do when doctors don’t agree on how to treat your cancer.
• You may need to travel far from your home and family to get treatment for your rare cancer.

For doctors:

• You may not know what to tell your patient about what to expect with their rare cancer.
• You may not have been trained in how to treat this type of rare cancer.
• It is hard to find an expert in the rare cancer who can answer questions or to whom you can refer your patient.

For scientists:

• There may be no information about the rare cancer to give you ideas on which drugs could treat it.
• There may be no animal or cell models of the rare cancer in which to test your ideas.
• There may not be enough tumor samples from rare cancer patients available for your research.
• If you have an idea of a drug that could treat the cancer, it may be hard to find enough patients with the rare cancer to test your idea.

Rare cancers of childhood are cancers not usually seen in children.

Cancer in children and adolescents is rare. Since 1975, the number of new cases of childhood cancer has slowly increased. Since 1975, the number of deaths from childhood cancer has decreased by more than half.

The cancers listed in this summary are so rare that most children's hospitals are likely to see less than a handful of some types in several years. Because these cancers are so rare, there is not a lot of information about what treatment works best. A child's treatment is often based on what has been learned from treating other children. Sometimes, information is available only from reports of the diagnosis, treatment, and follow-up of one child or a small group of children who were given the same type of treatment.

Many different cancers are listed in this summary. They are grouped by where they are found in the body.

Rare bone tumors include bone cancer and cartilage cancer. They can be called by different names depending on where they are in the body. For example, a chordoma tumor that forms at the skull base might be called a clival tumor, and one that forms near the tailbone might be called a sacral tumor.

Some of the rare bone tumors that affect children, adolescents, and young adults are:

• Adamantinoma
• Chordoma
• Chondromyxoid fibroma
• Periosteal osteosarcoma

Adamantinoma is a rare bone cancer. Most of the time, adamantinoma grows in the lower leg. It often starts as a lump in the middle of the shinbone (tibia) or the calf bone (fibula). Adamantinoma can also occur in the jaw bone (mandible) or, sometimes, the forearm, hands, or feet. An adamantinoma lump can be painful, swollen and red, and can cause movement problems.

Adamantinoma is a serious condition. Treatment is important for survival but it is possible to make a full recovery.

Chondromyxoid fibroma, or CMF, is a tumor of the cartilage found between your bones. Cartilage is a rubber-like tissue that cushions and protects the ends of your bones, sits in between the disks in your spine, and makes up the ear and nose.

CMF tumors are benign, which means they are not cancer. While the cells of the CMF tumor do not travel to other parts of the body like cancer can, they can invade nearby tissues and can be painful and cause other symptoms.

Chordoma is a slow growing cancer of tissue found inside the spine. Chordoma can happen anywhere along the spine. It is most often found near the tailbone (called a sacral tumor) or where the spine meets the skull (called a clival tumor). Chordoma is also called notochordal sarcoma.

Chordomas form from the left-over cells that were important in the development of the spine before birth. These cells are called notochord cells. When the notochord cells don’t disappear after birth, they can turn into chordomas.

Chordomas grow very slowly. Many people don’t notice any change in their bodies for years. When they do start to have symptoms, it can take a while for the chordoma to be discovered and diagnosed.

Most people are diagnosed with chordoma in their 50s and 60s. Pediatric chordomas make up 5% of all chordoma diagnoses. Females are diagnosed slightly more often than males in childhood. Males are more often diagnosed as adults.

Periosteal osteosarcoma, or PO, is a rare type of bone cancer. It usually forms on the surface of bones of the legs called the tibia and femur. It also can form on the surface of bones in the arms called the ulna and the humerus.

Rare digestive system tumors form in organs that are important for digesting food and drinks. These organs include your esophagus, stomach, intestines, liver, and pancreas. The cancer may be named by the organ (liver cancer or stomach cancer) or by the type of cell it looks like (neuroendocrine, squamous cell, or stromal cell).

Some of the rare digestive system tumors that affect children, teens, and young adults are:

• Appendiceal cancer
• Cholangiocarcinoma
• Esophageal cancer
• Fibrolamellar hepatocellular carcinoma
• Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS)
• Hereditary diffuse gastric cancer (HDGC)
• SDH-deficient gastrointestinal stromal tumor (GIST)

Appendiceal cancer is a type of cancer that grows from cells that make up the appendix. The appendix is a small pouch of tissue in the abdomen. It is part of the intestines and colon, which absorb nutrients and remove waste from the body. We do not know what the appendix does, but it may help the immune system. There are two main types of appendiceal cancer: epithelial appendiceal cancer and neuroendocrine appendiceal cancer.

Epithelial appendiceal cancer grows from cells that make up the lining of the appendix. It may also be called adenocarcinoma. These cells help make a jelly-like substance called mucin. Mucin protects the lining of the stomach, intestines, and appendix. Most epithelial appendiceal cancers can lead to a build-up of mucin, which can cause the appendix to rupture. When mucin from the appendix builds up in the abdomen, it causes a condition called pseudomyxoma peritonei, or PMP.

Mucinous neoplasms are a rare and complex type of epithelial appendiceal cancer. Depending on how the cells look under a microscope they may be low grade (LAMN) or high grade (HAMN) and may spread to other parts of the body.

Neuroendocrine tumors of the appendix, grow from cells called enterochromaffin cells (ECs). ECs make chemicals involved in digestion and movement in the intestines. Neuroendocrine tumors of the appendix are the most common type of appendiceal cancer. They are also called carcinoid tumors.

Appendiceal cancer can spread to different parts of the abdomen directly from the appendix, usually when it ruptures. Less often, appendiceal cancer can spread through lymph nodes to areas outside the abdomen.

Cholangiocarcinoma (CCA), or bile duct cancer, is a type of rare cancer that grows in the small tubes that carry bile, a fluid that helps with digestion. These tubes are called the bile ducts. The bile ducts connect the liver to the gall bladder and small intestine.

There are three types of cholangiocarcinoma that are named for where they grow in the bile ducts:

• Intrahepatic cholangiocarcinoma grows in the parts of the bile ducts that are in the liver. This is the least common form of cholangiocarcinoma and accounts for only 10% of all cases.
• Hilar cholangiocarcinoma grows in the bile ducts right outside of the liver. It is also called perihilar cholangiocarcinoma.
• Distal cholangiocarcinoma grows in the parts of the bile ducts near the small intestine.

Sometimes, hilar cholangiocarcinoma and distal cholangiocarcinoma are grouped together and called extrahepatic cholangiocarcinoma.

Esophageal cancer is a type of rare cancer that grows in the esophagus. The esophagus is the hollow tube that connects your throat to your stomach and moves food and liquids from your mouth to the stomach. It is part of the digestive system. The two most common types of esophageal cancer are adenocarcinoma and squamous cell carcinoma.

Esophageal adenocarcinoma forms in the glandular cells. These cells are in the lining of the esophagus and make fluids, such as mucus. Esophageal squamous cell carcinoma forms in the squamous cells in the esophagus.

Fibrolamellar carcinoma, or FLC, is a rare cancer of the liver that usually grows in teens and adults under 40 years old. This type of cancer is different than other types of liver cancer because it happens in people who have healthy livers. Other liver cancers tend to grow in people with livers that have been damaged by alcohol abuse or infection with certain viruses. Fibrolamellar carcinoma may be called by many different names, including eosinophilic glassy cell hepatoma, fibrolamellar oncocytic hepatoma, fibrolamellar hepatocellular carcinoma (FLHCC) or FHCC.

GAPPS is a disease that affects the stomach, which is the organ that helps digest food. GAPPS causes many small bumps, called polyps, to form on the inside lining of the stomach. Polyps can be benign, meaning they cannot spread to other parts of the body. Polyps can also turn into cancer, meaning they can spread to other parts of the body.

GAPPS can be difficult to diagnose because polyps often do not cause any symptoms. Polyps can also be caused by more common diseases too. GAPPS is different than other types of stomach cancer because it grows in a specific part of the stomach. GAPPS is a newly discovered type of hereditary gastric cancer syndrome, which means this disease runs in families.

Hereditary diffuse gastric cancer, or HDGC, is a type of rare cancer that grows in the stomach, which is the organ that helps digest food. HDGC usually grows in more than one area of the stomach, so it can be difficult to detect and treat. It can grow quickly and can spread to other parts of the body.

This type of stomach cancer is caused by a genetic condition, which means parents can pass it on to their children. Having HDGC also increases the risk of getting other types of cancer, such as breast cancer.

SDH-deficient gastrointestinal stromal tumor, or SDH-deficient GIST, is a type of digestive tract cancer. It almost always grows in the stomach or small intestine, but sometimes in the large intestine. GISTs are “SDH-deficient” 5% to 7.5% of the time and usually grow only in the stomach. SDH is short for succinate dehydrogenase, a protein that is important for making energy for your body. Most people with SDH-deficient GISTs are children and some young adults.

People with SDH-deficient GIST are at higher risk for other types of cancer. They are at risk for pulmonary chondromas, a benign tumor in the lung, and paragangliomas, a rare tumor that grows in the nerve cell and can occur anywhere in the body.

Rare endocrine tumors form in glands or in cells that produce hormones. These include your thyroid, adrenal, and pituitary glands, and cells in your pancreas. Endocrine tumors can be called by different names depending on where they are in the body or what type of cell they look like.

Some of the rare endocrine tumors that affect children, teens, and young adults are:

• Adrenocortical carcinoma
• Anaplastic thyroid cancer
• Medullary thyroid cancer
• Paraganglioma
• Pheochromocytoma

Adrenocortical carcinoma, or ACC, is a cancer of the adrenal glands, which are two small triangular-shaped glands that sit on top of each kidney. The outside of these glands is called the adrenal cortex. The adrenal cortex makes important hormones that help your body control water balance, blood pressure, stress response, and cause the body to have male or female traits. ACCs form in the adrenal cortex.

An ACC may be functioning, which means it makes more hormone than normal, or non-functioning, which means it has no effect on hormone production. A functioning ACC tumor often makes too much of the hormones cortisol, aldosterone, testosterone, or estrogen.

Anaplastic thyroid cancer, or ATC, is a type of thyroid cancer. The thyroid is a gland located in the front of your neck, just below the Adam’s apple. It is responsible for sending out hormones to the rest of your body. ATC is different than other types of thyroid cancers because ATC invades other parts of the body very quickly. This type of cancer usually affects people over the age of 60. ATC can also be called anaplastic thyroid carcinoma.

Carcinoid tumor is a type of neuroendocrine tumor that grows from neuroendocrine cells. Neuroendocrine cells receive and send messages through hormones to help the body function. Neuroendocrine cells are found in organs throughout the body.

Carcinoid tumors often grow very slowly. In children and young adults, carcinoid tumors are most often found in the appendix, called appendiceal carcinoid tumors, or in the lungs, called bronchial tumors. In adults, carcinoid tumors are most often found in the digestive tract. This tumor may spread to other parts of the body but does so more often in adults than children.

Medullary thyroid cancer, or MTC, is a cancer that forms in the thyroid. The thyroid is a gland located in the front of your neck, just below the Adam’s apple. It is responsible for sending out hormones to the rest of your body. The inside of the thyroid is called the medulla. The medulla contains special cells called parafollicular C cells that produce and release hormones. MTC happens when the C cells become cancerous and grow out of control. MTC may also be called medullary thyroid carcinoma.

Paraganglioma is a type of neuroendocrine tumor that forms near certain blood vessels and nerves outside of the adrenal glands. The adrenal glands are important for making hormones that control many functions in the body and are located on top of the kidneys. The nerve cells involved in paraganglioma are part of the peripheral nervous system, meaning the part of the nervous system outside of the brain and spinal cord. These tumors can also be called extra-adrenal pheochromocytomas.

Approximately 35-50% of paragangliomas may spread to other parts of the body.

Pheochromocytoma is a type of neuroendocrine tumor that grows from cells called chromaffin cells. These cells produce hormones needed for the body and are found in the adrenal glands. The adrenal glands are small organs located in the upper region of the abdomen on top of the kidneys. About 80-85% of pheochromocytomas grow in the inner layer of the adrenal gland, called the adrenal medulla. About 15-20% of pheochromocytomas grow outside of this area and are called extra-adrenal pheochromocytomas or paragangliomas.

Most pheochromocytomas are benign, which means they are not cancer and do not spread to other parts of the body. Only about 10% of pheochromocytomas spread to other parts of the body.

Rare kidney tumors are tumors that form in the kidneys. The kidneys are organs that clean the blood by removing waste products. There are many different types of kidney tumors. Kidney tumors are named after where they grow in the kidney or what kind of cells the tumor cells look like.

Some of the rare kidney tumors that affect children, teens, and young adults are:

• Papillary Renal Cell Carcinoma
• Clear Cell Renal Cell Carcinoma
• Translocation Renal Cell Carcinoma

Clear cell renal cell carcinoma, or ccRCC, is a type of kidney cancer. The kidneys are located on either side of the spine towards the lower back. The kidneys work by cleaning out waste products in the blood. Clear cell renal cell carcinoma is also called conventional renal cell carcinoma.

Clear cell renal cell carcinoma is named after how the tumor looks under the microscope. The cells in the tumor look clear, like bubbles.

Papillary renal cell carcinoma, or PRCC, is a type of kidney cancer. The kidneys work by removing waste products from the blood. Papillary renal cell carcinoma is a cancer of the tubes that filter those waste products from the blood. There are two types of papillary renal cell carcinoma. Type 1 is more common and grows slowly. Type 2 is more aggressive and grows more quickly.

Renal cell carcinoma is cancer that grows in the kidney. There are many different types of kidney cancer and translocation renal cell carcinoma is one subtype. Translocation renal cell carcinoma is also called Xp11.2 translocation renal cell carcinoma or TRCC. It was recognized as a type of kidney cancer in 2004. This type of cancer usually grows slowly. Patients usually do not experience symptoms.

This type of cancer is more common in children and young adults than adults. It is also slightly more common in females. However, adults with this type of cancer tend to have more aggressive or fast-growing cancer.

Rare soft tissue tumors form in the body’s soft tissues such as muscle, fat, tendons, ligaments, lymph and blood vessels, nerves, or other tissue that connects and supports the body. These cancers can develop anywhere but are found mostly in the arms, legs, chest, and abdomen. They can be called by different names depending on the tissue where they start and what they look like under the microscope.

Some of the rare soft tissue tumors that affect children, teens, and young adults are:

• Alveolar soft part sarcomas
• Clear cell sarcoma
• Desmoid tumor
• Desmoplastic small round cell tumors
• Extra-cranial rhabdoid tumor
• Infantile myofibromatosis
• Inflammatory myofibroblastic tumor
• Leiomyosarcoma
• Malignant peripheral nerve sheath tumor
• Myxoid/round cell liposarcoma
• NUT carcinoma
• Schwannoma
• Sclerosing Epithelioid Fibrosarcoma (SEF)
• Synovial sarcoma

Rare vascular tumors form in cells that make blood or lymph vessels. They can occur anywhere in the body, such as the skin, in the tissues below the skin, or in an organ. These tumors are named for the type of cells they look like and how they grow.

Some of the rare vascular tumors that affect children, teens, and young adults are:

• Angiosarcoma
• Epithelioid hemangioendothelioma