Cancer

Common and Rare Types of Cancer

Cancer Types

Cancer isn't a single disease, but rather a collection of over 200 different diseases. As such, it is difficult to talk about cancer without understanding the specific type of cancer someone has developed. There are several ways in which cancers are categorized. Understanding how cancers are named and classified may help you better understand some of the foreign sounding terms used when talking about these concerns.

Classification of Cancer Types

Some of the ways cancers are separated into different groups include:

  • By the type of cell or tissue where the cancer began
  • By the organ or organ system where the cancer originated

Cancers may also be referred to as "solid" or blood-related cancers. Blood-related cancers include leukemias, lymphomas, and myelomas, while solid cancers include all other cancers. Other distinguishing characteristics of tumors are discussed below.

Primary Cancer and Metastases

An often confusing point in discussing cancer types occurs when a cancer spreads (metastasizes) to another region of the body. When a cancer spreads, it is named for the type of cancer cell or organ in which it began, not for the region of the body where it spreads. This is the primary cancer.

For example, if breast cancer begins in the breast and later spreads to the lung it would not be called lung cancer. Instead, it would be referred to as "primary breast cancer metastatic to the lungs." In this example, breast cancer would be the primary cancer and the lungs would be the site of metastasis.

Rarely, doctors are unable to determine where a cancer began but only find evidence of cancer where it has spread. This is referred to as an unknown primary or cancer of unknown origin with metastasis to the location where the cancer is discovered.

Benign vs. Malignant Tumors

Sometimes it can be difficult to decide if a tumor is benign (non-cancerous) or malignant (cancerous). There are many differences between benign and malignant tumors, but the key difference is that malignant tumors can spread (metastasize) to other regions of the body. It is actually this spread of cancer via the bloodstream or lymphatic system that is responsible for most deaths from cancer. To make this more confusing, tumors often contain a mixture of cells including normal cells, precancerous cells, and cancer cells.

There are many differences between cancer cells and normal cells that account for the behavior of cancers. Cancer cells lack "sticky" substances called adhesion molecules which hold cells together in the organ where they belong.

Cancer cells also fail to follow the "normal" rules of cell growth, multiplying and dividing when they should not, and failing to die off when they should.

A rule of thumb (with exceptions) for knowing if a tumor is benign or malignant based on its name is that malignant tumors usually include the name of the particular cell type in which it began. For example, a benign bone tumor might be called an osteoma, but a malignant tumor, an osteosarcoma. Likewise, an angioma refers to a benign tumor of blood vessels, whereas an angiosarcoma signifies a cancer of blood vessel tissue. One of the exceptions is melanoma, which is a cancerous tumor of cells called melanocytes. More on this next.

Cancers by Cell or Tissue Type

The name for many cancers derives from the type of cells in which cancer begins. Understanding these basic cell types can be very helpful if you have been diagnosed with cancer. For example, you may have been told you have kidney cancer, but kidney cancers can differ significantly based on the type of kidney cell in which these tumors start.

There are six major types of cancer based on cell type:

  • Carcinomas
  • Sarcomas
  • Myelomas
  • Leukemias
  • Lymphomas
  • Mixed types (including blastomas)

Carcinomas

Carcinomas are the most common cell type of cancer, accounting for 80 percent to 90 percent of cancers. These cancers arise in cells called epithelial cells. Epithelial cells include the cells of the skin and those that line body cavities and cover organs. Carcinomas may be further broken down into:

  • Adenocarcinomas: Adenocarcinomas begin in glandular cells that manufacture fluids, such as breast milk.
  • Squamous cell carcinomas: Examples of squamous cells include those in the top layer of the skin, the upper portion of the esophagus and airways, and the lower portion of the cervix and vagina.
  • Basal cell carcinomas: Basal cells are only present in the skin and are the deepest layer of skin cells.
  • Transitional cell carcinomas: Transitional cells are epithelial cells that are "stretchy" and are present in the bladder and parts of the kidney.

In addition to these more specific cell types, carcinomas may be named based on their location.

For example, breast carcinomas that arise in the mild ducts would be referred to as ductal carcinomas, whereas those that arise in the lobules are considered lobular carcinomas.

Carcinomas are the only cancer cell type that have a noninvasive phase, and therefore are the only cancers for which screening is routinely done. Cancers that are still "contained" and have not spread through the basement membrane are referred to as carcinoma in situ or CIN. Cancer detected at this early, pre-invasive stage should, theoretically, be completely cured with removal.

Sarcomas

Sarcomas are cancers of the bone and soft tissues of the body that are made up of cells called mesenchymal cells. These include cancers of the bone, muscles (both skeletal and smooth muscle), tendons, ligaments, cartilage, blood vessels, nerves, synovial tissues (joint tissues), and fatty tissues. Examples of sarcomas include:

  • Osteosarcoma (bone cancers): Osteocytes are bone cells.
  • Chondrosarcoma (cartilage cancers): Cartilage cells are called chondroblasts.
  • Liposarcoma (fatty tissue cancers)
  • Rhabdomyosarcoma (skeletal muscle cancers)
  • Leiomyosarcoma (smooth muscle cancers)
  • Angiosarcoma (blood vessel cancers)
  • Mesothelioma (cancers of the mesothelium, the tissues that line the chest and abdominal cavities)
  • Fibrosarcoma (cancers of fibrous tissues)
  • Glioma and astrocytoma (cells of the connective tissue in the brain)

Myelomas

Myeloma, also called multiple myeloma, is a cancer of cells in the immune system known as plasma cells. Plasma cells are the cells that manufacture antibodies.

Leukemias

Leukemias are cancers of the blood cells, and they originate in the bone marrow. Among blood-related cancers, leukemias are considered "liquid cancers" in contrast to myelomas and lymphomas. Since these cancers involve cells that circulate in the blood stream, they are often treated like solid cancers that have spread  Examples include:

  • Acute lymphocytic leukemias (ALL): These are cancers of white blood cells known as lymphocytes.
  • Chronic lymphocytic leukemia (CLL)
  • Acute myelocytic leukemias (AML): These are cancers of mature or immature cells known as myelocytes, such as neutrophils.
  • Chronic myelocytic leukemia (CML)

Lymphomas

Lymphomas are cancers that arise from cells of the immune system. These cancers may arise in lymph nodes or from extranodal sites such as the spleen, stomach, or testicles. These are broken down into:

  • Hodgkin lymphoma
  • Non-Hodgkin lymphoma

Mixed Types

It's not uncommon for a cancer to have characteristics of more than one type of tissue. Cancer cells differ from normal cells in many ways, one of which is referred to as differentiation. Some cancers can look very much like the normal cells in which they originate (these are called "well-differentiated tumors"), yet others may bear little resemblance to them (you may see the term "undifferentiated" on a pathology report). In addition to this, most tumors are "heterogeneous." This means that the cells in one part of a tumor may look very different from cells in another part of a tumor. For example, a lung cancer may have some cells that look like adenocarcinoma and others that appear to be squamous cell carcinoma. This would be described in a pathology report as having "adenosquamous" features.

A tissue type of cancer that is sometimes separated out is blastomas. These are cancers that occur in embryonic cells—cells that have not yet chosen a path to become epithelial cells or mesenchymal cells.

Cancers by Organ Systems From Head to Toe

Cancers are also often separated by the organs or organ systems in which they arise. Categorized in this way, some cancer include:

Central Nervous System Cancers

Central nervous system cancers include those that originate in tissues of either the brain or the spinal cord. Cancers that spread to the brain are not considered brain cancers, but rather brain metastases, and are seven times more common than primary brain cancers. Unlike tumors in other regions of the body, brain cancers do not often spread outside of the brain. Cancers that commonly spread to the brain include lung cancer, breast cancer, and melanoma. Overall, the incidence of brain cancer has been increasing in recent years.

Head and Neck Cancers

Head and neck cancers can affect any region of the head and neck from the tongue to the vocal cords. In the past, these cancers were most commonly seen in people who were both heavy drinkers and smokers. In recent years, however, human papillomavirus (HPV) has become an important cause of these cancers, with close to 10,000 people developing HPV-related head and neck cancers each year in the United States alone. Two such cancers are:

  • Oral cancer: Roughly 85 percent of head and neck cancers are oral cancers. These cancers may involve the mouth, the tongue, the tonsils, the throat (the pharynx), and the nasal passageways.
  • Laryngeal cancer: (cancer of the vocal cords)

Breast Cancers

Many people are aware that breast cancer is an all-too-common cancer in women, but it's important to point out that men get breast cancer also. Approximately 1 in 100 breast cancers occur in men. The most common type of breast cancer is ductal carcinoma.

Since most breast cancers are carcinomas, they may sometimes be detected before they have become invasive. This is considered "carcinoma in situ" or stage 0 breast cancer. Breast cancer stages 1 through 4 are invasive stages of the disease. You may hear these more specific names:

  • Ductal carcinoma in situ of the breast and lobular carcinoma in situ: Carcinoma in situ is the earliest stage at which breast cancer can be detected and is considered stage 0. These cancers have not yet penetrated through the basement membrane and are considered non-invasive. They are most often detected when a biopsy is done for an abnormality on a screening mammogram.
  • Invasive (infiltrating) breast cancer (both ductal and lobular): Once a breast cancer penetrates through the basement membrane, it is considered invasive. It can be frightening to hear that you have an "invasive" cancer, but this does not mean that your cancer has spread. As noted above, even stage 1 is referred to as "invasive" breast cancer based on the appearance of the tumor under a microscope.
  • Inflammatory breast cancer: Inflammatory breast cancer, in contrast to other breast cancers, does not usually present as a lump. Rather, the early stages of the disease look like a redness and rash on the breast.
  • Male breast cancer: Again, breast cancer does occur in men. When it does, it is more likely that there is a genetic component, and a family history of breast cancer in men in your family should prompt a discussion with your doctor.

Respiratory Cancers

Cancers of the lung and bronchial tubes are the leading cause of cancer deaths in both men and women in the United States. While smoking is a risk factor for these diseases, lung cancer occurs in never-smokers as well. In fact, lung cancer in these individuals is the sixth leading cause of cancer deaths in the United States. Lung cancer is decreasing overall, likely related to a decrease in smoking, but is increasing in young adults, especially young, never-smoking woman. The reason is not understood at this time. Types you may hear about:

  • Non-small cell lung cancer: Subtypes of non-small cell lung cancer (responsible for around 85 percent of lung cancers) include lung adenocarcinoma, squamous cell carcinoma of the lungs, and large cell lung cancer.
  • Small cell lung cancer: Small cell lung cancer accounts for around 15 percent of lung cancers and is more likely to occur in people who have smoked.
  • Mesothelioma: Mesothelioma is a cancer of the pleural mesothelium—the lining surrounding the lungs. It is strongly linked with exposure to asbestos.

Digestive System Cancers

Digestive tract cancers may occur anywhere from the mouth to the anus. Most of these cancers are adenocarcinomas, with squamous cell carcinomas occurring in the upper esophagus and most distant portion of the anus. Types include:

  • Esophageal cancer: The most common form of esophageal cancer has changed in recent years. Whereas squamous cell esophageal cancer (often related to smoking and drinking) was once the most common form of the disease, esophageal adenocarcinoma (often related to long-standing acid reflux) is the most common type today.
  • Stomach cancer: Stomach cancer is uncommon in the United States, but is a common type of cancer worldwide.
  • Pancreatic cancer: Pancreatic cancer is less common than some other cancers, but is the fourth most common cause of cancer-related deaths in both men and women. It is most often diagnosed in the later stages of the disease when surgery is no longer possible.
  • Liver cancer: Primary liver cancer is fairly uncommon, with cancer metastatic to the liver being much more common. Risk factors for liver cancer include alcohol abuse and chronic infections with hepatitis B or C.
  • Colon cancer: Colon cancer is often referred to as colorectal cancer and includes both cancers of the rectum and the upper colon. It is the third leading cause of cancer deaths in both men and women.
  • Anal cancer: Anal cancer differs from colon cancer both in treatments and causes. Infection with HPV now causes the majority of anal cancers.

Cancers of the Genitourinary System

The genitourinary system involves the kidneys, the bladder, the tubes connecting the kidneys and bladder (called the ureters), and the urethra (the passageway out from the bladder). This system also includes structures such as the prostate gland. Types include:

  • Kidney cancer: The most common types of kidney cancer include renal cell carcinoma (around 90 percent of cases), transitional cell carcinoma, and Wilms' tumor in children.
  • Bladder cancer: Roughly half of bladder cancers are caused by tobacco exposure. Those who work with dyes (ink) are at a higher risk.
  • Prostate cancer: Prostate is the second leading cause of cancer death in men, but now has a very high five-year survival rate.

Reproductive System Cancers

Reproductive organ cancers may occur in men and women. Ovarian cancer is the fifth most common cause of cancer deaths in women, and though curable in the early stages, is often diagnosed when it has already spread. Types include:

Endocrine Cancers

Most endocrine cancers, with the exception of thyroid cancer, are fairly rare. The endocrine system is a series of glands that produce hormones and, as such, may have symptoms of an over- or underproduction of these hormones. A combination of different endocrine cancers may run in families and is referred to as MEN, which stands for multiple endocrine neoplasia.

  • Thyroid cancer: The incidence of thyroid cancer is increasing the United States more than any other cancer. Thankfully, the survival rate for many of these cancers is high as well.

Bone and Soft Tissue Cancers

As noted above, cancers may occur in bones as well as soft tissues of the body such as muscles, ligaments, fibrous tissue, and even blood vessels. In contrast to primary bone and soft tissue cancers, which are uncommon, cancer that is metastatic to bone is common. Bone cancer, either primary or metastatic, often presents with symptoms of pain or of a pathologic fracture—a  fracture that occurs in a bone that is weakened by the presence of tumor. Types include:

Blood-related cancers

Blood-related cancers include both those involving blood cells and those involving solid tissue of the immune system, such as lymph nodes.The risk factors for blood-related cancers differ somewhat from solid cancers in that environmental exposures as well viruses (such as the Epstein-Barr virus, which causes mononucleosis) play a significant role. These are the most common cancers in children.

Skin Cancers

Skin cancers are often separated into primary groups: melanoma and non-melanoma skin cancers. While non-melanoma skin cancers are much more common, melanomas are responsible for most skin cancer deaths.

Other Ways in Which Cancers Are Classified

In addition to dividing cancers by cell types and organs, tumors are often classified in other ways as well. 

  • By the grade of the tumor: Grade is a measure of the aggressiveness of a tumor. A grade 1 tumor is less aggressive and the cells may closely resemble normal cells in which the cancer began. A grade 3 tumor, in contrast, is usually more aggressive, and the cells look very different than normal cells.
     
  • By the stage of the tumor: Tumors are staged in different ways, but many are given a number between 1 and 4, with 4 being the most advanced stage of the cancer.
     
  • Non-hereditary cancer vs hereditary cancerSome cancers are referred to as hereditary cancers. For example, around 10 percent of breast cancers are referred to as "hereditary breast cancer." There is much overlap, and genetics play a role in many cancers.
     
  • DNA/molecular profiles: As our understanding of genetics improves, tumors are more frequently being classified as to their particular genetic profile. For example, some lung cancers have EGFR mutations and other have ALK rearrangements.

Most Common Cancers

Take a moment to review the 10 most fatal cancers in men as well as the 10 most fatal cancers in women. An awareness of the early signs and symptoms of these diseases is important in order to catch these cancers as early as possible. Make sure to talk to your doctor about any risk factors you have for cancer and your family history of the disease, and discuss any screening tests she would recommend.

Rare Cancers

There are many cancers that are considered uncommon or rare—some  occurring in only a few people each year. These can range from rare types of ovarian cancer to rare skin cancers. It can be lonely if you are diagnosed with these cancers, but it's important to remember that research on the more common cancers is opening up treatments for people with less common cancers as well.

We know that experience can make a difference in health care. If you are diagnosed with a rare cancer, it may be worth asking for a second opinion at one of the large National Cancer Institute-designated cancer centers. These larger centers are more likely to have oncologists on staff who take a special interest in less common—but no less important—cancers. 

Causes, Symptoms, and Treatment of Different Types of Cancer

There are many different causes and risk factors for cancer, and some of these causes are more important with regard to specific types of cancer. For example, exposure to asbestos appears to be the causative factor in the majority of people with mesothelioma. While you may know that breast cancer may have a hereditary component, this can be the case with many other cancers too. For example, over 50 percent of melanomas are considered to have a genetic component. 

For most cancers, we do not yet have a screening test that can be used to find them in the earliest stages. At the same time, it's thought that cancers are most curable in these earlier stages. What this means is that having an awareness of the most common symptoms of cancer is critically important in taking care of your health.

The best treatments for cancer depend on your exact type of cancer and how far it has progressed. Learn more by exploring Verywell's dedicated section: Cancer Treatments.

A Word From Verywell

There are many cancers in addition to those mentioned here, and, as noted, there is sometimes significant overlap. With our increased understanding of genetics, it's likely that our classification of cancers will improve significantly in the next several years. It's important to understand that even with the same type and subtype of cancer, it is hard to know exactly how someone will do with treatment. If there were 200 people with breast cancer in a room, they would have 200 unique types of breast cancer from a molecular standpoint.

The statistics about cancer can be frightening: one in two men and one in three women are expected to develop cancer during their lifetime, not including skin cancer. While those are scary numbers, educating yourself about cancer raises the chance that you will find a cancer in the earlier more curable stages of the disease. That said, even if a cancer is not curable, it is almost always treatable, and both the treatments for, and survival from, cancer have been improving in recent years. More people are living—and thriving—with cancer than ever before.

Sources:

Centers for Disease Control and Prevention (CDC). Statistics for Different Kinds of Cancer. Updated 06/16/16. http://www.cdc.gov/cancer/dcpc/data/types.htm

Louis, D., Perry, A., Reifenberger, G. et al. The 2016 World Health Organization Classification of Tumors of the Central Nervous System: A Summary. Acta Neuropathologica. 2016. 131(6):803-20.

National Institute of Health. SEER Training Module. Cancer Classification. 2016. http://training.seer.cancer.gov/disease/categories/classification.html

Song, Q., Merajver, S., and J. Li. Cancer Classification in the Genomic Era: Five Contemporary Problems. Human Genomics. 2015. 9:27.

World Health Organization. International Classification of Diseases for Oncology, 3rd Edition (ICD-O-3). Updated 10/05/15. http://www.who.int/classifications/icd/adaptations/oncology/en/

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