How many types of cancer are there?

Cancer

Cancer is not a single disease, but a collection of hundreds of different diseases. The diagnosis and treatment methods of different cancers, as well as the treatment effects on patients, are different. As cancer research goes deeper into the molecular level and diagnostic and treatment methods improve, even for the same type of cancer (such as non-small cell carcinoma), the treatment methods and treatment results of patients vary greatly due to differences in cancer staging, pathological grading, molecular typing, etc. We can say that each case of cancer is unique, with its own different characteristics such as genetic variation and growth and spread. The diversity of cancer is one of the fundamental reasons for the complexity of cancer diagnosis and treatment.

Therefore, it is basically meaningless to talk about any aspect of cancer (including diagnosis, treatment, patient survival, etc.) without knowing the specific type of cancer a person has. There are several ways to name and classify cancer, including classification based on its origin (cell, tissue, location), tumor grade, stage, molecular profile, etc. Knowing more about the classification of cancer can help us make better medical decisions and better deal with cancer.


Cancer is classified by cell or tissue type

Many cancers get their names from the type of cell in which the cancer starts, such as epithelial cells or squamous cells.

Here are some cancers that start in specific types of cells:

  • Carcinoma
  • Sarcoma
  • Myeloma
  • Leukemia
  • Lymphoma
  • Melanoma
  • Brain and spinal cord tumors
  • Germinoma
  • Mixed: such as carcinosarcoma

Different types of cells

Human body cells
Human body cells

1. Carcinomas

Carcinoma is the most common type of cancer, accounting for 80% to 90% of all cancer cases. This is why all cancers are called “cancers”. Carcinomas form from epithelial cells, which are cells that cover the inner and outer surfaces of the body. There are many types of epithelial cells, which tend to have a columnar shape when viewed under a microscope.

Different types of epithelial cells, and cancers that originate from different epithelial cell types have specific names:

  • Adenocarcinoma is a cancer that forms in glandular epithelial cells, the type of cells that produce fluid or mucus in the body. This tissue of epithelial cells, sometimes called glandular tissue, forms the lining of all glands in the body, including those in the breast, intestine, stomach, ovaries, and prostate. Most breast, colon, and prostate cancers are adenocarcinomas.
  • Squamous cell carcinoma is a type of cancer that forms from squamous cells, the epithelial cells that line the outer surface of the skin. Squamous cells also form the lining of many other organs, including the stomach, intestines, lungs, bladder, and kidneys. When squamous cells are viewed under a microscope, they look flat, like fish scales. Squamous cell carcinoma is sometimes called epidermoid carcinoma.
  • Transitional cell carcinoma is a cancer that forms in a type of epithelial cell (urothelial cells or transitional cells) called the transitional epithelium, or urothelium. This tissue, made up of many layers of epithelial cells, is “elastic” and can grow or shrink, and forms the lining of the bladder, ureters, part of the kidney (renal pelvis), and some other organs. Some cancers of the bladder, ureters, and kidneys are transitional cell carcinomas.
  • Basal cell carcinoma is a type of cancer that begins in the bottom layer of the epidermis (the stratum basale).

There are two main reasons why epithelial cancers account for 80%-90% of all cancers:

1. Epithelial tissue is found throughout the body, both inside and outside. Epithelial tissue acts as the body’s interface with the rest of the world. Our skin is made up of this tissue, which also forms the lining of our body’s cavities and major organs.

Epithelial tissue lines
Epithelial tissue lines

2. One of the main functions of epithelial tissue is protection. It is the first line of defense of the human body. Epithelial tissue is usually the first and most frequently exposed to external carcinogens and is susceptible to damage from various sources. Because they have the property of rapid replication. But if replication errors occur, they can cause cancer and other abnormalities.

Carcinogens that epithelial tissue comes into contact with include chemicals in tobacco (which irritate the lining of the lungs, esophagus, and stomach, causing lung cancer, esophageal cancer, and stomach cancer, etc.); they also include radiation, such as ultraviolet radiation from the sun that irritates the skin (skin cancer); and they also include viral infections (such as HPV viruses that infect the cervix and hepatitis viruses that infect the liver).

Cancer is the only type of cancer that has a non-invasive stage of development. Routine screening is designed to detect these types of cancer, which include lung cancer, colorectal cancer, breast cancer, cervical cancer, and prostate cancer. Cancer that remains “localized” and has not spread through the basement membrane is called carcinoma in situ. In theory, early-stage, pre-invasive cancer should be completely curable through resection. For cancer screening, read previous articles: In-depth analysis of the pros and cons of early screening for lung cancer , understand mammography (X-rays), ultrasound, and MRI, receive correct breast cancer screening and examinations , cervical cancer screening and early detection that women must know , and family inheritance, risk, prevention, and screening of colorectal cancer .

2. Sarcomas

Sarcomas are cancers of the bones and soft tissues of the body that are made up of cells called mesenchymal cells. These include cancers of bones, muscles (skeletal and smooth), tendons, ligaments, cartilage, blood vessels, nerves, synovial tissue (joint tissue), and fatty tissue. Sarcomas usually occur in young people.

Sarcomas are rare. They account for less than 1% of all cancers . There are two main types of sarcomas:

  • Osteosarcoma found in bones
  • Soft tissue sarcomas occur in other supporting soft tissues of the body, including muscles, tendons, fat, blood vessels, lymphatic vessels, nerves, and tissues around joints. The most common types of soft tissue sarcomas are Kaposi’s sarcoma, leiomyosarcoma, liposarcoma, malignant fibrous histiocytoma, and dermatofibrosarcoma protuberans.

For more information about sarcomas, read the articles Classification, Family History, Risk, Signs and Symptoms of Soft Tissue Sarcomas and Classification, Risk Factors, Diagnosis, Staging, and Treatment of Bone Tumors .

Some examples of sarcomas:

  • Osteosarcoma (originates in bone)
  • Chondrosarcoma (originates in cartilage)
  • Leiomyosarcoma (arising from smooth muscle)
  • Rhabdomyosarcoma (originates in skeletal muscle)
  • Mesothelioma or mesothelioma (originates in the membranous lining of body cavities)
  • Fibrosarcoma (originates from fibrous tissue)
  • Angiosarcoma, epithelioid hemangioendothelioma (arising from blood vessels)
  • Liposarcoma (originates in fat tissue)
  • Gliomas or astrocytomas (which originate in the nerve connective tissue in the brain)
  • Myxosarcoma (arising from primitive embryonic connective tissue)
  • Stromal or mixed mesodermal tumors (arising from mixed connective tissue types)

3. Myeloma

Myeloma, also known as multiple myeloma, begins as a cancer of cells in the immune system called plasma cells. Plasma cells are cells that make antibodies and some of the proteins in the blood. Abnormal plasma cells, called myeloma cells, build up in the bone marrow and form bone tumors throughout the body. Multiple myeloma is also called plasma cell myeloma and Kahler disease.

4. Leukemia

Leukemia (“liquid cancer” or “blood cancer”) is a cancer that begins in the blood-forming tissue of the bone marrow. The word “leukemia” means “white blood” in Greek, and leukemia is considered a “liquid cancer” that is different from myeloma and lymphoma and does not form solid tumors. The disease is often associated with an overproduction of immature white blood cells. Large numbers of abnormal white blood cells (leukemia cells) accumulate in the blood and bone marrow, crowding out normal blood cells. These immature white blood cells cannot perform their due functions, and low levels of normal blood cells can make it more difficult for the body to get oxygen to tissues, control bleeding, or fight infection. As a result, patients are often prone to infection. Leukemia can also affect red blood cells and may cause poor clotting and fatigue due to anemia.

There are four common types of leukemia, grouped according to how quickly the disease worsens (acute or chronic) and the type of blood cell in which the cancer starts (lymphoblastic or myeloid).

  • Lymphocytic leukemias: These are cancers of white blood cells called lymphocytes.
  • Myeloid leukemias: These are cancers of mature or immature cells, such as neutrophils.

Both lymphocytic and myeloid leukemias have forms that develop rapidly (acute leukemias) and forms that take longer to develop (chronic leukemias).

Leukemia is relatively rare, accounting for about 2% of all cancers.

5. Lymphoma

Lymphoma is a cancer that begins in the glands or nodes of the lymphatic system, starting in lymphocytes (T cells or B cells). The lymphatic system is a network of lymphatic vessels, lymph nodes, and lymphatic organs (especially the spleen, tonsils, and thymus) that purify body fluids and produce infection-fighting white blood cells, or lymphocytes. These disease-fighting white blood cells are part of the immune system.

In lymphoma, abnormal lymphocytes accumulate in the lymph nodes and lymph vessels, as well as in other organs. Unlike leukemia, which is often referred to as a “liquid cancer,” lymphoma is a “solid cancer.” Lymphomas may also occur in specific organs, such as the stomach, breast, or brain. These lymphomas are called extranodal lymphomas.

Lymphoma is divided into two categories: Hodgkin lymphoma and non-Hodgkin lymphoma. The diagnosis is based on the presence or absence of Reed-Sternberg cells.

  • Hodgkin lymphoma: People with this disease have abnormal lymphocytes called Reed Sternberg cells. These cells usually form from B cells.
  • Non-Hodgkin lymphoma: This is a group of cancers that start in lymphocytes. The cancer can grow quickly or slowly and can form from B cells or T cells.

Lymphoma is also relatively rare, accounting for about 3% of all cancers.

6. Melanoma

Melanoma is a cancer that starts in melanocytes, which are specialized cells that produce melanin (the pigment that gives skin its color). Most melanomas develop on the skin, but melanoma can also develop in other pigmented tissues, such as the eyes.

7. Brain and spinal cord tumors

There are different types of brain and spinal cord tumors. These tumors are named based on the type of cells they form in and where in the central nervous system the tumor originates. For example, astrocytomas begin in star-shaped brain cells called astrocytes, which help keep nerve cells healthy. Brain tumors can be benign (not cancer) or malignant (cancer).

8. Mixed

It is not uncommon for cancer to have characteristics of more than one tissue.

Cancer cells and normal cells are very different in many ways, one of which is called differentiation. Some cancers look a lot like the normal cells from which they originated (these are called well-differentiated tumors), while others bear little resemblance to the normal cells from which they originated (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 the tumor may look very different from the cells in another part. For example, a lung cancer may have some cells that look like adenocarcinoma and other cells that look like squamous cell carcinoma. This would be described on the pathology report as having adenosquamous features.

9. Other types of tumors

l) Germ cell tumors

Germ cell tumors are tumors that originate in the cells that produce sperm or eggs. These tumors can occur almost anywhere in the body and can be either benign or malignant.

These “germ cell” tumors include seminomas (dysgerminomas in women), choriocarcinomas, embryonal carcinomas, endodermal sinus tumors, and teratomas. Although all of these tumors are most commonly ovarian or testicular tumors, ovarian and testicular cancers also occur in extragonadal locations.

Another group of gonadal tumors arises from the connective tissue stroma. In males, these include Leydig cell tumors, and in females, granulosa-thecoma cell tumors, hilar cell tumors, and lipid cell tumors.

2) Neuroendocrine tumors

Neuroendocrine tumors form in cells that release hormones into the blood in response to signals from the nervous system. These tumors may cause higher than normal levels of hormones, resulting in many different symptoms. Neuroendocrine tumors may be benign or malignant.

3) Carcinoid

Carcinoids are a type of neuroendocrine tumor. They are slow-growing tumors that usually develop in the gastrointestinal system (most often in the rectum and small intestine). Carcinoids may spread to the liver or other sites, and they may secrete substances such as serotonin or prostaglandins, causing carcinoid syndrome.


Cancers are also often classified and named according to the body site/organ system in which they originate.

How cancer is classified by primary site/organ system

All mammals, including humans, have the same ten organ systems: digestive, respiratory, circulatory, urinary, nervous, muscular, skeletal, reproductive, endocrine, and integumentary. The same organ system has adjacent anatomical structures and/or similar biological characteristics, which is the reason why many different clinical internal and external surgery departments in modern medicine are set up , such as gastroenterology/liver surgery/pancreatic surgery/gastric surgery/colorectal surgery, respiratory/thoracic surgery, hematology, urology, neurosurgery/neurology, orthopedics, endocrinology, dermatology, etc.

If we classify cancer by its primary site, the top ten most common cancers we hear about are: lung cancer, breast cancer, stomach cancer, esophageal cancer, liver cancer, colorectal cancer, thyroid cancer, prostate cancer, cervical cancer, ovarian cancer, etc. Of course, in reality, under this classification method, there are far more than 10 types of cancer. The following are just some of the types of cancer for your reference.

Respiratory system cancer

  • Non-small cell lung cancer: Subtypes of non-small cell lung cancer (accounting for about 85% of lung cancer) include lung adenocarcinoma, lung squamous cell carcinoma and large cell lung cancer.
  • Small cell lung cancer: Small cell lung cancer accounts for about 15% of lung cancers and is more likely to occur in people who smoke.
  • Malignant mesothelioma: Mesothelioma is a cancer of the pleural mesothelium, which surrounds the lungs. It is strongly associated with exposure to asbestos.
  • Thymoma and thymic carcinoma

Digestive system cancer

Cancers of the digestive tract can occur anywhere from the mouth to the anus. Most cancers are adenocarcinomas, and squamous cell carcinomas occur in the upper esophagus and farthest from the anus. Types include:

  • Anal cancer
  • Appendiceal cancer
  • Cholangiocarcinoma
  • Intestinal carcinoid
  • Colon cancer, rectal cancer
  • Esophageal cancer
  • Gallbladder cancer
  • Gastric cancer
  • Gastrointestinal stromal tumors (GIST)
  • Islet cell tumors, pancreatic neuroendocrine tumors
  • Primary liver cancer in adults
  • Liver cancer in children
  • Pancreatic cancer
  • Small Intestine Cancer
  • Gastric cancer

Urinary tract cancer

The urinary system includes the kidneys, bladder, tubes connecting the kidneys and bladder (called ureters), and the urethra (the passageway where the bladder exits). This system also includes structures such as the prostate gland. Types of urinary system cancers include:

  • Bladder Cancer
  • Kidney cancer
  • Penile cancer
  • Prostate cancer
  • Renal pelvis and ureteral carcinoma, transitional cell
  • Testicular cancer
  • Urethral cancer
  • Wilms Tumor and Other Childhood Kidney Tumors

Reproductive system cancer

Reproductive system cancers can occur in both men and women. Types of reproductive system cancers include:

  • Testicular cancer
  • Ovarian cancer (including germ cell tumors)
  • Uterine cancer (also called endometrial cancer)
  • Fallopian tube cancer
  • Cervical cancer

Endocrine and neuroendocrine cancers

The endocrine system is a series of glands that produce hormones, and therefore, there can be symptoms of too much or too little production of these hormones. With the exception of thyroid cancer, most endocrine cancers are fairly rare. Combinations of different endocrine cancers occur, called multiple endocrine neoplasia, or MEN/ multiple endocrine neoplasia.

  • Adrenal cortical carcinoma
  • Gastrointestinal carcinoid
  • Islet cell tumor, pancreatic neuroendocrine tumor
  • Merkel cell carcinoma
  • Neuroendocrine tumors, non-small cell lung cancer
  • Neuroendocrine tumors, small cell lung cancer
  • Parathyroid cancer
  • Pheochromocytoma
  • Pituitary tumors
  • Thyroid cancer

Blood-related cancers

Blood-related cancers include cancers involving blood cells and cancers involving solid tissues of the immune system, such as lymph nodes. Risk factors for blood-related cancers differ from those for solid tumors because environmental exposures and viruses, such as the Epstein-Barr virus, which causes mononucleosis, play important roles. These are the most common cancers in children.

Blood-related cancers include:

1) Leukemia

  • Adult acute lymphoblastic leukemia
  • Childhood acute lymphoblastic leukemia
  • Adult acute myeloid leukemia
  • Acute Myeloid Leukemia in Children
  • Chronic lymphocytic leukemia
  • Chronic myeloid leukemia
  • Hairy cell leukemia

2) Lymphoma

  • AIDS-related lymphoma
  • Cutaneous T-cell lymphoma
  • Adult Hodgkin Lymphoma
  • Childhood Hodgkin Lymphoma
  • Hodgkin lymphoma during pregnancy
  • Mycosis fungoides
  • Adult Non-Hodgkin Lymphoma
  • Non-Hodgkin Lymphoma in Children
  • Non-Hodgkin Lymphoma During Pregnancy
  • Primary Central Nervous System Lymphoma
  • Sezary syndrome
  • Cutaneous T-cell lymphoma
  • Waldenstrom’s macroglobulinemia

Musculoskeletal cancer

  • Chondrosarcoma
  • Ewing’s sarcoma
  • Osteosarcoma and malignant fibrous histiocytoma of bone
  • Rhabdomyosarcoma in children
  • Soft tissue sarcoma

Nervous system cancer

  • Brain tumors in adults
  • Childhood Brain Tumors
  • Astrocytoma
  • Brainstem glioma
  • Atypical teratoma/rhabdoid tumor of the central nervous system
  • Central nervous system embryonal tumor
  • Central nervous system germ cell tumors
  • Craniopharyngioma
  • Ventricular membranous tumor
  • Neuroblastoma
  • Pituitary tumors
  • Primary Central Nervous System Lymphoma

Skin-related cancers

  • Cutaneous T-cell lymphoma
  • Kaposi’s sarcoma
  • Melanoma
  • Merkel cell carcinoma
  • skin cancer

Breast-related cancers

  • Breast cancer
  • Male Breast Cancer

Eye tumors

  • Intraocular melanoma
  • Retinoblastoma

Gynecologic Oncology

  • Cervical cancer
  • Endometrial cancer
  • Fallopian tube cancer
  • Gestational trophoblastic tumor
  • Epithelial ovarian cancer
  • Ovarian Germ Cell Tumor
  • Ovarian low-grade tumor
  • Primary peritoneal cancer
  • Uterine sarcoma
  • Vaginal cancer
  • Vulvar cancer

Head and Neck Cancer

  • Hypopharyngeal cancer
  • Laryngeal cancer
  • Lip and Oral Cancer
  • Metastatic squamous neck carcinoma with occult primary
  • Nasopharyngeal carcinoma
  • Oropharyngeal cancer
  • Sinus and nasal cavity cancer
  • Parathyroid cancer
  • Pharyngeal cancer
  • Salivary gland cancer
  • Throat Cancer
  • Thyroid cancer

Other

  • Chronic myeloproliferative neoplasms
  • Langerhans cell histiocytosis
  • Multiple Myeloma/Plasmacytoma
  • Myelodysplastic syndrome
  • Myelodysplasia/Myeloproliferative Neoplasms
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