What are the main types of cancer?

Cancer is not a single disease , and there are over 100 types of cancer, which are generally named after the organ or tissue from which the cancer originates (for example, colon cancer originates from cells lining the intestines). Another way of classifying is by the type of cells the cancer is made of, with the main subtypes being carcinomas, sarcomas, lymphomas, leukemias, and myelomas.

Carcinoma

Carcinoma is the most common type of cancer. It arises from epithelial cells that cover the outer and inner surfaces of the body, such as the skin, lungs, breasts, and intestines. There are several types of epithelial cells, which can be distinguished under a microscope, and cancers can be further divided into subgroups. Adenocarcinoma is a cancer that arises in epithelial cells that produce fluid or mucus. Tissues with this type of cell are sometimes called glandular tissues. The majority of breast, bowel, and prostate cancers are adenocarcinomas. Basal cell carcinoma is a cancer that begins in the lower (basal) layer of the outer layer of the skin (epidermis). Squamous cell carcinoma is a cancer of the cells just below the outer surface of the skin (above the basal cells). Squamous cells also line many other internal organs, such as the stomach, intestines, lungs, bladder, and kidneys. Under a microscope, they look flat, like fish scales. Transitional epithelial carcinoma is a cancer that arises from urothelial cells, which can be found in the bladder, ureter, and part of the kidney (renal pelvis).

Sarcoma

Sarcoma is a malignant tumor that arises from cells of the supporting tissue such as bone, cartilage, fat, connective tissue, and muscle. They are roughly divided into bone sarcomas and soft tissue sarcomas (all others). Osteosarcoma is the most common malignant bone tumor, while the most common soft tissue sarcomas are leiomyosarcoma, Kaposi's sarcoma, malignant fibrous histiocytoma, liposarcoma, and dermatofibrosarcoma protuberans.

Lymphoma

Lymphoma develops in the lymph nodes and cells of the immune system, specifically in cells called lymphocytes (T or B cells). Lymphocytes are a type of white blood cell and their function is to defend against disease as they are part of the immune system. In lymphoma, abnormal lymphocytes accumulate in the lymph nodes and vessels, as well as other organs in the body. There are two main types of lymphoma: Hodgkin lymphoma and non-Hodgkin lymphoma, and they differ in appearance and the type of cells affected.

Leukemia

Leukemia arises from immature blood cells that grow in the bone marrow. These tumors do not cause solid masses to form, but rather cause abnormal blood cells to accumulate in large numbers in the blood and bone marrow, crowding out normal cells. This results in low numbers of normal blood cells, making it difficult for tissues to get adequate oxygen, control bleeding, and fight infection. There are four main types of leukemia, classified by how quickly the disease progresses (acute/chronic) and the type of cell in which the leukemia arises (lymphoblastic/myeloid).

Myeloma

Myeloma is a malignant tumor that arises in the cells of the bone marrow.

Image 1. A view of a resected section of the intestine, where the cross-section shows 2 polyps (benign tumors) and 1 malignant tumor. Malignant tumors of the intestine are mainly adenocarcinomas.

What is the difference between cancer, carcinoma and tumor? In medicine, a tumor is a term that can be used for any growth. From an oncological perspective, tumors are divided into benign (benign) and malignant (malignant), as explained in the question What are malignant diseases (cancer)? Oncology and oncologists primarily deal with malignant tumors because they can infiltrate surrounding tissue and spread to distant parts of the body, thus posing a serious threat to a person's life. Cancer is a common term for malignant tumors, and carcinoma is just one of the subtypes of malignant tumors, as explained above. The term carcinoma is often used by insufficiently qualified people as a synonym for cancer, which is incorrect.

Additional interesting facts

Cancers that originate from the same type of cells but in different locations in the body can behave completely differently . For example, prostate adenocarcinoma and lung adenocarcinoma are two completely different diseases, both in terms of behavior, treatment, and prognosis. This is because in the above example, the cells from which lung adenocarcinoma and prostate adenocarcinoma arise, although they share some common characteristics, are still significantly different. After all, their function in a healthy organism is also significantly different. Therefore, both classifications of cancer mentioned at the beginning of this article are important and necessary, both by cell type and by localization/organ of origin of the malignant disease. Only by taking both data into account can the best decision be made in treating the patient.

Continue reading:

Cancer statistics in Croatia and the world

Need more information on this topic? Contact us.