Types of cancer: definition, risks and how they are classified

A serious disease that, unfortunately, has a high incidence in the West.

Cancer, unfortunately, is a disease that is talked about very often nowadays.. According to estimates of the Spanish Society of Medical Oncology (SEOM), in 2015, 220,000 new cases were diagnosed in the Spanish territory.

Likewise, the same institution states that the future is alarming, since taking into account the forecasts of the United Nations (UN), it is estimated that in 2020 246,713 new cases of cancer will be diagnosed in Spain, 97,715 in women and 148,998 in men.

What is cancer?

Our bodies are made up of millions of billions of cells, which are so small that they can only be seen through a microscope. These cells are grouped together to form the tissues and organs of our organism, and among them we find a great diversification as they perform different functions. With this complementation they cover the vital needs of an organism, such as the maintenance of the body structure, nutrition and respiration.

Cancer occurs when normal cells become cancerous, i.e. they multiply uncontrollably and invade adjacent organs or tissues. and invade adjacent organs or tissues.

Types of cancer

Cancer can start in any part of the body and is named and classified according to different characteristics. But what types of cancer are there? what types of cancer are there? Below we explain them to you.

A) Types according to prognosis (benign or malignant)

Although many people think that the word cancer and the term tumor are the same, they are not. Tumors can be benign or malignant. If the tumor is benign, the cells multiply uncontrollably but do not spread to other parts of the body. The benign tumor does not usually pose a risk to the patient's life, but if not treated in time, it could develop into a malignant tumor or cancer.

Malignant tumor or cancer occurs when uncontrolled cells spread to other areas of the body.This is called metastasis.

B) Types of cancer according to origin

Depending on the origin, cancers are given specific names. For example:

• Breast or breast cancer
• Lung cancer
• Colon cancer
• Prostate cancer
• Kidney cancer

C) According to tissue type

The International Classification of Diseases for Oncology (ICD-O) has been in use for almost 25 years and is considered a prognostic and diagnostic tool for coding tumors and cancers.

Considering the third edition of this manual, there are six types of cancer:

Carcinoma

This is the most common type of cancer, and has its origin in the epithelial layer of the epithelial cells.. These cells line the entire surface of the body as well as internal structures and cavities. Carcinomas can occur in different parts of the body, e.g. the lung, breast, prostate and colon.

There are different types of carcinomas:

• Embryonal carcinomaoriginates in the cells of the testicles and ovaries.
• Carcinoma in situis not yet at an early stage and has not yet spread. They are removed by surgery.
• Carcinoma of unknown originIts site of origin is not known.
• Invasive carcinomais one that has invaded other areas. It is called carcinomatosis.

Sarcoma

Sarcoma is a malignant tumor of the connective tissues, including the muscles.including: muscles, bones, cartilage and fat.

Depending on the origin, there are different subtypes of sarcoma:

• Osteosarcomabone sarcoma
• Chondrosarcomacartilage sarcoma
• LeiomyosarcomaLeiomyosarcoma : affects smooth muscles
• Rhabdomyosarcoma: impact on skeletal muscles
• MesotheliomaAffects the tissue lining the lungs and chest cavity (pleura), the abdomen (peritoneum) or the sac containing the heart (pericardium).
• FibrosarcomaAffects fibrous tissue
• Angiosarcoma. has its effect on the Blood vessels
• Liposarcomasarcoma affecting adipose or fatty tissue.
• Gliomaoriginates in the brain or spinal cord. It arises from glial cells.
• MyxosarcomaIt occurs in the primitive embryonic connective tissue).

3. Myeloma

Myeloma or multiple myeloma is a cancerous tumor originating in the plasma cells of the bone marrow.. Normal plasma cells are an important component of the immune system, as the immune system is composed of several types of cells that act together to fight disease and infection. For example, lymphocytes.

4. Leukemia

Leukemia is a type of blood cancer that affects about 5,000 people in Spain each year.. Leukemia occurs when certain cells become cancerous, affecting the bone marrow. Although it may seem that leukemia and myeloma (explained in the previous point) are the same, in reality they are not.

Even more doubts may arise when hearing the name of a type of leukemia called myeloid leukemia. Well, multiple myeloma and myeloid leukemia involve different types of cells. Although the cells affected in leukemia are also generated in the bone marrow, they are not plasma cells.

Leukemias can be classified on the basis of different criteria:

• Based on their historyBased on their history: "de novo", when there is no previous process; and "secondary", when there is a previous process (for example, blood disease) that leads to leukemia.

• On the basis of transformation and speedThe following terms are used: "acute leukemia", if the development is rapid; and "chronic leukemia", i.e., with slow progression.

• According to their place of originAccording to their place of origin: "lymphoblastic", affecting lymphocytes; and "myeloblastic" (myeloid or myeloid), affecting the precursor cell of the myeloid series or red series, such as red blood cells and platelets.

5. Lymphoma

If there could be any doubt between leukemia and myeloma, the terms lymphoma and leukemia can also be confusing. But leukemia is often called a liquid cancer because it affects the blood, lymphomas are known as solid cancers because they originate in the lymph nodes..

Lymphomas are classified in two ways: Hodgkin's lymphoma and non-Hodgkin's lymphomas. These types of lymphomas are different in behavior, spread and treatment.

6. Mixed types

These cancerous tumors are characterized by the presence of two or more carcinogenic components. They are rare and may be caused by a poor prognosis. A mixed type cancer is, for example, carcinosarcoma, a mixture of carcinoma and sarcoma. That is, it is a cancer of epithelial tissue and at the same time connective, bone, cartilaginous or fatty tissue. However, there are other rare "mixed type cancers", such as mixed mesodermal tumor, adenosquamous carcinoma or teratocarcinoma.

D) Types according to grade

According to the degree of evolution, the cancer can be classified into 4 levels. The greater the differentiation or abnormality and the greater or lesser the speed of evolution, the higher the grade number.

The grades of this classification, proposed by the World Health Organization (WHO), "should be considered as degrees of malignancy and not as stages of malignancy, independently of whether certain grade III or IV tumors are the result of a malignant transformation of a pre-existing tumor", as explained by this institution. Therefore, according to grade, the WHO classifies tumors as follows:

1. low grade or slow progression

Depending on whether or not they are circumscribed

• Grade ISlow evolution and circumscribed limits. Better prognosis than grade II
• Grade IISlow evolution but with diffuse limits and imprecise extension. Poorer prognosis than grade I.

2. High grade and rapid growth

According to the evolution of the prognosis and the degree of abnormality.

• Grade IIIAnaplastic foci (poorly differentiated or undifferentiated cells) give the grade III label to an existing tumor, i.e. it was low grade.
• Grade IVis the most severe and undifferentiated cells occupy all or most of the tumor.