3.1. Definition

Uncontrolled growth of abnormal cells.

Cancer is defined as the uncontrolled and abnormal growth of cells in the body. This means that unlike normal cells, which grow, divide, and die in an orderly way, cancer cells continue to grow and divide without control. They can invade nearby tissues and can spread to other parts of the body through the blood and lymph systems, forming new tumors.

Think of cancer like a garden where one type of flower starts to take over. In a healthy garden, flowers grow evenly, but if one type starts to grow uncontrollably, it can choke out other plants. In the same way, cancer cells can overwhelm healthy cells and disrupt normal bodily functions.

• Carcinomas: Originates in skin or epithelial tissues. • Sarcomas: Connective tissues like bone or muscle. • Leukemia: Blood cancer. • Lymphomas: Lymphatic system.

Cancer can be classified into several types. Carcinomas are cancers that begin in the skin or tissues that line internal organs. Sarcomas arise from connective tissues such as bones and muscles. Leukemia is a type of cancer that affects blood and bone marrow, leading to the uncontrolled production of abnormal white blood cells. Lymphomas affect the lymphatic system, which is crucial for the body's immune function.

Imagine the body's tissues are like different types of building materials in a construction project. Carcinomas are like issues that arise in walls (skin and linings), sarcomas might be problems in the framework (bones and muscles), leukemias are like faulty wiring (blood), and lymphomas could be leaks in pipes (lymphatic system). Each type needs a specific solution to fix.

• Chemicals (tobacco) • Radiation (UV, X-rays) • Viruses (oncoviruses)

Cancer can be caused by various factors that damage the DNA in cells. Chemicals like those found in tobacco can lead to mutations that trigger cancer. Radiation from sources like sunlight (UV rays) or medical imaging (X-rays) can also cause DNA damage. Additionally, certain viruses, known as oncoviruses, can lead to cancer development by altering cell function.

Think of DNA as the instructions for building a model. If you spill some chemicals (like tobacco) on the instructions, or if they are exposed to direct sunlight for too long (like UV) or handled carelessly (like X-rays), the instructions can get smudged or torn. This damage can lead to the model (cells) being built incorrectly, which is how cancer begins.

• Detection: Biopsy, imaging (MRI, CT) • Treatment: Surgery, chemotherapy, radiation, immunotherapy.

Cancer detection often involves procedures like biopsies, where a small tissue sample is removed for testing, or imaging techniques such as MRI or CT scans that help visualize the presence of tumors. Treatment options vary based on the cancer type and may include surgery for tumor removal, chemotherapy that uses drugs to kill cancer cells, radiation therapy that targets and destroys cancer cells, and immunotherapy that enhances the body's immune response against cancer.

Diagnosing cancer is like troubleshooting a car problem. Just as a mechanic might use diagnostic tools (like scans and tests) to find out what's wrong with a car, doctors use biopsies and imaging to figure out where the cancer is. Treatment options are like different repairs: sometimes you need to fix specific parts (surgery), replace the engine (chemotherapy), clean the fuel system (radiation), or give it a better fuel source (immunotherapy).

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