Carcinogens: What They Are and What Causes Cancer

A carcinogen is an agent that, by virtue of its physical or chemical properties, is capable of causing irreversible damage to the genetic apparatus of a cell. According to oncologists' estimates, 80–90% of all human cancers are associated with the action of such environmental factors. At the same time, contact with a carcinogen in itself does not mean that the disease will develop.

What carcinogens are and how they act on cells

Carcinogens can be chemical in nature (various substances), physical (ionizing radiation, ultraviolet), and in some cases biological (oncogenic viruses, certain bacteria). The WHO International Agency for Research on Cancer divides them into groups: carcinogenic to humans (120 of them), probably and possibly carcinogenic (82 and 311), and unclassifiable (499). The mechanism at the cellular level is described as follows: most chemical carcinogens are electrophiles; they bind to DNA bases, forming adducts; during replication of such DNA, mutations arise, and their accumulation leads to the transformation of a normal cell into a tumor cell.

What causes cancer: main risk factors

Cancer is a genetic disease: it is caused by changes in genes, but only some of them are inherited from parents, while the rest arise during life. Among the factors that increase the risk of certain types of cancer are age, family history, smoking, excess weight, excess sun exposure, alcohol abuse, certain viruses (HPV, hepatitis), certain conditions (severe acid reflux, Lynch syndrome), and environmental conditions — for example, asbestos or air pollution. The body's ability to eliminate damaged cells declines with age.

Everyone has cancer cells: truth or myth

Normally, the body forms new cells as needed and removes old ones, and removes damaged cells before they become cancerous. A tumor arises when this process breaks down: new cells grow without need, and old cells do not die. Benign growths are not cancer; malignant ones can grow into tissues and spread — this is called metastasis.

What kills cancer cells and when they "wake up"

Normally, the body recognizes and removes damaged cells, and it is precisely this ability that declines with age. Everyday methods to deliberately "wake up" or "kill" cancer cells have no evidence base.

What is known about cancer prevention

Cancer cannot be completely prevented, but the risk of some types can be reduced. The following reduce risk: participation in screening recommended by a doctor (cervical, mammography, bowel cancer screening), vaccines against HPV and hepatitis B, quitting smoking, maintaining a healthy weight, limiting alcohol, sun protection (SPF of at least 30 and shade).

• Participation in screening reduces risk
• Vaccination against HPV and hepatitis B reduces risk
• Limiting alcohol reduces risk
• Quitting smoking and maintaining a healthy weight reduce risk
• Sun protection reduces risk

When to see a doctor

You should see a doctor for any symptoms that are unusual for you: a new lump, prolonged sweating or fever, unusual fatigue, bleeding or bruising without cause, unexplained weight loss, changes in a mole, non-healing ulcers, problems swallowing, a prolonged cough, or blood in sputum. Most such symptoms are caused by other conditions, but checking helps detect the disease earlier. Diagnosis is not limited to a single test: the doctor takes a history, performs an examination, and may order tests, imaging, or a biopsy.

The presence of symptoms in itself is not a reason to call an ambulance; 103 or 112 — for severe bleeding, vomiting blood or coughing up blood, or marked shortness of breath that is rapidly worsening.

This material is for reference and does not replace a doctor's consultation: the decision on examination is made individually.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer