Cancer is a group of diseases characterized by the uncontrolled growth and spread of abnormal cells in the body. These cells can invade nearby tissues and organs and may also spread (metastasize) to distant parts of the body through the blood and lymphatic systems.
There are more than 100 different types of cancer, commonly named after the organ or tissue where they begin — such as lung cancer, breast cancer, prostate cancer, or blood cancer (leukemia).
Symptoms
Cancer symptoms vary depending on the type, location, and stage of the disease. Early stages may show no signs, but as cancer develops, common symptoms can include:
Unexplained weight loss or loss of appetite
Persistent fatigue or weakness
Pain that doesn’t go away
Lumps or swelling (especially in the breast, neck, or other body parts)
Changes in skin — dark spots, yellowing, sores that don’t heal, or new moles
Prolonged cough, hoarseness, or difficulty swallowing
Abnormal bleeding or discharge (such as in urine, stool, or from the uterus)
Frequent infections or fever
Changes in bowel or bladder habits
Causes
Cancer develops when genetic mutations cause normal cells to grow and divide uncontrollably. These mutations may be inherited or caused by external (environmental) and internal factors.
1. Genetic Factors
Family history of certain cancers (e.g., breast, ovarian, colon).
Inherited gene mutations such as BRCA1 and BRCA2.
2. Lifestyle Factors
Smoking and tobacco use — leading cause of lung, mouth, and throat cancer.
Unhealthy diet — high in processed foods and low in fruits and vegetables.
Alcohol consumption — increases risk of liver, breast, and digestive cancers.
Obesity and lack of physical activity — linked to several cancer types.
