What is cancer and how to diagnose?

Cancer is one of the most challenging health conditions worldwide. It is not a single disease but a group of disorders that occur when abnormal cells grow uncontrollably, spread to other parts of the body, and disrupt normal bodily functions. Early awareness about cancer—its types, stages, symptoms, classification, and methods of diagnosis — can play a vital role in prevention, timely treatment, and survival.

What is Cancer?

Cancer is a disease caused by the uncontrolled division of cells. Normally, cells grow and divide in a controlled way, but in cancer, this process goes wrong. The abnormal cells form masses known as tumors, which can be benign (non-cancerous) or malignant (cancerous). Malignant tumors invade nearby tissues and can spread (metastasize) to other parts of the body.

Types of Cancer

There are more than 100 different types of cancer, classified based on the origin of the cells. The most common types include:

• Carcinomas – begin in the skin or tissues lining internal organs (e.g., lung, breast, colon cancer).

• Sarcomas – develop in bone, cartilage, fat, or muscle.

• Leukemias – cancers of blood-forming tissues such as the bone marrow.

• Lymphomas affect the immune system, especially the lymph nodes.

• Melanomas start in pigment-producing skin cells.

Stages of Cancer

Cancer staging helps determine how far the disease has progressed:

• Stage 0: Abnormal cells present but not invasive.

• Stage I: Small and localized tumor.

• Stage II & III: Larger tumor, possible spread to nearby tissues or lymph nodes.

• Stage IV: Cancer has spread (metastasized) to distant organs.

Symptoms of Cancer

Symptoms vary depending on the type and stage of cancer, but may include:

• Unexplained weight loss

• Persistent fatigue

• Pain or discomfort

• Unusual bleeding or bruising

• Lumps or swelling in the body

• Changes in skin (moles, sores, pigmentation)

• Chronic cough or difficulty swallowing

Classification of Cancer

Cancers are classified based on their origin, cell type, and growth pattern:

• Histological classification – based on microscopic cell features.

• Molecular classification – uses genetic and biomarker testing.

• Anatomical classification – by organ or tissue affected.

Diagnosis of Cancer

Early and accurate cancer diagnosis improves treatment outcomes. Common diagnostic methods include:

• Physical examination

• Imaging tests (CT scan, MRI, X-ray, PET scan)

• Laboratory tests (blood and urine analysis)

• Biopsy (tissue sampling for microscopic study)

• Genetic and molecular testing

Treatment of Cancer

Treatment depends on the type, stage, and overall health of the patient. The main approaches include:

• Surgery – removal of the tumor.

• Chemotherapy – using drugs to kill cancer cells.

• Radiation therapy – targeting cancer cells with high-energy rays.

• Immunotherapy – boosting the body’s immune system to fight cancer.

• Targeted therapy – drugs that specifically target cancer cell mechanisms.

• Hormone therapy – used for hormone-sensitive cancers like breast and prostate.