Overview
Cancer is not one disease but a group of more than 200 conditions in which cells grow abnormally, divide uncontrollably, and can invade nearby tissues or spread to distant organs. Understanding cancer at its specific type is essential, as each type behaves differently and requires different treatment.
How common is it?
About 1 in 2 people in the UK will develop some form of cancer during their lifetime. Cancer is the second leading cause of death worldwide after cardiovascular disease.
Causes and risk factors
Cancer begins when the DNA in a cell is damaged or mutated in ways that allow it to escape normal growth controls. These mutations accumulate over time from both external causes and random errors during cell division.
Common risk factors
- Smoking (causes 15 different types of cancer)
- Obesity
- Alcohol consumption
- Ultraviolet radiation from sun or sunbeds
- Age (cancer risk increases with age)
- Inherited gene faults (BRCA, Lynch syndrome)
- Certain infections (HPV, Hepatitis B and C, H. pylori)
- Exposure to carcinogens in the workplace
Symptoms
- Unexplained weight loss
- Unexplained fatigue
- A lump or thickening anywhere in the body
- Changes in bowel or bladder habits
- Persistent cough or hoarseness
- Unusual bleeding or discharge
- A sore that does not heal
- Changes in a mole (size, shape, colour, bleeding)
When to see a doctor
See a doctor promptly for any persistent, unexplained symptom lasting more than 3 weeks. For warning signs such as blood in urine, coughing blood, or a new lump, seek assessment within 2 weeks. You are not wasting the doctor's time.
Diagnosis
Diagnosis requires a biopsy (tissue sample) for microscopic examination. Imaging including CT, MRI, PET, and ultrasound stages the cancer. Blood tests (tumour markers) support monitoring. The exact type and stage determine treatment.
Treatments
Surgery
Removal of a tumour or affected organ. Often the primary curative treatment for solid cancers detected at an early stage.
Radiotherapy
High-energy radiation kills cancer cells and shrinks tumours. Used alone or alongside surgery and chemotherapy.
Systemic treatments
Chemotherapy, targeted therapy, immunotherapy, and hormone therapy work throughout the body to destroy cancer cells or disrupt their growth. Choice depends on cancer type and molecular characteristics.
Self-care and lifestyle
- Attend all offered cancer screening programmes (bowel, cervical, breast)
- Not smoking, limiting alcohol, maintaining healthy weight, and using sun protection prevent the majority of preventable cancers
- Being aware of cancer warning signs enables earlier diagnosis when outcomes are best
- Cancer rehabilitation helps regain strength, function, and wellbeing during and after treatment
Prevention
Up to 4 in 10 cancers in the UK are preventable. Not smoking is the single most important step. HPV and Hepatitis B vaccination protect against virus-related cancers.