Cancer is a group of diseases in which abnormal cells grow and divide without normal control. Cancer can begin in almost any organ or tissue and may remain localized or spread to other parts of the body. Outcomes vary widely according to cancer type, stage, biology and available treatment.
Common cancer topics
- Breast Cancer — symptoms, diagnosis, screening and treatment.
- Cancer Immunotherapy — how immune-based cancer treatments work and possible side effects.
Possible warning signs
Many symptoms have causes other than cancer, but persistent or unexplained changes should be assessed. These may include a new or changing lump, unexplained weight loss, persistent fatigue, unusual bleeding, persistent changes in bowel or bladder habits, a cough or hoarseness that does not resolve, difficulty swallowing, a changing skin lesion or persistent unexplained pain.
Diagnosis
Evaluation depends on the suspected cancer and may include physical examination, blood tests, imaging, endoscopy and biopsy. A biopsy allows tissue to be examined and is often essential for confirming the diagnosis and determining tumor characteristics.
Treatment
Cancer treatment is individualized. Options include surgery, radiation therapy, chemotherapy, hormone therapy, targeted therapy, immunotherapy and stem cell transplantation. Many people receive a combination of treatments. Supportive and palliative care can be provided at any stage to control symptoms and improve quality of life.
Screening and early detection
Screening can detect some cancers before symptoms develop. Recommended screening depends on age, sex, family history, previous findings and individual risk. Screening is not available or appropriate for every cancer, and decisions should follow evidence-based guidance.
Related health areas
When to seek urgent care
People receiving cancer treatment should follow the urgent-care instructions provided by their oncology team. Fever during treatments that suppress the immune system can require immediate assessment. Severe breathing difficulty, uncontrolled bleeding, new confusion, seizures, sudden weakness or rapidly worsening illness also require urgent medical care.
Sources and further reading
Last reviewed: 4 September 2026. This page provides general health information and does not replace individual medical assessment or treatment.