This article explains what cancer is, how it is diagnosed and staged, and the main approaches to cancer treatment — from surgery and radiotherapy to systemic therapies such as chemotherapy, targeted drugs and immunotherapy. It also summarises common symptoms, major cancer types and basic terms you will meet when discussing care with your clinical team.

All organs and tissues in the body are built from many different types of cells. As part of normal renewal, healthy cells divide to replace those that die. The timing and rate of cell division are controlled by the cell’s DNA. When DNA becomes damaged, cells can begin to divide abnormally and persist longer than they should. Cancer is the term for diseases that arise when the body’s own cells grow in an uncontrolled way.

Uncontrolled cell growth can produce a mass, commonly called a tumour (also called a mass or nodule). Tumours may be benign (non‑cancerous) or malignant (cancerous). Many benign tumours remain local, do not invade surrounding tissue and are unlikely to threaten life after removal; however, there are exceptions and each lesion needs clinical assessment. Malignant tumours can invade nearby structures, compress normal tissues or spread — via lymphatic channels or the bloodstream — to form new tumours elsewhere in the body.

Several risk factors increase the chance that cells become cancerous. These include persistent infections with some viruses (for example, hepatitis B and C virus are linked to liver cancer, and certain human papillomavirus strains to cervical and other cancers), tobacco use, long‑term exposure to carcinogenic chemicals or radiation, and inherited genetic mutations. Risk reduction — for example, quitting smoking, protecting skin from excessive UV exposure and using available vaccines such as hepatitis B and HPV where recommended — is an effective way to lower cancer risk (see NHS or National Cancer Institute guidance for details).

What is Cancer Treatment?

Cancer treatment is the range of medical approaches used to remove, control or relieve symptoms of cancer. The exact pathway depends on the cancer type, its location, how far it has spread (stage) and the person’s overall health. Diagnosis typically follows a standard cascade: a clinical history and examination, blood and other laboratory tests, radiological imaging, and a biopsy of any suspicious mass; staging investigations (scans) then determine whether the cancer has spread.

Treatment decisions are made by a multidisciplinary team and may aim to cure, control disease for a long time, or relieve symptoms (palliative care). Treatments are often combined and can be given before or after surgery — for example, neo‑adjuvant therapy (before surgery) or adjuvant therapy (after surgery) to reduce the risk of recurrence.

Surgery: Surgery removes the tumour and some surrounding tissue to achieve clear margins. Surgery is a mainstay of curative treatment for many localised cancers and can also be used for symptom relief.

Chemotherapy: Cytotoxic drugs circulate in the bloodstream to target rapidly dividing cells and can shrink tumours or kill cancer cells systemically. Chemotherapy is used in curative, adjuvant, neo‑adjuvant and palliative settings; regimens and side effects vary by drug and cancer type.

Targeted therapies: Also called molecular treatments, these drugs block specific genetic or molecular features of cancer cells. They are selected after tests show the tumour has the relevant alteration and may be given as tablets or infusions, alone or with other treatments.

Immunotherapy: Immune‑based treatments (for example, immune‑checkpoint inhibitors) boost the patient’s immune system so it can recognise and kill cancer cells more effectively. These therapies have transformed outcomes for some cancers but do not work for all patients and can cause immune‑related side effects.

Radiotherapy: Also called radiation therapy, this delivers focused radiation to destroy tumour cells while sparing surrounding organs where possible. Radiotherapy may be curative on its own for some localised cancers or combined with other treatments.

Other approaches include hormone therapy for hormone‑sensitive cancers, bone marrow or stem cell transplantation for certain blood cancers, and participation in clinical trials that test new treatments or combinations. Each option has potential benefits and side effects; discuss treatment aims, likely outcomes and expected side effects with your oncology team so you understand the practical choices for your situation.

What are the Symptoms of Cancer?

Symptoms of cancer vary by cancer type and by person. Many cancers cause no obvious signs in early stages; others produce symptoms that should prompt medical review. If any of the following are new, persistent or unexplained, see your GP for assessment and tests.

  • Unexplained weight loss: Losing weight without trying can be an early sign of several cancers, including stomach, oesophageal and pancreatic cancers.
  • Persistent fever: A long‑standing fever without an obvious infection can occur with some cancers (for example, certain blood cancers) but is not a common feature of most solid tumours.
  • Fatigue and weakness: Ongoing tiredness not relieved by rest can be a symptom of cancer or many other conditions and should be investigated if persistent.
  • A new lump or mass: A palpable lump in the breast, armpit, testis or elsewhere warrants prompt examination — not all lumps are cancer, but they need assessment.
  • Unexplained bleeding or discharge: Blood in the stool, urine, or unexpected vaginal bleeding should be evaluated; while many causes are benign, these symptoms can indicate colorectal, bladder, cervical or endometrial cancer.
  • Persistent cough or hoarseness: A cough or hoarse voice that does not settle after a few weeks — especially in people who smoke — may signal lung or throat cancer.
  • Changes in bowel or bladder habits: Ongoing diarrhoea or constipation, or changes in urination, including blood in urine, should be checked.

These signs are not specific to cancer and often have other causes, but early diagnosis improves treatment options and outcomes. Avoid unproven remedies; evidence‑based treatment is most effective when cancers are detected early. For reliable, detailed guidance on symptom checklists and screening (for example for breast cancer, cervical screening and bowel cancer screening) consult NHS.uk or the National Cancer Institute.

What are the Types and Varieties of Cancer?

There are more than 100 recognised cancer types, each named for the tissue or organ where it begins. Below are some common cancer types, with typical risk factors and brief notes on screening or presentation.

  • Breast cancer: Arises from breast tissue cells and is far more common in women than in men. Risk factors include age, family history and some genetic mutations (for example BRCA1/2). Population screening (mammography) exists in many countries to detect early disease.
  • Lung cancer: Originates in lung cells; the main avoidable risk factor is tobacco smoke, though air pollution and occupational exposures also contribute. Persistent cough or haemoptysis (coughing up blood) are common presenting features.
  • Primary brain tumours: These start in brain tissue and differ from metastatic deposits that spread to the brain from other sites. Symptoms depend on tumour location and may include headaches, seizures or focal neurological changes.
  • Cervical cancer: Strongly linked to persistent infection with high‑risk human papillomavirus (HPV) types. Many countries run cervical screening programmes (smear tests) and offer HPV vaccination to reduce incidence.
  • Colon (colorectal) cancer: Incidence rises with age and is associated with dietary factors, family history and some inherited syndromes. Many health services recommend screening from middle age to detect polyps and early cancers.

What are the Cancer Terms?

Below are commonly used terms you may hear when discussing cancer diagnosis, staging and treatment. Short, clear definitions help you understand reports and conversations with your clinical team.

  • Tumour (also called a mass or nodule): An abnormal growth of cells that forms a lump or swelling. Tumours can be benign (non‑cancerous) or malignant (cancerous).
  • Benign: Non‑cancerous. Benign growths usually do not invade nearby tissues or spread to other parts of the body and are less likely to be life‑threatening, though they may still need treatment.
  • Malignant: Cancerous; these tumours can invade surrounding tissue and may spread (metastasise) to other organs.
  • Metastasis: The process by which cancer cells spread from the primary site to other parts of the body, typically via the lymphatic system or bloodstream.
  • Marker (tumour marker): A substance, often measured in the blood or tissue, that can indicate the presence or behaviour of certain cancers (for example, PSA for prostate cancer or CA‑125 for ovarian cancer) — markers are used alongside other tests, not alone, for diagnosis.
  • Leukopenia: A lower than normal count of white blood cells in the blood; this can be a side effect of treatments such as chemotherapy and increases infection risk.
  • Adjuvant/Neo‑adjuvant therapy: Adjuvant therapy is given after primary treatment (for example, after surgery) to reduce recurrence risk; neo‑adjuvant therapy is given before the main treatment to shrink a tumour.

If you encounter other terms in reports or clinic letters, ask your oncology team or consult reliable sources such as the National Cancer Institute or NHS for plain‑language explanations and a more comprehensive glossary.

What Causes Cancer?

Cancer begins when normal cells acquire changes that allow them to grow and divide in an unregulated way. Most cell types in the body can divide to replace cells that are lost; a few tissues (for example many nerve and some muscle cells) divide much less frequently. When the DNA that controls cell behaviour is damaged, the normal checks on growth and death may fail and abnormal cells can accumulate to form a tumour.

Damage to DNA can come from many sources. Common carcinogenic causes include:

  • Tobacco smoke — strongly linked to lung, head and neck and other cancers.
  • Ultraviolet (UV) radiation from sunlight — a major cause of skin cancers.
  • Ionising radiation — increases risk of various cancers depending on dose and site.
  • Certain chemicals and occupational exposures — for example some industrial agents linked to bladder or liver cancer.
  • Persistent infections — some viruses can cause cancer (for example hepatitis B and C with liver cancer; high‑risk human papillomavirus with cervical and other cancers).
  • Inherited genetic mutations — some families carry mutations (for example BRCA1/2, Lynch syndrome) that markedly increase the risk of specific cancer types.

Normally, cells possess DNA‑repair pathways that correct damage. If repair mechanisms fail, mutations can accumulate and disrupt genes that regulate the cell cycle, death (apoptosis), DNA repair or the immune recognition of abnormal cells. Other contributing processes include chronic inflammation and changes to the tumour microenvironment such as new blood vessel growth (angiogenesis), which helps tumours access nutrients.

While many causes are avoidable (for example by not smoking, using sun protection and following vaccination recommendations), others — such as inherited mutations — cannot be changed. If you are concerned about inherited risk, ask your GP about referral for genetic counselling. For evidence‑based advice on reducing risk and links to detailed information, see resources such as NHS.uk or the National Cancer Institute.

What are the Stages of Cancer?

Staging describes how advanced a cancer is and helps guide treatment choices. Most solid tumours use the TNM system: T (size and extent of the primary tumour), N (whether cancer has spread to nearby lymph nodes) and M (presence of distant metastasis). These factors are combined to give an overall stage, commonly labelled Stage I–IV, with higher stages generally indicating more extensive disease.

A simplified outline of typical stage meaning:

  • Stage I: Localised disease, usually small and confined to the organ of origin.
  • Stage II–III: Larger primary tumours and/or involvement of regional lymph nodes.
  • Stage IV: Distant spread (metastasis) to other organs such as bone, liver or lungs.

Treatment can sometimes reduce tumour size and downstage disease — for example, neo‑adjuvant chemotherapy or radiotherapy given before surgery may allow a previously inoperable tumour to be removed. Staging systems and implications vary by cancer type, so discuss specific staging and prognosis with your oncology team.

Early diagnosis generally improves the chance of curative treatment for many cancers, which is why screening programmes and symptom awareness are important. For reliable information about staging, treatment options and support services, see NHS guidance or the National Cancer Institute, and ask your clinical team about clinical trials or specialist support if relevant.