Cancer
By The Treatment Registry editors
Cancer treatment varies fundamentally by tumour type, stage, biology (including molecular profile), and patient fitness. Modern oncology is multimodal and increasingly precision-driven, combining surgery, radiotherapy, systemic therapies (chemotherapy, targeted therapy, immunotherapy, hormonal therapy), and supportive care. Continuity of care across the treatment course is critical, which makes cross-border treatment particularly difficult to coordinate.
Clinical overview
Signs and symptoms
Early cancer usually produces no symptoms; signs and symptoms appear as the mass grows or ulcerates, and the findings depend on the tumour's type and location. Few symptoms are specific, so cancer can act as a great imitator. Local effects reflect the mass or its ulceration: a bronchial obstruction may cause cough or pneumonia, oesophageal narrowing may make swallowing difficult, and colorectal tumours may alter bowel habit; breast or testicular masses may be felt as lumps, and ulceration may cause haemoptysis, anaemia, rectal bleeding, haematuria, or abnormal vaginal bleeding. Systemic features include fatigue, unintentional weight loss, cachexia, persistent fever, dyspnoea, and paraneoplastic syndromes such as hypercalcaemia or hyponatraemia. Almost all cancers can metastasise, most often to the lungs, liver, brain, and bones.
Causes and risk factors
About 90 to 95 per cent of cancers are attributed to environmental and lifestyle factors and the remaining 5 to 10 per cent to inherited genetics. Major contributors to cancer death include tobacco use (25 to 30 per cent), diet and obesity (30 to 35 per cent), infections (15 to 20 per cent), and ionising and non-ionising radiation (up to 10 per cent), alongside physical inactivity and pollution. Tobacco smoke, which contains over fifty known carcinogens, causes around 90 per cent of lung cancer, and alcohol raises the risk of several cancers. Infective agents such as Helicobacter pylori, hepatitis B and C, and HPV cause roughly 16 to 18 per cent of cancers worldwide. Mechanistically, cancer is a disorder of tissue-growth regulation requiring multiple alterations to oncogenes and tumour suppressor genes.
How it is diagnosed
Most cancers are first recognised through signs and symptoms or through screening, but neither provides a definitive diagnosis, which requires a pathologist to examine a tissue sample. People with suspected cancer are investigated with medical tests commonly including blood tests, X-rays, contrast CT scans, and endoscopy. The biopsy identifies the proliferating cell type, its histological grade, and genetic abnormalities, information used to assess prognosis and select treatment. Cytogenetics and immunohistochemistry provide further detail on molecular changes such as mutations, fusion genes, and numerical chromosome changes. Screening seeks to detect cancer before symptoms appear and is considered useful for cervical and colorectal cancer.
Who it affects
An estimated 18.1 million new cases of cancer and 9.6 million deaths occurred globally in 2018. About 20 per cent of males and 17 per cent of females develop cancer at some point, while 13 per cent of males and 9 per cent of females die from it, and cancers account for almost one in six deaths. The most significant risk factor is age: although cancer can occur at any age, most people with invasive cancer are over 65.
Clinical overview sourced from encyclopaedic medical reference; see sources below. General information only — not a substitute for individual clinical assessment.
Treatment ladder
Conservative options are first-line where appropriate; surgical options are typically reserved for cases where lower-tier options are unsuitable or have failed. Decisions are individual and depend on clinical assessment.
Conservative
- Active surveillance / watchful waiting
For selected indolent cancers (low-risk prostate, some early thyroid and chronic lymphocytic leukaemia), structured surveillance with intervention deferred until progression. Avoids treatment morbidity in patients who may never need active treatment.
- Best supportive care
Symptom-focused care without disease-modifying treatment, appropriate when curative or life-prolonging treatment is not feasible or not in the patient's interest.
Procedural
- Chemotherapy · View procedure page
Systemic cytotoxic anti-cancer therapy, delivered as cycles of intravenous or oral drugs. Indications, regimens, and protocols are tumour- and stage-specific.
- Radiotherapy
External-beam, brachytherapy, or systemic radioisotopes. Used as primary therapy, adjuvant therapy, or palliation depending on the cancer.
- Targeted therapy and immunotherapy
Drugs targeting specific molecular alterations (kinase inhibitors, monoclonal antibodies) or immune checkpoints (PD-1/PD-L1 inhibitors). Eligibility depends on tumour molecular profiling.
Surgical
- Curative oncologic surgery
Resection of localised tumour with margins, often combined with regional lymphadenectomy. Cornerstone of curative treatment for most solid tumours when surgically resectable.
- Cytoreductive (debulking) surgery
Removal of as much tumour bulk as possible to improve response to subsequent systemic therapy; commonly used in ovarian cancer.
- Palliative surgery
Surgery to relieve symptoms (e.g. obstruction, pain) when cure is not the aim.
Related procedures
Sources
- [1]ESMO — Clinical Practice Guidelines — esmo.org(accessed 2026-05-09)
- [2]Wikipedia — Cancer — en.wikipedia.org(accessed 2026-07-24)
- [3]ASCO/ONS Chemotherapy Administration Safety Standards — ascopubs.org(accessed 2026-05-09)
Sources marked “on file” are held by The Treatment Registry but are not publicly accessible.