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How Cancer Develops
Cancer develops when altered cells escape normal controls, with different cancers following different biological paths.
#Cell growth can escape its usual controls
NCI contrasts normal cell growth and replacement with cancer cells that grow when they should not or ignore signals to stop dividing or die. Cancerous tumours can invade nearby tissues and spread elsewhere through metastasis. Many cancers form solid tumours, but some, including leukaemias, generally do not.
A tumour is not automatically cancer: NCI also describes benign tumours that do not invade or spread, although they can still cause serious problems. These terms introduce mechanisms and categories; they cannot classify a person's lump, scan or tissue sample.
Evidence: NCI: what is cancer
#Changes can affect growth control and DNA repair
NCI describes cancer-related changes affecting proto-oncogenes, tumour suppressor genes and DNA repair genes. Proto-oncogenes normally participate in growth and division; certain changes can make them promote inappropriate growth. Altered tumour suppressor genes can weaken growth control, while problems in DNA repair genes can allow additional changes to accumulate.
NCI also describes changes in how DNA is packaged that alter gene activity without changing its sequence. Cancer development is therefore not a single universal DNA error. This overview provides no variant classification, biomarker interpretation or treatment selection.
Evidence: NCI: what is cancer / NCI: the genetics of cancer
#Genetic does not always mean inherited
NCI explains that cancer-related genetic changes can arise through errors during cell division, environmental damage to DNA or inheritance. An inherited change can raise cancer risk without making cancer inevitable. Changes can continue to accumulate as cancer cells divide, and cells within one tumour can differ genetically.
The word genetic describes the role of DNA and gene regulation; it does not by itself establish a hereditary cancer syndrome. This page does not calculate family risk, recommend testing or screening, or estimate a person's prognosis. Mynd does not provide oncology or genetic counselling.
Evidence: NCI: the genetics of cancer / NCI: what is cancer
Source note
The sections above were checked against the linked sources. No clinical review has been performed. This is general research education, not a clinical guideline.