# Benign versus malignant

Source: https://onco.cc/terms/benign-vs-malignant/  
OnCo record `benign-vs-malignant` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A benign tumour grows but stays put and does not invade; a malignant tumour invades surrounding tissue and can spread. Only malignant tumours are cancer.

## Summary

Benign tumours (lipomas, most moles, adenomas) are usually harmless unless their size or position causes trouble, though some, such as colon polyps, are steps on the road to malignancy and are removed for that reason. Malignancy is defined by invasion through the tissue boundary and the capacity to metastasise; under the microscope, malignant cells show abnormal nuclei, high division rates and loss of normal architecture. A pathologist's job on a biopsy is first to make this call, and the whole staging system, treatment intent and prognosis flow from it.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: benign; malignant; malignancy; malignancies; benign tumour; benign tumours; benign tumor; benign tumors; malignant tumour; malignant tumours; malignant tumor; malignant tumors; non-cancerous; noncancerous; cancerous

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Benign_tumor
- Wikipedia: https://en.wikipedia.org/wiki/Benign_tumor

## Connected records

- terms: [Biopsy](https://onco.cc/terms/biopsy/), [Grade](https://onco.cc/terms/tumour-grade/), [Histology](https://onco.cc/terms/histology/), [In situ](https://onco.cc/terms/in-situ/), [Invasive](https://onco.cc/terms/invasive-cancer/), [Metastasis](https://onco.cc/terms/metastasis/)

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