Cancer
Peer reviewed by Dr Hayley Willacy, FRCGP Last updated by Dr Krishna Vakharia, MRCGPLast updated 11 Feb 2023
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Cancer is a disease of the cells in the body. There are many different types of cells in the body, and many different types of cancer which arise from different types of cells.
At a glance
Cancer occurs when abnormal cells multiply out of control in the body.
Different types of cancer behave and spread differently.
Some cancers grow and spread more quickly than others.
Treatments include chemotherapy, radiotherapy, or surgery.
The outlook for cancer varies greatly depending on its type and stage.
In this article:
Video picks for Information about cancer
Continue reading below
What is cancer?
Cancer occurs when cells become abnormal and multiply out of control. Different cells in the different parts of the body when multiplied cause different cancers.
Some grow and spread more quickly than others and some are easier to treat than others, particularly if diagnosed at an early stage.
Treatments can vary - some respond to chemotherapy, radiotherapy, or other treatments, while some may need surgery.
Some cancers have a better outlook (prognosis) than others - having a very good chance of being cured. For some types of cancer, the outlook is much poorer and therefore these have to be managed in a different way.
So, each cancer is different and behaves differently. We cannot put 'cancer' into one box. In each case it is important to know exactly what type of cancer has developed, how large it has become, whether it has spread and how well the particular type of cancer responds to various treatments. This will enable you to get reliable information on treatment options and outlook.
Patient picks for Information about cancer

Cancer
Types of cancer
There are more than 100 different types of cancer. Each type is classified by the type of cell the cancer originates from.
by Dr Hayley Willacy, FRCGP

Cancer
Stages of cancer
If left untreated, cancers often go through three stages: local growth, spread to lymph channels and spread to other areas of the body.
by Dr Toni Hazell, MRCGP
Frequently asked questions
Can all cancers be cured, or do some have a better chance of being cured than others?
The chance of being cured varies greatly between different types of cancer. Some cancers have a very good outlook and a high chance of being cured, especially if diagnosed early. However, for other types of cancer, the outlook is poorer, and these may need to be managed in different ways.
How do doctors determine the best way to treat a specific cancer?
To determine the best course of treatment, doctors need to understand several key factors. This includes knowing the exact type of cancer, its size, whether it has spread to other parts of the body, and how well that specific cancer type responds to various available treatments. This detailed information allows them to provide reliable advice on treatment options.
Is it true that different cancers grow and spread at different rates?
Yes, some cancers grow and spread more quickly than others. The speed at which a cancer develops and whether it spreads can significantly impact its treatment and overall prognosis.
Does early diagnosis make a difference in cancer treatment?
Yes, diagnosing cancer at an early stage can make a significant difference. Cancers found early are often easier to treat, which can lead to a better outcome.
If someone has cancer, does it always mean they will need chemotherapy?
Not all cancers are treated with chemotherapy. Treatments can vary widely depending on the cancer type. Some cancers respond well to chemotherapy, while others may be treated effectively with radiotherapy, surgery, or other types of treatments.
Further reading and references
- Kirkegaard H, Johnsen NF, Christensen J, et al; Association of adherence to lifestyle recommendations and risk of colorectal cancer: a prospective Danish cohort study. BMJ. 2010 Oct 26;341:c5504. doi: 10.1136/bmj.c5504.
- What is Cancer?; National Cancer Institute
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About the authorView full bio

Dr Krishna Vakharia, MRCGP
Chief Medical Officer for Health, Optum UK
MBChB, MRCGP(2013), BMedSci (hons), DFSRH, DRCOG, PGDipDerm (Distn)
Dr Krishna Vakharia is an NHS GP. She is also a regular examiner for the postgraduate Diploma in Practical Dermatology at Cardiff University as well as being the Chief Medical Officer for health at Optum UK.
About the reviewerView full bio

Dr Hayley Willacy, FRCGP
General Practitioner, Medical Author
MBChB (1992), DRCOG, DFFP, MRCOG (Part 1) MRCGP (2007), DFSRH (2013), MSc - medical education (2020)
Dr Hayley Willacy was an NHS GP working in northwest England, who retired from clinical practice in 2022 after 30 years.
Article history
The information on this page is written and peer reviewed by qualified clinicians.
Next review due: 9 Jan 2028
11 Feb 2023 | Latest version

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