Written with men in mind. Most of this guide applies to everyone. Details specific to women — such as screening ages and risks that differ — are not covered yet; female health guides are being written.
What it is
Cancer is a disease in which some of the body's cells grow uncontrollably and can spread to other parts of the body. It can start almost anywhere. A cancer keeps the name of where it started even if it spreads — prostate cancer that spreads to bone is still prostate cancer.[1]
Normally cells grow and divide as needed and die when old or damaged. Cancer cells ignore these signals. Many form solid lumps called tumours; blood cancers usually do not. Benign tumours don't spread; malignant ones can invade nearby tissue and spread (metastasise) through the blood or lymph system.[1]
Cancer results from genetic changes affecting cell growth and division, inherited or acquired through exposures such as tobacco smoke and radiation. Staging systems (most commonly TNM — tumour, node, metastasis) describe anatomical extent and are combined with grade and biomarkers to guide prognosis and treatment.[1][2]
Open the Cancer concept view in the 3D Explorer — clearly labelled illustrations on real anatomy.
See it in 3DScreening: who, when and how
Screening looks for cancer in people who have no symptoms — for example colorectal screening from 45 or lung screening for some people with a heavy smoking history.[3][4] Diagnosis is what happens after a symptom or an abnormal screening result, usually including a biopsy. Screening is recommended only where evidence shows the benefits outweigh the harms, which is why recommendations differ between cancers.[5]
Stages in general terms
Stage describes how much cancer there is and how far it has spread. Many cancers use the TNM system; doctors also use summary terms:[2]
- In situ: abnormal cells that haven't spread into nearby tissue.
- Localised: limited to where it started.
- Regional: spread to nearby lymph nodes, tissues or organs.
- Distant: spread to distant parts of the body.
An illustration, not a stage. Human Atlas never assigns a stage. Only your own tests and your care team can do that.
Types of treatment
- Surgery. Removing the cancer.[6]
- Radiation therapy. High doses of radiation to kill cancer cells.[6]
- Chemotherapy. Drugs that kill fast-growing cells.[6]
- Hormone therapy. Slows or stops cancers that use hormones to grow, such as most prostate cancers.[6]
- Immunotherapy and targeted therapy. Help the immune system fight cancer, or target the changes that help cancer cells grow.[6]
Many people have a combination. Which treatment fits depends on the type and stage of cancer and the person. Your care team decides with you.
What you can do
Ask for the details
The type, stage and grade of a cancer shape everything else — ask your team to explain them.[2]
Use the screenings that work
Colorectal, lung (for some smokers) and the PSA conversation.[3][4][5]
Get support
If a diagnosis leaves you struggling, tell your team. For a crisis, call or text 988.[7]
Questions to ask your doctor
- What type of cancer is it, and where did it start?
- What is the stage and grade, and what do they mean for me?
- What are my treatment options, and what is the goal of each?
- Are there clinical trials I could join?
- Who do I call with questions between visits?
Myth vs. fact
Guided lesson
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Follow this topic step by step on the 3D body.
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Bladder cancer
Much more common in men than women. Blood in the urine — even once, even painless — is the sign never to ignore.
Colorectal cancer
Cancer of the colon or rectum. Screening from age 45 can find it early — or prevent it by removing polyps before they turn into cancer.
Kidney cancer
Often found by chance on a scan done for something else. Smoking, extra weight and high blood pressure raise the risk.
Lung cancer
By far the leading cause of cancer death in the US. Smoking causes most of it — and a yearly low-dose CT scan can find it early in people at high risk.
Prostate cancer
Apart from skin cancer, the most common cancer in American men. Many grow slowly; some don't. Here's what it is, who is at risk, and how the PSA decision works.
Testicular cancer
A cancer of younger men — the average age at diagnosis is about 33. It's uncommon and usually very treatable. Know what's normal for you.
Sources
- National Cancer Institute. What Is Cancer?. Checked 23 October 2026.
- National Cancer Institute. Cancer Staging. Checked 23 October 2026.
- US Preventive Services Task Force. Colorectal Cancer: Screening (May 2021). Checked 23 October 2026.
- US Preventive Services Task Force. Lung Cancer: Screening (final recommendation, March 2021). Checked 23 October 2026.
- US Preventive Services Task Force. Prostate Cancer: Screening (May 2018; an update is in progress). Checked 23 October 2026.
- National Cancer Institute. Types of Cancer Treatment. Checked 23 October 2026.
- 988 Suicide & Crisis Lifeline. 988 Suicide & Crisis Lifeline. Checked 23 October 2026.
The owner of this website is not a doctor. Human Atlas provides educational anatomy information and does not diagnose, stage, or treat disease. Talk to a qualified clinician about anything concerning your own health.