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🩺 Medically reviewed by the Health Decoded Guide Editorial Team· Last reviewed: August 2026
🔍 Quick Summary
A tumour is an abnormal growth of cells. Tumours can be benign (non-cancerous) or malignant (cancerous).
Benign tumours usually remain in one place and do not spread to distant organs.
Malignant tumours can invade surrounding tissues and may spread to other parts of the body.
👉 Finding a tumour does not automatically mean cancer.
1️⃣ Introduction
The word tumour can be frightening, but it simply describes an abnormal mass or growth of tissue.
Some tumours are harmless and may never require treatment. Others are cancerous and need medical care.
• benign means non-cancerous
• malignant means cancerous
• tests are often needed to determine which type is present
You cannot reliably tell whether a tumour is cancerous simply by looking at or feeling it.
2️⃣ How tumours develop
Normally, the body carefully controls how cells grow and divide.
A tumour may develop when:
• cells begin multiplying more than they should
• abnormal cells accumulate
• a mass of tissue gradually forms
What happens next depends on the behaviour of those cells.
👉 The key difference is not simply whether a lump exists—it is how the abnormal cells behave.
3️⃣ Types
Benign tumours
• are not cancer
• usually grow slowly
• generally remain in their original location
• do not invade distant organs
Malignant tumours
• are cancerous
• can invade surrounding tissues
• may enter the blood or lymphatic system
• can spread to distant parts of the body
Benign and malignant tumours can sometimes look similar initially, which is why proper medical assessment matters.
4️⃣ What causes tumours?
Tumours develop because cells begin growing abnormally, but the exact reason varies.
Genetic and biological factors
• DNA changes within cells
• inherited genetic conditions
• hormonal influences
Environmental and lifestyle factors
• tobacco
• radiation
• certain infections
• exposure to some cancer-causing substances
The presence of a tumour does not necessarily tell us what caused it—or whether it is cancerous.
5️⃣ Symptoms
Tumours may cause no symptoms at all.
When symptoms occur, they depend on the tumour's location and size.
• a new lump or swelling
• pressure or pain
• changes in the function of a nearby organ
• unexplained bleeding
• bowel or bladder changes in some cases
Symptoms alone usually cannot determine whether a tumour is benign or malignant.
6️⃣ Can benign tumours still cause problems?
Yes. Benign does not always mean harmless.
A benign tumour may:
• become very large
• press against nerves or organs
• produce hormones
• cause pain or bleeding
• become dangerous because of its location, such as inside the brain
Malignant tumours can additionally invade and destroy surrounding tissues or spread elsewhere.
The seriousness of a tumour depends on its type, size, location and behaviour.
7️⃣ 🩺 When should a lump or tumour be checked? 🚨
Seek medical assessment for:
• a new unexplained lump
• a lump that continues growing
• a hard or fixed lump
• unexplained bleeding
• unexplained weight loss
• persistent symptoms caused by pressure on an organ
👉 These may indicate:
• a benign or malignant tumour, or another medical condition
• need for appropriate medical investigation
8️⃣ Management / treatment
Benign tumours
• may simply be monitored
• may be removed if they cause symptoms or complications
• treatment depends on their location and behaviour
Malignant tumours
• surgery
• chemotherapy
• radiotherapy
• targeted therapy, immunotherapy or hormone therapy when appropriate
Treatment is based on the specific diagnosis—not simply the presence of a lump.
9️⃣ Diagnosis
Doctors may use:
• physical examination
• ultrasound, CT, MRI or other imaging
• blood tests in selected situations
• biopsy
During a biopsy, a tissue sample is examined under a microscope.
👉 A biopsy can often provide the definitive answer about whether a tumour is benign or malignant.
🟢 Important Message
Tumour and cancer do not mean exactly the same thing.
A tumour may be benign or malignant, and some cancers—such as leukaemia—do not form solid tumours at all.
👉 If a new lump is discovered, avoid assuming the worst. Get it properly assessed so you know what it actually is.
FAQ
• Does every tumour mean cancer?
No. Many tumours are benign and are not cancerous.
• Can a benign tumour spread?
Benign tumours do not metastasise to distant parts of the body.
• Can a benign tumour still be dangerous?
Yes. Its size, location or hormone production can sometimes cause serious problems.
• How do doctors know whether a tumour is cancerous?
Imaging can provide important clues, but a biopsy is often needed to confirm the diagnosis.
🧠 Why We Delay
Some people avoid getting a lump checked because the word tumour immediately makes them think of cancer. Others delay because the lump does not hurt and assume that anything painless must be harmless.
Many lumps are not cancerous, but pain alone cannot reliably tell the difference. Medical assessment can often provide reassurance or identify a problem while treatment options are still available.
👉 Finding a lump does not mean you have cancer—but finding out what it is matters.
🔗 Related Health Topics
• What Is Cancer?
• How Cancer Develops
• What Causes Cancer?
• How Cancer Spreads
• Cancer Warning Signs
📚 Medical References
• National Cancer Institute (NCI). What Is Cancer?
• Cancer Research UK. What is cancer?
• American Cancer Society. What Is Cancer?
• National Health Service (NHS). Cancer.
• Cleveland Clinic. Benign Tumor.
⚠️ Medical Disclaimer
This article is for educational purposes only and does not replace professional medical advice.
If you have a new or changing lump, unexplained symptoms or abnormal test results, consult a healthcare professional.