A tumour is an abnormal mass of tissue that forms when cells grow and multiply out of control. It can develop in almost any part of the body. Understanding what a tumour is, how it forms, and what symptoms to watch for can help you take charge of your health. This article explains the causes, types, warning signs, screening options, and treatment approaches in plain language.
What Is a Tumour?
A tumour — also called a neoplasm — is a lump or growth caused by the uncontrolled division of abnormal cells. These cells no longer respond to the body’s normal signals that tell cells when to stop growing. As a result, they keep multiplying when they should not.
In a healthy body, the immune system plays a key role. White blood cells normally detect and destroy isolated abnormal cells before they can form a mass. However, a true tumour develops only when those abnormal cells become resistant to the immune system’s defences. At that point, the growth can take hold and expand.
It is important to know that not all tumours are cancer. Tumours are broadly grouped into two categories: benign (non-cancerous) and malignant (cancerous). Each behaves very differently in the body.
What Causes a Tumour?
Tumours can have many different causes, and sometimes more than one factor works together. Researchers have identified four main categories of causes.
Genetic Factors
Some people inherit gene mutations that make them more likely to develop certain tumours. For example, a strong family history of colon or breast cancer can raise personal risk. However, having a genetic risk factor does not mean a tumour will definitely develop.
Chemical Causes
Exposure to harmful chemicals is a well-known trigger. Tobacco use — including smoking and chewing tobacco — is one of the most studied chemical causes of tumours. Other workplace or environmental chemicals can also damage cell DNA over time.
Physical Causes
Radiation is a physical factor that can cause tumour formation. Prolonged exposure to ultraviolet (UV) rays from the sun, for instance, damages skin cells and is strongly linked to skin tumours. Ionizing radiation from certain medical procedures, if overused, can also play a role.
Biological Causes
Some viruses can trigger abnormal cell growth. For example, the human papillomavirus (HPV) is linked to cervical tumours, and the hepatitis B and C viruses are associated with liver tumours. These biological triggers can sometimes combine with genetic or chemical factors to raise the overall risk.
In some cases, no clear cause is ever found. This can be frustrating, but it is not uncommon. The World Health Organization provides detailed information on cancer causes and global risk factors.
Types of Tumours: Benign vs. Malignant
Understanding the difference between a benign and a malignant tumour is one of the most important distinctions in health care. The two types behave very differently and require different approaches to treatment.
Benign Tumours
A benign tumour tends to grow slowly and stay in one place. It pushes against nearby tissues rather than invading them. Benign tumours do not spread to other parts of the body, which means they do not form metastases.
In most cases, benign tumours are not life-threatening. However, they can still cause problems depending on their size and location. For example, a benign brain tumour can press on surrounding tissue and cause serious symptoms, even though it is not cancerous.
Furthermore, benign tumours are usually well-defined and easy to separate surgically from surrounding tissue. After removal, they rarely come back.
Malignant Tumours
A malignant tumour is cancerous. It tends to grow more quickly and has poorly defined edges. Malignant tumours invade nearby tissues and can spread to distant parts of the body through the bloodstream or lymphatic system, forming new growths called metastases.
Malignant tumours are more likely to return after removal. They require more aggressive treatment, which may include surgery, radiation therapy, and chemotherapy. Early detection is key to improving outcomes.
Therefore, any new or unusual lump or growth should be assessed by a healthcare provider as soon as possible. Mayo Clinic offers a comprehensive overview of cancer and malignant tumour behaviour.
Tumour Symptoms and Warning Signs
Tumours do not always cause obvious symptoms. In fact, many are discovered by accident during routine exams or imaging tests done for another reason. This is why regular check-ups are so valuable.
Common Physical Signs
The most noticeable sign of a tumour is a lump or mass you can feel under the skin. Deeper tumours may not be felt but can show up on an X-ray, ultrasound, or CT scan. Many tumours are painless, at least in the early stages.
Hormone-Related Symptoms
Some tumours produce hormones or hormone-like substances. For example, a benign tumour of the thyroid gland can cause the gland to produce too much thyroid hormone. This can lead to symptoms like unexplained weight loss, a rapid heartbeat, and anxiety — even though the tumour itself is non-cancerous.
Pressure on Nearby Organs
As a tumour grows, it can press on nearby nerves, blood vessels, or organs. A brain tumour, for instance, may cause weakness on one side of the body or changes in vision. A tumour near the bowel may cause digestive problems or a feeling of fullness.
General Warning Signs
Certain general symptoms can indicate a more advanced malignant tumour. These include unexplained fever, persistent fatigue, and unintended weight loss. Blood tests may also show signs of inflammation in the body.
In addition, night sweats and a general decline in wellbeing are signs worth discussing with a doctor. These symptoms are not specific to tumours — they can have many causes — but they should never be ignored.
Tumour Screening and Early Detection
Screening means looking for a tumour before symptoms appear. Early detection significantly improves treatment success for many types of tumours and cancers.
Screening for the General Population
In Canada, several screening programmes are available through provincial health plans at no direct cost to patients. For example, regular breast self-exams and mammography are recommended for women at certain ages. Cervical cancer screening through Pap tests is also widely available.
Colorectal cancer screening, including colonoscopy or stool tests, is recommended for adults starting around age 50 in most provinces. Your family doctor can advise you on what screening is right for your age and health history.
Screening for High-Risk Groups
Some people face a higher risk due to personal or family health history. For instance, a colonoscopy may be recommended starting at age 40 — or even earlier — for people with a personal or family history of polyps or colorectal cancer.
Similarly, people with a strong family history of certain tumours may be referred for genetic counselling. This can help identify risks early and guide prevention strategies. Health Canada provides guidance on cancer screening programmes available across the country.
Treatment Options for Tumours
Treatment for a tumour depends on whether it is benign or malignant, its size, its location, and the overall health of the patient. Treatment has advanced greatly in recent decades, and many tumours are highly treatable when caught early.
Treating Benign Tumours
Not all benign tumours need treatment. If a benign tumour is small and not causing symptoms, a doctor may choose to monitor it over time rather than remove it right away. This approach is sometimes called “watchful waiting.”
However, if a benign tumour is growing, causing discomfort, or pressing on vital structures, surgical removal is the standard approach. Because benign tumours are well-defined, surgery is usually straightforward and outcomes are generally excellent.
Treating Malignant Tumours
Malignant tumours typically require a combination of treatments. The most common approaches include surgical removal, radiation therapy, and chemotherapy. These may be used alone or in combination, depending on the specific cancer and its stage.
In recent years, targeted therapy and immunotherapy have become important new tools. These treatments are more precise and can target cancer cells while sparing healthy tissue. Your oncology team will recommend the best combination for your individual situation.
Treatment plans are coordinated through cancer care centres in each province. In Canada, your family doctor or specialist can refer you to the appropriate programme through your provincial health plan.
When to See a Doctor
You should speak with a healthcare provider if you notice any new lump, unusual growth, or change in your body that does not go away within a few weeks. Do not wait to see if it gets worse on its own.
If you have a family doctor, book an appointment as soon as possible. If you do not have a regular family doctor — which is the reality for many Canadians — a walk-in clinic is a good first step. The clinic can arrange for further tests or refer you to a specialist if needed.
Seek urgent care if you experience sudden neurological symptoms like weakness, vision changes, or severe headaches alongside a known or suspected tumour. These can indicate pressure on the brain or nervous system and need prompt attention.
Remember: early detection saves lives. Do not let worry or busy schedules delay a conversation with a healthcare provider. Always consult your doctor before drawing any conclusions about a lump or growth on your own.
What is the difference between a tumour and cancer?
A tumour is simply an abnormal mass of cells — it can be either benign (non-cancerous) or malignant (cancerous). Cancer refers specifically to malignant tumours that can invade nearby tissue and spread to other parts of the body. Not every tumour is cancer, but all cancers involve malignant tumour growth.
Can a benign tumour turn into cancer?
In some cases, a benign tumour can change over time and become malignant, though this does not happen with all types. Certain benign conditions, like colon polyps, carry a higher risk of progressing to cancer if left untreated. This is one reason why regular monitoring and screening are so important.
What does a tumour feel like?
A tumour near the surface of the skin often feels like a firm lump or mass under your fingers. Some tumours are soft, while others feel hard or rubbery. Many tumours, especially in early stages, are painless — which is why any new lump should be checked by a doctor even if it does not hurt.
Are all tumours serious?
Not all tumours are life-threatening — many benign tumours cause no serious harm and may never need treatment. However, even a benign tumour can cause problems if it grows large or presses on nearby organs. A malignant tumour is always considered serious and requires prompt medical attention.
How is a tumour diagnosed in Canada?
Diagnosis usually begins with a physical exam by your family doctor, followed by imaging tests such as an ultrasound, X-ray, CT scan, or MRI. A biopsy — where a small sample of the tumour is removed and examined in a lab — is often needed to confirm whether a tumour is benign or malignant. These services are covered under provincial health plans for medically necessary investigations.
What is the most common type of tumour?
The most common types of tumours vary by age and sex, but skin tumours — including both benign growths and malignant melanoma — are among the most frequently diagnosed overall. Breast, colorectal, prostate, and lung tumours are also among the most common malignant types in Canada. Regular screening through your provincial health plan can help catch these early.
Key Takeaways
A tumour is an abnormal mass caused by uncontrolled cell growth, also known as a neoplasm.
Tumours can be benign (non-cancerous) or malignant (cancerous) — the difference has a major impact on treatment and outlook.
Common causes include genetic factors, tobacco use, sun exposure, and certain viruses.
Many tumours produce no obvious symptoms, especially in early stages — regular screening is essential.
Benign tumours are usually treated with surgery if needed; malignant tumours may require surgery, radiation, and chemotherapy.
Screening programmes through Canadian provincial health plans can detect tumours early, when treatment is most effective.
If you find a new lump or experience unexplained symptoms, see your family doctor or visit a walk-in clinic promptly.
Always consult a qualified healthcare provider for diagnosis and treatment — do not rely on self-assessment alone.
