The body of a living organism is made up of cells. A cell’s life cycle involves dividing to generate new cells that replace the older ones which eventually die. The rate at which regeneration occurs and the lifespan of a given cell depends on its location and function in the body. For instance, epithelial cells in the skin and cells that line the oesophagus regenerate at a much higher rate than those found in the brain and liver. Similarly, regeneration increases in the event of injury or recovery from surgery.
A tumour (also referred to as neoplasm) may form if cells divide at a faster rate than normal, or if they do not die when they should, resulting in the formation of an abnormal mass of tissue. This is usually triggered by mutations that occur in the cell’s DNA, causing them to behave erratically rather than follow their normal cell cycle.
The size of this abnormal tissue may vary from a tiny nodule to a large lump, and could occur anywhere in the body. The cells within a tumour – most often in malignant rather than benign tumours – often display one or more of the following changes:
- hyperplasia, an increase in the density of cells in a given area
- hypertrophy, an increase in the size of each tumour cell
- anaplasia, a reversion to a previous or undifferentiated version of the cell
Benign and Malignant Tumours
There are two types of tumours that we commonly refer to.
– benign tumours (also referred to as non-cancerous tumours) – These are harmless tumours that generally do not spread to other parts of the body or invade surrounding tissues (i.e., they remain localised). This is largely due to the presence of a capsule of connective tissue that encases benign tumours. The cells of these tumours usually maintain their normal appearance and remain attached to one another to form a solid mass. Benign tumours do not usually return if removed from the body. Although they are inherently harmless, benign tumours that press against nerves or blood vessels could cause pain or other issues, and some benign tumours have the potential to become malignant over time.
Examples of benign tumours include:
- adenomas (in glandular epithelial tissue)
- fibromas (also known as fibroids, in fibrous or connective tissue)
- hemangiomas (in blood vessels)
- osteomas (in bones)
- chondromas (in cartilage)
- lipomas (in fat tissue)
– malignant tumours (also referred to as cancerous tumours or cancers) – These tumours often invade surrounding tissues or organs. Unlike benign tumours, they are not usually encapsulated and their cells, which are usually distorted in appearance and disassociated from one another, undergo metastasis (spread to other parts of the body via the circulatory or lymphatic systems). As such, each malignant tumour cell has the potential to give rise to a new malignant tumour at a new site in the body. While growth rate may vary, malignant tumours often grow quickly and can be life-threatening. Cancer cells that originate at one site but metastasise and invade other organs maintain the identity of the original cell type. For example, if ovarian cancer cells spread to the breast, they still remain as ovarian cancer cells despite invading the other organ.
Examples of malignant tumours include
- carcinomas (in epithelial cells)
- sarcomas (in connective tissue, fat, nerves and bones)
- blastomas (in developing cells or embryonic tissue – more common in children)
- meningiomas (in the meninges of the brain or spinal cord)
- germ cell tumours (in the ovaries or testicles, but sometimes also in the brain, chest or abdomen)
In some instances, a third category of tumours may also be referred to, known as pre-malignant tumours. These are tumours that are not yet malignant or cancerous, but have the potential to become cancerous in the future.
Examples of pre-malignant tumours include
- lung metaplasia (in the bronchi)
- cervical dysplasia (in the cervical lining)
- actinic/solar keratosis (on the skin)
- leukoplakia (in the mouth)
Once an abnormal tissue growth is observed or suspected, the following diagnostic methods may be used in order to determine whether a tumour is benign or malignant:
- scanning – The presence of a tumour is often confirmed by means of a suitable scan – this could be an ultrasound scan, an MRI, a mammogram, etc. depending on the location of the (suspected) tumour. Benign tumours are usually smoother in appearance and appear encapsulated by a ‘sac’ of connective tissue, whereas malignant tumours are more irregular or ‘jagged’ in appearance. Location of the tumour and other sonographic characteristics may also be studied to identify the type of tumour.
- blood test – A sample of blood would be drawn from the patient in order to check for the presence of specific cancer markers that would be present if a tumour is malignant.
- biopsy – A small sample of the abnormal tissue is taken, either by needle aspiration, pap smear, endoscopy/colonoscopy or surgical procedure, to study the tumour cells under a microscope in order to determine if they are benign or malignant.
Risk factors for benign tumours include:
- family history of tumours
- repeated exposure to environmental toxins
- repeated exposure to radiation
- repeated or frequent infections
- poor or unhealthy diet
Risk factors for malignant tumours (cancers) include:
- family history of cancer
- exposure to carcinogens (substances that have the potential to cause cancer)
- repeated exposure to environmental toxins
- repeated exposure to radiation
- excessive alcohol use
- infections such as HPV
- poor/unhealthy diet
- being overweight or obese
Symptoms, Treatment and Complications
Depending on their location, some tumours maybe be felt as ‘lumps’ to the hand, and might even be visually apparent.
Benign tumours are usually painless and only cause discomfort or complications as they grow and press on surrounding nerves, blood vessels or tissues. As such, symptoms observed would be specific to the areas or organs that are affected. For instance, brain tumours could cause symptoms that range from headaches and nausea to seizures, memory issues, vision or speech impairment and even partial paralysis. Hence, even though benign tumours are non-cancerous and essentially harmless by themselves, doctors sometimes recommend for them to be removed in order to avoid or get rid of other complications that arise as a result of their presence and growth.
Malignant tumours, or cancers, are a lot more complicated from the onset as their presence itself is life-threatening. Therefore, the sooner they are detected, the better. Depending on their size, location and spread, and in the absence of other complications, doctors usually recommend immediate surgical removal of cancers whenever possible. In the event that surgery could endanger/damage other organs appears to be futile due to the extent of spread, chemotherapy, radiotherapy or a combination of the two may be sought to try to shrink the tumour or its reach before performing surgery. Quite often, surgery itself is also followed by chemotherapy and/or radiotherapy. The prognosis of a patient who has been affected by cancer is determined by several factors including the degree and rate of growth of the original tumour, the extent of spread at the time of diagnosis, which organs – and how many – have been affected, as well as the patient’s general strength and immunity. Since malignant tumours have the possibility of returning even after a patient has been given the all-clear after treatment, it is imperative that periodic screening is carried out as per the doctor’s recommendation.
While it might be impossible to prevent the incidence of most tumours, following are some measures that could be taken in order to reduce the risk of incidence:
- avoiding exposure to environmental toxins and radiation
- maintaining a healthy diet and avoiding or limiting processed foods
- maintaining a healthy weight/BMI
- maintaining body immunity
- being aware of and informing your GP of any history of cancer in the family
- regular screening, as recommended by your doctor (e.g. pap smear tests, mammograms, PSA tests, post-cancer screening)
- being attentive to physical and/or physiological changes in your body
- avoiding stress
- not smoking
- limiting or avoiding alcohol consumption
Early detection of cancer helps to achieve a better prognosis and saves lives.
PS – Cysts are NOT Tumours
Similar to tumours, cysts may also occur in any part of the body and are often similar in appearance. However, while tumours are solid masses of abnormal tissue, cysts are sacs that are filled with fluid or air. They therefore feel softer to touch when compared to tumours. (A few benign tumours may feel soft to touch, too, and therefore diagnostic testing may be required to determine the nature of any lumps that may be observed.)
Cover illustration from flaticon.