Cancer: Types, Causes, Diagnosis, Treatment, and Prevention

Cancer Definition:

Cancer is a disease that is characterised by the uncontrolled growth of living cells, which leads to the formation of abnormal growth referred to as tumours that can invade other tissues and be transported to other parts of the body. Cancer is an illness that, if its causes are not well understood, becomes difficult to diagnose, treat, and manage. If the necessary information about the illness is not available, then people will not be able to manage the medical condition in the best way possible. This paper aims to discuss the definition of cancer, its staging, aetiology, signs, symptoms, diagnoses, management, and anticipations for the future.

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This Story also Contains

1. Cancer Definition:
2. What is Cancer?
3. How cancer develops
4. Normal vs. Cancerous Cell Behaviour
5. Types of Tumours
6. Types of Cancer
7. Causes and Risk Factors
8. Mechanisms of Cancer Development
9. Stages of Cancer Development
10. Symptoms of Cancer
11. Diagnosis of Cancer
12. Treatment of Cancer
13. Prevention and Early Detection
14. Role of Genetics in Cancer
15. Recommended Video on Cancer

What is Cancer?

Cancer is a conglomeration of various diseases that are characterised by several specific genetic mutations that interfere with normal cell functions. These mutations can thus change normal cells into malignant cells that start multiplying on the surface of the blood vessels. Different from ordinary cells that multiply in a specific manner; divide, grow, and die, cancerous cells keep dividing without the dying process and this forms a mass or tumour.

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How cancer develops

Cancer occurs when the proto-oncogenes and the tumour suppressor genes that are involved in cell division are mutated. When these genes become unhealthy, the cells are led to divide aggressively. This can be inherited through either polygenic patterns or mutations that occur during the development of the foetus or one's childhood.

Normal vs. Cancerous Cell Behaviour

Normal cells have a crystal clear environment for growth and division and after getting damaged, they can die within a short time. Cancerous cells, however, do not undergo apoptosis, grow chaotically, and can breach other tissues.

Diagram: Comparison of Normal and Cancer Cells

Types of Tumours

Benign Tumours

Benign tumours are new formations of cells that do not metastasize and are not considered cancerous. They develop at a very slow rate, and they possess clear boundaries. There are types such as lipomas, which are fatty tissue tumours, and fibromas, which are fibrous tumours. Benign tumours may sometimes be a problem by making their pressure on vital organs or tissues apparent. Examples: Lipomas, fibromas

Malignant Tumours

Malignant tumours are cancerous, can exert considerable pressure on the surrounding tissues, and can grow to a very large size. They can also extend (metastasize) to other areas of the body via the blood or lymphatic system. Some examples include Carcinomas- such as breast cancer; Sarcomas- such as Osteosarcoma, Carcinomas, etc.

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Diagram: Benign vs. Malignant Tumours

Pre-malignant Tumours

Pre-malignant precursors are not malignant growths, but on the other hand, they have neoplastic characteristics and can turn into invasive malignant growths. There are conditions such as dysplasia and carcinoma in situ. As already mentioned, timely diagnosis of the diseases and their appropriate treatment are essential to avoid metastasis and cancer progression. Examples: Dysplasia, carcinoma in situ

Types of Cancer

Carcinomas

Carcinomas are those types of cancer that begin in the epithelial cells; these are the cells that form the lining of the internal and outer surfaces of the body. These are prevalent, general types of cancer and comprise breast, lung, prostate, and colorectal cancers, among others. Carcinomas are typically categorised into two subtypes: adenocarcinomas, the cancer that originates in the glandular cells, and squamous cell carcinoma, which originates in the squamous cells. Carcinomas are known to metastasize to other tissues in the body via the blood or lymph nodes, hence the need to conduct an early diagnosis.

Sarcomas

Sarcomas are cancers that occur in the connective tissue, tissues that support the body’s structure, like bones, muscles, fat, blood vessels, and cartilage. They can affect any part of the body but are often seen in the arms, legs, and trunk. Types of sarcomas include osteosarcoma, which is a cancer that originates in the bones, and liposarcoma, which is a cancer that begins in fatty tissues. While carcinomas commonly come from epithelial cells, sarcomas originate from mesenchymal cells, which are cells of connective tissues. Sarcomas are not very common and can be located in varying areas of the body; therefore, diagnosing and particularly treating them can be quite complex.

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Leukemias

Leukaemias are blood and bone marrow disorders that are classified in the group of cancers due to the overproduction of immature or dysfunctional white blood cells. These mutated cells can hinder the manufacturing of proper blood cells and are capable of travelling to different organs of the body through circulation. Leukaemias are classified into four main types: a. all; b. acute myelogenous leukaemia; c. chronic lymphocytic leukaemia; and d. chronic myelogenous leukaemia.

Some of the common signs that people who have this disease exhibit include fatigue, recurrent infections, and bleeding/bruising. Leukaemia, like all types of cancer, is treated through the application of chemotherapy, radiation therapy, and, in certain cases, hematopoietic stem cell transplantation.

Lymphomas

Lymphomas are classified as cancers of the lymphatic system, a component of the body’s immune system made up of, amongst others, the lymph nodes, the spleen, the thymus gland, and bone marrow. There are two main types of lymphomas: Hodgkin's disease, which is specifically characterised by the presence of Reed-Sternberg cells, and non-Hodgkin which includes a large spectrum of LCA.

Lymphomas' first symptoms are swollen lymph nodes, fever, sweating at night and intermittent loss. The treatment is usually chemotherapy, radiation therapy for stages I and II, and targeted therapy to reduce the effects of immunotherapy for stages III and IV.

Central Nervous System Cancers

CNS cancers are cancers that start in the brain and spinal cord of the body. : CNS cancers are classified under head and neck cancers since they involve the brain and spinal cord. These cancers can be primary, which originated in the CNS, or secondary, in which cancers spread to the CNS from other parts of the body.

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Some of the types of cancer are invasive brain tumours such as glioblastoma, or, at times, an arising tumour by the name of meningioma, which is usually a benign tumour common to the protective membrane of the brain and spinal cord called meninges. As for the CNS cancer symptoms, they can differ a lot based on the tumour’s location: pain, seizures, confusion or changed personality, and trouble coordinating movements. The common forms of therapy include surgery, radiation, and chemotherapy.

Melanoma

Melanoma is a skin cancer that originates in the melanocyte cells, which are the skin cells that make melanin, which is the pigment that gives the skin its colour. Melanoma, although not as common as other forms of skin cancer, is more hazardous since the cancerous cells can spread to other parts of the body if checked early. Some of the causes of melanoma are staying for long in the sun without a protective layer or using a tanning bed, having light skin, and having a history of melanoma in a family.

Myeloma

Myeloma, also known as multiple myeloma, is a form of cancer that affects plasma cells – a category of white blood cells prevalent in the bone marrow. Plasma cells are related to the production of antibodies that assist in combating diseases and other disorders. Cancer of Plasma cells in multiple myeloma takes place in the bone marrow and hinders the production of normal blood cells.

Consequently, this may result in symptoms like bone pain, fractures, fatigue, recurrent infections, and anaemia for the patient. Some of the different Myeloma treatments include Chemotherapy, Radiation therapy, Targeted therapy, Immunotherapy, and Stem cell transplant types.

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Table: Types of Cancer and Affected Areas

Causes and Risk Factors

Genetic factors

Some gene changes can be inherited by parents, so people can have a predisposition to some types of cancer. For instance, certain changes in the genes known as BRCA1 and BRCA2 are associated with breast and ovarian cancer. Although the actual genetic makeup is predetermined, genetic counselling and testing can aid in the early detection of people genetically susceptible to the said diseases, thus ensuring early prevention. It is important to establish the relevance of genetics for the differential treatment of cancer and the creation of new therapies.

Environmental factors

These lifestyle choices and exposures put a person at a higher probability of acquiring the disease; for instance, exposure to carcinogens, radiation, or chemicals. Carcinogens are agents capable of causing cancer, be it chemical, such as asbestos, benzene, or formaldehyde, or physical, such as UV light, radiation from surgeries, or atomic explosion. The regular use of these carcinogens results in DNA changes for the worse, which lead to cancer. To minimise the number of cases of cancer, people should avoid being exposed to various environmental carcinogens that may increase the incidence of the deadly disease.

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Lifestyle factors

Lifestyle factors are some of the risks that can easily be modified to fit the needs of a cancer-free life. Unhealthy behaviours, for example, smoking, taking too much alcohol, having an unhealthy diet, and a lack of exercise often put one at high risk of developing many types of cancer. For example, smoking is associated with lung cancer; increased quantities of processed foods and red meat are associated with colorectal cancer. Also, daily exercise and the intake of foods that are produced from fruits, vegetables, and whole grains can help reduce the rate of cancer. A longer, healthy life is one of the main components of the fight against cancer, so it is important to make the right choices when it comes to our diets.

Infections

Some of these are viruses, bacteria, and parasites that, when they infect a person, cause cancer. It is widely understood that HPV is linked to cervical and other cancers, as well as hepatitis B and C, which are the leading causes of liver cancer. For instance, H. pylori is known to cause stomach cancer, while Epstein-Barr virus is in some ways connected to some types of lymphomas. It should be noted that these infections can cause chronic inflammation or directly lead to genetic mutations that provoke the development of malignant neoplasms. Other preventive measures include vaccination against HPV and hepatitis B and the availability and application of effective infection-curing treatments.

Mechanisms of Cancer Development

Genetic Mutations

Genetic mutations are alterations in the DNA sequence of a cell’s genome and are considered the main cause of cancer. These mutations may be inherited or sought through genomic exposure to the carcinogens or may be the result of mistakes in DNA replication. These are inherited changes in the genes that cause cells to become cancerous, possibly through the activation of oncogenes or the loss of functions of the tumour suppressor genes, hence altering the natural control of cells’ division. Through the process of time, various abnormalities combine and the ability to form cancer emerges.

Oncogenes and Tumour Suppressor genes

These are mutated proteins that affect the growth and division of cells, while the other one is the gene that is involved in the control of a cell's growth and division. Oncogenes are genes changed from normal genes (proto-oncogenes) that operate cell division that is settled on the genetic change. They act in such a way that when they are over-expressed, they lead to the uncontrollable growth of cancer cells.

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On the other hand, the tumour suppressor genes normally prevent cell division and promote apoptosis. Mutations of tumour suppressor genes result in disruption of the pathway that stimulates cell growth and stops proliferation, which leads to cancer. The normal functioning of a cell depends on the regulation of oncogenes that promote cell division and the tumour suppressor genes that slow down or stop this process.

Stages of Cancer Development

Cancer progression includes initiation, promotion, progression, and metastasis.

1. Initiation: Changes in the genes take place in a cell, and the latter suffers DNA changes which serve as the basis for cancer formation.

2. Promotion: For more cell division, mutated cells are characterised by extra modifications and aspects, as well as promoting structures such as inflammation and hormones.

3. Progression: The progressing neoplastic cell mass undergoes still more mutations, becomes even more malignant, and has the capability of invading adjacent tissues.

4. Metastasis: They result when, from the primary tumour mass, cancerous cells break away and are transported through the blood or lymph nodes, producing new tumours.

Symptoms of Cancer

General Symptoms

Some of the common signs of cancer are the following; abrupt and sudden loss of weight, fatigue, fever, and pains that will not go away. Such signs ensue because cancer impacts bodily processes and causes inflammation and metabolic shifts. Some of the frequent symptoms are night sweats, lack of appetite, and any changes in bleeding or discharges. It is important to note that these signs can be due to several other illnesses; nonetheless, the sustained manifestation of one or several or their occurrence together must not be excluded on the grounds of cancer.

Symptoms Specific To Different Types Of Cancer

Tumour markers specific to certain kinds of cancer depend on the organ or tissue affected. For instance, breast malignant neoplasms can manifest within a woman through breast mass, breast modification in shape, or even discharge from the nipple. Some signs of colorectal cancer include a change in bowel movement, blood in bowel movement, and stomach ache.

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Prostate cancer would present symptoms that relate to a man’s urinary system, whereas skin cancer could show itself through the formation of new moles or a change in their appearance. These are the specific symptoms that, if identified, can enable early diagnosis of the condition, thereby improving the outcome of the treatment.

Diagnosis of Cancer

Table: Diagnostic Methods for Different Types of Cancer

Physical Examination

A physical assessment is, in many circumstances, the first procedure in the detection of cancer. During the exam, the physician may search for signs of cancer, including, for instance, hard, unusual skin texture and/or swelling and lumps of certain organs. The examination may also help to determine the state of the patient’s health and reveal any other pathologic conditions that should be investigated

Laboratory Tests (Blood Tests, Urine Tests)

Other diagnostic tests that can be performed on patient’s blood and urine can also be used to diagnose cancer among patients. For example, laboratory tests can indicate high levels of tumour or incorrect blood patterns typical for leukaemia. A chemical examination includes an examination of urine and can indicate such things as abnormal proteins or blood, indicating the possibility of bladder or kidney cancer. Some of these tests are sometimes conducted as part of other groups of tests.

Imaging Tests (X-rays, CT Scans, MRI)

Common diagnostic or screening tools such as X-rays, CT scanners, or MRIs are critical in cancer diagnosis. X-rays can define tumours in bones and internal organs, while Computer Tomography or CT scans offer a sectional picture of the whole body and the size and position of tumours. MRI employs the use of magnets to generate very clear images of soft tissues and is thus quite effective in identifying cancers in the brain, spine, and joint areas. Such imaging procedures assist in ascertaining the stage at which the disease has progressed and even in the planning of the appropriate treatment.

Biopsy

A biopsy is the physical removal of small tissue from the suspected site of cancer and examination under a microscope. It is the gold standard in cancer diagnosis because it enables pathologists to identify the presence of cancerous cells and differentiate between the kind of tumour and its stage. A biopsy of a tumour can be done by needle, endoscopic, or through an operation, depending on the location and size of the tumour.

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Treatment of Cancer

Surgery

Surgery is one of the most recommended forms of treatment and is usually the first line of treatment, especially where the cancer is detected early. Surgical intervention entails excision of the tumour and, in certain circumstances, may also include excision of normal tissue or even lymph nodes with the view of trying to stop the spread of cancer.

Some surgical operations may be done with minor incisions, which are less severe than Laparoscopic surgery, others may require more incisions, which are major surgeries, than Open surgery. Many factors can affect the success of the operation such as the type, size, and location of the tumour, and the general health status of the patient. Therefore, it requires a critical and intensive recovery and rehabilitation period to minimise the possibility of recurrence as well as to attain functional capacity.

Radiation Therapy

Radiation therapy consists of using rays or particles with high energy to cause damage to the DNA of the cancerous cell. It can be given from outside the body using a machine (external beam radiation) or by putting a radioactive source into the body close to the cancer (brachytherapy). Cancer treatment using radiation is common to reduce tumour size before surgery, eliminate the remaining cancerous cells after surgery, or treat cancers that are too advanced for surgery. Radiation therapy is still a powerful weapon in cancer treatment, but it also harms healthy skin, causing tiredness, redness, or other symptoms relevant to the irradiated area.

Chemotherapy

Chemotherapy entails the use of drugs to eliminate cancerous cells that reproduce at an increased rate. It is orally active or given intravenously and is commonly used in treating cancers that have spread, or are not easily operable. Chemotherapy is administered in a manner that kills the rapidly dividing cancer cells but at the same time impacts other cells in the body that also divide rapidly hence, some of the side effects include hair loss, nausea and vomiting, fatigue, and increased susceptibility to infections. Nevertheless, this treatment method is considered to be the standard of care for cancer, along with other therapeutic approaches.

Immunotherapy

Immunotherapy relies on the body’s immune system to combat cancer by improving its effectiveness. These are various forms, including checkpoint inhibitors that assist the immune system in identifying cancer cells to destroy them and CAR T-cell therapy that acts on the patient’s T-cells to make them target cancer.

Despite this fact, Immunotherapy has recorded very positive outcomes in curing cancer types that do not respond to conventional treatments, like melanoma and forms of lung cancer. Some of the possible side effects include extended inflammation and typical flu-like symptoms but immunotherapy can be quite effective in the long-term fight against cancer.

Prevention and Early Detection

Table: Preventative Measures for Common Cancers

Lifestyle Changes (Diet, Exercise)

Changes in lifestyle, like regular exercise, eating a balanced diet, and avoiding certain activities, such as smoking, can help prevent cancer. Nutritious foods such as fruits, vegetables, whole grain products, and lean meat contain nutrients and antioxidants that prevent cell damage. Exercise keeps all the hormones balanced and enhances the body’s immune system, and that plays a vital role in controlling cancer. The above lifestyle changes do not only reduce the chances of developing cancer but also the general quality of life.

Avoiding Risk Factors (Tobacco, Alcohol)

Several factors, such as tobacco use and excess alcohol consumption, should therefore be avoided to prevent cancer. Smoking is also related to many other diseases, of which lung cancer is the most apparent; there are others like mouth cancer, throat cancer, bladder cancer, etc. Likewise, the consumption of alcohol is also clearly linked to cancer-type diseases like liver, breast, and colon cancer. According to the information received, it can be noted that many dangers are associated with smoking and alcohol consumption, and most of them can be mitigated by stopping the vice.

Vaccinations (HPV, Hepatitis B)

Some specific viruses can cause cancer, and certain vaccinations keep one from getting infected by these viruses. The HPV vaccine is a vaccine that prevents HPV, which is known to cause most cervical cancers and some head and neck cancers. The hepatitis B vaccine lowers the occurrence of liver cancer since it protects against chronic hepatitis B virus infection. These vaccines are highly effective and are considered preventive measures against the forms of cancer highlighted when provided before contact with the viruses.

Regular Screenings and Self-examinations

Checkups and self-examination are important in the early diagnosis of cancer, a process that enhances survival rates when the disease is spotted at its early stage. Procedures like mammography, Pap smears, colonoscopies, and low-dose computed tomography are screening tests and they can identify cancers such as breast, cervical, colorectal, and lung cancer at stages that are easier to manage. These include examinations that one feels free to conduct on their body, such as checking for funny lumps or changes of the skin. Screening recommendations from different organisations and raising awareness of body changes can save lives.

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Role of Genetics in Cancer

Inherited vs. acquired mutations

Inherited mutations are genetic changes that are subsequently passed from one generation to the next, which increases the risk of developing cancer. These mutations are somatic and are located in every cell of the body, and though rare, they greatly increase an individual’s likelihood of developing particular types of cancer, for instance, BRCA 1 & 2 in breast and ovarian malignancies.

Somatic mutations, in contrast, are those mutations that occur in a person’s lifetime through the influence of factors such as UV light, chemicals, or errors made during DNA replication. It is significant to know both epigenetic and considered hereditary mutations as a risk factor responsible for the initiation of the cancer even if they are secondary.

Genetic counselling

It is the process of informing individuals and families about the existing hereditary risks of developing cancer. It involves assessing the wellness risks of inherited mutations depending on their respective personal and family group medical histories. These professionals accompany patients through genetic testing and explain the significance of the results to them. This service is very useful in decision-making on the use of prevention measures and the screening and treatment of probable diseases. Genetic counselling also deals with the psychological aspects and the methods of handling genetic information.

Example: BRCA1 and BRCA2 genes in breast cancer

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