Cancer

What is cancer?

Cancer is the name given to diseases in which uncontrolled cell division is observed. Cells are the basic units of the body, like “bricks”. Normally, the body generates new cells as needed, replacing aging cells as they die. Sometimes this process is not normal or expected and unnecessary new cells grow and the aged cells do not die when they should. These additional cells can form a tumor or neoplasm, which can be benign (non-cancerous) or malignant (cancerous). Malignant cells can invade other tissues and parts of the body, a process known as metastasis. The most common cancers are skin cancer, lung cancer, breast cancer and colorectal cancer.

The malignancy of cancer is variable, depending on the aggressiveness of the cells and the other biological characteristics of each type of tumor. Normally, cancer cells are characterized by not having the reproductive control required by their original function, losing their original characteristics and acquiring others that do not correspond to them, such as the capacity to progressively invade nearby organs, growing and dividing beyond the normal limits of the organ and spreading through the body via the lymphatic or circulatory system, which can cause new tumors in other parts of the body.

Cancer can affect all ages, including fetuses, but the risk of cancer increases with age.

There are more than 100 different types of cancer. They are usually named after the organ or tissue where they occur. Some of the categories of cancers that begin in specific cells include:

• Carcinoma. They are the most common. They are formed in the epithelial cells, that is, those that cover the surfaces of the body. There are different types: adenocarcinoma (forms in the cells that produce fluids or mucus, and are the majority of breast, colon and prostate cancers), basal cell carcinoma (starts at the base of the epidermis), squamous cell carcinoma (cells that are under the outer surface of the skin and other organs, such as the stomach, intestines, lungs, bladder and kidneys) and transitional cell carcinoma (forms in an epithelial tissue called transitional epithelium or urothelium, and is in the lining of the bladder, ureters and part of the kidneys).
• Sarcoma. They form in bone and soft tissues, including muscle, fatty tissue, lymphatic vessels, blood vessels and fibrous tissue, such as ligaments and tendons. Osteotoma is the most common bone sarcoma. In soft tissues they are Kaposi’s sarcoma, leiomyosarcoma, malignant fibrous histiocytoma, liposarcoma and dermatofibrosarcoma protuberans.
• Leukemia. Cancer that begins in the blood-forming tissues, in the bone marrow. It does not form solid tumors but abnormal white blood cells accumulate in the blood and bone marrow and displace normal blood cells. This can make it difficult for the body to get oxygen to the tissues, make it difficult for the body to control bleeding, or make it unable to fight infection.
• Lymphoma. A cancer that starts in the lymphocytes, the white blood cells that fight infection and disease and are part of the immune system. The abnormal lymphocytes go on to accumulate in the lymph nodes and vessels, as well as in other organs.
• Multiple myeloma. This is a cancer that originates in plasma (also immune) cells. The abnormal plasma cells (myeloma cells) accumulate in the bone marrow and form tumors throughout the body.
• Melanoma. This is the cancer that originates in cells that become melanocytes, that is, those specialized in producing melanin (pigment that gives color to the skin). Most of them form in the skin, but they can also appear in other pigmented areas, such as the eyes.
• Brain and spinal cord tumors. There are different types and they are named after the cell where they formed and where the tumor first formed in the central nervous system. Brain tumors can be benign or malignant.
• Germ cell tumors. They start in the cells that form sperm or eggs. They can occur anywhere in the body and can be malignant or benign.
• Neuroendocrine tumors. They are formed in cells that secrete hormones into the blood, in response to some signal from the nervous system. They can produce hormones in larger than normal amounts. They can also be benign or malignant.
• Carcinoid tumors. These are a type of neuroendocrine tumor. They grow slowly and are usually found in the gastrointestinal tract, especially in the rectum and small intestine, although they can also spread to the liver and other parts of the body.

The cancer is caused by abnormal cell division.

Prognosis of the disease

In general, cancer leads to death if the patient does not receive adequate treatment. The risk of cancer increases with age and causes 13% of all deaths.

The chances of survival, once the diagnosis has been made, depend on whether the tumor has been identified early and on the type of cancer, as some will be much more aggressive than others. With the exception of skin carcinoma, which is usually curable in almost 100% of cases, cancer is curable in 50% of patients. The prognosis will be influenced by

• The histological type with degree of cellular differentiation.
• The location of the tumor.
• The extent of the disease.
• The age of the patient.
• The functional status of the patient.

Cancer symptoms

The symptoms of cancer will depend on its location, its size and how much the organ or tissues are affected. If the cancer has metastasized, symptoms may appear in different parts of the body.

As the tumor grows, it begins to put pressure on nearby organs, nerves and blood vessels. This pressure, in some cases, causes symptoms, especially if it is located in certain parts of the body, such as the brain.

Other symptoms that cancer can cause are fever, tiredness or weight loss. This is because cancer cells use a lot of the body’s energy or secrete substances that affect the way the body produces the energy it gets from food. On the other hand, cancer can also cause the immune system to react causing these symptoms.

There may also be other more obvious symptoms, depending on the organ affected. Some examples are bloody sputum in cases of lung cancer, problems urinating in bladder cancer, bleeding on defecation in colon cancer, palpable nodules in breast cancer, etc.

Medical tests for cancer

For the diagnosis of cancer, the first thing to do is to take a detailed medical history of the patient, to detail the symptoms. Then complementary tests should be done to confirm the cancer. The specialist in Medical Oncology will decide what tests are necessary, which may be: X-ray of the area where the cancer is located, endoscopy, blood tests, ultrasound, magnetic resonance imaging or computerized axial tomography. In addition, for a 100% reliable diagnosis, a biopsy will be necessary, which will allow the histological study of the tissue.

On the other hand, some specific genetic or molecular studies may also be performed:

• Biomarkers. These are molecules in the blood or found in tumor tissues and are not normally found in a normal cell. Their presence serves as an indicator of a possible pathological process or risk of suffering from it. Proteomic (protein), chromosomal, genomic markers or gene abnormalities in oncogenes can be studied.
• Grading and staging. It is used to classify cancer cells in terms of their difference from normal cells.

What are the causes of cancer?

Cancer does not have a single cause but is the result of the interaction of many risk factors. Most cancers (90-95%) are caused by environmental factors and 5-10% are due to genetic factors. There are also other factors that can cause it:

• High body mass index.
• Low fruit and vegetable intake.
• Lack of physical activity.
• Smoking. Tobacco is the cause of 20% of cancer deaths.
• Alcohol.
• Viral infections (hepatitis B and C and Human Papilloma Virus), responsible for up to 20% of cancer deaths.
• Radiation exposure. Up to 10% of invasive cancers are related to radiation exposure.
• Genetic. These are mutations that inactivate genes whose function is to limit cell division and eliminate dead cells.

Can it be prevented?

Cancer cannot be prevented but there are factors that influence its appearance. One third of cancer deaths are due to avoidable behavioral and dietary habits: high body mass index, low fruit and vegetable intake, lack of physical activity, smoking and alcohol consumption.

Cancer treatments

Cancer treatment is based on 4 fundamental points: surgery, chemotherapy, radiotherapy and immunotherapy. Other avenues of treatment, depending on the type of cancer, its stage and so on, also include bone marrow transplantation or hormone therapy.

In any case, treatment must be multidisciplinary, since tumors usually affect several organs and systems, even if they are located in a specific place. Thus, the family physician, the surgeon, the radiotherapist, the oncologist and the specialist in each specific area may be involved, depending on the location of the cancer: dermatologist, gynecologist, gastroenterologist, pulmonologist, etc.

Whether there is a treatment option should be decided with the specialist. The response to treatment may be complete, if all symptoms have disappeared, or partial, if there is a decrease in lesions.

It should also be decided before starting treatment whether the objective is palliative or curative. Given that some cancers are very difficult to cure if they are already very advanced, in some cases it is preferable to forego the curative option and choose a palliative treatment that provides the patient with the best quality of life and the least possible pain.

Which specialist treats it?

The specialist who treats the cancer is the expert in Medical Oncology. Doctors from other specialties will also intervene, depending on the location of the tumor: dermatologist, gynecologist, pulmonologist, gastroenterologist, among others. In addition, the patient will also be seen by expert radiologists, anesthesiologists (if necessary and for surgery) and other professionals, to ensure the best control of the cancer and provide the best treatment.