Cancer is a class of diseases characterized by uncontrolled growth of cells in the body. They can develop in any part of the human body. Normally, human cells grow and divide to produce new cells when the body needs them. When cells get too old or damaged and they die, then new cells take their place.
Cancer begins when this orderly process breaks down, causing cells to divide in an uncontrolled way. These extra cells may form a mass of tissue called a tumor (except cancers that involve the blood, such as leukemia). A tumor can be benign or cancerous. A benign tumor means the tumor can grow but it will not spread. A cancerous tumor is malignant which means it can grow and spread to other parts of the body.
How Cancer Spreads
As a cancerous tumor grows, the bloodstream or lymphatic system may carry cancer cells to other parts of the body. This process is called metastasis. One of the first places a cancer often spreads is to the lymph nodes. Lymph nodes are tiny, bean-shaped organs that help fight infection. They are located in clusters in different parts of the body, such as the neck, groin area, and under the arms.
Cancer may also spread through the bloodstream to distant parts of the body. These parts may include the liver, bones, or brain.
Cancer that has spread from the original site to other places in the body is generally classified as advanced. When the cancer has spread only to nearby tissues or lymph nodes, it is called locally advanced cancer. When the cancer has spread to other parts of the body, it is called metastatic cancer.
Types of Cancer
There are over 100 different types of cancer, and they are often named by the type of cell or the organ where they begin. For example, lung cancer starts in the lung, breast cancer starts in the breast, and prostate cancer starts in the prostate.
Different types of cancer can be grouped into several categories:
- Carcinoma: Cancer that begins in the skin or in tissues that covers internal organs and glands. Carcinomas usually form solid tumors. These types of cancer include prostate cancer, breast cancer, lung cancer, and colon cancer.
- Leukemia: Cancer that starts in the tissues that make blood cells, such as the bone marrow. These cancers do not form solid tumors. The four main types of leukemia are acute lymphocytic leukemia, chronic lymphocytic leukemia, acute myeloid leukemia, and chronic myeloid leukemia.
- Lymphoma: Cancer that affects the immune system. There are two main types of lymphoma: Hodgkin lymphoma and non-Hodgkin lymphoma.
- Multiple myeloma: Cancer that forms from plasma cells in the bone marrow. Multiple myeloma is also called plasma cell myeloma and Kahler disease.
- Sarcoma: cancer that forms in bone and soft tissues such as fat, muscle, blood vessel, nerves, or other connective tissue. The most common bone cancer is osteosarcoma.
- Melanoma: cancer that begins from the pigment-containing cells known as melanocytes which produce melanin – pigment that gives your skin its color. Most melanomas form on the skin, but melanomas can also form in other pigmented tissues, such as the eye.
What are the Causes and Risk Factors of Cancer?
It is often difficult to know exactly why one person develops cancer and another doesn’t. But research has shown that certain risk factors may increase a person’s chances of developing cancer.
Some risk factors such as lifestyle or environmental risk factors can be avoided, while others such as family history and inherited factors can not.
- Cigarette smoke: It is the leading cause of cancer and death from cancer – about one in nine cancers, and one in five cancer deaths. Cigarette smoke causes many types of cancer, including cancer of the lung, mouth, larynx, throat, bladder, pancreas, colon and rectum, as well as acute myeloid leukemia.
- Sunlight: Exposure to UV radiation from sunlight causes early aging of the skin and skin damage that can lead to skin cancer.
- Ionizing radiation: This radiation can damage normal cells and increase the risk of developing breast cancer, thyroid cancer, and lung cancer.
Excessive intake of particular foods, such as processed meat and fatty foods, are associated with an increased risk for some types of cancer, including uterine cancer, colorectal cancer and prostate cancer.
Drinking alcohol can increase your risk of cancer of the mouth, throat, esophagus, larynx (voice box), liver, and breast. The more you drink, the higher your risk. The risk of cancer is much higher for those who drink alcohol and also smoke tobacco.
Some families have higher risk for certain cancers compared with other families. For example, the risk for a woman to develop breast cancer increased by 1.5 to 3 times if her mother or sister had the cancer. Some types of cancer develop as a result of genetic factors that occur in families include breast cancer, ovarian cancer, colorectal cancer, prostate cancer, and skin cancer.
Certain infectious agents, including viruses, can disrupt signaling that normally keeps cell growth and proliferation in check. Also, some infections weaken the immune system, making the body less able to fight off cancer-causing infections.
Several viruses that can cause cancer include:
- Human papillomavirus (HPV) which can cause genital warts presumably, leading to cervical cancer in women.
- Hepatitis B and C which can cause liver cancer.
- Epstein-Barr virus which can cause cancers of the nose and throat.
- HIV virus which can cause lymphoma and other blood cancers.
Symptoms of Cancer
Cancer symptoms vary widely and depend on where the cancer is located and how big the tumor is. In certain cancers, such as colon cancer, symptoms often do not appear until the disease has reached an advanced stage. The following are some early symptoms associated with most cancer:
- Loss of appetite
- Persistent, unexplained fevers or night sweats
- Unexplained weight loss or weight gain
- Changes in bowel habits
- Unusual bleeding such as blood in the urine or blood in the stool
- A thickening or lump on or under the skin
- Skin changes, such as rash, changes in previous mole, etc
Specific Cancer Symptoms
The following are specific symptoms associated with certain types of cancer:
The common symptoms of brain cancer include headaches, seizures, weakness, numbness in arms and legs, difficulty walking, drowsiness, abnormal changes in vision, changes in personality, etc.
The common symptoms of breast cancer include a lump or thickening in the breast, changes in the size of the breast, unexplained swelling of the breast, pain in the breast or nipple, and nipple discharge.
The common symptoms of bladder cancer include frequent urination, Pain on urination, blood in the urine, and low back pain.
The common symptoms of cervical cancer include vaginal bleeding, unusual vaginal discharge, pelvic pain, and leakage of urine or feces from the vagina.
The common symptoms of colon cancer include change in bowel habit, constipation, blood in the stool, abdominal pain, and unexplained weight loss.
The common symptoms of lung cancer include chest pain, feeling tired, shortness of breath, a cough that doesn’t go away, coughing up blood, weight loss and loss of appetite.
Symptoms of ovarian cancer usually appear at the advanced stage. These include persistent abdominal bloating, frequent urge to urinate, fatigue, changes in bowel movements, sudden weight gain or weight loss, back pain, and vaginal bleeding.
The common symptoms of prostate cancer include Urinate more often than usual, especially at night, pain when passing urine, difficulty in having an erection, and pain during ejaculation.
The common symptoms of leukemia include chronic fatigue, fever, swollen lymph nodes, frequent infections, bleeding easily, recurrent nosebleeds, and unintended weight loss.
Most of these symptoms may also be caused by benign tumors or other health problems. If you have the symptoms that last for few weeks, it is important to consult with your doctor so that the problems can be diagnosed and treated as soon as possible.
Diagnosis of Cancer
Diagnosing cancer at its earliest stages often provide the best chance for a cure. Your doctor may ask about your personal and family medical history and do a physical exam. Your doctor also may use one or more approaches to diagnose cancer:
- Laboratory tests
Laboratory tests, such as blood and urine tests, may help your doctor identify abnormalities that can be caused by cancer.
- Imaging tests
Imaging tests create pictures of areas inside your body that help the doctor see whether a tumor is present. Imaging tests used in diagnosing cancer may include CT scan, MRI, PET scan, ultrasound and X-ray.
A biopsy is a procedure in which the doctor collects a sample of cells for testing in the laboratory. A pathologist then looks at the tissue under a microscope to see if it is cancer. In most cases, a biopsy is the only way to definitively diagnose cancer.
Treatments for Cancer
Cancer is one of the leading causes of death in the world. Most cancers can be treated and cured, especially if the treatment started early. There are many types of cancer treatment. The treatment you receive will depend on the type of cancer, the stage of the cancer, and your general health. The goal of cancer treatment is to kill or destroy the cancer cells while killing as few healthy cells as possible and improve your quality of life. The treatment options include:
Surgery is a procedure in which a surgeon removes cancer from your body. Surgery is often used in combination with chemotherapy and/or radiotherapy to make sure that any cancer cells remaining in the body are completely removed.
Chemotherapy is a type of cancer treatment that uses drugs to kill cancer cells. It is generally used to kill cancer that has spread because the medicines travel throughout the entire body. As well as killing cancer cells, chemotherapy also kills normal cells that are rapidly dividing. But, unlike cancer cells, normal cells can heal itself and recover.
Radiation therapy, also known as radiotherapy, is a type of cancer treatment that uses X-rays to kill cancer cells and shrink tumors. Although radiation also damages normal cells, cancer cells are especially sensitive to its effects. This makes radiation therapy an effective treatment for many types of cancer.
Radiation therapy can be given either from outside (external beam) or inside the body (brachytherapy), depending on the type and location of your cancer. In external beam radiation therapy, a machine directs radiation at the cancer and surrounding tissue. In internal radiation therapy, radioactive material is placed close to the cancer cells.
Stem Cell Transplant
Stem cell transplant, also known as bone marrow transplant, is a procedure that replaces unhealthy blood-forming cells with healthy cells. A stem cell transplant allows doctors to use higher doses of chemotherapy to increase the chance of eliminating blood cancer in the marrow and then restoring normal blood cell production. This treatment may be recommended for people with blood cancers such as leukemia, lymphoma or myeloma.
Hormone therapy is a treatment that aims to stop or slow the growth of certain types of cancer that use hormones to grow. These include breast and prostate cancers.
Breast cancer hormone therapy often focus on reducing estrogen levels while prostate cancer hormone therapy often focus on reducing testosterone levels. In addition, some leukemia and lymphoma cases can be treated with the hormone cortisone.
Immunotherapy, also known as biological therapy, uses your body’s immune system to fight cancer. Immunotherapy can be given in a number of ways, including orally, topically, intravenously (injected into a vein), and travesically (administered directly into the bladder).
Immunotherapy works better for some types of cancer than for others. It’s used by itself for some of these cancers, but for others it seems to work better when used with other types of treatment.
Targeted therapy is a newer type of cancer treatment that uses drugs or other substances to stop cancer from growing and spreading. Targeted therapy differs from standard chemotherapy because it is designed to act on specific molecular targets and attack cancer cells without harming healthy cells. This is done by targeting specific genes or proteins. These genes and proteins are found in cancer cells or in cells related to cancer growth, like blood vessel cells.
Targeted therapy can be used as the main treatment for some cancers, but in most cases it used with other treatments such as radiation therapy and/or chemotherapy.
How to Prevent Cancer
Many studies have shown that the majority of cancers are caused by unhealthy lifestyle habits such as unhealthy diet, obesity, smoking, and a lack of physical activity. So making a healthy lifestyle change is the most effective way to prevent cancer.
Although not all cancers are preventable, but the risk of developing cancer can be greatly reduced by applying these healthy habits to your lifestyle.
- Exercise regularly. Several studies have shown that regular physical activity can significantly reduce the risk of breast and colon cancer. By exercising regularly, you can reduce your risk of cancer by 30-50%.
- Eat a healthy balanced diet. There are many benefits that you can get from eating a healthy diet. In addition to weight loss, it is also useful to reduce the risk of cancer. Try to consume plenty of fruits and vegetables, and limit the intake of red and processed meat.
- Not smoking. If you do smoke, quit it. If you don’t smoke, don’t start it. Smoking is linked to several types of cancer. Stopping now will reduce your risk of cancer in the future.
- Limit alcohol intake. Drinking alcohol is known to increase the risk of some cancers, including breast cancer, colon cancer, mouth cancer, larynx cancer and oesophageal cancer. Experts recommend that if you drink alcohol, limit yourself to two drinks a day if you are a man and one drink a day if you are a woman.
- Maintain a healthy weight. Being overweight has been linked to cancers of breast, colon, kidney, prostate, and oesophageal. If you are overweight, cut some weight can make a difference. Learn more about how to lose weight.
- Avoid excessive sun exposure. Exposure to ultraviolet (UV) rays from the sun can increase your risk of skin cancer. To protect yourself from the sun’s ultraviolet rays, stay out of direct sunlight between 10:00 AM and 4:00 PM where the sun’s rays are the most intense; wear a wide-brimmed hat, a long-sleeve shirt and pants that covers as much of your skin as possible, or apply sunscreen with a sun protection factor (SPF) of 30 or higher.
Read also: 10 best foods to fight cancer