Cancer is the general name for a group of more than 100 diseases. Although there are many kinds of cancer, all cancers start because abnormal cells grow out of control. Untreated cancers can cause serious illness and death.
Cancer starts when cells in a part of the body start to grow out of control. Cancer cell growth is different from normal cell growth. Instead of dying, cancer cells continue to grow and form new, abnormal cells. Cells become cancer cells because of DNA damage. DNA is in every cell and it directs all the cell’s actions. In cancer cells, the damaged DNA is not repaired, and the cell doesn’t die like it should. Instead, the cell goes on making new cells that the body doesn’t need. These new cells all have the same abnormal DNA as the first cell does. People can inherit abnormal DNA, but most DNA damage is caused by mistakes that happen while the normal cell is reproducing or by something in the environment. Sometimes the cause of the DNA damage may be something obvious like cigarette smoking or sun exposure. But it’s rare to know exactly what caused any one person’s cancer.
Most people with cancer will lose weight as some point. When you lose weight for no known reason, it’s called an unexplained weight loss. An unexplained weight loss of 10 pounds or more may be the first sign of cancer. This happens most often with cancers of the pancreas, stomach, esophagus, or lung.
Fever is very common with cancer, but it more often happens after cancer has spread from where it started. Almost all patients with cancer will have fever at some time, especially if the cancer or its treatment affects the immune system. Less often, fever may be an early sign of cancer, such as blood cancers like leukemia or lymphoma.
Fatigue is extreme tiredness that does not get better with rest. It may be an important symptom as cancer grows. It may happen early, though, in some cancers, like leukemia. Some colon or stomach cancers can cause blood loss that’s not obvious.
Pain may be an early symptom with some cancers like bone cancers or testicular cancer. A headache that does not go away or get better with treatment may be a symptom of a brain tumor. Back pain can be a symptom of cancer of the colon, rectum, or ovary. Most often, pain due to cancer means it has already spread (metastasized) from where it started.
Along with cancers of the skin, some other cancers can cause skin changes that can be seen. These signs and symptoms include:
- Darker looking skin
- Yellowish skin and eyes
- Reddened skin
- Excessive hair growth
- Physical exam. Your doctor may feel areas of your body for lumps that may indicate a tumor. During a physical exam he or she may look for abnormalities, such as changes in skin color or enlargement of an organ that may indicate the presence of cancer.
- Laboratory tests, such as urine and blood tests, may help your doctor identify abnormalities that can be caused by cancer. For instance, in people with leukemia, a common blood test called complete blood count (CBC) may reveal an unusual number of white blood cells.
- Imaging tests. Imaging tests allow your doctor to examine your bones and internal organs in a noninvasive way. Imaging tests used in diagnosing cancer may include computerized tomography (CT) scan, bone scan, magnetic resonance imaging (MRI), ultrasound and X-ray, among others.
- Biopsy. During a biopsy, your doctor collects a sample of cells for testing in the laboratory. In most cases, a biopsy is the only way to definitively diagnose cancer.
- Surgery. Surgery can be used to diagnose, treat, or even help prevent cancer in some cases. Most people with cancer will have some type of surgery. It often offers the greatest chance for cure, especially if the cancer has not spread to other parts of the body.
- Chemotherapy. Chemotherapy (chemo) is the use of medicines or drugs to treat cancer. Chemo may be used to:
- Keep the cancer from spreading.
- Slow the cancer’s growth.
- Kill cancer cells that may have spread to other parts of the body.
- Relieve symptoms such as pain or blockages caused by cancer.
- Cure cancer
- Radiation Therapy. Radiation Therapy uses high-energy particles or waves to destroy or damage cancer cells. It is one of the most common treatments for cancer, either by itself or along with other forms of treatment.
- Targeted Therapy. Targeted therapy is a newer type of cancer treatment that uses drugs or other substances to more precisely identify and attack cancer cells, usually while doing little damage to normal cells. Targeted therapy is a growing part of many cancer treatment regimens.
- Immunotherapy. Immunotherapy is treatment that uses your body’s own immune system to help fight cancer.
- Hyperthermia. The idea of using heat to treat cancer has been around for some time, but early attempts had mixed results. Today, newer tools allow more precise delivery of heat, and hyperthermia is being studied for use against many types of cancer.
- Stem Cell Transplant (Peripheral Blood, Bone Marrow, and Cord Blood Transplants)
- Photodynamic Therapy. Photodynamic therapy or PDT is a treatment that uses special drugs, called photosensitizing agents, along with light to kill cancer cells. The drugs only work after they have been activated or “turned on” by certain kinds of light.
- Lasers in Cancer Treatment. Lasers, which are very powerful, precise beams of light, can be used instead of blades (scalpels) for very careful surgical work, including treating some cancers.
- Blood Product Donation and Transfusion. Transfusions of blood and blood products temporarily replace parts of the blood when a person’s body can’t make its own or has lost them from bleeding.
Cancer and its treatment can cause several complications, including:
- Pain. Pain can be caused by cancer of by cancer treatment. Medications and other approaches can effectively treat cancer-related pain.
- Fatigue. Fatigue in people with cancer has many causes, but it can often be managed. Fatigue associated with chemotherapy or radiation therapy treatments is common, but it’s usually temporary.
- Difficulty breathing. Cancer or cancer treatment may cause a feeling of being short of breath. Treatments may bring relief.
- Nausea. Certain cancers and cancer treatments can cause nausea. Medications and other treatments may help you prevent of cope with nausea.
- Diarrhea or constipation. Cancer and cancer treatment can affect your bowels and cause diarrhea or constipation.
- Weight loss. Cancer and cancer treatment may cause weight loss
- Unusual immune system reactions to cancer. In some cases the body’s immune system may react to the presence of cancer by attacking healthy cells. Called paraneoplastic syndromes, these unusual reactions can lead to a variety of signs and symptoms, such as difficulty walking and seizures.
- Cancer that spreads. As cancer advances, it may spread (metastasize) to other parts of the body. Where cancer spreads depends on the type of cancer.
- Cancer that returns. Cancer survivors have a risk of cancer recurrence. Some cancers are more likely to recur than others.