What is Cancer?

Cancer is not just one disease. It is a large and complex family of malignancies that can affect virtually every organ in the body. Cancer is second only to heart disease as the leading cause of death in the United States. Over 1.2 million new cases are diagnosed every year, with half of them occurring in the lung, prostate, breast, colon and rectum. Cancer can strike at any age, although it is most common in people over 50.

Cancer begins in the body’s cells, which are constantly dividing and multiplying to replace old, damaged cells. Sometimes, cells begin to divide unnecessarily, forming excess tissue known as a tumor. In most cases, tumors are benign, meaning that they are not cancerous. Benign tumors, although they may cause some health problems depending on their size and location, are not life-threatening.

However, if an abnormal cell begins to divide, it eventually forms a malignant or cancerous tumor. Most malignant tumors grow quite rapidly, invading nearby organs and tissues. Cancerous cells can also travel through the bloodstream to other regions of the body. When cancer spreads from its original site, the process is known as metastasis.

The good news is that cancer death rates have been declining in recent years, especially among men who generally experience higher rates than women.  Increasing public awareness has resulted in more people getting regular cancer screenings and practicing healthy lifestyles to reduce their risk.

Types of Cancer

There are many different types of cancer. Several factors, including location and how the cancerous cells appear under the microscope, determine how cancer is diagnosed. For example, there are several forms of breast cancer, classified according to where the tumors originate within the breast and their tendency to invade surrounding organs and tissue.

All cancers fall into one of four broad categories:

  • Carcinomas are tumors that arise in the tissues that line the body’s organs. About 80% of all cancer cases are carcinomas.
  • Sarcomas are tumors that originate in bone, muscle, cartilage, fibrous tissue or fat.
  • Leukemias are cancers of the blood or blood-forming organs.
  • Lymphomas affect the lymphatic system, a network of vessels and nodes that acts as the body’s filter. The lymphatic system distributes nutrients to blood and tissue and prevents bacteria and other foreign “invaders” from entering the bloodstream. There are over 20 types of lymphoma.

Symptoms of Cancer

Unfortunately, many types of cancer don’t display any obvious symptoms or cause pain until well advanced. Because early-stage cancer symptoms tend to be subtle, they are often mistaken for signs of other less-threatening diseases. The seven warning signs of cancer are:

  • Changes in bowel or bladder habits
  • A sore that does not heal
  • Unusual bleeding or discharge
  • Thickening or lump in the breast or any other part of the body
  • Indigestion or difficulty swallowing
  • An obvious change in a wart or mole
  • A nagging cough or hoarseness

Some symptoms are specific to certain types of cancer, such as difficult urination for prostate cancer or flu-like symptoms for acute leukemias. Don’t be afraid to discuss unusual symptoms with your doctor!  Diagnostic tests are available for most common cancers. If diagnosed early, your chances of surviving cancer are greatly increased.

Diagnosis of Cancer

There is a wide array of methods to diagnose cancer. As researchers learn more about the mechanisms of cancer, new diagnostic tools are constantly being developed and existing methods refined. If your primary care physician suspects cancer, he or she may order some tests to confirm the diagnosis. These tests can either be conducted by your physician or by oncologists at cancer centers. A second opinion by a cancer expert is strongly recommended. Accurate identification of cancer allows oncologists to choose the most effective treatment. The most common diagnostic methods include:


A small tissue sample is surgically removed and examined under a microscope for the presence of cancer cells. Depending on tumor location, some biopsies can be done on an outpatient basis with only local anesthesia. If the tumor is filled with fluid, a fine needle may be inserted directly into the suspicious area to draw out fluid samples for examination.


A flexible plastic tube with a tiny camera on the end is inserted into body cavities and organs, allowing the physician to view the suspicious area.  There are many types of scopes, each designed to view particular areas of the body. For instance, a colonoscope is used to detect growths inside the colon and a laparoscope is used to examine the abdominal cavity.

Diagnostic imaging

Several techniques are used to produce an internal picture of the body and its structures. Types of imaging methods include x-rays, CAT scans, Magnetic Resonance Imagery, and Ultrasound.

Blood tests

Some tumors release substances called tumor markers, which can be detected in the blood. A blood test for prostate cancer determines the amount of prostate specific antigen (PSA). Higher than normal PSA levels can indicate cancer. A blood test for ovarian cancer is known as CA-125. However, blood tests by themselves can be inconclusive and other methods should be used to confirm the diagnosis.

Treatment of Cancer

At most cancer centers, a multidisciplinary approach to cancer care involves a team of specialists including a medical oncologist, a surgeon, a radiation oncologist, a pathologist, and other healthcare professionals. There are four major types of cancer treatment: surgery, radiation therapy, chemotherapy, and immunotherapy. These therapies can be used either alone or in combination with each other. Location, size and stage of the tumor, and your overall health determine which treatment or treatments you will receive. Many new treatments, including cancer vaccines and gene therapy, are being studied in clinical trials.

  • Surgery is the oldest form of treatment. About 60% of patients will undergo some sort of surgery, either by itself or in combination with other therapies.
  • Chemotherapy uses powerful drugs to kill cancer cells, control their growth, or to relieve pain symptoms.
  • Radiation uses large doses of high-energy beams or particles to destroy cancer cells in a specifically targeted area.
  • Immunotherapy, also known as biologic therapy, stimulates the body’s own defense systems to fight cancer.
  • Gene Therapy identifies missing or defective genes that cause cancer or increase cancer risk, and replaces them with normal copies.
  • Clinical Trials can provide options for patients who have not responded to standard therapies.

Prevention of Cancer

Up to 85% of cancers can be prevented by avoiding environmental risk factors like smoking, sun exposure, alcohol abuse and poor nutrition. Knowing your personal cancer risk can help you devise a prevention strategy with regular screenings and healthy lifestyle choices. Many people considered high-risk never develop cancer while others with no known risk factors become ill.

Many cancer treatment centers have Cancer Prevention Programs that can help you with risk assessment, cancer screening, genetic testing and other services, including information on nutrition and smoking cessation. Follow the road to cancer prevention by taking charge of your health.


Reference: M.D. Anderson Cancer Center