Cancer Basics

Whether you or a loved one has been diagnosed with cancer, there are many resources that can help you cope. Knowing what to expect is one of the best resources during treatment and recovery.

Learn about cancer, its causes, risk factors, and how radiation therapy can treat cancers throughout the body.

What is Cancer?

Image courtesy of NCI Center for Cancer Research, Thomas Ried.

Cancer is not a single disease, but instead refers to a collection of related diseases. There are over 100 types of cancer which can occur all throughout the body. Some types spread quickly while others are slow-growing. In all types of cancer, the body’s cells divide without stopping and cause damage to healthy tissue.

Normally, cells divide, age, die or are damaged, and are replaced by new cells. Cancerous cells do not follow this orderly process; instead, they grow uncontrollably. Old or damaged cells do not die while new cells form when they are unneeded. Normal cells become crowded out. These excess cells may form solid growths of abnormal cells called tumors. Many, but not all cancers form tumors.

Some tumors can be painless. Others, such as those which grow in a bone or near sensitive nerves, are painful. Some tumors can cause problems in the part of the body where the cancer is located, disrupting a patient’s comfort or daily life. For example, a tumor near the esophagus can make activities such as eating or drinking difficult or painful.

Cancerous tumors are malignant and can spread into surrounding tissue. Cancer can also metastasize, which means that it can spread to other more distant parts of the body. After surgery, cancerous tumors may grow back after being removed if all cancerous cells are not neutralized.

How Cancerous Cells Spread

Image courtesy of Cancer Research UK.

There are many ways that cancerous cells can grow out of control, unlike normal cells.

Most normal mature cells are specialized, meaning that they develop into distinct types that each have a specific function to perform. Cancerous cells are less specialized and do not perform a specific function, which is one reason they continue to grow without stopping.

Cancer cells also can ignore rules that normal cells follow. For example, cancer cells can ignore signals that tell normal cells to stop dividing. Cancerous cells can also ignore signals to begin apoptosis, ‘programmed cell death’, so that the body can get rid of unnecessary cells.

Cancer cells sometimes metastasize, which means that they can break off from the main tumor and spread to other parts of the body. When this happens, additional malignant tumors can form.

The body’s immune system normally keeps an individual healthy and protected from infections and illness. Cancerous cells, however, may evade the immune system by manipulating immune system cells to stop killing cancerous cells. Without the body’s natural defense, cancer cells can spread unchecked.

In addition to evading the immune system, cancer that spreads into bone marrow can weaken the immune system. Bone marrow creates new blood cells necessary to fight infections and illness, including cancer.

Cancerous cells can create a microenvironment from surrounding normal cells to provide an ideal environment for them to grow. This may include inducing normal cells to forming new blood vessels that gives a tumor resources such as oxygen, nutrients, and waste removal.

Types of Cancer Treatment

There are many types of cancer treatment options. The exact type used will depend on the type and location of the cancer. As such, your doctor may use one or a combination of treatments for optimal effect.

The most common types of cancer treatment include:

• Chemotherapy
• Surgery
• Targeted therapy
• Immunotherapy
• Radiation therapy

Photodynamic therapy, blood transfusions, laser treatment, and other techniques may also be used to treat cancer.

Not all types of cancer respond to treatment in the same way, so it’s important for a patient to receive the right type of treatment for their specific cancer.

Blue Ridge Radiation Oncology specializes in Radiation Therapy to treat a wide range of cancer sites and various nonmalignant disorders.

Stages of Cancer

The progression of a patient’s cancer is usually classified in stages. The stage of a cancer refers to its size and how far it has spread from the point of origin.

A cancer in one of the lower stages (1 or 2) means that it has not spread very much. Cancer in a higher stage (3 or 4) has spread farther.

Determining the stage of a cancer helps your doctor determine the severity of a cancer and your chances of survival. The stage will also help your doctor determine the best type of treatment for you.

The stage of a cancer will always be referred to as the one given at diagnosis even if a cancer improves or worsens.

What Causes Cancer?

Cancer is a genetic disease, which means that it is the result of changes in the DNA. When working properly, genes make sure that cells act like they should – reproducing and dividing, dying, and being replaced in a normal, orderly way.

Cancer is caused by changes to the genes which control the way that cells work. This change can occur in one or a small group of cells.

Cells can normally repair damaged genes. However, damage can accumulate over time. When damage occurs faster than it can be repaired, abnormal cells may spread and form tumors.

There are many potential factors that can cause changes in a gene:

• It is possible to inherit faulty genes from one or both parents.
• Environmental factors such as exposure to UV rays and carcinogens can also damage DNA.
• Cells may become faulty over time, causing errors in the way that cells divide.
• Gene changes can even occur by chance when a cell divides.

At least half a dozen mutations need to take place in a given cell before it turns cancerous.

Genetic changes may be the result of one or a combination of factors that are unique to every person:

• A cell may produce too many proteins for replication.
• A cell may not produce the proteins that tell a cell to stop dividing.
• A cell may produce abnormal proteins that can affect its normal instructions or function, causing it to grow uncontrolled.

As a tumor grows and spreads, additional genetic changes can take place. Multiple genetic changes can take place in a single tumor.

Risk Factors for Cancer

It is unclear why some people develop cancer while others do not. Few cancers have a single, identifiable cause.

Risk factors are potentially contributing causes that may, on their own or in combination with other risk factors, increase a person’s chances of developing cancer. Many years may pass before cancer develops following exposure to a risk factor.

There is no guaranteed way to prevent cancer. For instance, some people develop lung cancer without ever smoking a cigarette, while some long term smokers live cancer-free. Reducing risk factors may improve the relative risk associated with developing a given type of cancer.

Some risk factors are controllable, such as lifestyle behaviors. Others, such as age or family history, are not controllable.

Risk factors for cancer include:

• Age
• Alcohol
• Carcinogens (cancer-causing substances)
• Chronic Inflammation
• Diet
• Family History
• Hormones
• Immunosuppression (medication to deliberately suppress the immune system)
• Infectious Agents (viruses, bacteria, parasites)
• Obesity
• Radiation
• Sunlight
• Tobacco

Even if a person has one or more of these risk factors, it is uncertain how or to what extent a risk factor may contribute to the development of cancer later in life.

How Does Radiation Therapy Treat Cancer?

Radiation therapy uses specific doses of radiation over a set period of time to kill cancer cells. Radiation damages the DNA of the cancerous cells, destroying their ability to reproduce and spread. As a result, the tumor may shrink or go into remission.

The dose is carefully planned by a radiation care team so that enough radiation is being delivered to the cancer to kill abnormal cells while minimizing the damage to healthy cells.

Healthy cells which are damaged during radiation therapy can usually self-repair following treatment.