Like the tips of a magnet, cancer and autoimmunity share a common origin but exert powerful forces that work in opposite directions. Both diseases result from failures in the body’s immune system. Cancer often develops because the immune system failed to do its job in attacking defective cells, allowing the cells to divide and grow. Conversely, an autoimmunity—a faulty immune response that leads to diseases such as colitis and lupus—occurs when the immune system has mistakenly attacked healthy cells.
On their own, cancer and autoimmunity often create difficult and challenging circumstances for doctors and patients. In patients diagnosed with either disease, these two opposing forces may collide, further complicating treatments and side-effect management efforts. “There is a definite connection between many autoimmune diseases and cancer,” says Anthony Perre, MD, Internist at our Philadelphia hospital and Chief of the Division of Outpatient Medicine for Cancer Treatment Centers of America® (CTCA). “For example, many autoimmune diseases may lead to inflammation, which has been implicated as a factor in the development of cancer.”
WHAT IS AUTOIMMUNE DISEASE?
- Autoimmune diseases occur when the body’s immune system, designed to only attack defective or foreign cells, attacks healthy cells.
- Like cancer, autoimmune disease usually starts in a single organ or body part.
- Symptoms are wide-ranging, depending on the disease and the part of the body it affects.
- Autoimmune disease may attack an organ that prevents production of certain hormones. Type 1 diabetes, for instance, attacks the pancreas, limiting the production of insulin.
- Some autoimmune diseases, such as rheumatoid arthritis, lupus or colitis, cause chronic inflammation or pain.
- There are more than 80 different types of autoimmune disease.
- More than 25 million Americans have been diagnosed with some type of autoimmune disease.
- About 75 percent of autoimmune diseases are diagnosed in women.
- Autoimmune diseases may be treated with steroids, immunosuppressant drugs or monoclonal antibodies designed to reduce inflammation.
Autoimmune disease and immunotherapy
Autoimmune disease and cancer both seek to control the body’s immune system, pushing and pulling immune cells in different directions. For patients diagnosed with both diseases, a medical oncologist acts as a referee to see that neither side of this cellular war has an overwhelming advantage, especially if the cancer treatment involves immunotherapy drugs called checkpoint inhibitors. Patients with autoimmune disease, who already have overactive immune systems, may have difficulty tolerating these immunotherapy drugs, which stimulate immune cells to better recognize and attack cancer. “You need to have that conversation upfront, because immunotherapy may not be an option, unfortunately,” says Ashish Sangal, MD, Medical Oncologist and Medical Director of the CTCA® Lung Cancer Center at our Phoenix hospital. “If you have an active autoimmune disease, immunotherapy can cause your immune system to flare up, so you have a worsening of your autoimmune disease.”
In the seven years since the U.S. Food and Drug Administration approved the first checkpoint inhibitor drug ipilimumab (Yervoy®), these immunotherapies have changed the course of cancer treatment for many patients. So far, six checkpoint inhibitors have been approved to treat a variety of cancers. “We all have an immune system that needs to step on the gas pedal to fight infections quickly when a foreign invader comes in,” says Alan Tan, MD, Clinical Research Medical Director and Medical Oncologist and Hematologist at our Phoenix hospital. “Immunotherapy fights cancer by releasing the brakes of the immune system and unleashes the power of the immune system to fight cancer cells.” Immunotherapy may be a safe cancer treatment option for some patients with autoimmune disease, by balancing immune suppressive drugs with immune-stimulating checkpoint inhibitors, Dr. Tan says. “The autoimmune condition can often be managed,” he says. “And many times, autoimmune adverse events are a good indicator that the immunotherapy is also working to fight the cancer as well. As always, weigh the risks and benefits and have a well-informed conversation with your physician.”
COMMON AUTOIMMUNE DISEASES:
- Addison’s disease attacks the adrenal glands and prevents production of certain hormones.
- Celiac disease occurs when the immune system attacks gluten in the intestine, causing inflammation.
- Graves’ disease attacks the thyroid gland, causing severe fatigue, weight loss and bulging eyes.
- Inflammatory bowel disease is caused by chronic inflammation of the lining of the digestive tract.
- Multiple sclerosis is caused by damage to nerve cells, which leads to numbness and weakness.
- Psoriasis and psoriatic arthritis occurs when the body produced new skin cells faster than it can shed old ones, causing red and scaly patches. In some cases, psoriasis patients may develop swelling and pain in their joints.
- Rheumatoid arthritis occurs when the immune system attacks joints, causing stiffness and pain.
- Sjorgren’s syndrome attacks the glands that produce saliva and tears.
- Type 1 diabetes occurs when the immune system attacks insulin-producing cells in the pancreas.
Risks from disease and treatment
Autoimmune disorders generally attack a single organ or part of the body, often causing inflammation in the affected area. In some cases, that inflammation may increase cancer risk. Autoimmune diseases that affect the gastrointestinal tract—inflammatory bowel disease, Crohn’s disease and colitis, for instance—cause chronic inflammation in the digestive system that increases the risk of colorectal cancer. Chronic inflammation may damage cell DNA, which may lead to uncontrolled cell growth, one of the hallmarks of cancer.
“Chronic inflammation may also suppress our immune system and affect our ability to repair the damage to our DNA,” Dr. Perre says. To battle inflammation and limit autoimmune flare-ups, doctors often prescribe drugs called TNF inhibitors, which help reduce inflammation, or an immunosuppressant such as cyclosporin. These drugs are suspected of increasing the risk of multiple cancers. “Treatments that suppress our immune system are commonly used to treat autoimmune disorders, but they may impair our ability to kill cancer cells,” Dr, Perre says. “Some drugs used to treat arthritis and psoriasis may increase a patient’s risk of developing lymphoma.”
Challenging side effects
Autoimmune diseases cause a variety of side effects, depending on which organ or body part is affected. Many of the symptoms of these side effects, such as diarrhea, skin rashes, fatigue and bone and joint pain, mirror those that some cancer patients experience due to the disease itself or certain treatments. A patient who has irritable bowel syndrome or Crohn’s disease may already have issues with diarrhea and gastrointestinal distress. Or a patient with lupus or psoriasis may struggle with rashes, itchy skin or bone pain. Chemotherapy or immunotherapy may worsen these symptoms in some patients. “A medical oncologist must balance effectiveness of a treatment against side effects and quality of life,” Dr. Perre says. “There are times when the side effects of treatment may limit the ability to give treatment.”
Doctors and researchers know more than ever about the connection between autoimmune disease and cancer, how to balance treatments and manage side effects. Doctors are also learning more about how to balance the benefits of immunotherapy drugs, which were once off limits to cancer patients with autoimmune disease. “When checkpoint inhibitors were first being studied, they excluded patients with autoimmune disease, especially if it was active or required suppressive drugs,” Dr. Tan says. “With more experience, we are more comfortable with trying immunotherapy on patients with active autoimmune disease, as long as it is, in general, under control. Patients should talk to their doctor and consider the benefits and risks of doing so.”
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