autoimmune diseases | CTCA
Cancer and autoimmunity, like the ends of a magnet, share a common origin but exert powerful forces that run in opposite directions. Both diseases are the result of a failure in the body’s immune system. Cancer often develops because the immune system fails to do its job of attacking the defective cells, allowing the cells to divide and grow. Instead, autoimmunity, a defective immune response that leads to diseases such as colitis and lupus, occurs when the immune system mistakenly attacks healthy cells.
Cancer and autoimmunity alone often create difficult and challenging conditions for clinicians and patients. In patients diagnosed with either disease, these two opposing forces can collide, further complicating treatments and efforts to manage side effects. “There is a clear association between many autoimmune diseases and cancer,” says Anthony Berry, MD, chief of ambulatory medicine at Cancer Centers of America. ® (CTCA). “For example, many autoimmune diseases can cause inflammation, which is a factor in the development of cancer.”
What is an autoimmune disease?
- Autoimmune diseases occur when the body’s immune system, which is designed to attack only defective or foreign cells, attacks healthy cells.
- Like cancer, autoimmune diseases generally begin in one organ or part of the body.
- Symptoms vary greatly depending on the disease and the affected part of the body.
- Autoimmune diseases can attack an organ that blocks the production of certain hormones. Type 1 diabetes, for example, attacks the pancreas and limits insulin production.
- Some autoimmune diseases, such as rheumatoid arthritis, lupus, or colitis, cause chronic pain or inflammation.
- There are more than 80 different types of autoimmune diseases.
- More than 25 million Americans have been diagnosed with some form of autoimmune disease.
- Autoimmune diseases can be treated with steroids, immunosuppressive drugs, or monoclonal antibodies designed to reduce inflammation.
Autoimmune diseases and immunotherapy
Autoimmune diseases and cancer seek to control the body’s immune system, pushing and pulling immune cells in different directions. For patients diagnosed with both diseases, the medical oncologist acts as an arbiter to know that neither side in this cellular war has an overwhelming advantage, especially if the cancer treatment includes immunotherapy drugs called checkpoint inhibitors. Patients with autoimmune diseases, who already have an overactive immune system, may find it difficult to tolerate these immunotherapy drugs, which stimulate immune cells to better recognize and attack cancer.
Since 2011, when the US Food and Drug Administration approved the first drug ipilimumab (Yervoy® ) , these immunotherapies have changed the course of cancer treatment for many patients. To date, seven checkpoint inhibitors have been approved to treat a variety of cancers. “We all have an immune system that needs to press on gas to fight infection quickly when a foreign invader arrives,” says Alan Tan, MD, medical director of clinical research and an oncologist and hematologist at Phoenix Hospital. “Immunotherapy fights cancer by unleashing the brakes on the immune system and unleashing the power of the immune system to fight cancer cells.”
Immunotherapy may be a safe cancer treatment option for some patients with autoimmune diseases, by balancing immunosuppressive drugs with immune-stimulating checkpoint inhibitors. An autoimmune condition can often be controlled. And oftentimes, autoimmune adverse events are a good indication that immunotherapy is also working to fight cancer, says Dr. Tan. “As always, weigh the risks and benefits and have an informed conversation with your doctor.”
Common autoimmune diseases:
- Addison’s disease attacks the adrenal glands and blocks the 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 puffy eyes.
- Inflammatory bowel disease results from chronic inflammation of the lining of the digestive tract.
- Multiple sclerosis is caused by damage to nerve cells, resulting in numbness and weakness.
- Psoriasis and psoriatic arthritis occur when the body produces new skin cells faster than old ones, causing red, scaly patches to appear. In some cases, patients with psoriasis may develop joint pain and swelling.
- Rheumatoid arthritis occurs when the immune system attacks the joints, causing stiffness and pain.
- Sjögren’s syndrome attacks the glands that secrete saliva and tears.
- Type 1 diabetes occurs when the immune system attacks the insulin-producing cells in the pancreas.
Disease risks and treatment.
Autoimmune disorders generally attack one organ or part of the body, often causing inflammation in the affected area. In some cases, this inflammation can increase the risk of developing cancer. Autoimmune diseases that affect the digestive system — inflammatory bowel disease, Crohn’s disease, and colitis, for example — cause chronic inflammation in the digestive system that increases the risk of colorectal cancer. Chronic inflammation can damage cellular DNA, which can lead to uncontrolled cell growth, a hallmark of cancer.
“Chronic inflammation can also suppress our immune system and affect our ability to repair damage to our DNA,” Dr. Berry says.
To fight inflammation and reduce autoimmune flare-ups, doctors often prescribe medications called TNF inhibitors, which help reduce inflammation, or immunosuppressants such as cyclosporine. These drugs are suspected of increasing the risk of developing multiple cancers. “Therapies that suppress our immune system are commonly used to treat autoimmune disorders, but they can affect our ability to kill cancer cells,” Dr. Berry says. “Some medications used to treat arthritis and psoriasis can increase a patient’s risk of developing lymphoma.”
Autoimmune diseases can also increase the risk of cancers of the blood, bone marrow, and lymph nodes, such as leukemias and lymphomas. According to a 2012 study in Hematology , about 10 percent of all cases of acute myeloid leukemia are thought to result from treatments for other conditions, such as chemotherapy and radiotherapy for cancer, or immunosuppressive drugs that treat autoimmune diseases.
Some autoimmune diseases alone, and not necessarily the medications that treat them, are associated with an increased risk of acute myeloid leukemia, such as rheumatoid arthritis and ulcerative colitis. It is believed that patients whose immune systems do not function optimally (either due to illness or treatment, including those with autoimmune diseases) are at increased risk of developing acute leukemia.
The immunosuppressant cyclophosphamide for rheumatoid arthritis has been found to specifically increase the risk of leukemia, bone marrow and lymph nodes, which is one reason it is now used less frequently and for short periods of time only in serious cases. Other rheumatoid arthritis medications, such as azathioprine and methotrexate, have also been linked to lymphoma. Researchers have found that advanced-stage rheumatoid arthritis increases the risk of developing lymphoma.
Lupus, rheumatoid arthritis, Crohn’s disease, Graves’ disease/hyperthyroidism, and sarcoidosis have been associated with an increased risk of lung cancer. Although researchers have found a link between autoimmune diseases and lung cancer risk, the incidence of autoimmune diseases and lung cancer does not appear to affect the prognosis or overall survival of lung cancer.
Interestingly, a lower risk of breast cancer is associated with some autoimmune diseases, such as lupus, rheumatoid arthritis, and pernicious anemia (Addison’s anemia). The opposite is true for psoriasis, which is associated with an increased risk of breast cancer. Researchers are still studying why people with psoriasis have an increased risk of breast cancer, but they have ruled out a treatment for the condition.
Autoimmune diseases affecting muscles, polymyositis, and dermatomyositis are most strongly associated with an increased risk of bladder cancer. Additionally, studies have shown an increased risk of all urinary tract cancers, including bladder, prostate, and kidney cancers, in people with autoimmune diseases.
Challenge side effects
Autoimmune diseases cause a variety of side effects, depending on the affected organ or part of the body. Many of the symptoms of these side effects, such as diarrhea, rashes, fatigue, and bone and joint pain, are similar to those experienced by some cancer patients because of the disease itself or some treatments. A patient with irritable bowel syndrome or Crohn’s disease may already have problems with diarrhea and digestive upset. Or a patient with lupus or psoriasis may have problems with rashes, itchy skin, or bone pain. Chemotherapy or immunotherapy can worsen these symptoms in some patients. “A medical oncologist must balance treatment efficacy, side effects, and quality of life,” says Dr. Perry. “There are times when the side effects of treatment can limit the ability to give it.”
Doctors and researchers know more than ever the relationship between autoimmune diseases and cancer, and how to balance treatments and manage side effects. Doctors are also learning more about balancing the benefits of immunotherapy drugs, which were previously out of reach for cancer patients with autoimmune diseases. “When checkpoint inhibitors were first studied, patients with autoimmune diseases were excluded, especially if they were active or needed suppressive medications,” says Dr. Tan. With more experience, we feel more comfortable testing immunotherapy in patients with of active autoimmune disease, provided it is generally under control. Patients should speak to their physician and consider the benefits and risks of doing so.”