Our immune system works hard to fight viruses, bacteria and infections. However, in some of us, the immune system doesn't work like it should. When you have an autoimmune disease, it causes your immune cells to attack your body. This can happen anywhere in the body. Autoimmune diseases are more common in women and are thought to be caused by both genetics and environmental factors.
There are more than 80 autoimmune diseases, according to the National Institute of Environmental Health Sciences. In the U.S., autoimmune diseases affect more than 24 million people, the NIEHS reports. Some of the most common autoimmune diseases include:
-- Autoimmune thyroid disease.
-- Inflammatory bowel disease.
-- Lupus (also called systemic lupus erythematosus).
-- Rheumatoid arthritis.
-- Type 1 diabetes.
You may have heard that people with an autoimmune disease are at a higher risk for cancer. The truth is, it can vary depending on the type of autoimmune disease you have and the medications you use.
"The risk is very particular to the specific autoimmune disease diagnosis, and usually the risk is for a specific type or types of cancer," says Dr. Timothy Niewold, a professor of rheumatology and pathology and director of the Colton Center for Autoimmunity at NYU Langone Health in New York. "This suggests that there is something in common in the causal factors between certain autoimmune diseases and specific types of cancer."
The treatments used for certain autoimmune diseases also play a role in increasing the risk for cancer. It's challenging for researchers to analyze cancer risk in patients with autoimmune diseases because of the many factors that appear to link them together, says Dr. Rosalind Ramsey-Goldman, Arthritis Research Society Research Professor at the Feinberg School of Medicine, Northwestern University in Chicago. She's also a Lupus Foundation of America Medical-Scientific Advisory Council member.
Autoimmune Disease and Cancer Risk
Here are a few examples to show the connection between autoimmune disease and a potentially higher risk for cancer.
Rheumatoid Arthritis and Lung Cancer
Rheumatoid arthritis is an inflammatory disorder that causes painful swelling of the joints. However, it also can cause heart and breathing problems. People with rheumatoid arthritis are at a slightly increased risk for certain types of cancer, including lung cancer, says Dr. Anne R. Bass, a rheumatologist with the Hospital for Special Surgery in New York. If you have rheumatoid arthritis and you smoke, you have a 40% higher risk of developing lung cancer than those who smoke but don't have the disease, the Arthritis Foundation reports.
This higher risk could be caused by chronic inflammation -- a known cancer risk factor -- occurring in someone who has rheumatoid arthritis. At the same time, people who smoke are at a higher risk for both arthritis and lung cancer, Bass explains. This could be part of the environmental link between rheumatoid arthritis and lung cancer, along with the potential genetic factors that have a role.
Sjögren's Syndrome and Lymphoma
Sjögren's syndrome is an autoimmune disease most commonly associated with dry eyes and dry mouth. You can have Sjögren's on its own, or you can have it secondary to another autoimmune disease, such as lupus or rheumatoid arthritis. Like rheumatoid arthritis, Sjögren's can affect other parts of your body beyond the eyes and mouth, such as the kidneys and lungs.
People with Sjögren's are at a 7-fold to 19-fold higher risk for lymphoma, a type of cancer that affects the lymph nodes. Our lymph nodes are part of the system in our body that filters harmful substances. The lymphoma that occurs when you have Sjögren's is much more likely to occur in your salivary glands, which are a part of the body affected deeply by this particular autoimmune disease. The lymphoma that occurs is often easily treatable, according to the Sjögren's Syndrome Foundation.
Vasculitis and Bladder Cancer
Vasculitis is the word used to describe a few rare autoimmune conditions associated with inflammation of the blood vessels. In severe cases, a drug called cyclophosphamide (Cytoxan) may be used, Niewold says. This drug has some risk of bladder and other cancers. Cyclophosphamide is an immunosuppressant. This means it's a drug that works to dampen the response of the immune system. Those with severe vasculitis using cyclophosphamide may survive thanks to the drug but then later go on to develop leukemia/lymphoma or bladder cancer, according to information reported by the Johns Hopkins Vasculitis Center.
The risk is associated with how long the drug is used and at what dosage. The risk of bladder cancer also appears to be greater when cyclophosphamide is administered in the oral daily form. A National Institutes of Health study of 145 patients with Wegener's granulomatosis (a type of vasculitis) treated with daily cyclophosphamide found that 6% developed bladder cancer. Among patients followed for up to 15 years, the projected incidence of bladder cancer was as high as 16%.
There are other autoimmune diseases that carry a possible increased risk of cancer, either due to the disease itself or because of the medications used. Here are a few more examples:
-- Rheumatoid arthritis also is associated with a higher risk of lymphoma.
-- There's an increased risk of lung cancer with scleroderma, a group of diseases that chronically affect the skin and connective tissue.
-- Dermatomyositis, an autoimmune disease causing muscle weakness and a rash, is associated with a higher risk of several cancers, including breast, ovarian, lung and gastronintestinal tumors, Niewold says.
[SEE: Lupus Diet and Nutrition.]
Benefits and Risk
Even though some of the medications used for autoimmune diseases have a higher associated cancer risk, that doesn't mean you should stop using them, Bass says. "When we say there is an increased risk, it's still small. It might be that there's even a 20% increased risk, for example, versus patients without these diseases, but it still may be only 1 in 1,000 or 1 in 500 patients (who develop cancer)," she says. Your doctor treating your autoimmune disease will carefully balance your need to use a medication against any potential risks or side effects.
Make sure to use your medications as recommended and keep up with any scheduled doctor's appointments so they can monitor your autoimmune disease progress, advises Dr. Nilanjana Bose of the Rheumatology Center of Houston in Houston.
How Cancer Treatment Changes When You Have an Autoimmune Disease
If you have an autoimmune disease, can you receive the normal treatments when you have cancer? Chemotherapy can usually be normally administered. A newer treatment called immunotherapy may offer more promise. Immunotherapy turns on your immune system to help it fight cancer. Rheumatologists, the doctors who treat many autoimmune diseases, and oncologists are still researching this area.
Niewold points to a recent review at NYU Langone Medical Center of patients with rheumatoid arthritis who received immunotherapy. The review found that many of them did well, without a flare of arthritis or other serious immune-related event. Generally speaking, some autoimmune-type side effects -- such as pain, swelling or flu-like symptoms -- are expected with immunotherapy, Bass says. However, this seems to be a positive predictor of survival as it shows the immune system is being activated. For example, more than 80% of people without autoimmune disease also develop autoimmune-type side effects from immunotherapy, Bass explains.
A person with an autoimmune disorder who develops cancer may or may not be able to continue using their autoimmune treatments while also using immunotherapy, Bass says. It depends on the individual, the drug used and the disease that's present.
If you have cancer, it's important for your oncologist to get in touch with your rheumatologist or other specialist monitoring your autoimmune disease, Bose says. Rheumatologists often will consult with an oncologist after cancer treatment is complete to ask about appropriate changes to autoimmune disease treatment.
For instance, a drug called methotrexate (used for certain cancers and autoimmune diseases) and a class of drugs called tumor necrosis factor inhibitors (also used for many autoimmune diseases) may not be appropriate because they could contribute to the recurrence of the same cancer or a different cancer.
The results of immunotherapy are not as well-established for rarer autoimmune conditions. At this point, the risks and benefits need to be reviewed individually for each patient, Niewold says.
Monitoring for Cancer Risk
If you have an autoimmune disease, there are a few things you can do to monitor for any increased cancer risk.
Keep up with any regularly scheduled cancer screenings. People with autoimmune diseases usually don't have more cancer screenings than the general population, Bass says. However, it still is important to keep up with any age-appropriate cancer screenings your health care team recommends, be it for skin cancer, breast cancer or other cancer types.
For some diseases, doctors may advise extra monitoring for cancer. If you have psoriasis, your regular visits with a dermatologist can help monitor for skin cancer. For patients on immunosuppressants, your doctor might advise annual Pap smears to check for cervical cancer if you're female or lung cancer screening for past or current heavy smokers, Ramsey-Goldman says. Regular dental visits can help those with Sjögren's syndrome monitor their oral health and the risk for lymphoma in the salivary glands.
Do what you can to keep a healthy lifestyle, Bose advises. Eat a well-balanced diet, exercise regularly and manage your stress. These all can go a long way for anyone to help prevent cancer.
Vanessa Caceres began writing for U.S. News in 2017, originally specializing in diabetes. She's a nationally published health, travel and food writer with an undergraduate degree in journalism and psychology from Hampshire College in Amherst, Massachusetts, and a graduate degree in linguistics/bilingual education from Georgetown University in Washington, D.C. In addition to U.S. News, Vanessa's health writing has been published with Everyday Health, Self, Newsday HealthLink, EyeWorld, The Rheumatologist and various other publications. She is a member of Business Networking International (BNI). Connect with her on Twitter at @FloridaCulture.