Autoimmune diseases are when the immune system attacks healthy cells in your body. There are many different types of autoimmune diseases, from ulcerative colitis and Crohn’s disease to psoriasis and psoriatic arthritis (PsA).
Some autoimmune diseases have been linked to an increased risk for various types of cancer such as lymphoma.
For example, research suggests that people with rheumatoid arthritis (RA) and lupus are at slightly higher risk and people with Sjögren syndrome are at significantly higher risk for lymphoma than people who don’t have these conditions.
It’s been harder to determine whether psoriasis and PsA also increase the risk of lymphoma. Some studies have suggested an increased risk, while others haven’t.
Read on to see what the research so far says about the risk of lymphoma in people with psoriatic disease.
Lymphoma is the most common type of blood cancer. It starts in white blood cells called lymphocytes, which normally help your body fight off infections. Lymphocytes are located in lymph nodes and lymphoid tissues throughout the body, including in the skin, bone marrow, and gastrointestinal tract.
Lymphoma can occur anywhere you have lymphocytes. There are two main types of lymphomas:
- non-Hodgkin lymphoma, which accounts for the majority of cases
- Hodgkin lymphoma
Psoriasis and PsA are chronic inflammatory conditions. Psoriasis inflammation causes red and scaly patches to form on the skin.
About 30 percent of people with psoriasis also have PsA. In PsA, the immune system also produces inflammation that damages the joints, causing swelling, stiffness, and pain.
Some research suggests that lymphoma risk is anywhere from
Psoriasis is most often linked to an increased risk of T-cell lymphoma, which is a type of non-Hodgkin lymphoma.
It’s unclear whether psoriasis itself increases the risk for T-cell lymphoma. It may be that this cancer is sometimes misdiagnosed as psoriasis. The two diseases cause similar symptoms, including scaly, itchy patches of skin. A skin biopsy may be needed to tell them apart.
While some research suggests that people with more severe psoriasis may be more likely to get lymphoma than those with milder disease, other studies have found no link between PsA severity and lymphoma risk.
The risk of lymphoma doesn’t seem to be as high with PsA as it is with psoriasis. PsA wasn’t linked to an increased risk of cancer in a
Researchers don’t know exactly why people with autoimmune diseases like psoriasis and PsA are at higher risk for lymphoma. Studies point to a few possible reasons for the connection.
An overactive immune system
Psoriasis and PsA are autoimmune disorders, which is when your immune system overreacts against your own body. Immune system cells attack the joints and skin just as they normally attack bacteria and other potentially dangerous invaders.
Lymphoma starts in a type of immune cell called a lymphocyte. The overactive immune system in people with psoriatic diseases may cause lymphocyte cells to divide faster than normal, leading to cancer.
Certain drugs that treat psoriasis and PsA work by tuning down your body’s immune system response so that inflammation can’t damage your joints and skin. A weakened immune system could also increase the risk for lymphoma.
Another 2014 study found people with PsA had a 20 percent higher likelihood of lymphoma than the general population. That risk increased to 70 percent in people who were treated with the conventional disease-modifying drugs (DMARDs) methotrexate and/or sulfasalazine.
Inflammation isn’t always a bad thing. When you’re injured, it can help your body heal. But when inflammation is chronic, like in psoriasis and PsA, it can damage cells.
Long-term chronic inflammation can disrupt DNA, which is the genetic material inside cells. DNA changes can cause cells to divide uncontrollably and become cancer.
Shared risk factors
Some of the same factors put you at risk for more severe psoriasis and PsA may also increase the risk for lymphoma, including:
- being overweight (body mass index [BMI] of 25 to 29.9)
- having obesity (BMI of greater than or equal to 30)
- having metabolic disorders
- increased alcohol use
There might be other risks connecting the two diseases that researchers don’t know about yet.
The link between psoriasis, PsA, and lymphoma hasn’t been proven. And even if having psoriatic disease does make you more likely to get this cancer, your overall risk is very small.
Risk increases if you have psoriasis or PsA and other conditions that have been linked to lymphoma, such as Sjögren syndrome.
It’s still a good idea to be aware of your cancer risk, especially if you also have a strong family history of lymphoma or other known risk factors. If you have psoriasis or PsA, know the lymphoma symptoms:
- swollen glands
- unexplained weight loss
- night sweats
- tiredness that doesn’t go away
- shortness of breath
Report these and any other unusual symptoms to your doctor. You can have tests to rule out or diagnose cancer.
Also have a conversation about your medicines with the doctor who treats your psoriatic disease. Find out if your treatment might put you at increased risk for lymphoma, and if so, whether you need extra screening.