Psoriasis Linked to Higher Risk of Developing, Dying of Cancer

People with psoriasis could be at greater risk of developing or dying of cancer, according to scientists.

After trawling through existing studies investigating the link between the two diseases, scientists concluded those with psoriasis had a 1.18-fold increased risk of developing a range of different types of cancer when compared with those without the condition. These included colon, colorectal, kidney, laryngeal, liver, lymphoma, mouth, esophagus, pancreas and non-melanoma skin cancers. The risk of developing, and dying, of cancer was 1.22 in those with severe psoriasis.

The study published in the journal JAMA Dermatology featured data from 58 observational studies. Due to the reporting of the studies it was not possible for the researchers to tally the total number of participants involved.

The chronic autoimmune disease, which makes skin cells grow faster than normal, can cause patches of thick, red skin and scales to develop on the body. These are most often found on the knees, scalp, elbows, lower back, face, soles of the feet and palms. It is usually treated using creams, but approaches like ultraviolet light therapy and drugs are also used.

Psoriasis is a chronic inflammatory disease, which has in the past been linked to cancer, the authors argued. The treatments used against the condition could also explain the link, they said.

Alex Trafford, co-author of the study in the Pharmacy Department at the U.K's Manchester University, told Newsweek: "This study is significant as it brings together a large body of literature considering the association between psoriasis and cancer in order to provide a more concise picture.

"To our knowledge, it is the first meta-analysis to consider how cancer risk differs according to the severity of psoriasis and it is also the first to explore how lifestyle factors, such as smoking and obesity, influence this risk."

However, he acknowledged as each study was designed differently and there were disparities in the results, the study is somewhat limited.

Addressing concerns those suffering from psoriasis may have due to the findings, Trafford said: "Although our study found an association between psoriasis and cancer, we also found considerable heterogeneity in the results.

More research is needed before any strong conclusions can be drawn, he said.

"It is also important to note that we found lower cancer risk in studies that took lifestyle factors, such as smoking and obesity, into account," he said. "This provides some evidence to suggest that, as with people without psoriasis, making healthy lifestyle changes might lower the risk of cancer."

The study comes after the World Health Organization highlighted psoriasis as a condition that requires more attention, explained Trafford. He is part of the Global Psoriasis Atlas project, which links people with the condition to researchers to plug gaps in our knowledge.

On World Psoriasis Day on October 29, the project is launching a website for those with and those who study the condition.

Psoriasis, skin, dermatology, stock, getty,
Psoriasis is show in an a stock image. Scientists think the condition is linked to cancer. Getty

Professor Brian Kirby of the British Association of Dermatologists, who was not involved in the research, stressed to Newsweek the study showed psoriasis is associated with certain cancers, but not that it causes it.

"As stated by the authors, certain factors associated with psoriasis and in particular more severe psoriasis such as obesity, cigarette smoking and excessive alcoholic intake are all strongly associated with certain cancers," he said. "These factors probably contribute most of the increased cancer risk rather than psoriasis itself."

"The increased risk of skin cancer in this study may reflect sunbathing activity 20 or more years ago, and at that time the long term use of an immunosuppressive drug (cyclosporine) for the treatment of severe psoriasis which is known to increase the risk of skin cancer," he added.

Katie Patrick, the health information officer of the charity Cancer Research UK who was also not involved in the study told Newsweek: "The link between psoriasis, inflammation and cancer is a complex area of research with lots of questions remaining.

"And as the authors of this research mention, smoking, obesity and drinking lots of alcohol, which we know can cause cancer, have all been shown to be more common in people with psoriasis, which might be muddying the water when we look at their findings."

Chiming with the study authors and Kirby, she said: "We need to make sure these other factors aren't playing a role before we could say if there is a direct link."

This article has been updated with comment from Professor Brian Kirby and Katie Patrick.