A new study finds that lung cancer patients who also have autoimmune diseases are totally ineligible for the latest immunotherapy treatments.

Researchers found that about a quarter of lung cancer patients have autoimmune conditions that prevents them from receiving immunotherapy treatments even as they improve and save more lives, according to a UT Southwestern Medical Center statement. The study was published in the journal JAMA Oncology.

That means a total of about 20 to 50 million patients in the United States will be excluded from receiving immunotherapy treatments.

Scientists used two separate algorithms of more than 210,000 lung cancer patients who were older than 65 years old. Most of them had autoimmune diseases like rheumatoid or psoriasis, for example.

Immunotherapy works by stimulated the immune systems in the body to fight off the cancer.

“Our team wanted to determine if this practice had a significant impact. The new immunotherapy treatments also convey the risk of unpredictable, possibly severe, and potentially irreversible autoimmune toxicities affecting a variety of organs. With combination immunotherapy regimens, rates of these adverse events may exceed 50 percent,” said first author Dr. Saad Khan, Assistant Professor of Internal Medicine in the Division of Hematology and Oncology.

“Our findings provide the first robust estimate of autoimmune conditions among lung cancer patients,” added epidemiologist Dr. Sandi Pruitt, Assistant Professor in the Department of Clinical Sciences’ Division of Outcomes and Health Services Research, and a member of the Simmons Cancer Center. “This study will influence clinical practice and the design of clinical trials, and raise additional research questions of critical importance to lung cancer patients and their doctors.”

Dr. David Gerber, Co-Director of UT Southwestern’s Experimental Therapeutics Program, said that “examining the effectiveness and toxicity of these promising treatments among patients with autoimmune diseases” will be essential in the future, which is what makes this sutdy so important.

“While prior research has suggested that administering immune therapy to patients with autoimmune disease may be feasible, doing so carries the risk of making their disease worse, and requires careful monitoring,” he said.