Immunotherapy uses the body's natural defenses to fight cancer by stimulating the immune system to improve its ability to attack cancer cells or by giving the patient laboratory-made immune system proteins.
Also known as biologic therapy, the treatment is hailed as one of the greatest medical advances in the field of cancer treatment in the past three decades. Unfortunately, the treatment is not recommended for some cancer patients who have autoimmune diseases such as psoriasis, ulcerative colitis and rheumatoid arthritis.
Patients with autoimmune disorders have immune systems that attack the body. These patients have been excluded from clinical trials that test immunotherapies because of fear that the treatment can worsen their condition or cause new conditions to appear since the treatment uses the body's own immune system to fight cancer.
In the new study published in JAMA Oncology on June 4, Saad Khan, from the University of Texas Southwestern Medical Center, and colleagues said that a chunk of lung cancer patients with autoimmune disease are not eligible to receive the latest immunotherapy treatments.
The researchers looked at government insurance data covering the period between 1991 and 2011 and national data from 1992 to 2009 to get an estimate of the number of lung cancer patients in the U.S with autoimmune conditions.
They found that of the 210,509 lung cancer patients, 28,453, or about 14 percent, had been hospitalized for an autoimmune disease. Nearly 25 percent of the patients also had at least one insurance claim for autoimmune conditions.
The findings show that about a quarter of individuals diagnosed with lung cancer have autoimmune conditions, which means that about 20 to 50 million patients in the U.S. will be excluded as immunotherapy treatments for cancer become more widely used.
"A considerable proportion of patients diagnosed with lung cancer may also have autoimmune disease," the researchers wrote in their study.
"Although prior series have suggested that administering immune therapy to patients with autoimmune disease may be feasible, doing so conveys risk of disease exacerbation and requires careful monitoring."
The researchers said that the relatively high prevalence of autoimmune diseases among lung cancer patients can be attributed to advanced age at diagnosis and smoking history, which has been known to increase likelihood of developing certain autoimmune diseases.
Lifestyle practices are associated with some autoimmune disorders. Alcoholism, stress and sedentary lifestyle are also known to drive these medical conditions.