Simple SummaryThis study analyzed patients receiving immunosuppressive drugs (IMD) for the prevention of organ transplant rejection or treatment of other conditions (rheumatoid arthritis, lupus, myasthenia gravis, interstitial lung disease, fibromyalgia, and other autoimmune diseases). This retrospective study utilized Medicare claims data from all Texas Medicare beneficiaries between 2007 and 2018. In these patients, the risk of developing cancer was evaluated. We found an increased risk of cancer for all patients using IMD, regardless of its indication or duration, with a distribution of the types of cancer different from that previously described and with a higher risk for liver cancer. We also observed a higher risk of cancer in younger patients and ethnic minorities.AbstractImmunosuppressive drugs (IMD) are widely utilized to treat many autoimmune conditions and to prevent rejection in organ transplantation. Cancer has been associated with prolonged use of IMD in transplant patients. However, no detailed, systematic analysis of the risk of cancer has been performed in patients receiving IMD for any condition and duration. We analyzed Medicare data from Texas Medicare beneficiaries, regardless of their age, between 2007 and 2018, from the Texas Cancer Registry. We analyzed the data for the risk of cancer after IMD use associated with demographic characteristics, clinical conditions, and subsequent cancer type. Of 29,196 patients who used IMD for a variety of indications, 5684 developed cancer. The risk of cancer (standardized incidence ratio) was particularly high for liver (9.10), skin (7.95), lymphoma (4.89), and kidney (4.39). Patients receiving IMD had a four fold greater likelihood of developing cancer than the general population. This risk was higher within the first 3 years of IMD utilization and in patients younger than 65 years and minorities. This study shows that patients receiving IMD for any indications have a significantly increased risk of cancer, even with short-term use. Caution is needed for IMD use; in addition, an aggressive neoplastic diagnostic screening is warranted.