Rheumatoid arthritis (RA) is a chronic inflammatory condition that can result in pain and functional disability. It is also associated with an increased occurrence of comorbidities, including an increased risk of certain cancers such as lung cancer and lymphoma. The aetiopathogenesis of this increased cancer risk is likely multifactorial and includes shared risk factors as well as chronic inflammation. There is also a concern that the treatment for RA itself may increase this risk further, particularly treatment with biologic disease-modifying anti-rheumatic drugs (DMARDs). This paper aims to review the evidence for the increased risk of cancer in RA as well as the latest evidence for the association between DMARDs and tumorigenesis. It also discusses the evidence for the management of patients with biologic DMARDs in the setting of existing cancer.