A significant number of lung cancer patients develop more than one primary tumor. The tumors arise independently and are not cases of one original tumor spreading to other sites or recurring after removal. This condition, known as multiple primary lung cancer (MPLC), is often treated surgically. However, not all patients are eligible for surgery. A recent study retroactively examined the records of patients with early-stage MPLC who had been treated with stereotactic ablative radiotherapy (SABR), a form of radiotherapy that uses high radiation doses over relatively few sessions, instead of surgery. Patients experienced good tumor control rates, and almost half survived for 4 years or more. SABR may be an effective treatment option for patients with inoperable MPLC.