Oncologists' ability to treat a certain subset of early-stage lung cancer patients after they've had tumors removed is about to get a big improvement. On Friday, AstraZeneca (NYSE:AZN) released clinical trial results that show treatment with Tagrisso tablets reduced the risk of disease recurrence or death by 83% in the adjuvant setting.

The phase 3 Aduara trial enrolled people who had recently had epidermal growth factor receptor-mutated (EGFRm) tumors removed from their lungs. The study wasn't supposed to wrap up for about two more years, but independent data monitors found unequivocal evidence of a benefit from the drug during a scheduled interim assessment. As is usually the case in such situations, the trial was halted early to give those study participants who had been receiving placebos a chance to try the real thing. 

Businessperson holding a stethoscope against a stock chart.

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Among patients with stage 1B through 3A lung cancer, adjuvant treatment with Tagrisso reduced patients' risk of disease recurrence or death by 79%. Two years after beginning the trial, 89% of participants treated with Tagrisso were still alive and disease-free, compared to just 53% of the placebo group.

The first thing investors need to understand about cancer drugs is that long treatment durations can drive sales steadily higher for years -- not that Tagrisso needs any help. As a first-line treatment for advanced-stage lung cancer patients with EGFRm-positive tumors, Tagrisso reached an annualized sales level of $3.9 billion during the first three months of 2020. 

Adding early-stage lung cancer patients to Tagrisso's addressable patient population could more than double sales of AstraZeneca's drug over the next few years. Investigators will present their results in further detail on Sunday during the plenary session of the American Society of Clinical Oncology's first virtual meeting.