OBJECTIVES: To quantify the potential benefit of early cancer detection using the latest data from the Surveillance, Epidemiology, and End Results (SEER) Program to estimate hypothetical reductions in absolute cancer mortality if metastatic cancers were diagnosed earlier, when the likelihood for survival is higher.

METHODS: Data were obtained on persons aged ≥50 years when diagnosed with primary invasive cancer in 18 SEER regions between 2006-2015. Among cancer sites for which American Joint Committee on Cancer 6th edition staging information was available, stage-specific incidence and 5-year cancer-specific mortality rates were calculated. Hypothetical 5-year mortality rates were estimated assuming earlier detection (stage shift) and assigning associated stage-specific mortality rates. Incidence and mortality rates were multiplied to estimate numbers and percentages of deaths averted under two scenarios: (1) mortality rates of stage IV cancers were stage-shifted and assigned mortality rates associated with stage III detection, and (2) mortality rates were stage-shifted from stage IV to III, stage III to II, and stage II to I detection and assigned the associated mortality rates.

RESULTS: In a hypothetical cohort of 100,000 persons, 1,233 were estimated to be diagnosed with any cancer, of whom 414 were expected to die within 5 years. Of 229 diagnosed with metastatic cancer, 174 were expected to die within 5 years. If all metastatic cancers were diagnosed at stage III, 79 fewer cancer deaths would be expected, a reduction of 45% in the deaths due to metastatic cancer, or 19% of all cancer deaths. If all metastatic cancers were diagnosed at stage III, all stage III diagnosed at stage II, and all stage II diagnosed at stage I, 131 fewer cancer deaths would be expected, a reduction of 32%.

CONCLUSIONS: Diagnosing cancer before metastasis, even at stage III, could result in substantial reductions in the overall cancer mortality rate.