The impact of underreported Veterans Affairs data on national cancer statistics: analysis using population-based SEER registries.

Reduced cancer reporting by the US Department of Veterans Affairs (VA) hospitals in 2007 (for patients diagnosed through 2005) impacted the most recent US cancer surveillance data. To quantify the impact of the reduced VA reporting on cancer incidence and trends produced by the Surveillance, Epidemiology, and End Results Program, we estimated numbers of missing VA patients in 2005 by sex, age, race, selected cancer sites, and registry and calculated adjustment factors to correct for the 2005 incidence rates and trends. Based on our adjustment factors, we estimated that as a result of the underreporting, the overall cancer burden was underestimated by 1.6% for males and 0.05% for females. For males, the percentage of patients missing ranged from 2.5% for liver cancer to 0.4% for melanoma of the skin. For age-adjusted male overall cancer incidence rates, the adjustment factors were 1.015, 1.012, and 1.035 for all races, white males, and black males, respectively. Modest changes in long-term incidence trends were observed, particularly in black males.