Time trends in Hodgkin's disease incidence. The role of diagnostic accuracy.

A prior study of Hodgkin's disease (HD) incidence using national cancer survey data (1969-1980) identified unprecedented rate declines among white persons older than 40 years, and rate increases among young adults aged 15 through 39. These trends could be due to improved diagnostic accuracy. To investigate this hypothesis, the authors updated incidence rates in whites by age, sex, and histologic subtype through 1984; quantified diagnostic accuracy in corresponding detail using Repository Center for Lymphoma Clinical Studies data, which include original and expert review diagnoses on lymphoma patients; and recalculated HD incidence rates (1969-1984) corrected for diagnostic error. Updated HD incidence rates through 1984 continued to decline in older adults and showed persistent increases for young adults with the nodular sclerosis (NS) histologic subtype. The percentage of original HD diagnoses confirmed on review (confirmation rate) decreased with age and increased over time; in older adults, these patterns opposed observed incidence trends. However, for young adults, confirmation rates of NS, the most common subtype at these ages, were high and changed little over time. After adjustment for diagnostic error, incidence rates for older adults were lower than previously observed and showed no secular changes. However, young adults with NS had slightly larger rate increases than in uncorrected data. Thus, contemporary changes in HD incidence for whites primarily involve growing risk to persons at the start of adult life. These patterns are compatible with trends in suspected sociodemographic risk factors that suggest an infectious etiology for HD.