Childhood determination of Hodgkin lymphoma among U.S. servicemen.

BACKGROUND Hodgkin lymphoma in young adults is inexplicably linked to economic development. METHODS We conducted a nested case-control study of the 656 servicemen with Hodgkin lymphoma diagnosed between ages 17 to 32 while on active duty in the U.S. military during 1950-68. Controls, chosen randomly from the servicemen on duty at the time, were matched on service, birth year, and induction date. Information came from preinduction records and military records for the period ending at onset or the equivalent date. RESULTS Risk was independently increased with small sib-ship size [OR, 2.3; confidence interval (CI), 1.6-3.5], low birth order (OR, 1.9; CI, 1.4-2.6), and an interval of at least 5 years between birth and that of a previous or subsequent sibling (OR, 2.1; CI, 1.5-3.1). Other factors independently and significantly associated with elevated risk of Hodgkin lymphoma were: tallness, high body mass index, more education (but not higher income) in the county of birth, BB or AB blood type, and past infectious mononucleosis (but a deficit of other childhood viral infections). Early fatherhood conveyed high risk (OR, 2.6; CI, 1.4-4.8), especially if with a high-risk sibling configuration. Factors unrelated to risk included personal education, preinduction or military occupation, induction test score, and rank. Findings were similar for nodular sclerosis and mixed cell histologic subtypes. CONCLUSIONS Protection from the environment in childhood, but not in adulthood, increases the likelihood of young adult Hodgkin lymphoma, which may result from nonspecific isolation from early infections and/or exposure to late infection by a specific but unidentified ubiquitous childhood virus. IMPACT Events in childhood protect against later Hodgkin lymphoma.