title: Excess diagnosis of non-Hodgkin's lymphoma during spring in the USA.
abstract: A seasonal peak in hematologic malignancies may support hypotheses of infection-related precipitating events. Moderately increased incidence rates have been observed during the spring for leukemias and Hodgkin's disease but few studies have been conducted of non-Hodgkin's lymphoma (NHL). Our study consisted of 77,173 NHL patients in the Surveillance, Epidemiology, and End Results database diagnosed during 1973 - 99. Chi-square analyses showed excess observed-vs.-expected diagnoses during March, April, and June (P < 0.0001). B-cell origin subtype, but not T-cell/NK, was diagnosed more frequently in March. Controlling for age, sex, geographical location, and diagnosis year, multivariate Poisson regression revealed peaks in both March and April (P < 0.0001). Excluding cases in December, due to consistent troughs, regression uncovered greater-than-expected incidence during spring months for patients aged 20 - 39 years and 40 - 64 years (P = 0.043, P = 0.0001) but not among patients >or= 65 years. Future studies are needed to discern if a spring peak is due to diagnostic bias or other uncontrolled factors.
authors.affiliation: Division of Chronic Disease Epidemiology, Department of Epidemiology and Public Health, Yale School of Medicine, New Haven, CT, USA.
authors.forename: Stella
authors.initials: S
authors.lastname: Koutros
authors.forename: Teodore R
authors.initials: TR
authors.lastname: Holford
authors.forename: Theresa
authors.initials: T
authors.lastname: Hahn
authors.forename: Paul M
authors.initials: PM
authors.lastname: Lantos
authors.forename: Philip L
authors.initials: PL
authors.lastname: McCarthy
authors.forename: Harvey A
authors.initials: HA
authors.lastname: Risch
authors.forename: Helen
authors.initials: H
authors.lastname: Swede
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D008228:Lymphoma, Non-Hodgkin / Q000145:classification / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012042:Registries; D012307:Risk Factors; D018426:SEER Program; D012621:Seasons; D013997:Time Factors; D014481:United States / Q000453:epidemiology