highly significantP<0.00001
the time from diagnosis (in radically treated patients) until the first appearance of regional recurrences or distant spread, and overall patient survival (survival time until death from thyroid cancer) were compared across seasons. RESULTS Registry cases The 2627 thyroid cancer cases diagnosed in Norway during 1970-85 showed a highly significant time-effect when incidence was compared across 12 months (X2 = 119.3, P<0.00001) or four seasons (x2 = 35.6, P<0.00001), being highest during the last 3- month period October-December (Figure IA).