The duration of symptoms before diagnosis (lag time) was defined for 1
84 of 236 children diagnosed as having a malignancy at the Royal Hospi
tal for Sick Children, Edinburgh for the time period January 1982 unti
l December 1990. The natural logarithm of the lag time was correlated
with age, gender, diagnostic group, white cell count in acute leukaemi
a, clinical stage of disease in solid tumours, and event free survival
. Age was significantly associated with lag time, older children prese
nting later. In the diagnostic groups, mean lag time ranged from 2.8 w
eeks in nephroblastoma to 13.3 weeks for brain tumours. Diagnostic gro
up was predictive for lag time after adjustment for age, with for exam
ple, a significantly longer lag time for those with brain tumours. How
ever lag time was not predictive of event free survival and it is like
ly that lag time has other major determinants. When compared with prev
ious studies, there also appears to be a regional variation in lag tim
e for diagnostic groups. It seems likely that this is a reflection of
geographical difference in the structure of health systems and is ther
efore yet another important determinant.