Risk of bladder tumours after childhood cancer: the British Childhood Cancer Survivor Study.
OBJECTIVE
To estimate the risk of a second primary tumour (SPT) of the bladder in a cohort of childhood cancer survivors, investigate factors associated with a bladder SPT developing, and compare the risk observed with that expected from the general population.


METHODS
The analysis included 17981 individuals diagnosed with childhood cancer, between 1940 and 1991 in Britain, and surviving for ≥5 years. Ascertainment of a bladder SPT was primarily through the National Health Service Central Registers (NHSCR).


RESULTS
From the NHSCR, 17 bladder SPTs were ascertained; this corresponded to four times (95% confidence interval 2.5-6.4) the expected number of bladder tumours. Standardized incidence ratios (SIRs) varied significantly (P < 0.05) by first primary tumour (FPT) type, follow-up period, attained age and chemotherapy. The highest SIRs were in those: with heritable retinoblastoma (31.4); treated with chemotherapy (12.0); 0-9 years of follow-up (10.8); and aged 0-19 years (9.3). The absolute excess risk (AER) for a bladder SPT was 3.7 cases/100000 survivors per year. The AER varied significantly by FPT type, follow-up period, attained age and gender. The highest AERs were in those: diagnosed with heritable retinoblastoma (34.0); 20-29 years of follow-up (14.2); aged 40-49 years (13.0); and male (5.8). Using multivariable Cox regression, FPT and chemotherapy were significantly associated with the risk of a bladder SPT developing. By the age of 55 years, 0.4% of survivors developed a bladder SPT.


CONCLUSIONS
Although the absolute risk of a bladder tumour within childhood cancer survivors was low, the risk was four times that expected from the general population. Specific groups, e.g. survivors of heritable retinoblastoma and those treated with chemotherapy, were at the highest risk.
Frobisher
Clare
C
Centre for Childhood Cancer Survivor Studies, School of Health and Population Sciences, Public Health Building, University of Birmingham, Edgbaston, Birmingham, UK. c.frobisher@bham.ac.uk
Gurung
Pratik M S
PM
Leiper
Alison
A
Reulen
Raoul C
RC
Winter
David L
DL
Taylor
Aliki J
AJ
Lancashire
Emma R
ER
Woodhouse
Christopher R J
CR
Hawkins
Michael M
MM
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000453:epidemiology*; D012042:Registries; D017741:Survivors / Q000706:statistics & numerical data*; D006113:United Kingdom / Q000453:epidemiology; D001749:Urinary Bladder Neoplasms / Q000453:epidemiology*; D055815:Young Adult