Gender differences in the trend of colorectal cancer incidence in Singapore, 1968-2002.
OBJECTIVE
Over the past decades, incidence trends of colorectal cancer are sharply increased in Singapore. In this population-based study we describe changes in colorectal cancer incidence in Singapore and explore the reasons behind these changes through age-period cohort (APC) modeling.


METHODS
We included all 22,609 colorectal cancer cases reported to the Singapore Cancer Registry between 1968 and 2002. Poisson regression, using age-period (AP) and age-cohort (AC) models was used to determine the effects of age at diagnosis, calendar period, and birth cohort.


RESULTS
Male colorectal cancer rates between 1968 and 2002 from 20 to 40 per 100,000 person years. The increase was sharpest among older men, for whom there was a significant AC effect. Female colorectal cancer rates increased until 1992 (from 16 to 29 per 100,000 person years) and stabilized afterward. For women under 65 years, we observed a significant AP effect, corresponding to a sudden rise in colorectal cancer incidence around 1978.


CONCLUSIONS
This study demonstrates important gender differences in colorectal cancer incidence in Singapore, with increasing rates among men, and stabilized rates in women. The increase in men is mainly attributable to an incidence increase in the oldest age groups, probably due to increased exposure to dietary and lifestyle risk factors earlier in life. The stabilization in female colorectal cancer risk could be due to lower exposure to lifestyle risk factors and prophylactic removal of precancerous lesions.
de Kok
Inge M C M
IM
Centre for Molecular Epidemiology, Faculty of Medicine, National University of Singapore, Singapore, Singapore 119077. i.dekok@erasmusmc.nl
Wong
Chia Siong
CS
Chia
Kee Seng
KS
Sim
Xueling
X
Tan
Chuen Seng
CS
Kiemeney
Lambertus A
LA
Verkooijen
Helena M
HM
D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000208:ethnology / Q000209:etiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016012:Poisson Distribution; D011159:Population Surveillance; D012042:Registries / Q000706:statistics & numerical data; D012307:Risk Factors; D017678:Sex Distribution; D012737:Sex Factors; D012846:Singapore / Q000453:epidemiology