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Associations between birth weight and colon and rectal cancer risk in adulthood
Natalie R Smith1, Britt W Jensen2, Esther Zimmermann2
1Department of Biostatistics, University of North Carolina Gillings School of Global Public Health, Chapel Hill, NC, USA.
Insights
Higher birth weight is linked to increased colon cancer risk. However, rectal cancer risk shows an inverse association only for birth weights above 3.5kg, highlighting distinct cancer pathways.
Area of Science:
- Oncology
- Epidemiology
- Public Health
Background:
- Inconsistent associations between birth weight and colorectal cancer suggest anatomical differences between the colon and rectum.
- Previous research has not consistently differentiated between colon and rectal cancer in relation to birth weight.
Purpose of the Study:
- To investigate the separate associations between birth weight and colon cancer risk.
- To examine the distinct relationship between birth weight and rectal cancer risk.
Main Methods:
- Prospective follow-up of 193,306 children born between 1936-1972 using Danish health registers.
- Colon and rectal adenocarcinomas identified using International Classification of Disease version 10 codes.
- Cox regression analyses stratified by birth cohort and sex to estimate hazard ratios (HR) and 95% confidence intervals (CI).
Main Results:
- A positive association was observed between birth weight and colon cancer (HR=1.14 per kg).
- For rectal cancer, an inverse association was found for birth weights above 3.5kg (HR=0.77 at 4.5kg).
- The association between birth weight and colon cancer significantly differed from that of rectal cancer (p=0.006).
Conclusions:
- Birth weight is positively associated with adult colon cancer risk.
- Rectal cancer risk shows an inverse association with birth weight only above 3.5kg.
- Colon and rectal cancers should be studied as distinct entities due to differing associations with birth weight.
Background:
Birth weight has inconsistent associations with colorectal cancer, possibly due to different anatomic features of the colon versus the rectum. The aim of this study was to investigate the association between birth weight and colon and rectal cancers separately.
Methods:
193,306 children, born from 1936 to 1972, from the Copenhagen School Health Record Register were followed prospectively in Danish health registers. Colon and rectal cancer cases were defined using the International Classification of Disease version 10 (colon: C18.0-18.9, rectal: 19.9 and 20.9). Only cancers classified as adenocarcinomas were included in the analyses. Cox regressions were used to estimate hazard ratios (HR) and 95% confidence intervals (CI). Analyses were stratified by birth cohort and sex.
Results:
During 3.8 million person-years of follow-up, 1465 colon and 961 rectal adenocarcinomas were identified. No significant sex differences were observed; therefore combined results are presented. Birth weight was positively associated with colon cancers with a HR of 1.14 (95% CI, 1.04-1.26) per kilogram of birth weight. For rectal cancer a significant association was not observed for birth weights below 3.5kg. Above 3.5kg an inverse association was observed (at 4.5kg, HR=0.77 [95% CI, 0.61-0.96]). Further, the associations between birth weight and colon and rectal cancer differed significantly from each other (p=0.006).
Conclusions:
Birth weight is positively associated with the risk of adult colon cancer, whereas the results for rectal cancer were inverse only above values of 3.5kg. The results underline the importance of investigating colon and rectal cancer as two different entities.
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