© 2000 by Oxford University Press
Journal of the National Cancer Institute, Vol. 92, No. 23, 1949,
December 6, 2000
© 2000 Oxford University Press
CORRESPONDENCE |
RESPONSE: More About: Prospective Study of Colorectal Cancer Risk in Men and Plasma Levels of Insulin-Like Growth Factor (IGF)-I and IGF- Binding Protein-3
Affiliations of authors: J. Ma, Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; M. Stampfer, Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical, and Departments of Nutrition and Epidemiology, Harvard School of Public Health; M. Pollak, Cancer Prevention Research Unit, Departments of Medicine and Oncology, Lady Davis Research Institute of the Jewish General Hospital and McGill University, Montreal, PQ, Canada.
Correspondence to: Jing Ma, M.D., Ph.D., Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Ave., Boston, MA 02115 (jing.ma{at}channing.harvard.edu).
In their small study, Paterson et al. found no statistically significant differences in circulating IGF-I among three groups who were referred for colonoscopy: subjects found negative for colorectal cancer, subjects with a family history of colorectal cancer, and subjects with history of adenomatous polyps or polyps found at colonoscopy. The lack of associations in this cross-sectional analysis certainly does not contradict our previous findings from prospective studies in which cases were defined as incident colorectal cancer (1) and/or "high risk of adenomas" (2). The study by Paterson et al. provides no information about the size or histology of the adenomatous polyps and did not measure IGFBP-3 levels. Their overall results are generally consistent with the findings of Renehan et al. (3) and with our findings (2). In a prospective analysis of a cohort of U.S. women, we found that high plasma levels of IGF-I and low levels of IGFBP-3 were statistically significantly associated with risk of colorectal cancer, nonsignificantly associated with "high-risk" (
1 cm or tubulovillous/villous histology) adenomas, and not associated with "low-risk" (<1 cm or tubular histology) adenomas (2). Our findings are consistent with the hypothesis that individuals with higher circulating IGF-I levels have higher rates of progression of high-risk adenoma to adenocarcinoma (1,2). Since the current studies had limited statistical power to yield precise estimates of risk, especially for high-risk adenomas, larger studies of this issue are necessary.
REFERENCES
1
Ma J, Pollack M, Giovanucci E, Chan JM, Tao X, Hennekens CH, et al. Prospective study of colorectal cancer risk in men and plasma levels of insulin-like growth factor (IGF)-I and IGF-Binding protein-3. J Natl Cancer Inst 1999;91:620–5.
2
Giovannucci E, Pollak MN, Platz EA, Willett WC, Stampfer MJ, Majeed N, et al. A prospective study of plasma insulin-like growth factor-I and binding protein-3 and risk of colorectal neoplasia in women. Cancer Epidemiol Biomarkers Prev 2000;9:345–9.
3
Renehan AG, O'Dwyer ST, Shalot SM. Re: Prospective study of colorectal cancer risk in men and plasma levels of insulin-like growth factor (IGF)-I and IGF-binding protein [letter]. J Natl Cancer Inst 1999;91:2051–2.
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