© 2001 by Oxford University Press
Journal of the National Cancer Institute, Vol. 93, No. 6, 480,
March 21, 2001
© 2001 Oxford University Press
CORRESPONDENCE |
Re: Cost-Effectiveness Studies Fan Colonoscopy Debate
Correspondence to: John S. Spratt, M.D., Division of Surgical Oncology, University of Louisville Health Sciences Center, James Graham Brown Cancer Center, Rm. 317, 529 S. Jackson St., Louisville, KY 40202.
With respect to the news article by Newman (1), there are clinical issues regarding the biology of colonic neoplasms that should be considered when evaluating the study of screening by colonoscopy reported by Lieberman et al. (2). In an editorial, Podolsky (3) correctly observed that the study by Lieberman et al. did not demonstrate that screen by colonoscopy enhanced survival. Colon cancers exhibit extreme biologic diversity, and the probability of metastasis, which is directly related to survival, is completely independent of the size of the cancers (4,5).
Neoplasms of the colorectum exhibit enormous variance in growth rates, with many growing so slowly that they accumulate over time as the colon ages (6). This variance in growth rates can lead to length bias sampling and lead-time bias in assessing prognosis. The only valid assessment of what is in the aging colon is an autopsy study (7). Autopsy studies have consistently shown dissimilarity between the distributions of cancers and the benign polyps that are more frequently detected by colonoscopy. The great number of benign polyps with respect to the small number of cancers found at autopsy supports a very low probability of a benign polyp becoming a cancer. Less-frequent villous adenomas may become cancerous with increasing size (>2 cm). Only a controlled clinical trial for screening strategies will establish that survival can be enhanced by colonoscopic screening.
REFERENCES
1
Newman L. Cost-effectiveness studies fan colonoscopy debate [news]. J Natl Cancer Inst 2000;92:1796–8.
2
Lieberman DA, Weiss DG, Bond JH, Ahnen DJ, Garewal H, Chejfec G. Use of colonoscopy to screen asymptomatic adults for colorectal cancer. Veterans Affairs Cooperative Study Group 380. N Engl J Med 2000;343:162–8.
3
Podolsky DK. Going the distance—the case for true colorectum screening [editorial]. N Engl J Med 2000;343:207–8.
4 Spratt JS Jr, Spjut HJ. Prevalence and prognosis of individual clinical and pathologic variables associated with colorectal carcinoma. Cancer 1967;20:1976–85.[CrossRef][Medline]
5 Spratt JS Jr, Watson FR, Pratt JL. Characteristics of variants of colorectal carcinoma that do and do not metastasize to lymph nodes. Dis Colon Rectum 1970;13:243–6.[Web of Science][Medline]
6 Spratt JS, Spratt JA. Growth rates of benign and malignant neoplasms of the colon. Prog Clin Biol Res 1985;186:103–20.[Medline]cancerlit;85298572
7 Vatn MH, Stalsberg H. The prevalence of polyps in the large intestine in Oslo: an autopsy study. Cancer 1982;49:819–25.[CrossRef][Web of Science][Medline]cancerlit;82114973
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||