Evidence for the existence of different types of large bowel tumor: Suggestions from the clinical data of a population‐based registry

Abstract

The clinical findings of a population-based colorectal tumor registry have been analyzed to determine elements of supporting or not supporting the existence of different types of large bowel cancer. Age-specific incidence rate of the 409 registered patients rose sharply with increasing age in all segments of the large bowel; however, regarding left colon and rectum, the male: female ratio showed a marked male preponderance, more evident in the more advanced age groups. Histopathology, studied in 87% of patients, revealed adenocarcinoma as the most frequent feature; however, adenocarcinoma with concomitant adenoma (i.e., presumably arising in adenoma) was observed in 14.3% of cancers of the left colon, in 17.7% of rectal tumors, but in only 5.7% of neoplasms of the proximal colon (P less than 0.05 and P less than 0.01, respectively, vs. left colon and rectum). Some histological features (carcinoid and mucinous carcinoma) were observed in right-side tumors only. Analysis of the familial occurrence of cancer showed that a significantly larger proportion of patients with neoplasms located in proximal colonic segments had three or more first-degree relatives affected by (or deceased from) cancer of all sites. Similarly, colorectal tumors among relatives were more frequent in patients with right-side cancer. The location of the 793 polyps observed during 3 years of registration showed that more than 70% of adenomas were located beyond the splenic flexure, overlapping the distribution of cancers. In conclusion, the differences of sex ratio at different colonic subsites, the higher fraction of adenocarcinomas with adenomas in cancer of the more distal tracts of the large bowel, and the more marked familial occurrence of colorectal cancer in patients with right-side neoplasms tend to support the view that cancer of the proximal colon, cancer of the distal colon, and cancer of the rectum may actually be three different types of tumors.

Colorectal cancer mass-screening: Estimation of faecal occult blood test sensitivity, taking into account cancer mean sojourn time

“…With regard to analysis by subsite, estimates of MST and test sensitivity from the maximum likelihood and Gibbs sampling methods were consistent with our empirical approach. As a whole, our results strongly suggest that tumour growth rates were very different according to subsite, slowest for distal cancer and speediest for rectal cancer, which is consistent with the numerous publications on differences in clinical, epidemiological and genetic characteristics of cancers of the proximal colon, distal colon and rectum (Buffil, 1991;Pocard et al, 1995;Inoue et al, 1995;Ponz de Leon et al, 1990).…”

“…Probably because of the availability of randomised trial data for the last quarter of a century, almost all models have been applied to breast cancer-screening data and very few to colorectal cancer screening. Moreover, clinical, epidemiological and genetic evidence together suggest differences in natural history for proximal colon, distal colon and rectal cancers (Buffil 1991;Pocard et al, 1995;Inoue et al, 1995;Ponz de Leon et al, 1990). These differences may reflect differences in MST.…”

Continued Rightward Shift of Colorectal Cancer

“…8,16 Such differences have led to the hypothesis that different genetic and environmental factors could be implicated in the cause of two different cancer types. 26 In our study of age-standardized time trends, we did not observe any striking difference in the proportional increase of proximal lesions among various gender and ethnic groups.…”

Potential for Colorectal Cancer Prevention of Sigmoidoscopy Versus Colonoscopy: Population-Based Case Control Study

“…However, risk reduction might be different for both locations of colorectal cancer for several reasons, including incompleteness of colonoscopy (4) or suggested differences in mechanisms of tumorigenesis (5)(6)(7).…”