The concept of field cancerization has been worked out in Head and Neck cancers, however the validity in colorectal cancer (CRC) still remains to be proven. Although the carcinogenic load in the large bowel varies according to location, each segment of the colon and rectum has rather uniform environmental exposure. In addition, little data exist regarding clinical findings in the context of the field cancerization hypothesis. We postulate that the field effect results in the clustering of CRC and adenomas. Methods: Retrospective chart review of pts treated at the City of Hope from 1983-2003 evaluated 569, 194 pts excluded based on insufficient endoscopic evaluation and data. Of the remaining 375 pts, data on age, sex survival, stage, location, recurrence and adenoma number, size, location were entered into Excel data base and analysed. Results: The mean age was 62 years (range 17-90) and 54% were males. Left sided CRC comprised of 67%, rectal and rectosigmoid 31%. The stage distribution was 0/I 12%, II 21%, III 34% and stage IV 42%. CRC with synchronous adenoma was 33% and combined with metachronous adenoma was 42%. The clustering effect is shown for adenomas (columns) in relation to the CRC (rows), and numbers of each displayed in Table 1. And in 33 pts with multiple adenomas, the clustering effect relative to the largest adenoma showed similar spatial distribution. Conclusions: Location of CRC and adenomas are generally clustered in one or two anatomical segments around the CRC and the largest adenoma. This clustering of neoplasms clinically reflect the field effect, which can be further confirmed based on molecular differences. The CRC field effect and its molecular changes can become a surrogate marker for detection of early or recurrent CRC and for prevention studies. Work supported by 1RO3-CA107819-01

[Proc Amer Assoc Cancer Res, Volume 46, 2005]