No-touch isolation technique reduces intraoperative shedding of tumor cells into the portal vein during resection of colorectal cancer

Background. The mutant-allele-specific amplification (MASA) method is capab le of detecting 1 genetically altered tumor cell among thousands of normal cells. The MASA enabled us to detect occult tumor cells undetectable by his topathologic examination of lymph nodes and blood samples. Methods. To investigate whether tumor manipulation during operation enhance s cancer cell dissemination into the portal vein with use of MASA and to as sess the effect of the no-touch isolation technique in the treatment of col orectal cancers, 27 colorectal cancers (17 were operated on conventionally and 10 were operated on according to the no-touch isolation technique) were screened for mutations in K-ras or p53. We next examined blood samples of the portal vein collected before, during, and after manipulation of tumors, using MASA to look for the specific mutation found in the primary tumors. Results. Somatic mutations were identified in 18 of these primary tumors (1 1 were in the conventional resection technique group and 7 were in the no-t ouch isolation technique group). In 8 of 11 (73%) conventional resection te chnique cases, we identified the same genetic alteration of the primary tum or in the portal blood during operation, whereas only 1 patient (14%) in th e no-touch isolation technique group had a positive result. Conclusions. The no-touch isolation technique may be useful to prevent canc er cells from being shed into the portal vein during surgical manipulation.