Molecular Staging of Rectal Cancer Using RT-PCR Analysis on Intraoperative Pelvic Lavage Samples

Naohiro Tomita, Masatomo Tada, Mitsugu Sekimoto, Masayuki Ohue, Tadashi Ohnishi, Tetsushi Morita, Masakazu Ikenaga, Yasuhiro Miyake, Nariaki Matsuura^* and Morito Monden

Department of Surgery II, Osaka University Medical School

^*Department of Pathology, School of Allied Health Sciences, Faculty of Medicine, Osaka University

In the operation for advanced rectal cancer, some cancer cells may possibly emigrate from lateral blood- or lymph-vessels during mobilization of the rectum. This could be related to lateral lymphnode metastasis or local recurrence, although its detail is quitely unknown. In order to clarify this point, we tried to detect cancer cells in pelvic lavage fluid during rectal surgery by RT-PCR analysis using a new epithelial cell-specific gene marker, GS04094 (Cancer Res., 58, 2440-2444, 1998). During the operation for rectal cancer, pelvic lavage with 100 ml saline was performed before rectal manipulation (pre) and after complete mobilization of rectum (post), and each sample was then examined by cytologic and RT-PCR analyses. Among 14 cases of rectal cancer, 5 cases were shown to be positive by RT-PCR analysis indicating the possible presence of cancer cells. These included 4 cases with pre (+) and post (+), and 1 case with pre (-) and post (+). A correlation was demonstrated between RT-PCR positive diagnosis and depth of tumor invasion, lymph node metastasis, lymphatic invasion, or tumor location (only for pre (+) cases). These preliminary results suggest that the emigration of cancer cells by breakdown of lateral vessels or the leakage of cancer cells to the serosal surface could be detected with high sensitivity using RT-PCR analyses of GS04094 on pelvic lavage samples during operations for rectal cancer. This indicates that RT-PCR analyses may be useful for tumor staging and/or the determination of therapeutic procedures.

Key words
colorectal cancer, RT-PCR, molecular staging

Reprint requests
Naohiro Tomita Department of Surgery, Kansai Rosai Hospital, 3-1-69 Inaba-so, Amagasaki-city, 660-8511 JAPAN

Accepted
December 22, 1999

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