BMC Cancer 2008, 8:213 http://www.biomedcentral.com/1471-2407/8/213 Table 1: Clinical and pathologic parameters in patients with positive and negative k-ras mutations. k-ras marker Positive 12/7 65,8 ± 9.3 k-ras marker Negative 127/91 64.8 ± 11.8 13 6 7 6 3 2 1 0 2 9 8 6 6 7 15 4 12 3 4 4 7 5 88 79 41 4 6 176 42 19 21 105 47 125 64 24 180 38 155 56 7 70 31 37 P n.s n.s n.s n.s n.s n.s n.s n.s n.s p = 0.03 p = 0.002 Gender male/female Age mean ± st.dv Operation technique APR LAR Hartmann's procedure EkspI.lap Tumour reduction Primary rectal cancer Locally recurrent rectal cancer pT0-T1 pT2 pT3 pTx N0 N1/N2 NX M0 M1 R0 R1 R2 Distant metastasis during follow-up Local recurrence during follow-up Tumour perforation APR: Abdominoperineal resection LAR: Low anterior resection EkspI. Lap: Explorative laparotomy Local recurrence in this study means locally recurrent in the pelvis. Distant metastasis in this study is distant metastasis or peritoneal carsinomatose. Discussion This study accessed the incidence of free colorectal cancer cells or remnants of such cells in the pelvic cavity imme- diately after surgery, and correlates their presence with several clinicopathological parameters and survival. A sig- nificant number of local recurrences following rectal can- cer surgery cannot be explained by incomplete resection, lymphatic or vascular invasion [21]. This suggests that via- ble tumour cells with proliferate and perhaps metastatic potential have been shed from the primary tumour site either before removal of the tumour or during the surgical procedure. In our study we found that 19 rectal cancer patients had disseminated tumour cells in the 237 lavage fluids from the rectal patients. And we found that these patients with invisible tumour material in abdomen immediately after surgery tend to have a worse prognosis than patients without free tumour cells that could not be explained by differences in other risk factors. Only N- and R-stage were statistically significantly different between the k-ras positive and negative groups. In both cases this should be to the advantage of the k-ras negative group containing relatively more N0 and R0 stages. Page 4 of 8 (page number not for citation purposes)