Bombesin-like peptides and their receptors are widely distributed throughout the gut and are potential mitogens for a number of gastrointestinal (GI) cancers. We have analysed the expression of bombesin-like peptides and their receptor subtypes in normal and neoplastic colorectal tissue. Expression was analysed by reverse transcription polymerase chain reaction (RT-PCR) using receptor and ligand subtype-specific primers and then expression localized by in situ hybridization (ISH) with riboprobes synthesized by in vitro transcription of cloned PCR products. Colorectal cancer tissue and matched normal mucosa from 23 patients were studied. Two of these patients had synchronous adenomatous polyps and two had synchronous hepatic metastases which were also studied. An additional two patients with adenomatous polyps were studied along with matched normal mucosa. Gastrin releasing peptide (GRP) receptor and ligand expression was present in all samples but with overall greater expression in the tumour samples. Neuromedin B (NMB) receptor expression was not detectable. NMB ligand was detected in all but one mucosal sample with overall overexpression in the tumour samples. Bombesin receptor subtype 3 (BRS-3) receptor expression was not detectable. These data support the possibility that GRP may be an autocrine growth factor in colorectal cancer. © 2000 Cancer Research Campaign

INTRODUCTIONManagement of malignant colorectal polyps is controversial. The options are resection or surveillance. Resection margin status is accepted as an independent predictor of adverse outcome. However, the rate of adverse outcome in polyps with a resection margin of <1mm has not been investigated.METHODSA retrospective search of the pathology database was undertaken. All polyp cancers were included. A single histopathologist reviewed all of the included polyp cancers. Polyps were divided into three groups: clear resection margin, involved resection margin and unknown resection margin. Polyps were also analysed for tumour grade, morphology, Haggitt/Kikuchi level and lymphovascular invasion. Adverse outcome was defined as residual tumour at the polypectomy site and/or lymph node metastases in the surgical group and local or distant recurrence in the surveillance group.RESULTSSixty-five polyps (34 male patients, mean age: 73 years, range: 50–94 years) were included. Forty-six had clear polyp resection margins; none had any adverse outcomes. Sixteen patients had involved polyp resection margins and twelve of these underwent surgery: seven had residual tumour and two of these patients had lymph node metastases. Four underwent surveillance, of whom two developed local recurrence. Three patients had resection margins on which the histopathologist was unable to comment. All patients with a clear resection margin had no adverse outcome regardless of other predictive factors.CONCLUSIONSPolyp cancers with clear resection margins, even those with <1mm clearance, can be treated safely with surveillance in our experience. Polyp cancers with unknown or involved resection margins should be treated surgically.