Usefulness of FDG-PET scan in the assessment of suspected metastatic or recurrent adenocarcinoma of the colon and rectum

PURPOSE: The purpose of this study was to evaluate the clinical efficacy of positron emission tomography with 2-[F-18] fluoro-2-deoxy-D-glucose compar ed with computed tomography plus other conventional diagnostic studies in p atients suspected of having metastatic or recurrent colorectal adenocarcino ma. METHODS: The records of 105 patients who underwent 101 computed tomogra phy and 109 2-[F-18] fluoro-2-deoxy-D-glucose positron emission tomography scans for suspected metastatic or recurrent colorectal adenocarcinoma were reviewed. Clinical correlation was confirmed at time of operation, histopat hologically, or by clinical course. RESULTS: The overall sensitivity and sp ecificity of 2-[F-18] fluoro-2-deoxy-D-glucose positron emission tomography in detection of clinically relevant tumor were higher (87 and 68 percent) than for computed tomography plus other conventional diagnostic studies (66 and 59 percent). The sensitivity of 2-[F-18] fluoro-2-deoxy-D-glucose posi tron emission tomography in detecting mucinous cancer was lower (58 percent ; n = 16) than for nonmucinous cancer (92 percent; n = 93). The sensitivity of 2-[F-18] fluoro-2-deoxy-D-glucose positron emission tomography in detec ting locoregional recurrence (n = 70) was higher than for computed tomograp hy plus colonoscopy (90 vs. 71 percent, respectively). The sensitivity of 2 -[F-18] fluoro-2-deoxy-D-glucose positron emission tomography in detecting hepatic metastasis (n = 101) was higher than for computed tomography (89 vs . 71 percent). The sensitivity of 2-[F-18] fluoro-2-deoxy-D-glucose positro n emission tomography in detecting extrahepatic metastases exclusive of loc oregional recurrence (n = 101) was higher than for computed tomography plus other conventional diagnostic studies (94 vs. 67 percent). 2-[F-18] fluoro -2-deoxy-D-glucose positron emission tomography altered clinical management in a beneficial manner in 26 percent of cases (26/101) when compared with evaluation by computed tomography plus other conventional diagnostic studie s. CONCLUSION: 2-[F-18] fluoro-2-deoxy-D-glucose positron emission tomograp hy is more sensitive than computed tomography for the detection of metastat ic or recurrent colorectal cancer and may improve clinical management in on e-quarter of cases. However, 2-[F-18] fluoro-2-deoxy-D-glucose positron emi ssion tomography is not as sensitive in detecting mucinous adenocarcinoma, possibly because of the relative hypocellularity of these tumors.