FDG-PET assessment of rectal cancer response to neoadjuvant chemoradiotherapy is not associated with long-term prognosis: a prospective evaluation.
Academic Article
Overview
abstract
BACKGROUND: At present there is no defined role for routine FDG-PET in the preoperative evaluation of nonmetastatic rectal cancer. OBJECTIVE: The primary objective of this study was to evaluate the ability of FDG-PET to predict long-term prognosis based on the response to neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer. DESIGN: This was a prospective study. SETTINGS: This study was performed at an academic, tertiary care, comprehensive cancer center. PATIENTS: One hundred twenty-seven patients with locally advanced rectal cancer were enrolled between September 1999 and December 2005. INTERVENTIONS: All patients underwent FDG-PET scans before and after neoadjuvant chemoradiotherapy. MAIN OUTCOME MEASURES: FDG-PET parameters were evaluated by at least 2 study board-certified nuclear medicine physicians, and included mean standard uptake value, maximum standard uptake value, total lesion glycolysis, and visual response score. The main outcome measures were time to recurrence and disease-specific survival. RESULTS: Of 127 patients, 82 (65%) were men, the median age was 60 years (range, 27-82), 110 patients had stage II/III disease, and 17 patients had stage IV disease. Median follow-up among survivors was 77 months (range, 1-115 months). Nine patients had unresectable metastatic disease and were excluded from the time-to-recurrence analysis. At 5 years, 74% (95% CI = 66%-81%) of patients had not had recurrences (locally and/or distantly). The 5-year disease-specific survival was 89% (95% CI = 81%-93%). On univariate analysis, visual response score and time to recurrence came closest to having an association (HR = 0.83, 95% CI = 0.68-1.01, p = 0.06). On multivariate analysis, the visual response score was not significant (p = 0.85). No FDG-PET parameter was associated with disease-specific survival. CONCLUSIONS: Assessment of rectal cancer response to neoadjuvant chemoradiotherapy by FDG-PET provides no prognostic information. Therefore, serial FDG-PET before and after neoadjuvant chemoradiotherapy should not be performed for this purpose.
