Does post-treatment surveillance imaging improve outcomes in patients with locally advanced rectal cancer?

Abstract

548 Background: The optimal post-treatment surveillance strategy for pts with rectal cancer is undefined. Trials examining surveillance with serial CEA measurements and/or imaging for colorectal cancer have yielded conflicting results, and no prospective trials have been done specific to rectal cancer pts. In the absence of data, reputable guidelines advocate serial chest, abdomen and pelvic imaging, CEA and colonoscopy after definitive treatment of rectal cancer. The rationale is to identify recurrence before it is symptomatic: if local, to avoid morbidity and if distant, because of the possibility of curative therapy. However, frequent imaging raises concerns regarding radiation exposure, consequences from false-positive findings, and cost. Methods: We performed a retrospective cohort study of patients with stage II/III rectal cancer treated definitively with neoadjuvant chemoradiation followed by surgical resection over the past 10 years. CEA, imaging studies and colonoscopies were recorded for all pts with follow-up of at least 6 months, along with clinical endpoints of locoregional recurrence, development of distant metastases, nature of subsequent therapies, and survival. Results: 55 pts with complete follow-up data were identified (median follow-up, 3.2 years). Surveillance was performed with imaging, CEA and colonoscopy in 89%, 72% and 49% of pts, respectively. 6 local recurrences were identified (11%): two were diagnosed via surveillance imaging, 3 underwent surgery with curative intent, with one patient with no evidence of disease at last follow-up. In contrast, 13 pts (24%) developed distant metastases (6 liver, 5 lung, 2 diffuse metastases), of which 9 were detected on surveillance imaging, 7 underwent therapy with curative intent, and 6 had no evidence of disease at last follow-up. There were 8 false-positive imaging results, 2 of which resulted in unnecessary surgery. Conclusions: Our findings suggest that post-treatment surveillance imaging is useful for detecting oligometastatic disease amenable to curative therapy, but may be less so for locoregional recurrences. Prospective data is needed to further assess the utility of post-treatment imaging in this population.