Predicting Indeterminate Lesion Turned to Distance Metastasis in Patients with Rectal Cancer Undergoing Curative Resection after Preoperative Chemoradiotherapy

Abstract

Objectives: It is controversial about factors associated with indeterminate lesion turned to be malignant lesion after preoperative concurrent chemoradiotherapy(CCRT) in rectal cancer that may cause over-treating and over-diagnosing. So, The aim of this study was to evaluate the prevalence of indeterminate pulmonary nodules or liver nodule at primary staging CT and risk of indeterminate lesion being malignant to help better understanding of indeterminate lesion in rectal cancer undergoing preoperative CCRT and proper treatment. Methods: A total of 679 patients with rectal cancer were assessed from January 2015 to December 2019. 152 patients with rectal cancer undergoing curative resection after preoperative CRT were included. Associated factors were reviewed for their effect on metastasis. The median follow-up time was 28 months. Results: Of 152 patients, The prevalence of indeterminate lesion was 3.29% and turned to be malignant around 40% of patients. The clinical N2, preoperative FOLFOX regimen, No clinical response were significantly higher in malignant group (p 0.03, <0.001 and 0.003, respectively). Conclusions: Such a low incidence of indeterminate lesion should not cause further preoperative diagnostic workup besides routine regimens. In addition, it is not necessary to perform excessive surveillance routinely for all rectal cancer patients underwent preoperative CCRT who have indeterminate lesion. Intensive follow up chest CT or invasive diagnosis modalities should be considered in patients who had clinical stage N2, receiving preoperative FOLFOX4 regimen and no clinical response after preoperative CCRT.