Clinical parameters predicting pathologic complete response following neoadjuvant chemoradiotherapy for rectal cancer

Introduction:Preoperative chemoradiotherapy(CRT),followed by total mesorectal excision,has become the standard of care for patients with clinical stages II and III rectal cancer.Patients with pathologic complete response(pCR) to preoperative CRT have been reported to have better outcomes than those without pCR.However,the factors that predict the response to neoadjuvant CRT have not been well defined.In this study,we aimed to investigate the impact of clinical parameters on the development of pCR after neoadjuvant chemoradiation for rectal cancer.Methods:A total of 323 consecutive patients from a single institution who had clinical stage II or III rectal cancer and underwent a long-course neoadjuvant CRT,followed by curative surgery,between 2005 and 2013 were included.Patients were divided into two groups according to their responses to neoadjuvant therapy:the pCR and non-pCR groups.The clinical parameters were analyzed by univariate and multivariate analyses,with pCR as the dependent variable.Results:Of the 323 patients,75(23.2%) achieved pCR.The two groups were comparable in terms of age,sex,body mass index,tumor stage,tumor location,tumor differentiation,radiation dose,and chemotherapy regimen.On multivariate analysis,a pretreatment carcinoembryonic antigen(CEA) level of <5 ng/mL[odds ratio(OR) = 2.170,95%confidence interval(CI) = 1.195-3.939,P = 0.011]and an interval of >7 weeks between the completion of chemoradiation and surgical resection(OR = 2.588,95%CI = 1.484-4.512,P = 0.001) were significantly associated with an increased rate of pCR.Conclusions:The pretreatment CEA level and neoadjuvant chemoradiotherapy-surgery interval were independent clinical predictors for achieving pCR.These results may help clinicians predict the prognosis of patients and develop adaptive treatment strategies.

Effect of preoperative injection of carbon nanoparticle suspension on the outcomes of selected patients with mid-low rectal cancer

Background:Carbon nanoparticles show significant lymphatic tropism and can be used to identify lymph nodes surrounding mid-low rectal tumors.In this study,we analyzed the effect of trans anal injection of a carbon nanoparticle suspension on the outcomes of patients with mid-low rectal cancer who underwent laparoscopic resection.Methods:We collected the data of 87 patients with mid-low rectal cancer who underwent laparoscopic resection between November 2014 and March 2015 at Cancer Hospital,Chinese Academy of Medical Sciences & Peking Union Medical College.For 35 patients in the experimental group,the carbon nanoparticle suspension was injected transanally into the submucosa of the rectum around the tumor 30 min before the operation;52 patients in the control group underwent the operation directly without the injection of carbon nanoparticle suspension.We then compared the operation outcomes between the two groups.Results:In the experimental group,the rate of incomplete mesorectal excision was lower than that in the control group,but no significant difference was found(2.9%vs.7.7%,P = 0.342).The distance between the tumor and the circumferential resection margin was 5.8 ± 1.4 mm in the experimental group and 4.8 ±1.1 mm in the control group(P = 0.001).The mean number of lymph nodes removed was 28.2 ± 9.4 in the experimental group and 22.7 ± 7.3in the control group(P = 0.003);the mean number of lymph nodes smaller than 5 mm in diameter was 10.1 ± 7.5and 4.5 ±3.7,respectively(P< 0.001).Three patients in the experimental group received lateral lymph node resection.Among the three patients,we retrieved three nodes(one stained node) from the first patient,three nodes(two stained nodes) from the second patient,and two nodes(no stained nodes) from the third patient.Conclusions:Injecting a carbon nanoparticle suspension improved the outcomes of patients who underwent laparoscopic resection for mid-low rectal cancer;it also improved the accuracy of pathologic staging.Moreover,for selected patients,this technique narrowed the scope of lateral lymph node dissection.