Safety And Efficacy Evaluation Of Microwave Ablation In The Treatment Of Locally Recurrent Rectal Cancer

Background and Objective:CRC is the most common malignant tumor of digestive tract in the world,with incidence ranks third and mortality ranks fourth.Although China has a low incidence of CRC,its morbidity and mortality have increased significantly in the past decades,with three prominent characteristics:a high proportion of young patients,about 15%;the higher incidence of rectal cancer than colon cancer,about 1.5-2:1.the higher incidence of lower rectal cancer,about 75%.Currently,the mainly effective and curative treatment is surgery,supplemented by radiotherapy,chemotherapy and targeted drug therapy.Locally recurrent rectal cancer(LRRC)is the main cause of treatment failure and an important factor of poor prognosis with proportion of 15%-30%which appears in the 2 years following local recurrence.The most common sites are the anterior sacral space and iliac perivascular tissue which leading to persistent and intractable pain,affecting the quality of life and survival seriously.Due to the different response to traditional therapies,many patients gained little benefit and poor survival with less than one year.Therefore,it is imperative to explore a new,safe,effective and economical treatment.MWA with characteristics of higher thermal efficiency,faster warming,wider range of thermal field,less affection of the organization electrical impedance becomes promising therapy which can effectively relive pain of LRRC as palliative care.Image guided MWA supplying real-time,accurate and effective treatment of tumor,which reduces the risk of local recurrence,with little damage to the surrounding tissues,mild systemic reaction,and rapid recovery,thus can be used for LRRC who cannot tolerate surgery,postoperative pelvic radiation,chemotherapy and targeted drug treatment.Satisfactory local control and obvious pain relief can be achieved,thus improvement of life quality and prolonged survival will be realized.This research contains 31 cases of LRRC who cannot be tolerate of surgery,either chemoradiation or targeted drugs,treated with CT guided percutaneous MWA,the primary objective was to investigate the safety and efficacy of the new minimally invasive thermal ablation.Local tumor control,EQ-5D,NRS,KPS,incidence of complications and side effect were the evaluation indicators.Materials and Methods:Thirty-one inpatients with 31 locally recurrent lesions suffering LRRC from May 2009 through May 2014 in Shandong Provincial Hospital affiliated to Shandong University who were treated by both surgical and adjuvant chemoradiotherapy previously underwent MWA with CT guidance.For the 31 locally recurrent lesions,22 patients who accepted concurrent chemoradiotherapy were evaluated as SD or PD,and 2 patients were treated with local I125 radioactive seed implantation,and 7 patients received no anti-tumor therapy,then MWA was performed for palliative care.All patients were informed consent before the treatment.Local anesthesia combined with preemptive analgesia was applied,with strict implementation of aseptic operation technical specifications.MWA power was set at 60-80W,ablation time was 6-8min.In order to reach the maximum reduction of tumor volume and minimum damage to the surrounding organs,we can take three kinds of ablation mode according to tumor size:single microwave ablation antenna and single point(less than 3.0cm in tumor diameter),single antenna and multiple points(3.1-4.9cm in tumor diameter),multiple antennae and points(tumor diameter≥5.0cm,with 1.0cm distance between two pin at least).We need to adjust the angle and depth of the ablation antenna according to the intraoperative CT images in the latter two models,and it is necessary to avoid repeated puncture and adjustment of the antenna to increase the risk of bleeding and implant.The final goal of ablation is to ensure that the target area is completely covered by the ablation zone or the preset imaging endpoint appears.Local tumor control was evaluated by RECIST,NRS,KPS,and EQ-5D score were evaluated with a follow-up for 32 months.Complications and side were also recorded.Results:During follow-up for 4-32 months,20 patients died,whose overall survival was 5-26months(average of 10.4±2.68 months).Technical success was achieved in all patients.Local efficacy:the local effective rate at 1 month,3 months and 6 months after MWA was 67.7%,74.2%and 77.8%,respectively.Changes of NRS.KPS and EQ-5D:The median NRS pre-MWA was 7 and 0 post-MWA,respectively,with statistically significant difference(P<0.05).The median KPS pre-MWA was 70,and 80 post-MWA,with the difference without statistically significance.The EQ-5D in 1 week post-MWA with a median of 0.607 as the baseline level,median score was 0.694 post-MWA,which was statistically significant difference(P<0.05).The NRS showed a decreasing trend,with statistically significant difference between different gender(P<0.05).KPS and EQ-5D increased within 3 months post-MWA,and decreased from 6 months post-MWA,however,both of KPS and EQ-5D were still significantly higher than the pre-MWA,with statistically significant differences among different age(P<0.05).Survival analysis:Within 32 months for follow-up,20 patients died,with survival time range from 5 to 26 months,and the median survival time was 10.4±2.7 months.27 patients survived within 6 months,with median QALY as 0.36 years(4.3 months).There were statistically significant differences among different age.Conclusions:Ct-guided MWA for can provide rapid,effective and continued pain relief,locally control tumor growth,and bring survival benefits to patients with LRR.It is safe and efficient minimally invasive treatment.