The Application Of Microwave Ablation In Early-Stage Kidney Tumor

Objective: The early-stage kidney cancer accounts for the proportion of new kidney cancer is increased year by year and Nephron Sparing Surgery(NSS) has become the“gold standard” in surgical treatment of early-stage renal cell carcinoma. Since NSS required a higher technical and complex operation skills as well as the doctor adroitness masters celiac mirror technique. The Warm Ischemia Time(WIT) is almost decided by the time of resection of the tumor and renal wound suture. Laparoscopic Microwave ablation Assisted Partial Nephrectomy(LMWAA-PN) is a kind of new way of the treatment of renal tumors. Using thermal coagulation effect of the microwave ablation, it can inactivate the tumor cells and then completely resect the tumor without blocking the renal pedicle as well as control intraoperative bleeding effectively. As a kind of zero ischemia surgery, it’s very helpful in reducing kidney warm ischemia injury. But only a few comparative studies have accessed the safety and efficacy of LMWAA-PN in systematic literature research revealed and there is no uniform standard in selection for patients with indications and MWA melting parameters settings. For this reason we reviewed our initial experience of LMWAA-PN and compared the perioperative and postoperative outcomes between LMWAA-PN and traditional LPN to provide practice basis for the further development of it.Materials and Methods: The clinical data of 236 cases of LPN and 89 cases of LMWAA-PN operated in the Department of Urology of Renji Hospital of the School of Medicine of Shanghai Jiaotong University from 2011 to 2014. The analysis of the factors in this study including the basic data of patient(age, gender, BMI, the chief complaint, ASA score and Charlson preoperative complications index, preoperative e GFR), tumor characteristics(maximum diameter, R.E.N.A.L. score, postoperative pathological types and Fuhrman grading), operation indicators(operation time,intraoperative estimated blood loss, microwave ablation time, intraoperative warm ischemia time, hemoglobin percentage difference before and after operation) and postoperative follow-up indicators(hospitalization days, complications, last e GFR,tumor local recurrence and metastasis), etc. We matched the patients of these two groups 1:1 by propensity score matching method and then compared the differences of above aspects. The single factor correlation analysis and multivariable linear regression analysis were used to explore the factors which impacted the changes in renal function before and after LMWAA-PN(p<0.05).Results: There were 89 patients in each group after matching. And there was no significant difference between proportion of age, gender, BMI, preoperative ASA score and Charlson complications index, preoperative e GFR, tumor R.E.N.A.L.grading and maximum diameter in this two groups. The length of operation time(71.01±33.36 min vs 105.06±36.52 min, P<0.01), intraoperative estimated blood loss(66.91±92.16 ml vs 106.40±99.49 ml, P=0.007), △HB(%)(8.25±7.19% vs14.71±7.36%, P=0.009) and hospitalization days(3.10±1.24 day vs 5.04±1.85 day,p<0.001) was significantly shorter in LMWAA-PN group. But there was no significant difference of the complications incidence between them(8.99% vs 14.61%,p=0.281). There was certain difference between the △e GFR%(5.61±12.39 vs12.42±9.77ml/min·1.73m2, P=0.043) and the group of LMWAA-PN seemed better. In addition to one patient in the group of LMWAA-PN found local recurrence nine months after the operation, which was gastrointestinal mesenchymal tumor by postoperative pathology, the remaining patients were alive during the follow-up period and had no local recurrence and distant metastasis. According to the results of multifactor linear regression analysis, tumor R.E.N.A.L score, operation time and tumor pathology classification had no significant correlation with △e GFR%, which were positive in single factor correlation analysis. Patient’s age and preoperative e GFR level were the only two factors affecting the change of renal function after surgery( p=0.008 and p=0.001), the other factors had no impact on renal function change after LMWAA-PN.Conclusion: The operation safety and tumor control between LMWAA-PN and traditional LPN was similar in short-term outcomes, but LMWAA-PN had more advantages in indicators related to the operation, surgery complexity and postoperative kidney protection. Patient’s age and preoperative e GFR level would affect the recovery of renal function after surgery. For larger and more complex tumor treatment, the safety and efficacy of the LMWAA-PN remains to be seen.