Microwave Thermal Ablation versus Open Partial Nephrectomy for the Treatment of Small Renal Tumors in Patients Over 70 Years Old

Background and objectives: Microwave thermal ablation (MWT) is one of the treatment options for kidney cancer. However, for patients over 70 years old the safety and oncological efficacy of this treatment is still controversial. The goal of this study was to compare MWT with open partial nephrectomy (OPN) and to find out whether MWT is preferable in maintaining patient renal function and reducing the risk of postoperative complications. Materials and Methods: Depending on the treatment choice, all patients were divided into two groups: an MWT group and an open kidney resection (OPN) group. Data have been retrospectively collected for 7 years, starting with January 2012 up to January 2019. A total number of 33 patients with exophytic, single small renal masses were treated with either OPN (n = 18) or MWT (n = 15). All patients had histologically proven T1 kidney cancer. MWT was performed for patients who refused to have OPN or in those cases where the collecting system, renal calyx, and great vessels were free from tumor margins of more than 1 cm. Results: In the MWT group a median (IQR) patients’ age was 75 years (71–79) years, in the OPN group—71.5 (70–75) years, p = 0.005. A median (IQR) Charleston comorbidity index in the MWT group was 7.5 (5–10) and in the same way in the OPN group it was 5.22 (5–6), p = 0.005. A median (IQR) estimated glomerular filtration rate (eGFR) before surgery was higher in the MWT group 59.9 (49.5–73.8) mL/min/1.73 m(2) vs. 46.2 (42.7–65.8) mL/min/1.73 m(2) in the OPN group, p = 0.12. Three days following the surgery a median (IQR) eGFR was 56.45 (46.6–71.9) in MWT group mL/min/1.73 m(2) vs. 43.45 (38.3–65) mL/min/1.73 m(2)) in the OPN group, p = 0.30. A median (IQR) of primary hemoglobin level was lower in the MWT group compared with the OPN group (134.5 (124–140) g/L vs. 125 (108–138) g/L), p = 0.41. However, after the surgery a median (IQR) lower hemoglobin level was detected in the OPN group (123.5 (111–134) g/L vs. 126 (112–135)), p = 0.53. The median (IQR) duration of the procedure in MWT group was shorter compared with the OPN group (26 (25–30) min vs. 67.5 (55–90) min), p < 0.0001. A median (IQR) hospitalization time was shorter in MWT group (3 (2–3) days vs. 89 (7–11.5) days), p < 0.0001. Pain by the visual analogue scale (VAS) scale the first day after surgery was significantly lower—median (IQR) in the MWT group was 2 (1–3) vs. 4 (3–6)), p = 0.008. Treatment failure rate was numerically higher in MWT (1/15 vs. 0/18, p = 0.56). Conclusions: Pain level on the next day after surgery, mean number of hospitalization and operation time were significantly lower in the MWT group than in the OPN group. The blood loss estimated glomerular filtration rate and oncologic data between the two groups was not statistically significant.