The purpose of this study was to retrospectively compare microwave (MWA) and radiofrequency (RFA) ablation in the percutaneous treatment of primary and secondary lung tumors.

A total of 115 patients with a total of 160 lung tumors (primary, n=41; secondary, n=119) were retrospectively included. There were 56 men and 59 women with a mean age of 67.8±12.7 (SD) years (range: 42–89 years) who underwent either MWA (61 patients; 79 tumors) or RFA (54 patients; 81 tumors). The primary study endpoints were local recurrence during follow-up and the incidence of complications during and following thermal ablation. The MWA and RFA groups were compared in terms of treatment efficacy and complication rates.

Demographics were similar in the two groups. Mean tumor diameter was smaller in RFA group (13.1±5.1 [SD] mm; range: 4–27mm) than in MWA group (17.1±8.3 [SD] mm; range: 5–36mm) (P<0.001). Ablation volumes at one month were 24.1±21.7 (SD) cm³ (range: 2–97.8 cm³) in RFA group and 30.2±35.9 (SD) cm³ (range: 1.9–243.8 cm³) in MWA group (P=0.195). During a mean overall follow-up duration of 488±407 (SD) days (range: 30–1508 days), 9/160 tumors (5.6%) developed local recurrence: six (6/79; 7.6%) in the RFA group and three (3/81; 3.7%) in the MWA group (P=0.32). Pneumothoraces were more frequent in the RFA group (32/79; 40.5%) than in the MWA group (20/81; 24.7%) (P=0.049). The mean length of hospital stay was 4.5±3.7 (SD) days (range: 1–25 days) in the RFA group and 4.7±4.6 (SD) days (range: 2–25 days) in the MWA group (P=0.76).

MWA favorably compares with RFA and can be considered as an effective and safe thermal ablation technique for lung tumors, especially in situations where RFA has limited efficacy.