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Zhao et al. Mini-invasive Surg 2018;2:26 I http://dx.doi.org/10.20517/2574-1225.2018.27 Page 7 of 10

Table 2. Repeat ablation treatment outcomes and complications
Total (n = 13)
Technically successful
No 1 (8)
Yes 12 (92)
Complications
No 7 (54)
Yes 6 (46)
Pneumothorax (CTCAE grade 1) 1
Pneumothorax (CTCAE grade 1) and death within 30 days of procedure (CTCAE grade 5) 1
Pneumothorax (CTCAE grade 2) 2
Pneumothorax (CTCAE grade 2) and subcutaneous emphysema 1
Pleural effusion (CTCAE grade 1) 1
Length of hospital stay (days) 2 (1-2)
Post-ablation diameter (mm) † 54.0 (41.0-60.0)
Diameter on latest follow-up (mm) (n = 12) 38.5 (25.3-49.9)
Local tumour response to ablation (n = 12)
Complete ablation 10 (83)
Local tumour progression 2 (17)
Nodal or distant metastasis on follow-up imaging (n = 12)
No 6 (50)
Yes 6 (50)
Mortality
Alive 8 (62)
Deceased 5 (38)

†
For MWA, maximum axial diameter on 24 h post-ablation CT scan. For RFA, maximum axial diameter on immediate post-ablation CT
scan. Data are presented as n (%) for categorical variables and as median [interquartile range (IQR)] for continuous variables. MWA:
microwave ablation; RFA: radiofrequency ablation; CTCAE: Common Terminology Criteria for Adverse Events.

dian time to death 37 months (range 2 days-43 months). Median overall survival was 43 months (95% con-
fidence interval 36-49).

In the 9 patients with NSCLC, 5 (56%) were alive [median follow-up 30 months (range 30-91)] and 4 (44%)
had died [median time to death 38 months (range 27-43)]; all 4 had metastatic NSCLC at time of death. All
were alive at 2 years.

All 3 patients with metastatic colorectal cancer were alive at the last date of follow-up [median follow-up 23
months (range 3-38)].

Local response to ablation and corresponding survival status at follow-up for all patients is summarised in
Table 3.

DISCUSSION
We described the safety and efficacy of repeat ablation in a heterogeneous population of locally progress-
ing lung tumours after prior ablation, including both primary and metastatic lesions. Repeat ablations were
safe and well-tolerated, and often achieved local control despite local progression after prior technically
successful ablation. Pneumothorax was the most common procedural complication, asymptomatic or man-
ageable with chest tube insertion. Rate of pneumothorax requiring chest tube insertion (23% of procedures)
was similar to that of other studies (11%-29%) [7,12-18] . Other reported complications of lung ablation include
pain, post-ablation syndrome, pleural effusion, subcutaneous emphysema, pneumonia , bronchopleural
fistula, pulmonary haemorrhage, haemoptysis, nerve injury and, rarely, death [7,11-18] . Our study had one
30-day post-procedural death, but the cause of death and relation to the procedure were unknown. Other
studies have estimated the 30-day mortality rate after thermal ablation to be 0%-3% [12-15,19] .