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Freedman. Hepatoma Res 2020;6:10 I http://dx.doi.org/10.20517/2394-5079.2019.32 Page 3 of 7

on follow-up imaging within an area of 1 cm surrounding the ablation zone, applying the LIRADS criteria
[16]
for HCC . In the case of ablation site recurrence or new intrahepatic lesions on follow-up, patients were
retreated with minimally invasive microwave ablation whenever possible.

[17]
Data on patient and tumour characteristics were extracted from the Swedish Liver registry .
[18]
Complications were classified according to the Clavien-Dindo classification , with major complication
defined as a grade 3b or higher within thirty days of treatment. Data on tumour recurrence were extracted
from patient’s medical records. Overall survival (OS) was calculated from the day of the index treatment,
with all patients being followed until death or censored on 15 October 2019.

Descriptive statistics was used to describe baseline characteristics with medians and range for non-
normally distributed data. Categorical variables were expressed as total and percentages. Ratios were
2
analysed with the c -test. Overall survival was illustrated using Kaplan-Meier curves and differences in
survival analysed with log-rank test. Factors influencing survival were analysed with the Cox proportional
hazards method. All statistical computations were made with SigmaPlot 13.0 (Systat software, Inc, San Jose
CA)

RESULTS
In total, 193 patients treated with MWA at the age of 70 or above were included in this study. Of these,
32 (17%) were 80 or above years of age and 161 (83%) were 70-80 years of age. Patient and tumour
characteristics are outlined in Table 1.

In the group of octogenarians, there was less underlying liver disease with cirrhosis of various reasons (59%
vs. 80%, P = 0.021) and the proportion of females was higher (34% vs. 19%, P = 0.08). In the other baseline
characteristics, and somewhat fewer tumours treated. The age distribution is presented in Figure 1.

Major complications within one month occurred in seven (5%) of the septuagenarians and none of the
octogenarians. These were one liver abscess that responded well to drainage and antibiotics, one hematoma,
one patient with ascites that was drained, one with a pneumothorax that was evacuated, one patient had a
coronary infarction one week after the ablation and one patient had a bleeding oral polyp a week after the
ablation. The last developed progressive liver failure with intensive care needs, alas irreversible and died
two months after the ablation.

There was no difference in OS between the two groups with a median survival time of 3.9 years for patients
between 70 and 80 years of age and 4.3 years for octogenarians (P = 0.416). One-, three- and five-year OS were
89%, 59% and 38% (70-80 years of age) and 100%, 100% and 30% (octogenarians), respectively [Figure 2].

In the Cox proportional hazards model, no single analysed factor significantly influenced survival including
gender, associated liver disease, ASA-score, Child-Pugh grade, number of tumours treated and largest
tumour treated.

Local ablation site recurrence occurred in 19 % (36/194) and 26% (50/194) had a new tumour in another
part of the liver within one year of follow-up.

The distribution of repeat treatments is shown in Figure 3. Patients were retreated when there was a chance
of cure, not as an upfront palliative measure.