4.3 Interpretation
AWE, a rare disease with variable presentation, results in pain and
reduced quality of life [25]. Surgical resection of the AWE mass is
currently the first-line treatment option; however, several studies have
examined HIFU ablation as a noninvasive treatment approach. One study
focused on the efficiency of HIFU and revealed that HIFU is safe and
effective for treating AWE [10,26]; nevertheless, these studies are
limited by the lack of a surgical resection comparison group. The
current meta-analysis compared the efficiency and safety of HIFU
ablation with surgery for managing AWE and found that noninvasive HIFU
ablation appears to be beneficial for treating AWE, with fewer adverse
events and a more rapid recovery.
Pain scores were evaluated before and after treatment using the VAS,
which has been demonstrated to be reliable for assessing therapy
effectiveness. We compared the decrease in pain score from baseline to
the time of follow-up between the HIFU and surgery groups, as the
baseline pain scores in each group varied across studies. The results
showed that the changes in pain scores immediately after management were
significantly higher in the HIFU groups than in the surgery group.
Surgical removal includes wide local excision, which causes more damage
and more severe pain than HIFU [3]. Moreover, pain in the immediate
postoperative period can negatively affect patient quality of recovery,
prolong hospital stay, and increase the risk of developing persistent
pain [27]. However, the relief of periodic pain between the HIFU and
surgery groups was not significantly different at the 3-, 6- and
12-month follow-up periods. This demonstrates that HIFU ablation is as
effective as surgery regarding symptom relief.
Furthermore, the largest diameter of an AWE lesion after treatment, as
assessed by ultrasound, was clearly more noticeable in the surgery group
than in the HIFU group. This is because the AWE lesion was destroyed in
the HIFU group, whereas the lesion was removed in the surgery group.
HIFU ablation uses targeted ultrasonic energy to instantaneously heat
tissue, resulting in coagulative necrosis and dysfunction of the ectopic
endometrium. A previous study found that, as necrotic tissue is slowly
absorbed, ultrasound imaging shows a gradual reduction in HIFU ablation
lesions, along with no obvious blood signal during follow-up[28].
HIFU ablation not only relieves abdominal cyclic pain and shrinks the
lesion but also serves as a minimally invasive treatment option for
patients. Compared with surgery, HIFU does not cause intraoperative
blood loss or abdominal wall defects. Wide local excision with 1 cm
margins via laparotomy is currently accepted as the optimal treatment
for AWE[29]. However, these lesions often leave fascial defects much
larger than the original mass due to fibrosis causing fascial retraction
around the lesion[30]. For larger abdominal wall defects,
reconstruction with mesh should be considered to lessen tissue tension
and prevent hernia formation. In this meta-analysis, all the included
studies showed that the patients in the HIFU group had a significantly
shorter duration of hospital stay than those in the surgery group. The
reason may be that, as a noninvasive treatment approach, HIFU enables
the patient to avoid surgery (thereby avoiding surgery-related
complications), reduces the volume of lesions significantly without
incision, and leads to faster recovery to usual activities.
We found that differences in adverse events incidence between the HIFU
and surgery groups was not statistically significant. Most adverse
events were minor and self-limiting during follow-up. The main adverse
events were intestinal injury, pain at the treatment area, skin burns
along the acoustic path, and injury of the urinary tract mucosa in the
HIFU group and haemorrhage, infection, pneumonia, irritation sign of the
bladder, and urinary retention in the surgery group. A previous study
showed that after HIFU treatment, no severe complications occurred,
except for one patient who had a first-degree skin burn, during a
48-month follow-up period[31]. The incidence of adverse events in
different studies varied, and one of the reasons is that there is no
consensus on the definition of adverse events.
Horton et al. [24] reported a recurrence rate of 4.3% among 445
patients after surgery in a systematic review. Most studies in the
meta-analysis of Horton et al were single-arm trials, whereas all
studies in our meta-analysis were comparative studies. Our study showed
that there was no statistically significant difference in the recurrence
rate between the HIFU and surgery groups. The symptom recurrence rate
ranged from 0 to 12% and from 0 to 17.2% in the surgery and HIFU
groups, respectively, during the 6-48 months of follow-up. X Zhu et
al.[14] reported that there was recurrence of AWE in one patient
after HIFU treatment a year later, ultimately requiring wide surgical
excision. Z Lin et al. showed that there was no recurrence in either
group during a 12-month follow-up. However, L Zhao et al. implied that
the recurrence rate was high (12% and 17.2% in the surgery and HIFU
groups, respectively) during a 30-month follow-up. Recurrence rates
across studies varied, possibly due to the following factors: (1)
Studies had different lengths of follow-up time, ranging from 6 to 48
months; (2) The surgeons in each study were different; (3) The depth of
lesion invasion for each patient was different. In the HIFU groups, if
the lesion was deeper and closer to the parietal peritoneum, to avoid
intestinal injury, lower energy exposure was used, preventing the
complete destruction of the lesion.