Interpretation
The main findings of our study that LNG-IUS achieved higher 16-week CR
rate than MA in AEH patients were consistent with findings from previous
retrospective studies 12, 13. A meta-analysis
evaluating 24 observational studies showed that oral progestin achieved
lower pooled regression rate (69% vs. 90%, P=0.03) compared with
LNG-IUS in AEH patients 13. Although our study for the
first time provides evidence from prospectively randomized and
controlled trial, the sample size was not large enough to draw a
conclusion. Further confirmation is needed in phase III study with
sufficient sample size.
Our study also found that LNG-IUS was associated with fewer adverse
events than MA or MA+LNG-IUS. This is important because fertility
preserving treatment takes long time which is at least four to six
months 7-9. Long-term usage of MA might cause many
adverse events such as weight gain, edema, vomiting that affect quality
of daily life, and even cause thrombosis which is life-threatening4. In this context, LNG-IUS instead of oral progestin
might provide patients with higher life-quality for less and milder
side-effects, and thus, might increase the patient compliance of
fertility-sparing treatment 35-37.
Data in our study suggested that the efficacy of LNG-IUS alone might be
better than MA alone in AEH patients with BMI≥28
kg/m2. This is important because obesity has been
shown to be the most important factor adversely affecting the
fertility-preserving treatment in AEH and EEC patients24, 38, 39. Long term oral progestin usage might also
lead to higher risk of thromboembolism in obese women. Our results
support that LNG-IUS might be more suitable in AEH patients with BMI≥28
kg/m2.
Our data did not find better treatment effect using LNG-IUS plus MA
compared with LNG-IUS or MA alone, which was an unexpected result. It
might be because LNG is a highly effective progestin, and the drug
concentration of LNG using LNG-IUS could reach nearly a thousand times
in endometrium than oral MA 40. Thus, LNG-IUS alone is
effective enough on endometrial lesion, and adding systemic MA could not
add more value on the treatment effect in endometrial lesion.
In our study, differences in the CR rate between groups became less
significant from 16 weeks to 32 weeks of treatment. The reason might be
that all patients received
hysteroscopic evaluation and
treatment which had been shown to effectively increase the CR rate in
AEH and EEC patients 8. With the prolongation of
treatment time, the effect of lesion removal by hysteroscopy plays
important role in improving treatment effect regardless of the different
type of progestin treatment.