4. Discussion
This study shows that MWA is a successful treatment modality and
provides a rapid improvement in Ca and PTH values in a short period of
24 h. Both PTH and Ca levels returned to normal range in 28 of 32
patients (87.5%) and remained normal for 6 months. A similar success
rate was observed in the literature 5,10. In the study
of Fan et al. 10, PTH and Ca decreased to normal
levels in 19 of 22 patients (86.3%) and remained within the normal
range for 12 months after MWA. In the study of Liu C et al.5 all the fifteen patients had good response to
initial therapy. However, 2 patients relapsed (5 months and 32 months
after the initial therapy) and they underwent second MWA sessions. The
authors argued that MWA can reduce nodule size, decrease serum PTH, and
Ca levels in a single session in most patients, and the second session
can be applied when necessary. In our study the procedure was not
repeated in unsuccessfully treated lesions.
In the study by Liu et al. 9, comparing surgery and
MWA, the success ratio of MWA and surgery were found to be similar in
the sixth month of treatment (82.1%, 89.3%, respectively). While PTH
levels in the surgery group decreased much faster than the MWA group in
the first 3 months of treatment, no significant difference was detected
between the two groups in the sixth month after treatment. There was no
significant difference in mean serum Ca and P levels between the MWA
group and the surgery group during the 6 months after treatment.
Although the authors drew attention to literature data showing the cure
rates of over 95% in centers specializing in parathyroid surgery, they
declared similar clinical efficacy with MWA and surgery in PHPT.
Although the efficacy of MWA in secondary hyperparathyroidism has been
found to be related to baseline PTH level in a study15, a reason that can be directly associated with
treatment success in PHPT has not been clearly revealed. In our study,
there was no difference in PTH values between the groups in terms of
treatment success.
Patient with the largest lesion diameter (4.8 cm diameter) did not
respond to MWA in the study of Liu et al. 9. Fan et
al. 10 observed that treatment efficacy was not
significantly associated with lesion size, PTH and Ca levels, as in our
study. We argue that the main reason for not responding to treatment may
be related to the procedure technique. Probably some parathyroid tissues
could not be completely removed by this technique depending on the
experience of radiologist applying the process.
This treatment procedure was well tolerated as we did not observe major
complications or need for hospitalization during MWA or follow-up
period. Complication rate in the present study was low. According to
Society of Interventional Radiology Clinical Practice Guidelines17, no major complications were observed except than
the minor one of a case of cellulitis requiring drainage and
antibiotics. Therefore, the MWA procedure was observed as safe.
The limitations of the study are the small sample size and the short
follow-up period. Longer follow-up is required to determine the
long-term effectiveness of the treatment and whether there will be a
recurrence.
In conclusion, MW ablation is a safe and effective treatment method in
the treatment of PHPT, and it can reduce Ca and PTH levels and nodule
size. Although surgery is still the gold standard, it is an alternative
for patients for whom surgeries are risky or who refuse surgery.