Discussion
RCC mortality is still increasing despite increased incidence of renal cell carcinoma,
incidental early diagnosis, localized staging and improvement in surgical techniques of radical
or partial nephrectomy. (10). The fact that ablative procedures are performed in the imaging
guideline significantly reduces the mortality and morbidity rates. In addition, the advantages
of these ablative treatment modalities compared to surgical treatments, such as less complication rate, shorter recovery time, no ischemic damage to the kidney, and curative and
nephron sparing treatment, increase their use in routine practice (8,11). We performed total 36
ablation applications due to the reasons of high surgical and anesthesia risk such as the
presence of accompanying diseases, presence of tumor in solitary kidney, elderly patients
with comorbidities.
Factors that may affect the results of RFA application include; tumor size and localization,
tissue resistance, ablation time, amount of energy applied and surface area of the used probe.
In RFA application, approximately 85% ablation rate has been reported in renal masses of 3
cm and smaller (11, 12). Of 17 tumors ≥3 cm, 12 were performed RFA and 5 were performed
MWA. Recurrence occured in 10 (7 RFA and 3 MWA) of these 17 tumors. Therefore,
recurrence did not ocur in any tumors < 3cm in our study and the success rate were 100%.
The results of our study show that tumor size is an important point to decide RFA or MWA
for treatment of SRMs. Thus, high recurrence rates of RFA and MWA should be consider in
patients with renal tumor > 3cm. In addition to assessing the effect of tumor size, we also
invesitigated the effect of tumor localization on the reccurence rates of RFA and MWA. Of 3
patients with recurrent tumor after MWA, only one (33.3%) had endophytic tumor. Of 7
patients with recurrent tumor after RFA, 4 (57.1%) had endophytic tumor. Thus the outcomes
of our study show that tumor localisation (endophytic or exophytic) is the other important
factor for recurrent disease.
Significant studies have recently taken place in the international literature on the long-term
oncologic efficacy of RFA administration in small renal masses. In a study that evaluated the
long-term oncologic efficacy of RFA, Psutka et al noticed the long-term (6.5 years) outcomes
of RFA in 185 renal cancers with T1a (30). They reported that the median mass size was 3 cm
and the local recurrence rate was 6.5%. 5-year recurrence-free, metastasis free, diseasespecific
and overall survival rates were 95.2%, 99.4%, 99.4% and 74%, respectively. The authors suggested that RFA treatment in the high-risk group of patients provides local control
at long-term acceptable rates of renal cancer at T1a and low risk of metastasis. In our study,
seven of the 20 tumors (35%) who underwent RFA had recurrence in 3 (23%) tumors after 13
MWA application. When recurrent tumors were examined within themselves, it was observed
that 3 tumors in MWA applications had tumor recurrence of the same patient. The tumor size
of the patient was measured as 4 cm, 3.4 cm and 2.7 cm, respectively. The tumor was
endophytic in the posterior middle pole. Although the patient’s tumor size was regressive, the
procedure was considered ineffective. In RFA applications, the tumor size of ≥3 cm and the
size of 1 tumor were measured as <3 cm in 6 patients with recurrent 7 patients. In four
patients, the tumor localization was endophytic, while three patients were exophyticly
localised. When evaluated in this respect, it was thought that tumor size was a more dominant
factor than localization in terms of full ablation in RFA application.
The lack of contrast image in ablated live tumor tissue at the follow-up in the first
postoperative month was considered non-tumor recurrence and non-residual tumor. Patients
undergoing Re-RFA were not routinely biopsied. Because of the difficulties of routine biopsy
in terms of confirming the absence of recurrence following RFA follow-up in cases with
normal radiological findings, it does not appear to be an effective application for reasons such
as possible biopsy complications and significant cost increase. It should also be kept in mind
that the pathology reports, which are not rare, can not yield clear results (14). However, the
recurrence of a confirmed biopsy in the event of doubt cannot be ignored. Of 10 patients with
recurrent tumors, 4 (40%) were performed RFA, 3 (30%) were performed, 2 (20%) were
given targeted therapy and 1 (10%) was applied active survelliance. Although RFA and
MWA are less invasive than other surgical treatments, some complications of RFA and MWA
(such as perirenal hematoma, macroscopic hematuria, haemorrhage, infection, stenosis due to
renal collecting system damage or fistula formation, adjacent organ damage) were reported (15, 16).In our study, only 2 (6%) of the cases had complications after ablation. One of them
was a table of acute renal failure with oliguria and uremia symptoms on postoperative 5th day
after RFA administration. Nephrologic treatment was applied to the patient. Urea creatinine
levels returned to normal values at postoperative first month. The other complication was
local pain on the postoperative first day after MWA application and minor bleeding on
ablation site in USG. Clinical follow-up of the patient showed that the bleeding was limited
by itself. No additional treatment was needed and no hematuria was observed in clinical
follow-up.
The overall success in MWA administration was calculated as 76.9%, while the overall
success in RFA was 80%. One of the reasons for the low success rate of the procedure in
comparison with the studies in the literature is that in a patient with high comorbidities,
R.E.N.A.L. Classification was 7p and RFA was performed on the mass of 4 cm in the
posterior pole of the left kidney. After the RFA, the size of the mass was regressed to 3.4 cm,
but the procedure was considered unsuccessful and MWA application was performed 3 times
in total. The final post-administration mass size of the patient decreased to 2.5 cm. This
situation is considered to be a process failure.
Atwell et al. reported that percutaneous RFA (n = 222), which they applied to the renal mass
of <3cm size, had a local recurrence-free survival rate of 98% after 5 years of follow-up.
Major complication rates were reported to be 4.5%. The authors reported that effective
minimally invasive treatment modalities with low complication rates in the treatment of renal
masses <3 cm in size (17). In our study, disease-specific survival was 95% and overall
survival was 60%, while disease-specific survival was 100% and overall survival was 84.7%
in MWA treatment Mershon et al. reported that slightly higher rates of local recurrence rates (~1-10%) with thermal ablation are offset by lower complication rates and reduced morbidity, and equivalent or better renal function outcomes compared to surgery. The established modalities of radiofrequency, and microwave ablation offer equivalent outcomes with similar complication rates; technique choice is primarily based on tumor characteristics and operator preference. (18)