The largest study to date of radiofrequency
ablation in renal cell carcinoma has produced some remarkably
strong results, suggesting that this unproven treatment
could match partial nephrectomy for effectiveness, while
easily beating it for cost and convenience.
The retrospective study, in the
August issue of the American Journal of Roentgenology,
lacks controls and involved only 104 patients, but it
still goes beyond any previous attempt to measure the
success of this technique.
RF ablation is best known as a
treatment for uterine fibroids, but it got its start
in oncology with liver tumours nearly 20 years ago.
Logic suggested it might also work in renal cell carcinoma,
the commonest form of kidney tumour.
"I've performed many radiofrequency
ablations of renal tumours and the results looked promising,"
said lead author Dr Ronald Zagoria, in a statement.
"I wanted to scientifically review the data to better
assess the results and look for patterns that might
predict success or complications."
The data certainly is promising.
Of 125 tumours in 104 patients, 109 were eradicated
after a single treatment. Sixteen more were completely
destroyed after a second RF ablation. That translates
to a success rate of 93%, equivalent to nephron-sparing
surgery performed by experienced surgeons.
But unlike partial nephrectomy,
RF ablation involves no general anesthesia, few complications
and no inpatient stay in most cases. The most serious
complication was one perirenal hematoma. Dr Zagoria
cautions that these are rates from a centre with specialized
experience in this procedure.
The major caveat with these results
is the relatively short follow-up. The mean average
follow-up was 14 months. Dr Zagoria acknowledges this:
"Surgery should be the first option," he said, "since
the long-term results of this procedure have not been
substantiated."
But there is cause for optimism.
In nerve-sparing nephrectomy, kidney tumours that do
recur tend to do so early. A study of thermal ablation
in the Journal of Urology last year found that
the average time to recurrence was 12 months, less than
the mean follow-up in this study. Also, some very small
studies of RF ablation with longer-term follow-up have
shown extremely low rates of recurrence.
RF ablation certainly does look
like a valid option for patients who refuse surgery,
or are poor candidates due to comorbid conditions or
are prone to multifocal tumours.
Rates of kidney cancer may well
be rising - the detection rate certainly is - and there's
also some evidence that the incidence of hereditary
forms is slightly up. With many kidney cancers detected
incidentally during unrelated scans, a lot of the new
tumours are early-stage and small. These are the best
candidates for ablation. In this study, all of the failures
to achieve complete remission occurred in tumours bigger
than 3.7 cm. Below that size, the success rate was 100%.
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