Renal Cell Carcinoma Follow-Up - Is it Time to Abandon Ultrasound? - Beyond the Abstract

There are several international guidelines that outline a proposed imaging strategy for following up patients who have undergone surgery for renal cell carcinoma (RCC). There are variations between these guidelines but computed tomography (CT) and ultrasound (US) feature prominently in all. It is known that strict adherence to some of these guidelines can lead to a high rate of failed recurrence detection. Ultimately, the choice and timing of follow up imaging are largely at the discretion of the clinician who sees the patient in the post-operative period.

Nearly 20% of patients who undergo surgery for localized RCC may develop local +/- distant recurrences. Low volume tumour recurrences may be amenable to salvage local and systemic therapies while conversely, 5-year survival for untreated metastatic RCC ranges from just 2.7 to 9%. Furthermore, RCC recurrence size is an independent predictor for RCC-specific death when treated surgically. Thus, the importance of early and accurate detection of disease recurrence is obvious and that begs the question of what is the best imaging modality in this regard. In our study, we wished to compare CT versus US for detecting recurrent RCC.

We identified 22 patients who developed RCC recurrence after planned curative surgery. Sixteen had initially undergone radical nephrectomy (RN) and 6 had initially undergone partial nephrectomy (PN). Seven of the surgical specimens were Fuhrman Grade 2. Only one of the 6 PNs had a positive margin. Ten tumours were ≤ pT2. This all emphasises the aggressive nature of RCC and the fact that recurrences present even when the initial pathology is seemingly favourable. That, in turn, highlights the need for a timely, reliable and accurate follow-up imaging protocol.

Fourteen patients (64%) underwent US during their follow-up surveillance protocol and one case of disease recurrence was detected by US before subsequent confirmation with CT. All 22 patients underwent CT as part of their follow-up surveillance protocol and all recurrences were detected by this modality. Of the 6 patients who had recurrence in their ipsilateral kidney after PN, five had undergone US in their surveillance protocol and worryingly, this modality failed to detect a recurrence in four of these patients. This undoubtedly questions the capacity of US to discriminate between normal post-operative surgical findings and tumour recurrence in PN patients.

The critical finding of our study is that US is severely limited for detecting recurrent RCC and that it seems to perform especially poorly in patients post PN. We firmly believe that CT should be the imaging of choice, except, of course, when it is obviously contra-indicated. We have grave reservations about the standard utilisation of US in monitoring these patients. Concerns regarding radiation exposure from CT are legitimate but we believe the risk of missing a recurrent lesion outweighs the radiation risk given the inherent morbidity and indeed mortality with the former. While our study is small and has limitations and needs to be validated on a larger scale, we believe its preliminary findings provide a sound basis for challenging the inclusion of US in RCC follow-up guidelines.

Written by: Mark Quinlan, MD, University of Melbourne, Department of Surgery, Urology Unit, Austin Hospital

Read the Abstract