Metastatic renal cell cancer

Abstract

Targeted therapy is the treatment of choice in patients with metastatic renal cell cancer (mRCC) at most institutions although a combination of cytokine therapy and targeted therapy still is being investigated. Morphological size-based criteria (RECIST) has failed in monitoring the effect of targeted therapy in patients with mRCC, as successful therapy often does not result in a decrease in tumour size. Modifications of size-based criteria and criteria based on computed tomography (CT) contrast enhancement has been introduced. Different imaging modalities that rely on characteristics other than size such as dynamic contrast-enhanced (DCE) ultrasonography, DCE CT, DCE magnetic resonance imaging (MRI), diffusion-weighted MRI, positron emission tomography and texture analysis seem to contribute with prognostic information, even at baseline scans, and can predict tumour response early after initiating therapy. No new standard for the imaging follow-up of targeted therapy in mRCC has been established.

Figure 1

Liver metastases in a patient with renal cell cancer (a) before and (b) after sunitinib therapy. Semi-automatic lesion segmentation can be performed and quantitative data derived, (c) before and (d) after. The diameters, volume, mean attenuation of the whole lesion and histograms showing the distribution of voxels with a certain attenuation value can be displayed. In the liver lesion shown, it is obvious that the diameters and the volume of the lesion increased. The mean attenuation of the lesion decreased and the histogram changed dramatically. Instead of size measurements and mean attenuation, alterations in the histogram may be a more sensitive method for assessing treatment effect.

Figure 2

Lung metastases in a patient with renal cell carcinoma (a, b) before and (c, d) after targeted therapy. The most common site for metastases from RCC is the lung. Monitoring the effect of treatment on such lesions is a challenge, and some treatment evaluation criteria even omit lung metastases as target lesions.

Figure 3

A metastatic lymph node in the mediastinum was a target lesion in this patient with mRCC. In the first column, maximum intensity projection illustrations are presented, the next column illustrates perfusion maps and the third column shows blood volume estimations. The upper row represents baseline, the second row at week 5 and the third row at week 10 after targeted therapy. Visually, the diameter and the volume of the lesion remain unchanged, whereas the enhancement decreased over time. The perfusion and the blood volume also decreased (the green and red colours) within the lesion. Perfusion and blood volume seem to be predictive parameters much earlier than morphological criteria in response evaluation of targeted therapy in mRCC. Quantitative measurements can also be applied.

Figure 4

FDG-PET in the evaluation of RCC is hampered by the fact that FDG is excreted by the kidney and may mask FDG uptake in pathologic tissue. Other factors are also involved^[31]. In (a) a modest contrast enhancement on contrast-enhanced CT of the RCC at the upper pole of the kidney is seen. The corresponding PET/CT (b) showed no pathologic uptake of FDG in the tumour. In (c) a large RCC with inhomogeneous contrast enhancement on contrast-enhanced CT is demonstrated. In the corresponding PET/CT (d), a pronounced uptake of FDG in a large part of the tumour is depicted.