Iacovelli et al. explore the importance of tumour burden as a prognostic factor in metastatic RCC (mRCC). Although intuitively obvious, it has rarely been shown that the more extensively metastatic a patient's disease, the more negative is his/her prognosis. Indeed, there is probably more information to be extracted from tumour size and burden than has been done up until now.
With the chronicization of mRCC through the development of multiple therapeutic drugs, different profiles of patients are emerging. Some patients progress rapidly despite therapy, others are stable for a long time without treatment . It is also being discussed whether to treat asymptomatic patients at all. Nevertheless, we lack the ability to predict to which category each patient will belong, and tumour burden might be one of the factors influencing their outcome, although the present study does not correlate tumour burden to response to therapy.
Overall, measuring tumours remains the simplest way to estimate the severity of disease and predict response or, conversely, progression. Despite extensive literature on the potential of functional imaging [2–4], only tumour size is universally applicable and reliable [5,6]. The focus must be on finding clinically relevant criteria, which will help guide the oncologist in terms of therapeutic choices. Thus, collaboration must continue between oncologists and radiologists, to better understand when and how patients should be treated, or when they would not benefit from further therapy.