In metastatic renal cell carcinoma (RCC) many factors may influence the decision to switch therapies. From a radiographic angle, several principles help to guide the decision to switch, including the measurement of tumor growth and progression. However, before switching therapies, Brian I. Rini, MD, cautions, it is important for the oncologist to examine the scans themselves, rather than relying solely on the radiology report.

Several factors can cause a misleading radiology report, believes Rini. In addition to weeding out inaccuracies, reading the scans provides the oncologist with a better sense of change in tumor burden. If the tumor growth is slow, a change in therapy is not necessary. However, if the tumor is growing rapidly, a switch is required, notes Rini.

Radiologists are trained to view scans with the goal of finding dynamics within the scans, Robert A. Figlin, MD notes. As such, oncologists need to bridge the gap between radiologic interpretation and an understanding of the disease. The interpretation of tumor growth and imaging varies from cancer-to-cancer; as such, biology should be integrated into the report, believes Figlin.

In some cases, the radiology report may simply read "progression" rather than provide measurements, states Daniel J. George, MD. In this case, it is essential to look at the scans to determine the exact amount of growth. In many cases, George notes, growth of only a few millimeters is not necessarily clinically significant and may not warrant a change in treatment.

Another angle to consider, Figlin adds, is the increase in transparency and the patient’s interpretation of the radiographic readouts. It is important to recognize that a patient's interpretation of these scans may be different from the oncologist.