This report describes the case of a patient with metastatic renal cell carcinoma that was treated with sunitinib (50 mg, 4/2 schedule). Daily blood pressure and physical activity were measured during 12 consecutive cycles of treatment. Average blood pressure recordings showed an upward trend during all the on-periods of sunitinib administration and a downward trend during all the 2-week off-periods. Interestingly, physical activity, assessed with a pedometer, demonstrated a highly significant opposite pattern. This case study demonstrates for the first time that physical activity can be temporarily reduced by sunitinib treatment and that a pedometer could serve as a valuable (mechanical) marker to assess this side effect of sunitinib treatment. Moreover, since its negative correlation with hypertension, it might also serve as a marker for sunitinib efficacy.

(BELG J MED ONCOL 2012;6:22–25)