Sustained systemic response paralleled with ovarian metastasis progression by sunitinib in metastatic renal cell carcinoma: Is this an anti-angiogenic potentiation of cancer?

Metastatic renal cell cancer is associated with poor prognosis and survival and is resistant to conventional chemotherapy. Therapeutic targeting of molecular pathways for tumor angiogenesis and other specific activation mechanisms offers improved tumor response and prolonged survival. A 48-year-old, female patient presented with large right renal mass with features suggesting of renal cell cancer without metastasis on contrast enhanced computed tomography (CT). Right radical nephrectomy was done. After 9 months of surgery, she got metastasis in lung, liver and ovary. The patient received sunitinib via an expanded access program. After eight 6-week cycles of sunitinib, a reassessment CT scan confirmed an excellent partial response with the almost complete disappearance (90%) of liver and lung metastasis but the adnexal mass had increased in size (>10 times) and the possibility was thought of second malignancy. Excision of the mass performed. Histopathology of the mass depicted metastatic renal cell cancer. There is possibility of a 'site-specific anti-angiogenic potentiation mechanism' of malignancy in relation to sunitinib based upon the preclinical studies, in reference to the index case. Regression of one site with concurrent progression is possible. The exact mechanism of site-specific response, especially organ specific progression by vascular endothelial growth factor inhibitors in metastatic renal cell cancer warrants further study.