Tumour shrinkage measured with first treatment evaluation under VEGF-targeted therapy as prognostic marker in metastatic renal cell carcinoma (mRCC)

BACKGROUND: The aim of our analysis is to further characterise the prognostic relevance of early tumour shrinkage (TS) during VEGF-targeted therapy in mRCC, in order to explore whether this could define a group of patients with long-term survivorship.

METHODS: A hundred patients were stratified into five subgroups according to their change of tumour size with first treatment evaluation: -100% to -60%; -59% to -30% and -29% to 0% TS or gain of tumour size from 1% to 19% and ≤20% or occurrence of new lesions (i.e., progressive disease).

RESULTS: The median PFS and OS were 10.4 months and 28.2 months, respectively. The median OS stratified according to the subgroups as described above was 77.4, 33.5, 26.9, 30.0 and 14.3 months, respectively. Multivariate analysis revealed early TS as a prognostic marker (P=0.021; HR 1.624).

CONCLUSION: The extent of TS defines a small proportion of patients with an excellent prognosis. Larger studies are warranted to define the relationship of long-term survivorship and extent of TS with targeted therapies.