Circulating IGF-1, adiponectin, and others (IGFBP-3, HMW adiponectin) were also investigated in relation to renal cell carcinoma (RCC) risk, in a prospective study within the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trials (a population-based multi-center randomized screening trials in the US) [127]. Here, IGF1 is linked to renal cell carcinoma.