We found consistent evidence for association of 4 circulating inflammatory markers in risk of 4 site-specific cancers: positive associations between pro-adrenomedullin and breast cancer and interleukin-23 receptor and pancreatic cancer and inverse associations between prothrombin and basal cell carcinoma and interleukin-1 receptor-like 1 and triple-negative breast cancer. Here, IL1RL1 is linked to triple-negative breast carcinoma.