Among women with long‐term follow‐up after breast cancer treatment, increasing concentrations of circulating IGFBP‐2 and PAPP‐A, determined at start of treatment, were independently associated with adverse prognosis; but when these biomarkers were tested against a clinically used prognostic model, namely NPI, there was only a modest improvement in performance characteristics. Here, IGFBP2 is linked to breast cancer.