Prognostication is routinely performed using clinico-pathologic information; namely the Nottingham Prognostic Index (NPI),23 which comprises tumor size, grade and lymph node status, and an IHC panel to evaluate ER, PR and HER2 (with or without Ki67, a marker of proliferation).24 Ostensibly, the molecular signature market for breast cancer is a busy space (reviewed in ref. 25), however the utility in ILC of some of the existing commercial tests remains to be seen, and uptake is by no means global. The gene discussed is ESR1; the disease is breast cancer.