Various embodiments provide compositions and methods for detecting cancers containing an NRG1 fusion event and treating a patient with a therapeutic agent that is targeted to the NRG1 fusion. Exemplary compositions for treating cancers containing the NRG1 fusion may comprise therapeutic agents inhibiting Epidermal Growth Factor Receptor and/or ERBB2 such as cetuximab, panitumumab, Sym004, MM-151, mAb 806, mAb 528, MEHD794A, gefitinib, erlotinib, lapatinib, afatinib, PD153035, AG1478, trastuzumab, and pertuzumab. In some embodiments, the therapeutic agent may be a combination of trastuzumab, and pertuzumab.