This review aims to comprehensively analyze the impact of three newly identified peptides arising from the IGF-1 isoforms IGF-1Ea, IGF-1Eb, and IGF-1Ec, in both normal and carcinogenic contexts, and their use as possible therapeutical targets in BC that can complement the action of the newly developed anti-IGF-1R treatment. This evidence concerns the gene IGF1R and breast cancer.