Exosomes, particles measuring from 30 to 150 nm in diameter, are critical messengers in intercellular communication.[38, 39] Recent studies have shown that CAFs are one of the main sources of exosomes in the TME and that CAF‐derived exosomes play an important role in mediating drug resistance.[40, 41] Yeung and co‐workers reported that CAF‐derived exosomal miR‐21 confers paclitaxel resistance on ovarian cancer cells by targeting APAF1.[42] However, few studies have evaluated the role of CAF‐derived exosomes in tamoxifen resistance in breast cancer. This evidence concerns the gene APAF1 and breast cancer.