F. prausnitzii supernatants have been shown to inhibit interleukin-6/Signal Transducer and Activator of Transcription 3 (IL-6/STAT3) signaling, which in turn led to an inhibition of breast cancer cell growth, pointing to a possible mechanism how gut resident F. prausnitzii is able to influence distal tumor cells [12]. Here, STAT3 is linked to breast carcinoma.