Kaplan-Meier plots were determined for BALB/c mice receiving Trp53-null mammary transplants and fed a lifelong LFD (LFD; n= 37 glands), a lifelong HFD (HFD; n= 46), a puberty-restricted HFD (HFD-LFD, n=42), and an adult-restricted HFD (LFD-HFD, n=38). A. The number of tumor-free mammary glands over one year was significantly reduced in mice fed HFD-LFD and LFD-HFD. (Log-rank tests, LFD vs. HFD, p = 0.158; LFD vs. HFD-LFD, *, p = 0.042; LFD vs. LFD-HFD, **, p = 0.009). B. The number of tumor-free mammary glands over 500 days was significantly reduced by HFD and LFD-HFD, but not HFD-LFD. (Log-rank tests, LFD vs. HFD, *, p = 0.046; LFD vs. HFD-LFD, p = 0.131; LFD vs. LFD-HFD, **, p = 0.006).