ERBB2 and breast cancer: The differences between the Trp content in saliva for these breast cancer subtypes compared to others were statistically significant (TNBC vs. luminal A-like: +67.8%, p = 0.0149; TNBC vs. luminal B-like (HER2+): +61.1%, p = 0.0027; TNBC vs. non-luminal: +126.0%, p < 0.0001; luminal B-like (HER2-) vs. non-luminal: +61.5%, p = 0.0456).