Figure 2. Comparison of non-invasive and invasive biomarkers-Comparison of non-invasive and invasive biomarkers: The utilization of non-invasive approaches such as saliva and oral exfoliated cells conquer the drawbacks associated with invasive methods such as tissue biopsy and fine-needle aspiration cytology (FNAC). The painless, convenient, and safe nature of non-invasive sample collection methods provides an advantage over the painful, inconvenient, and risky aspects associated with invasive methods.