LDHA and head and neck neoplasm: Indeed, it has been observed that cells with high ALDH activity are able to induce greater tumor growth compared to ALDH-negative subpopulations, thus, high ALDH activity evaluation has been employed to identify and to isolate CSC from several tumors, such as ovarian cancer [13], prostate cancer [14], lung cancer [15], breast cancer [16], leukemic stem cell cancer [17], gastrointestinal neuroendocrine tumors [18], head and neck tumors [19], sarcoma [20], and more.