In this regard, LC and HNC differ from other types of cancer, such as breast cancer, in which we reported a decrease in serum PON1 activity [31], but without changes in concentration, and in other types of noncommunicable diseases associated with oxidative stress, in which an increase in the serum concentration of PON1 is often observed together with low enzyme activities [32]. Here, PON1 is linked to breast carcinoma.