The delta-5 desaturase activity was assessed using the ratio of arachidonic (ARA, 20:4 n-6) to dihomo-γ-linolenic acid (DGLA, 20:3 n-6) content and was lower in breast cancer patients than in the control group, albeit non-significantly, and there was a trend to decrease in patients in subsequent follow-ups (Table S2). Here, FADS1 is linked to breast carcinoma.