SUSD4 expression in breast cancer is associated with an improved prognosis. A cohort of breast cancer tissue samples were stained for SUSD4, and the intensity of the staining in tumor cells was scored 0, 1, or 2. Representative pictures were taken at 40X magnification (a). The scores were grouped into SUSD4+ (1, 2) or SUSD4− (0) tumors. The number of SUSD4+ infiltrating cells was counted in each section, and was grouped into low (0–15 cells/section) and high (16–100 cells/section). Representative pictures are shown in b. Kaplan-Meier analyses showed that SUSD4 expression by tumor cells was associated with prolonged breast cancer specific survival of the patients (c), but recurrence free survival was not affected (d). A higher number of SUSD4+ infiltrating cells in the stroma was also beneficial for the survival rate (e), while it did not affect recurrence free survival (f). SUSD4 transcript levels were analysed by qPCR in a second cohort of breast cancer samples. Increased levels of SUSD4 transcripts was associated with improved survival (g), but not with recurrence free survival (h).