IGHM and breast cancer: Among these, 26 proteins were quantifiable (Table 5), with 6 showing lower levels in the BC group compared to the CT group (PON1, apoA-4, TTR, CLEC3B, IGHM, and SAA2) (Figure 1A–F), and only 1 exhibiting higher levels in BC compared to the CT group (CNDP1) (Figure 1G).