B2M and neoplasm: Increased β2-M levels in body fluids (such as serum, plasma, or urine) are seen in patients with malignancies, including breast cancer, renal cell carcinoma, oral squamous cell carcinoma, lung cancer, gastrointestinal tract cancer, prostate cancer, lymphocytic malignancies, and multiple myeloma12–17, and can promote tumor growth through specific axes18.