In HNSCC, Principal Component Analysis (Fig. 2) showed that circulating immune complexes were associated with advanced tumor stage; furthermore, the vectors that represent these variables did not positively correlate to serum MUC1 and anti-MUC1 IgG antibody levels, and also were inversely correlated with MUC1 tumor expression. The gene discussed is MUC1; the disease is head and neck squamous cell carcinoma.