C4A and monoclonal gammopathy: The following baseline variables at diagnosis were associated with hematological cancer in the Cox regression analysis (Table 1): anemia (HR 2.07; p = 0.009), C3 levels <0.82 g/L (HR 2.07; p = 0.033), C4 levels <0.11 g/L (HR 2.23; p = 0.015), monoclonal gammopathy (HR 2.13; p = 0.028), and cryoglobulins (HR 4.37; p < 0.001).