Anti-MMP11 detection in plasma samples. MMP11 antibodies were measured by ELISA. Anti-MMP11 titers were calculated as the reciprocal limiting dilution of plasma producing an absorbance at least 3-fold greater than the absorbance of control samples average at the same dilution. The assay was run in duplicate and repeated twice. A threshold at 1:200 was arbitrarily set to identify seropositive patients. BR, breast; PROST, prostate; C, controls.