MASP1 and neoplasm: A six-gene prognostic signature (<i>PYGL</i>, <i>SFRP1</i>, <i>FGD3</i>, <i>OLR1</i>, <i>DUSP9</i>, and <i>MASP1</i>) was developed using Cox and Least Absolute Shrinkage and Selection Operator (LASSO) regression, which was validated across four cohorts and evaluated for its association with immune infiltration, tumor mutation burden (TMB), and immunotherapy response.