A proteinase therapy has been invented to eliminate solid tumors by destroying tumors' solid structure and killing cancer cells by cleaving vital extracellular matrix proteins C-terminally, N-terminally or both with cell membrane intact and limited adverse effects. The micro-scale intratumoral proteinase K therapy is tumor specific but not cancer type specific. Proteinase K therapy can be operated on multiple tumors on multiple occasions, if necessary. It may be employed to eliminate any solid tumor to prolong a cancer patient's life span.