A method of reducing or abolishing dissemination of malignant cells into a blood and/or lymph vessel of a subject having a malignant skin tumor and subjected to a surgical procedure for removing at least a portion of said malignant skin tumor, the method comprising administering to the subject, prior to, concomitant with or subsequent to the surgical procedure, a devitalizing effective amount of a tetramer of 2,2-dichloropropanoic acid or a pharmaceutical acceptable salt thereof, by locally administering the tetramer onto and/or into said skin tumor,
- wherein said tetramer comprises bonds between the monomeric units, said bonds being selected from the group consisting of ether bonds and ester bonds.