A method of selecting a collection of frame-shift peptides (CFSP) for producing a universal micro-satellite instability cancer vaccine peptide collection for prophylaxis or treatment of a patient with a cancer comprising hereditary and sporadic MSI cancer or being at risk of developing such a cancer, comprising the steps of: (i) selecting a collection of nucleic acids (CFSM) each comprising a frame-shift mutation each FSM being present in one or more of at least M cancer samples each of a different patient, wherein the cancer of the patient comprises cancer cells with an MSI phenotype; wherein at least 50% of the FSM that are selected fulfill criteria (a), (b), (c) and (d): (a) the FSM is present in a mononucleotide repeat of coding genes with a length equal to or longer than 6 nucleotides; (b) the FSM corresponds to a deletion of 1 nucleotide; (c) the number of DNA sequencing reads harboring the FSM is significantly higher in the tumor sample as compared to the matched normal sample (FDR-corrected Fisher test p-value equal to or lower than 0.05); (d) the FSM is present in the matched normal samples with an allele frequency lower than 25%, (ii) selecting X different frame-shift peptides (FSPs), wherein each selected FSP is the complete translation product of the protein-encoding segment of a nucleic acid comprising a FSM of the CFSM of at least 4 amino acid length, starting from the codon encoding the first amino acid that is different relative to the translation product of the corresponding wild type (wt) nucleic acid without the FSM, wherein X is at least 20 more preferably at least 35 and M is at least 5. (i) selecting a collection of nucleic acids (CFSM) each comprising a frame-shift mutation each FSM being present in one or more of at least M cancer samples each of a different patient, wherein the cancer of the patient comprises cancer cells with an MSI phenotype; wherein at least 50% of the FSM that are selected fulfill criteria (a), (b), (c) and (d): (a) the FSM is present in a mononucleotide repeat of coding genes with a length equal to or longer than 6 nucleotides; (b) the FSM corresponds to a deletion of 1 nucleotide; (c) the number of DNA sequencing reads harboring the FSM is significantly higher in the tumor sample as compared to the matched normal sample (FDR-corrected Fisher test p-value equal to or lower than 0.05); (d) the FSM is present in the matched normal samples with an allele frequency lower than 25%, (a) the FSM is present in a mononucleotide repeat of coding genes with a length equal to or longer than 6 nucleotides; (b) the FSM corresponds to a deletion of 1 nucleotide; (c) the number of DNA sequencing reads harboring the FSM is significantly higher in the tumor sample as compared to the matched normal sample (FDR-corrected Fisher test p-value equal to or lower than 0.05); (d) the FSM is present in the matched normal samples with an allele frequency lower than 25%, (ii) selecting X different frame-shift peptides (FSPs), wherein each selected FSP is the complete translation product of the protein-encoding segment of a nucleic acid comprising a FSM of the CFSM of at least 4 amino acid length, starting from the codon encoding the first amino acid that is different relative to the translation product of the corresponding wild type (wt) nucleic acid without the FSM,