This collection includes MALDI MS filedata underpinning the study by Russo et al entitled "Non-invasive screening of breast cancer from fingertip smears : a proof of concept study" and published in Scientific Reports. In particular the files correspond to the acquisition of MALDI MS spectra from the fingertip smears of 15 patients split in three diagnostic catergories: healthy, early breast cancer and metastatic. Mass Spectra data have been supplied in three formats: raw spectra (in the proprietary Waters Corp Synapt G2 HDMS format), exported as text files after processing (.txt) and as the associated processed dataset that has been used for downsteam ML (.csv). Additionally, a Jupyter notebook containing all the data pre-processing steps, and also the subsequent undersupervised learning analysis.