Anticancer treatments are frequently accompanied by cutaneous adverse effects: capecitabine treatment induces handfoot syndrome (HFS) in approximately 50% to 60% of patients, whereas hand-foot skin reaction (HFSR) has been reported in 19% to 34% of patients treated with the tyrosine kinase inhibitors (TKIs) sunitinib malate or sorafenib tosylate. 1 Ultimately, these cutaneous adverse events are believed to result in the loss of fingerprints, which, to our knowledge, has been described anecdotally for patients treated with capecitabine 2-6 and can cause serious identification problems. We assessed the association of HFS and HFSR with fingerprint quality.Methods | This prospective cohort study was performed at the Erasmus MC Cancer Institute, Rotterdam, the Netherlands, and included 337 ten-fingerprint sets from 150 patients. The principal inclusion criterion was a planned daily treatment with capecitabine (as monotherapy or combination therapy) or a TKI. Previous treatment with these drugs was not allowed. Fingerprints were taken from all patients' fingers using a digital fingerprint scanner (MorphoLivescan; Morpho) before treatment, within 6 to 10 weeks after the start of treatment, and after treatment discontinuation. At the same time, digital photographic images (Nikon Corporation) were made of the palms and fingers of patients to detect abnormalities that could affect the fingerprints. Three dactyloscopists and a detective from the Netherlands National Police Agency visually assessed fingerprints and images, respectively. The baseline fingerprints were compared with the fingerprints during treatment and were scored on the overall quality of friction ridge details and the suitability for individualization purposes. A 5-point scale was used on which slight improvement was scored as 1, no changes as 2, slightly decreased quality as 3, major loss of quality as 4, and total loss of fingerprint quality as 5. The scores were averaged, and, subsequently, these results were dichotomized to severe quality loss (score 4-5) or no severe changes in fingerprints (score 1-3). The severity levels of HFS and HFSR were graded according to the National Cancer Institute's Common Terminology Criteria for Adverse Events version 4.03. Groups were compared using a χ 2 test. The institutional review board of the Erasmus MC Cancer Institute approved the study protocol, and written informed consent was obtained from all patients.