Understanding a patient's allergy status is important for ensuring safe, high-quality patient care. In cancer patients, in whom the ability to use first-line chemotherapeutic agents is critical, an accurate allergy diagnosis is also necessary for proper management of HSR and for providing optimal therapy.
In our study, skin tests in cancer patients with symptoms of a possible HSR during the administration of a platinum salt helped to identify patients with platinum allergy and to evaluate the cross-reactivity between these agents in order to safely reintroduce an alternative platinum. Altogether, skin tests allowed platinum-based treatment to continue in 15 patients, of whom 14 (64%) continued with good long-term tolerance. Only in 7 of the patients did the oncologist decide to discontinue treatment. These results are similar to those observed in other published series that analyzed the treatment options followed in patients and their outcomes after performing skin tests. Pradelli et al.  in a recent publication reported that 65% of patients with suspected HSRs who were referred for the study of hypersensitivity continued with the platinum-based therapy, while Leguy et al.  in a previous study reported a somewhat lower percentage, 57%, probably because they did not perform controlled desensitization in patients with positive skin tests.
The high NPV found in our study (0.91) is consistent with that described in the literature, the latter being between 0.92–0.99, even reaching 100% true negatives in some cases [4, 6, 7]. Published data also indicate that in patients with false negative results subsequent reactions are usually mild, as happened with our patient [7, 8]. These data indicate that skin tests may predict with reasonable reliability the absence of a future HRS in case of further chemotherapy with a negatively tested platinum salt.
Regarding the risk factors for HSR to platinum salts, these reactions occur after patients have undergone several courses of treatment [6, 7, 9]. Although we found that the median number of courses before the suspected HSR was 9, consistent with those collected in the bibliography, we did not find statistical significance between the patients with positive and negative skin tests, probably due to the small sample size. It should be noted that with respect to another widely described risk factor, which is having a platinum-free interval greater than 12 or 24 months [9, 10], in our study, statistically significant differences were obtained in the platinum-free interval between patients with positive and negative results, with the median of positives at 22 months.
This study provides initial evidence of the value of skin testing as a diagnostic aid. Nevertheless, we must acknowledge some limitations, principally the small patient population and the retrospective and observational nature of the study. Prospective studies in wide series are needed to more precisely determine the usefulness of these tests.
In conclusion, skin testing allowed accurate identification of patients with platinum allergy and the resumption of platinum-based therapy in many patients for whom no suitable therapeutic alternative was clinically acceptable.