Eficacia de la suplementación con L-arginina sobre la respuesta a la quimioterapia neoadyuvante en pacientes con cáncer de mama

Background: Breast cancer is the first cause of mortality from malignant neoplasms among women in Mexico. Neoadjuvant chemotherapy has a reported efficacy of approximately 70%; however, patients with inadequate response must undergo additional coadjuvant methods that negatively affect their quality of life. High concentrations of nitric oxide have shown cytotoxic and tumoricidal effects, thus favoring an adequate response to antineoplastic treatment. L-arginine is a nitric oxide precursor and therefore supplementation with this substance can augment nitric oxide synthesis and consequently its plasma concentration. Objectives: To evaluate the efficacy of L-arginine supplementation in response to neoadjuvant chemotherapeutic treatment. Materials and methods: We conducted a randomized clinical trial in which 30. g of L-arginine was administered in each neoadjuvant chemotherapy cycle. Plasma nitrite concentrations were determined before and after supplementation, as well as tumoral size before the start of antineoplastic treatment and after its completion. A chi-square test was performed to evaluate the association between the supplementation and adequate treatment response; plasma nitrites were evaluated by performing Student's T-tests. Results: Forty-five patients were assessed, of whom 21 had an adequate response to antineoplastic treatment. No statistically significant association was found between supplementation and adequate response. Nitrite concentrations in plasma were significantly increased (p<0.05) in patients receiving the supplement than in those who receiving placebo. Conclusions: L-arginine supplementation can modulate nitric oxide synthesis and thus elevate plasma nitrite concentrations. However, this supplementation is not associated with an adequate response to neoadjuvant treatment; indeed, in this study, treatment response was lower than that reported in the literature, probably because the antineoplastic therapy was not tailored to specific tumoral characteristics.