Can We Adapt Neoadjuvant Rectal (NAR) Score with Systemic Immune-Inflammation Index (SII) and Prognostic Nutritional Index (PNI) as Prognostic Factors in Locally Advanced Breast Cancer?

Background Breast cancer is the most common malignancy among women, and despite therapeutic advances, many still present with locally advanced disease. Identifying simple prognostic tools to predict outcomes after neoadjuvant therapy remains a challenge. The neoadjuvant rectal (NAR) score, systemic immune-inflammation index (SII), and prognostic nutritional index (PNI) have shown prognostic value in various malignancies. In this study, we evaluated their prognostic significance in patients with locally advanced breast cancer (LABC).

Methods We retrospectively analyzed 187 female LABC patients treated with anthracycline- and taxane-based neoadjuvant chemotherapy between 2011 and 2020. HER2-positive patients also receive anti-HER2 therapy. The NAR score was calculated using the Valentini formula, and the SII and PNI were determined before (bNAT) and after (aNAT) the neoadjuvant treatment. Receiver operating characteristic (ROC) analysis defined the cut-off values for NAR (28.35), SII (bNAT: 656; aNAT: 687), and PNI (bNAT: 42.5; aNAT: 40.5). Associations with clinicopathological variables, disease-free survival (DFS), and overall survival (OS) were analyzed using the chi-square, Mann-Whitney U, and Kaplan-Meier tests.

Results Of all patients, 62% had low NAR scores (≤ 28.35) and 38% had high scores (> 28.35). High NAR scores correlated with advanced stage, lymphovascular invasion, lower pathological complete response (pCR), and higher mortality (p <0.01). Post-treatment, the SII increased (p = 0.012), while the PNI decreased (p = 0.001). Low PNI (aNAT <40.5) was associated with higher mortality (p = 0.027) and axillary nodal positivity (p = 0.033). The median follow-up period was 46 months.

Conclusion High NAR and low post-treatment PNI were associated with a poor prognosis in patients with LABC. These accessible parameters may complement the existing prognostic models; however, prospective validation in larger cohorts is warranted and the retrospective design and single-center nature of the study should be considered when interpreting results.