Tumor-Infiltrating Lymphocytes and Tumor Budding: Emerging Prognostic Markers in Breast Cancer.

Introduction Invasive breast carcinoma of no special type (IBC-NST) remains a significant global health burden. Tumor-infiltrating lymphocytes (TILs) reflect the host's anti-tumor immunity and are associated with favorable outcomes, whereas tumor budding (TB) is a marker of tumor aggressiveness. This study aimed to assess TILs and TB in IBC-NST and correlate them with clinicopathological parameters. Methods This retrospective study included 90 (100%) cases of IBC-NST. Stromal TILs (sTILs) and intratumoral TILs (iTILs) were quantified on hematoxylin and eosin (H&E)-stained sections per international guidelines. Tumor buds were counted at the invasive front and classified into low- and high-grade budding. Associations between TILs, TB, and clinicopathological features were analyzed using chi-squared and correlation tests. Results Among 90 cases, 89 (98.8%) were IBC-NST. Both sTILs and iTILs decreased with higher tumor grade, larger size, and increased mitotic count, with statistically significant associations for grade and mitosis (p < 0.05). High-grade TB was significantly associated with lymph node metastasis (35/53, 66.0%), higher tumor grade (50/78, 64.1%), tumor size > 5 cm (23/27, 85.2%), and lymphovascular invasion (32/42, 76.19%) (p < 0.05 for all). A moderate but non-significant positive correlation was noted between sTILs and TB (r = 0.163, p = 0.124). Conclusion Higher TIL levels correlate with favorable tumor characteristics, while increased TB reflects aggressive histological features. A combined evaluation of TILs and TB provides valuable prognostic insights and may assist in stratifying breast cancer patients for tailored therapeutic approaches.