The prognosis of tumors with only microscopic skin involvement without clinical T4b signs is significantly better than T4b tumors in breast carcinoma.

The number of studies forming a base for tumor (T)-node (N)-metastasis (M) classification by comparing T4b tumors with only histological skin involvement in breast carcinoma is limited and results are contradictory. In this study, the survival of patients with T4b tumor and patients whose tumor had only microscopic skin involvement without clinical T4b signs were compared. The file records of 101 patients with T4b tumor (group A) and 79 patients whose tumor had only microscopic skin involvement (group B) were reviewed. The endpoint was disease recurrence. For the whole series, disease-free survival (DFS) of group B patients was significantly better compared with group A patients treated with either adjuvant (p<0.001) or neoadjuvant (p<0.001) therapies. When patients were subgrouped according to tumor size, DFS of group B patients was significantly better than group A patients receiving either adjuvant or neoadjuvant therapy for all tumor size subgroups of ≤3, >3, ≤5, and >5cm. Presence of T4b clinical signs had independent prognostic value in multivariate Cox analysis. In conclusion, tumors with only histological skin involvement without clinical T4b signs should be classified as T1-T3 according to their size instead of T4 as stated in the TNM classification.