Heterogenety of stage I breast cancer: biological and prognostic value

The introduction of breast cancer screening programs worldwide led not only to the increase of non-invasive carcinoma and stage I breast cancer percentage but also to the redistribution of biological tumor subtypes in female population screened. The proportion of stage I breast cancer is only 21,4% in our country; biological and predictive value of tumor size (T1a, T1b and T1c) is still undefined. We analyzed clinical and morphological characteristics as well as tumor size prognostic value (T1a-c) for the recurrence and death from progression risk determination in 1341 breast cancer patients with stage I tumors. We revealed progressive increase of “small” tumors proportion (T1a and T1b) in stage I breast cancer population within the last 25 years. The percentage of microinvasive carcinomas raised from 0,3% to 4,3% while T1bN0M0 proportion increased from 8,7% to 22,1%; this is the evidence of early breast cancer diagnostics improvement. Stage I breast cancer is the heterogeneous group of tumors with favorable prognosis in case of T1a (≤5 mm) and more aggressive behavior in T1b (6–10 mm) and T1c (11–20 mm). Only T1a tumors have favorable biological profile (huge proportion of luminal A subtype) which reflects upon the long-term treatment results (minimum recurrences and cancer deaths, improved overall survival). Biological behavior of T1b and T1c tumors is more aggressive with high rates of ductal carcinoma, luminal B and triple negative subtypes which significantly worsen the prognosis. The biology of “small” tumors should be considered when choosing the optimal adjuvant treatment algorithm for breast cancer patients.