[en] Purpose: To study the relationship of tumor grade to the distribution of pathologic features and to the risk of local and distant recurrence following breast-conserving therapy in patients with pure infiltrating ductal carcinoma, and to explore the differences between this type and tubular carcinoma. Materials and Methods: Between 1968 and 1986, 1624 patients were treated for clinical Stage I or II invasive breast cancer with a complete gross excision and ≥60 Gy to the tumor bed. The original slides were reviewed in 1337 cases (82%). Of these, 1081 were pure infiltrating ductal carcinoma and 28 were tubular carcinoma and these constitute the study population. Fifty-five patients (5%) have been lost to followup after 7-181 months. Median followup for 742 survivors is 134 months (7-278 mos.). We evaluated the following features: histologic grade (modified Bloom-Richardson system), the presence of nodal metastases (in 891 pts. (80%) undergoing axillary dissection [pLN+]), an extensive intraductal component (EIC), lymphatic vessel invasion (LVI), mononuclear cellular response (MCR), and necrosis. We analyzed the incidence of clinical and pathologic characteristics as a function of histology and histologic grade (Table 1). We also examined the 10-year crude rates of first failure for evaluable patients (Table 2) and calculated actuarial curves for regional nodal failure or distant metastasis (RNF/DM) at any time during followup (Figure 1). Results: Conclusions: 1) The proportion of tumors with LVI, EIC, or lymph node involvement did not vary significantly by histologic grade. Low grade tumors tended to be smaller and exhibit less MCR and necrosis; 2) Grade did not predict for local recurrence. Distant recurrence rates were significantly higher in patients with grade II or III as compared with grade I tumors, although recurrence rates continued to rise for grade I tumors through 10 years of followup; 3) Although patient numbers are small, tubular breast carcinomas appear to have an excellent prognosis with little risk of distant recurrence up to 10 years after treatment