Relationship between the morphological and biological characteristics of intraductal components accompanying invasive ductal breast carcinoma and patient age.

We divided 324 cases with invasive ductal breast carcinoma into three age groups, and investigated the differences in proliferative activity and extension of the intraductal components among the age cohorts. Proliferative activity was expressed as the number of MIB1-positive nuclei per 1000 cancer cells in the intraductal components (MLI), and the intraductal component extension farthest from the invasive focus was defined as the maximum distance of ductal spread (MXDS). Moreover, analyses were conducted for three grade types, classified according to the classification system of ductal carcinoma in situ. The under-40 age group had significantly higher MXDS values than the other two age groups (p = 0.0280), and this trend was more marked in those with the non-high grade without necrosis type (p = 0.0045). The under-40 age group had higher MLIs, but the differences did not reach statistical significance (p = 0.0793). In regard to those with the high grade type, the under-40 age group had significantly higher MLIs than the other two age groups (p = 0.0269), and this trend was not significant in the cases with any other grade types. Associations between the age group and the margin status of the lumpectomy specimens were investigated in the 143 cases in which breast conserving surgery was tried. The under-40s had a significantly higher margin-positive rate in their lumpectomy specimens than the other two age groups (= 0.0362), and this trend was also seen in the groups with the non-high grade without necrosis type (p = 0.0256). These results confirm the importance of considering patient age when designing surgical procedures for breast conserving therapy.