Histological determinants for different types of local recurrence after breast-conserving therapy of invasive XXXX . Dutch Study Group on local Recurrence after Breast Conservation (BORST)

@entity1 @entity5 @entity0
The purpose of this study was to determine which histological factors are associated with an increased risk for local recurrence in the breast after breast-conserving therapy for early @entity0 (TNM stage I and II) and whether risk patterns vary according to menopausal status and type of local recurrence. Through complete follow-up of the @entity1 of eight regional radiation oncology departments, two @entity5 institutes and one surgical clinic in The Netherlands, 360 @entity1 were identified with local recurrence in the breast after having received breast-conserving therapy (local @entity5 excision, axillary dissection and irradiation of the whole breast and a boost to the @entity5 bed) during the 1980s. For each case, two controls with a follow-up of similar duration without local recurrence were randomly selected. Histological slides of the primary @entity5 were reviewed. Among premenopausal @entity1 the risk of recurrence for those younger than 35 years was significantly higher than that for premenopausal @entity1 of 45 years or older (relative risk (RR) 2.9; 95% confidence interval (95% CI) 1.3-6.6, P < 0.05). The risk of recurrence at or near the site of the primary @entity5 was most significantly increased for @entity1 with high grade extensive intraductal component (EIC) adjacent to the primary @entity5 (RR 4.1; 95% CI 1.7-9.8, P < 0.01). Microscopic margin involvement was an important risk indicator for diffuse recurrence and recurrence in the skin of the breast, especially in the presence of vascular invasion (RR 25; 95% CI 4.0-150, P < 0.001). To prevent local recurrence at or near the site of the primary @entity5 , local excision with a 1-2 cm margin of healthy tissue and a 15 Gy boost seemed adequate local treatment for @entity1 with well differentiated EIC. In contrast, a wider surgical margin, a higher boost dose or mastectomy should be considered for @entity1 with poorly differentiated EIC. Microscopic margin involvement in the presence of vascular invasion significantly increases the risk of diffuse recurrence or recurrence in the skin.
