Histological determinants for different types of local recurrence after breast-conserving therapy of invasive breast cancer

The purpose of this study was to determine which histological factors are a ssociated with an increased risk for local recurrence in the breast after b reast-conserving therapy for early breast cancer (TNM stage I and II) and w hether risk patterns vary according to menopausal status and type of local recurrence. Through complete follow-up of the patients of eight regional ra diation oncology departments, two cancer institutes and one surgical clinic in The Netherlands, 360 patients were identified with local recurrence in the breast after having received breast-conserving therapy (local tumour ex cision, axillary dissection and irradiation of the whole breast and a boost to the tumour bed) during the 1980s. For each case, mo controls with a fol low-up of similar duration without local recurrence were randomly selected. Histological slides of the primary tumour were reviewed. Among premenopaus al patients the risk of recurrence for those younger than 35 years was sign ificantly higher than that for premenopausal patients of 45 years or older (relative risk (RR) 2.9; 95% confidence interval (95% CT) 1.3-6.6, P < 0.05 ). The risk of recurrence at or near the site of the primary tumour was mos t significantly increased for patients with high grade extensive intraducta l component (EIC) adjacent to the primary tumour (RR 4.1; 95% CI 1.7-9.8, P < 0.01). Microscopic margin involvement was an important risk indicator fo r diffuse recurrence and recurrence in the skin of the breast, especially i n 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 tumour, local e xcision with a 1-2 cm margin of healthy tissue and a 15 Gy boost seemed ade quate local treatment for patients with well differentiated EIC. In contras t, a wider surgical margin, a higher boost dose or mastectomy should be con sidered for patients with poorly differentiated EIC. Microscopic margin inv olvement in the presence of vascular invasion significantly increases the r isk of diffuse recurrence or recurrence in the skin. (C) 1999 Elsevier Scie nce Ltd. All rights reserved.