Malignant Seeding of the Lumpectomy Cavity upon Breast-Conserving Surgery

One of the etiologic factors involved in local recurrence after breast-conserving surgery may be malignant seeding of the wound during the lumpectomy procedure. A total of 340 patients with stage I and II breast cancer were entered into the study. Of these, 270 patients received breast-conserving surgery (BCS group), and the other 70 patients underwent mastectomy (control group). After resection, lavage cytology was performed at the surgical wound. There were 55 patients (20.4%) who showed positive lavage cytology in the BCS group. In the control group, there were only 3 patients (4.3%) with positive cytology. Positivity was significantly higher in the former group (p = 0.00064). Patients with evidence of cutting across cancer lesions showed significantly higher positive rates in lavage cytology (p < 0.00001). Positivity in lavage cytology was significantly higher in patients with positive surgical margins evaluated by frozen sections (p = 0.0017), touch cytology (p < 0.0001) and formalin-fixed, paraffin-embedded sections (lateral or medial margin; p = 0.0036, anterior and posterior margin: p = 0.0210). The positivity was also significantly higher in patients with an extensive intraductal component (p < 0.0001), and less than or equal to 50 (p = 0.0061) years of age. Multivariate analysis revealed that the highest relative risk factor for positive cytology was evidence of cutting across cancer lesions (relative risk = 8.166; p < 0.00001).