RESUMEN
Intratumoral injection of a radiocolloid for lymphatic mapping enables the therapeutic excision of clinically occult breast cancer with the aid of a gamma-ray detection probe. The aim of this study was to determine the success rate of radio-guided tumour excision in addition to a guide wire and to identify factors predicting clear margins. Sixty-five consecutive patients underwent radio-guided tumour excision after intratumoral injection of 99mTc-nanocolloid guided by ultrasound or stereotaxis. A localization wire was inserted after scintigraphy had been performed (group 1). The results were compared with retrospective data from 67 consecutive patients who underwent therapeutic wire-directed excision alone (group 2). Factors predicting clear margins (> or = 1 mm) were determined in a logistic regression model. Adequate margins were obtained in 83% of group 1 and in 64% of group 2 (P = 0.014). The invasive component was incompletely excised in two patients in group 1 and in 14 patients in group 2. Further surgery was performed in four patients in group 1 and in 14 patients in group 2. Factors predictive of clear margins were decreasing pathological tumour diameter (P = 0.035), increasing weight of the specimen (P = 0.046), absence of microcalcifications (P = 0.004) and absence of carcinoma in situ component (P = 0.024). Radio-guided excision was an independent predictor of complete excision of the invasive component (P = 0.012). The application of radio-guided surgery combined with wire localization seems to improve the outcome of therapeutic excision of non-palpable invasive breast cancer compared with wire-directed excision alone.