99mTc–Evans Blue Dye for Mapping Contiguous Lymph Node Sequences and Discriminating the Sentinel Lymph Node in an Ovine Model

Background The aim of this study was to investigate the potential of ^99mTc–Evans blue for discriminating the sentinel lymph node in multitiered lymph node sequences by using an ovine model. ^99mTc–Evans blue is an agent that has both radioactive and color signals in a single dose. Previous studies in smaller animal models suggested that this agent could have advantages over the dual-injection technique of radiocolloid/blue dye. Methods Doses of ^99mTc–Evans blue (∼ 21 MBq) containing Evans blue dye (approximately 4 mg) were administered to the hind limbs or fore limbs of sheep to map the lymphatic drainage patterns, validate its ability to identify the sentinel lymph node, and examine the reproducibility of the technique. The study protocol was repeated with ^99mTc–antimony trisulfide colloid and Patent Blue V dye. After the operative exposure, lymph nodes were identified with the gamma probe and then excised and analyzed for radioactivity (percentage of injected dose) and blue color. Results After the administration of ^99mTc–Evans blue, all lymph nodes harvested (35 of 35) in either short chains or long basins were hot and blue. The sentinel lymph nodes concentrated more radioactivity than the second-tier nodes to the extent of 2:1 to 215:1. For radiocolloid/Patent Blue V, the ratios were lower, at 2:1 to 3:1. Conclusions ^99mTc–Evans blue was found to better discriminate the sentinel lymph node than ^99mTc–antimony trisulfide colloid/Patent Blue V in variable multitier lymph node anatomy, and it is an agent that promises to have positive clinical applications.     

A Pathologic Assessment of Adequate Margin Status in Breast-Conserving Therapy

Background The definition of a clear margin in breast-conserving therapy is uncertain. The purpose of this study was to correlate the tumor-margin distance of the excision specimen with the presence of residual tumor at reoperation. We also analyzed predictors of compromised margins and of residual disease. Methods All patients who underwent breast-conserving therapy for invasive disease from 1999 to 2003 were reviewed. Pathologic characteristics and the precise tumor distance from the radial margin were recorded. A radial margin was compromised if invasive or (ductal) in situ carcinoma was <5 mm from the margin. Results Of the 612 patients who underwent breast conservation, 211 (34%) had compromised margins, and 39 had undetermined margins. Of the 161 patients who had a reoperation for compromised margins, 87 (54%) had residual disease. Residual disease after reoperation was present in 58% (56 of 96), 56% (9 of 16), and 45% (22 of 49) of those with tumor-margin distances <1 mm, ≥1 and <2 mm, and ≥2 and <5 mm, respectively. There was a progressive decline in residual disease for each millimeter until a rate of 22% for tumor-margin distances of ≥4 mm and <5 mm was reached. Pathologic size (P = .004), an extensive intraductal component (P = .002), referral from a symptomatic rather than a population-based screening program (P = .02), and the absence of a preoperative diagnosis by core biopsy (P < .0001) were predictive of compromised margins. Only young age (<45 years) was predictive of finding residual disease on reoperation (P = .02). Conclusions A total of 45% of patients who had tumor 2 to 5 mm from the radial margin had residual disease on reoperation. Our results support a policy of requiring a 5-mm margin in patients undergoing breast-conserving therapy for invasive disease.     

Acute urinary retention: Who is at risk and how best to manage it?

In recent years, we have begun to understand the progressive nature of benign prostatic hyperplasia. By careful analysis of population studies and clinical trials, we can determine the factors most likely to predict progression to one of its most distressing complications, acute urinary retention. Acute urinary retention is a common urologic emergency and causes significant suffering, although rarely has it any serious consequences. Using our knowledge regarding the progression of benign prostatic hyperplasia, new treatment modalities are being assessed for their effectiveness at halting progression and ultimately preventing this distressing condition.