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IMPORTANCE: Although complete excision of breast cancer is accepted as the best means to reduce local recurrence and thereby improve survival, there is currently no standard margin width for breast conservation surgery. As a result, significant variability exists in the number of additional operations or repeat surgeries patients undergo to establish tumor-negative margins. OBJECTIVE: To determine the patient, tumor, and facility factors that influence repeat surgery rates in US patients undergoing breast conservation surgery. DESIGN, SETTING, AND PATIENTS: Patients diagnosed as having breast cancer at a Commission on Cancer accredited center from January 1, 2004, through December 31, 2010, and identified via the National Cancer Data Base, a large observational database, were included in the analysis. A total of 316 114 patients with stage 0 to II breast cancer who underwent initial breast conservation surgery were studied. Patients who were neoadjuvantly treated or whose conditions were diagnosed by excisional biopsy were excluded. MAIN OUTCOMES AND MEASURES: Patient, tumor, and facility factors associated with repeat surgeries. RESULTS: A total of 241 597 patients (76.4%) underwent a single lumpectomy, whereas 74 517 (23.6%) underwent at least 1 additional operation, of whom 46 250 (62.1%) underwent a completion lumpectomy and 28 267 (37.9%) underwent a mastectomy. The proportion of patients undergoing repeat surgery decreased slightly during the study period from 25.4% to 22.7% (P < .001). Independent predictors of repeat surgeries were age, race, insurance status, comorbidities, histologic subtype, estrogen receptor status, pathologic tumor size, node status, tumor grade, facility type and location, and volume of breast cancer cases. Age was inversely associated with repeat surgery, decreasing from 38.5% in patients 18 to 29 years old to 16.5% in those older than 80 years (P < .001). In contrast, larger tumor size was linearly associated with a higher repeat surgery rate (P < .001). Repeat surgeries were most common at facilities located in the Northeast region (26.5%) compared with facilities in the Mountain region, where only 18.4% of patients underwent repeat surgery (P < .001). Academic or research facilities had a 26.0% repeat surgery rate compared with a rate of 22.4% at community facilities (P < .001). CONCLUSIONS AND RELEVANCE: Approximately one-fourth of all patients who undergo initial breast conservation surgery for breast cancer will have a subsequent operative intervention. The rate of repeat surgeries varies by patient, tumor, and facility factors and has decreased slightly during the past 6 years.

Gemini surfactant p-phenylenedimethylenebis(n-hexadecyldimethylammonium) dibromide (abbreviated C16-DMB-C16, with DMB p-CH2C4H6CH2) with a rigid spacer was found to produce cubic MCM-48 silica mesophase by temperature-induced phase transition from the MCM-41 hexagonal phase. The synthesis involved two steps, a precipitation stage at room temperature for a period of time t1, followed by an aging step at higher temperature for a period of time t2. The synthesis was optimized for particular combinations of t1and t2periods. The phase transformation was studied under various pH and temperature conditions. Although it was observed that ethanol partitioning induced, at least partially, the formation of the cubic structure, the transformation was also shown to be influenced by the degree of silicate polymerization. The MCM-48 silica prepared under optimized conditions exhibited a type IV nitrogen adsorption isotherm, a BET surface area of 1164 m2/g, and a narrow pore size distribution with a maximum at 2.5 nm.

New ruthenium alkylidyne and alkylidene complexes are prepared, in which aryloxide groups function as pseudohalide ligands. The selectivity for alkylidene or alkylidyne products is controlled by steric matching or mismatching between pseudohalide and ancillary donor ligands. Alkylidene 5 achieves up to 40 000 turnovers in ring-closing metathesis of diethyl diallylmalonate.