Development of mouse models of malignant phyllodes tumors by transplantation of syngeneic mammary gland cells expressing mutant H-Ras.

Phyllodes tumors (PTs) are rare fibroepithelial tumors of the breast with epithelial and stromal components, and surgical resection is the standard and only available treatment for malignant PTs. To provide a better understanding of these tumors, we developed mouse models that recapitulate the pathological and clinical properties of human malignant PTs. Mouse undifferentiated mammary gland cells were infected with a retrovirus encoding the human oncoprotein H-RasG12V , and the infected cells were transplanted orthotopically into the mammary fat pads of syngeneic mice. The transplanted cells showed a high tumorigenic activity, with the resulting tumors manifesting pathological characteristics including stromal overgrowth similar to those of human malignant PTs. The tumors also showed high rates of both local recurrence and lung metastasis. Our models may prove useful for studies of the pathophysiology of malignant PTs as well as facilitate the development of new treatments.

MRI and ultrasound evaluation of invasive lobular carcinoma of the breast after primary systemic therapy.

AIM: To assess magnetic resonance imaging (MRI) and ultrasound (US) evaluation of invasive lobular carcinoma after primary systemic therapy compared to the primary surgery group. METHODS: A total of 218 breasts with invasive lobular carcinoma (ILC), which were diagnosed by core needle biopsy and underwent surgery between 2004 and 2010 in St. Luke's International Hospital, were reviewed. Of these, 44 breasts received primary systemic therapy (PST) and the residual 174 breasts underwent surgery first. Before surgery, MRI and second-look US were performed. Patients whose extent of lesion from MRI and US was over 90° were recommended to receive total mastectomy. Diagnostic image evaluation was categorized from the final pathology. A negative margin of breast-conserving surgery (BCS) and mastectomy which has over 90° tumor extent in pathology were regarded as "appropriate". A positive margin of BCS was regarded as "underestimated". "Overestimation" was determined when the pathological extension was small enough for BCS although MRI and US diagnosis was over 90°. RESULTS: Of 44 breasts which received PST, 26 breasts received BCS as initial surgery. Of these, 14 (53.8 %) breasts were "underestimated". Of these 14, 5 breasts received additional total mastectomy. Of 174 breasts that received surgery first, 121 (69.5 %) breasts received BCS as the initial surgery. Of these, 46 (38.0 %) breasts were "underestimated" and 6 breast of these 46 received additional total mastectomy. "Underestimated" rate was similar in the two groups, but the additional total mastectomy rate was significantly higher in the PST group (p = 0.025). There were no "overestimations". The "appropriate" rate was similar between the PST (68.2 %) and surgery-first groups (73.6 %). CONCLUSIONS: Although 68.2 % of ILC patients were evaluated "appropriately" even after PST, higher additional total mastectomy rates should be considered when selecting the surgical procedure.

Role of breast tomosynthesis in diagnosis of breast cancer for Japanese women.

INTRODUCTION: Mammography is the most basic modality in breast cancer imaging. However, the overlap of breast tissue depicted on conventional two-dimensional mammography (2DMMG) may create significant obstacles to detecting abnormalities, especially in dense or heterogeneously dense breasts. In three-dimensional digital breast tomosynthesis (3DBT), tomographic images of the breast are reconstructed from multiple projections acquired at different angles. It has reported that this technology allows the generation of 3D data, therefore overcoming the limitations of conventional 2DMMG for Western women. We assessed the detectability of lesions by conventional 2DMMG and 3DBT in diagnosis of breast cancer for Japanese women. METHODS: The subjects were 195 breasts of 99 patients (median age of 48 years, range 34~82 years) that had been pathologically diagnosed with breast cancer from December 20, 2010 through March 31, 2011. Both conventional 2DMMG and 3DBT imaging were performed for all patients. Detectability of lesions was assessed based on differences in category class. RESULTS: Of the affected breasts, 77 (75.5%) had lesions assigned to the same categories by 2DMMG and 3DBT. For 24 (23.5%) lesions, the category increased in 3DBT indicating improvement in diagnostic performance compared to 2DMMG. 3DBT improved diagnostic sensitivity for patients with mass, focal asymmetric density (FAD), and architectural distortion. However, 3DBT was not statistically superior in diagnosis of the presence or absence of calcification. CONCLUSIONS: In this study, 3DBT was superior in diagnosing lesions in form of mass, FAD, and/or architectural distortion. 3DBT is a novel technique that may provide a breakthrough in solving the difficulties of diagnosis caused by parenchyma overlap for Japanese women.