Can high school students help to improve breast radiologists in detecting missed breast cancer lesions on full-field digital mammography?

Aim: To investigate whether full-field digital mammography (FFDM) and contrast-enhanced mammography (CEM), evaluated by non-experienced high school students, improves detection of missed breast cancer lesions on FFDM, in the same cohort of patients. Methods: Non-experienced first- and second year high school students examined fourteen cases of patients diagnosed with breast cancer. These cases consisted of missed breast cancer lesions on FFDM by a breast radiologist. Sensitivity of assessment of the students on FFDM and CEM was analysed and compared with the initial results of the breast radiologists. Results: A total of 134 high school students participated in this study. Mean age was 12.8 years (range 10-14). Based on FFDM, mean overall sensitivity of the students was 29.2% (18.9 - 39.6%). When recombined CEM images were used, mean overall sensitivity of students improved to 82.6% (74.0 - 91.2%) (p=0.001). Mean overall sensitivity of FFDM exams evaluated by radiologists was 75.7% (64.2 - 87.3%), which was lower when compared to student's evaluations on recombined CEM exams, yet not statistically significant (p=0.098). Conclusions: Contrast-enhanced mammography evaluated by non-experienced high school students might improve detection rate of breast cancer when compared to evaluations of only full-field digital mammography by radiologists.

BCAR1, a human homologue of the adapter protein p130Cas, and antiestrogen resistance in breast cancer cells.

BACKGROUND: Treatment of breast cancer with the antiestrogen tamoxifen is effective in approximately one half of the patients with estrogen receptor-positive disease, but tumors recur frequently because of the development of metastases that are resistant to tamoxifen. We have previously shown that mutagenesis of human estrogen-dependent ZR-75-1 breast cancer cells by insertion of a defective retrovirus genome caused the cells to become antiestrogen resistant. In this study, we isolated and characterized the crucial gene at the breast cancer antiestrogen resistance 1 (BCAR1) locus. METHODS/RESULTS: Transfer of the BCAR1 locus from retrovirus-mutated, antiestrogen-resistant cells to estrogen-dependent ZR-75-1 cells by cell fusion conferred an antiestrogen-resistant phenotype on the recipient cells. The complete coding sequence of BCAR1 was isolated by use of exon-trapping and complementary DNA (cDNA) library screening. Sequence analysis of human BCAR1 cDNA predicted a protein of 870 amino acids that was strongly homologous to rat p130Cas-adapter protein. Genomic analysis revealed that BCAR1 consists of seven exons and is located at chromosome 16q23.1. BCAR1 transcripts were detected in multiple human tissues and were similar in size to transcripts produced by retrovirus-mutated ZR-75-1 cells. Transfection of BCAR1 cDNA into ZR-75-1 cells again resulted in sustained cell proliferation in the presence of antiestrogens, confirming that BCAR1 was the responsible gene in the locus. CONCLUSIONS: Overexpression of the BCAR1 gene confers antiestrogen resistance on human ZR-75-1 breast cancer cells. Overexpression of BCAR1 in retrovirus-mutated cells appears to result from activation of the gene's promoter. The isolation and characterization of this gene open new avenues to elucidating mechanisms by which the growth of human breast cancer becomes independent of estrogen.

Bcar1/p130Cas protein and primary breast cancer: prognosis and response to tamoxifen treatment.

BACKGROUND: The product of the Bcar1/p130Cas (breast cancer resistance/p130Crk-associated substrate) gene causes resistance to antiestrogen drugs in human breast cancer cells in vitro. To investigate its role in clinical breast cancer, we determined the levels of Bcar1/p130Cas protein in a large series of primary breast carcinomas. METHODS: We measured Bcar1/p130Cas protein in cytosol extracts from 937 primary breast carcinomas by western blot analysis. The levels of Bcar1/p130Cas protein were tested for associations and trends against clinicopathologic and patient characteristics, the lengths of relapse-free survival and overall survival (n = 775), and the efficacy of first-line treatment with tamoxifen for recurrent or metastatic disease (n = 268). RESULTS: Bcar1/p130Cas levels in primary tumors were associated with age/menopausal status and the levels of estrogen receptor and progesterone receptor. In univariate survival analysis, higher Bcar1/p130Cas levels were associated with poor relapse-free survival and overall survival (both two-sided P =.04; log-rank test for trend). In multivariate analysis, a high level of Bcar1/p130Cas was independently associated with poor relapse-free survival and overall survival. The response to tamoxifen therapy in patients with recurrent disease was reduced in patients with primary tumors that expressed high levels of Bcar1/p130Cas. In multivariate analysis for response, Bcar1/p130Cas was independent of classical predictive factors, such as estrogen receptor status, age/menopausal status, disease-free interval, and dominant site of relapse. CONCLUSION: Patients with primary breast tumors expressing a high level of Bcar1/p130Cas protein appear to experience more rapid disease recurrence and have a greater risk of (intrinsic) resistance to tamoxifen therapy. Thus, measurement of Bcar1/p130Cas may provide useful prognostic information for patients with primary or metastatic breast cancer.

Cloning and expression of interleukin-3 genes of chimpanzee and New World monkeys.

Interleukin-3 (IL-3) genes were cloned from chimpanzee (Pan troglodytes), tamarin (Saguinus oedipus) and marmoset (Callithrix jacchus) and expressed in COS cells. Although the IL-3 gene structure is well conserved in these primate species, sequence analysis revealed extensive base substitutions. The chimpanzee IL-3 protein, which is highly homologous (98.5% identity) to human IL-3, stimulated proliferation of human cells dependent on IL-3. In contrast, due to the numerous amino acid substitutions in the New World monkey IL-3 species, no stimulation of human cells was observed, illustrating the extensive evolutionary divergence of IL-3.

Induction of antiestrogen resistance in human breast cancer cells by random insertional mutagenesis using defective retroviruses: identification of bcar-1, a common integration site.

Duration of response to antiestrogen therapy in metastatic breast cancer is limited due to the development of antiestrogen-resistant tumors. The mechanisms involved are not understood but could originate from (epi)genetic alterations within the tumor cells. We have applied in vitro random insertional mutagenesis with replication defective retroviruses to identify those genes playing a key role in development of antiestrogen resistance in human breast cancer cells. Eighty antiestrogen-resistant cell clones were isolated from 7 x 10(8) estrogen-dependent ZR-75-1 cells, mass-infected with defective retroviruses and subjected to 4-OH-tamoxifen selection. Integration site-specific DNA probes were made by inverse polymerase chain reaction techniques and used to search for common integration sites. Six cell clones were identified with retroviral genome integrations in the same orientation in a single locus, designated breast cancer antiestrogen resistance locus-1 (bcar-1). These bcar-1 cell clones had lost estrogen receptor expression and had become estrogen independent. Our results strongly suggest that alteration of the bcar-1 locus is responsible for development of antiestrogen resistance in human breast cancer cells in vitro. In addition, we have shown that in vitro insertional mutagenesis using defective retroviruses can be applied for gene tagging in human cells.