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Biomedical subjects

A Borg

Publications and source records attributed to A Borg.

At least 127 records · Page 7Linked to original sources
PubMed1996

Founding BRCA1 mutations in hereditary breast and ovarian cancer in southern Sweden.

Nine different germ-line mutations in the BRCA1 breast and ovarian cancer susceptibility gene were identified in 15 of 47 kindreds from southern Sweden, by use of SSCP and heteroduplex analysis of all exons and flanking intron region and by a protein-truncation test for exon 11, followed by direct sequencing. All but one of the mutations are predicted to give rise to premature translation termination and include seven frameshift insertions or deletions, a nonsense mutation, and a splice acceptor site mutation. The remaining mutation is a missense mutation (Cys61Gly) in the zinc-binding motif. Four novel Swedish founding mutations were identified: the nucleotide 2595 deletion A was found in five families, the C 1806 T nonsense mutation in three families, the 3166 insertion TGAGA in three families, and the nucleotide 1201 deletion 11 in two families. Analysis of the intragenic polymorphism D17S855 supports common origins of the mutations. Eleven of the 15 kindreds manifesting BRCA1 mutations were breast-ovarian cancer families, several of them with a predominant ovarian cancer phenotype. The set of 32 families in which no BRCA1 alterations were detected included 1 breast-ovarian cancer kindred manifesting clear linkage to the BRCA1 region and loss of the wild-type chromosome in associated tumors. Other tumor types found in BRCA1 mutation/haplotype carriers included prostatic, pancreas, skin, and lung cancer, a malignant melanoma, an oligodendroglioma, and a carcinosarcoma. In all, 12 of 16 kindreds manifesting BRCA1 mutation or linkage contained ovarian cancer, as compared with only 6 of the remaining 31 families (P<.001). The present study confirms the involvement of BRCA1 in disease predisposition for a subset of hereditary breast cancer families often characterized by ovarian cancers.

Adult↗
PubMed1995

TP53 mutations and breast cancer prognosis: particularly poor survival rates for cases with mutations in the zinc-binding domains.

Acquired mutations in TP53 as well as immunohistochemically detectable protein expression have been implicated as prognostic factors for breast cancer. We have evaluated the relationship between mutations detected in 119 breast tumours and various clinicohistopathological indices, stratifying the mutations according to the functional domains as defined by the recent elucidation of the crystal structure of the protein. Patients with missense mutations located in regions encoding parts of the protein involved in zinc-binding had significantly decreased disease-free and overall survival relative to patients whose tumours had mutations in other domains. These results indicate that these biochemically defined domains also have biological relevance in terms of breast cancer disease course, and suggest that some mutations in TP53, more than others, can contribute to the development of clinically more aggressive and perhaps treatment resistant breast tumours. When confirmed, this will be of potential importance in predicting the clinical behaviour of breast cancer and its responsiveness to therapy.

Adult↗
PubMed1995

Recurrence-free survival in breast cancer improved by adjuvant tamoxifen--especially for progesterone receptor positive tumors with a high proliferation.

Although the beneficial effect on breast cancer of adjuvant tamoxifen (TAM) is well established, in the series studied by our group this effect seems to have been restricted to patients with steroid receptor (especially progesterone receptor (PgR)) positive tumors. However, as some patients with PgR-positive tumors manifested recurrence despite adjuvant TAM treatment, the question arose whether some other biological factor(s) could be used to identify these non-responding cases. The level of the S-phase fraction (SPF), as measured by flow cytometry, has been shown to be a useful prognostic marker, prognosis being better in cases where the SPF is low than in those where it is high. The aim of the present study was to relate the prognosis after adjuvant TAM to SPF among patients with PgR-positive tumors. In the PgR-positive group as a whole, the effect of TAM on prognosis was more pronounced in the high SPF group than in the low SPF group (p = 0.005) the respective decrease in 3 year recurrence rate was from 19 to 43% and from 17 to 9%. Multivariate analysis of the data for the TAM-treated group showed the level of PgR concentration (low positive vs. high positive), lymph node status, and tumor size to be independent predictive factors, but not the level of SPF (i.e. high vs. low). By contrast, among patients not treated with TAM, the SPF was a strong independent prognostic factor. To sum up, SPF was a strong independent predictor of outcome only for patients receiving no systemic adjuvant therapy, but not in patients receiving adjuvant TAM. Patients with PgR-positive and high S-phase tumors derived more benefit from TAM than patients with PgR-positive and low SPF tumors.

Adult↗
PubMed1995

Infrequent occurrence of microsatellite instability in sporadic and familial breast cancer.

Microsatellite instability was analysed in 93 primary breast tumours at 13 chromosomal loci frequently altered in breast cancer. RER (replication errors) were observed at a low (5%) frequency in sporadic, familial and hereditary breast tumours, as well as in breast tumours from patients with multiple primary cancers. Our study suggests that the RER+ phenotype is rare in breast tumours, and that breast cancer is not included in the hereditary non-polyposis colon cancer (HNPCC) syndrome. Moreover, the RER+ tumours revealed an atypical pattern of microsatellite alteration as compared with those usually seen in HNPCC tumours. In agreement with the findings in HNPCC tumours, all RER+ breast tumours were diploid, although having a similar frequency of allelic imbalance as RER- tumours. Thus, mismatch repair deficiency is rare in breast cancer, is most likely caused by somatic mutations, and possibly in a set of DNA repair genes different from that involved in the HNPCC syndrome.

Adult↗
PubMed1995

Prognostic significance of p53 overexpression in primary breast cancer; a novel luminometric immunoassay applicable on steroid receptor cytosols.

A novel quantitative luminometric immunoassay (LIA) has been developed for the measurement of wild-type and mutant p53 protein in extracts from breast tumour tissue. The LIA was found to yield reliable estimates of p53 expression in cytosol samples routinely prepared for steroid receptor analysis as compared with results obtained with immunohistochemical analysis. The LIA was evaluated on 205 primary breast tumour cytosols prepared for steroid receptor analysis and stored frozen at -80 degrees C for 6-8 years, p53 protein being detected in 65% of the samples (range 0.01-23 ng mg-1 protein). Using an arbitrary cut-off value of 0.15 ng mg-1 protein, 30% of the tumours were classified as manifesting p53 overexpression. Significant and independent correlations were found to exist between p53 overexpression and shorter disease-free (P < 0.001) and overall survival (P = 0.039) at a median duration of follow-up of 50 months. p53 overexpression was related to low oestrogen receptor content and high proliferation rate (S-phase fraction). No relationship was found to tumour size or the presence of lymph node metastasis. Three tumours possessed an extremely high p53 content (> 10 ng mg-1 protein), all of which were of medullary or high-grade ductal type, oestrogen and progesterone receptor negative, DNA non-diploid, had S-phase fractions of > 22% and recurred within 1-2 years. In summary, a new sensitive and quantitative LIA suitable for routine analysis of p53 protein in steroid receptor cytosol preparations from breast tumours has been developed to confirm the prognostic importance of p53 protein accumulation in human breast cancer.

Breast Neoplasms↗
PubMed1995

A cohort study comparing the detection of HPV DNA from women who stop and continue to smoke.

The objective of this study was to compare the detection of human papillomavirus (HPV) DNA in women who stopped smoking, and those who continued to smoke. Women entering a smoking cessation programme had tampon specimens collected and analyzed for HPV DNA using polymerase chain reaction (PCR) (L1 consensus primers). Women with HPV DNA in their initial specimens had follow-up specimens collected 1 year later. The stored initial specimens were reanalyzed in the same experiment with the follow-up specimen. In addition, Hybrid Capture and quantitative PCR were used to determine if the change in HPV DNA over the year of follow-up was greater in either group. Of 197 women who were recruited into the study, 57 (29%) were positive for HPV DNA. Second specimens were obtained from 49 of these 57 women. Of these 49 women, 13 had stopped smoking and 36 continued to smoke. The detection of HPV DNA in follow-up specimens was not significantly different in the women who stopped smoking (54%) compared to those who continued to smoke (50%, p = 0.81). Furthermore, the change in the amount of HPV DNA during follow-up was not different in women who stopped smoking compared to women who continued to smoke (p > 0.25). This study suggests that smoking cessation does not affect the detection of genital HPV DNA. On the basis of these findings it is likely that smoking does not increase the risk of invasive cervical cancer by prolonging the detection of HPV DNA.

Adult↗
PubMed1994

ERBB2 amplification is associated with tamoxifen resistance in steroid-receptor positive breast cancer.

Amplification and overexpression of the ERBB2 (HER-2/neu) oncogene has been implicated as contributing to the development of human breast cancer, and as a predictor of poor survival. In the present non-randomized study of 871 primary invasive breast tumours, ERBB2 activation was significantly correlated to a shorter disease-free and overall survival in the subgroup of patients receiving adjuvant tamoxifen therapy, but not in the untreated group. Further subcategorization demonstrated the relationship to poor prognosis to be confined to lymph node positive and steroid receptor-positive tumours. We suggest that steroid receptor and ERBB2-positive breast tumours are resistant to tamoxifen therapy and, supported by experimental evidence showing an oestrogen receptor dependent up-regulation of ERBB2 expression upon tamoxifen administration, possibly even growth stimulated by the drug.

Breast Neoplasms↗
PubMed1994

Cathepsin D, both a prognostic factor and a predictive factor for the effect of adjuvant tamoxifen in breast cancer. South Sweden Breast Cancer Group.

Cathepsin D is a lysosomal protease implicated in cancer metastasis. Its concentration in breast tumours has also been shown to be of prognostic importance, although to what extent this is subject to lymph node status, the use of adjuvant therapy and menopausal status has not been clearly evaluated. At a cut-off level of 45 pmol/mg protein (61% of the 623 samples were classified as high cathepsin D tumours; immunoradiometric assay), we found cathepsin D to be of prognostic importance only among breast cancer patients with lymph node-positive (N+) disease not treated with adjuvant tamoxifen. When the series was stratified according to cathepsin D content of their tumours, progesterone receptor (PgR) status and lymph node involvement, adjuvant tamoxifen was found to have a significant beneficial effect only among patients with N+ and PgR-positive breast cancer whose tumours had a high cathepsin D content.

Aged↗
PubMed1994

Breast imaging: a comparison of digital luminescence radiographs displayed on TV-monitor and film-screen mammography.

The purpose of this study was to compare the diagnostic accuracy of conventional film-screen mammograms with the corresponding digital luminescence mammograms saved on optical disk and viewed on a 1240-line monitor. One hundred mammograms from 100 patients, including 17 biopsy-proven cancers and one cancer confirmed by cytology, were reviewed. Five radiologists with different mammography experience served as observers, and receiver operating characteristic (ROC) curves were constructed. The result of the monitor interpretation was not inferior to the conventional mammogram interpretation. One observer with vast mammography experience obtained excellent results with a digital interpretation.

Adult↗
PubMed1994

Film-screen vs. digital radiography in rheumatoid arthritis of the hand. An ROC analysis.

In a prospective investigation the diagnostic accuracy of film-screen and digital radiography in rheumatoid arthritis of hands was compared. Seventy hands of 36 patients with established rheumatoid arthritis were included in the study. Each of 11 joints in every hand was evaluated regarding the following radiologic parameters: soft tissue swelling, joint space narrowing, erosions and periarticular osteopenia. The digital images were obtained with storage phosphor image plates and evaluated in 2 forms; as digital hard-copy on film and on a monitor of an interactive workstation. The digital images had a resolution of either 3.33 or 5.0 lp/mm. ROC curves were constructed and comparing the area under the curves no significant difference was found between the 3 different imaging forms in either resolution group for soft tissue swelling, joint space narrowing and erosions. The film-screen image evaluation of periarticular osteopenia was significantly better than the digital hard-copy one in the 3.33 lp/mm resolution group, but no significant difference was found in the 5.0 lp/mm group. These results support the view that currently available digital systems are capable of adequate diagnostic performance.

Adult↗
PubMed1993

An exon 5 deletion variant of the estrogen receptor frequently coexpressed with wild-type estrogen receptor in human breast cancer.

Recent evidence suggests that the expression of estrogen receptor (ER) variants in breast cancer may interfere with wild-type (wt) ER function and be related to tumor progression and resistance to hormone treatment. One of these variants, ER delta E5, lacking that part of the hormone-binding domain encoded by exon 5, has previously been identified in breast tumors with the unusual estrogen receptor negative (ER-) and progesterone receptor positive (PgR+) phenotype and found to possess constitutive and hormone-independent transcriptional activity. Using a ribonuclease protection assay, we analyzed 27 breast tumors and 4 breast cell lines for the presence of this variant. We found the ER delta E5 variant to be expressed, not only in all of three ER-/PgR+ tumors but also in 19 of 20 ER+/PgR+ or ER+/PgR- tumors. Moreover, the variant was always coexpressed with and often in excess of wtER. ER delta E5 was also found in three breast cancer cell lines (MCF7, T47D, and ZR75-1), although to a lesser extent than wtER. A complete absence of both ER delta E5 and wtER was noted in four ER-/PgR- tumors and one normal breast cell line (HBL-100). Thus, our data suggest that the occurrence of ER delta E5 in breast cancer may represent a critical stage in tumor progression to autonomy.

Breast Neoplasms↗
PubMed1992

c-myc amplification is an independent prognostic factor in postmenopausal breast cancer.

The c-myc proto-oncogene was analyzed in 311 cases of primary breast cancer, in 8% of which it was found to be amplified, usually at moderately increased copy number (2-5 copies). The adjacent pvt gene was co-amplified with c-myc in all tumors analyzed. C-myc amplification was significantly correlated to a high S-phase fraction and to amplification of the c-erbB-2 proto-oncogene. Weak relationships were found between c-myc amplification and the presence of lymph-node metastasis, advanced stage, DNA non-diploidy and premenopausal status, but not tumor size, estrogen receptor or progesterone receptor status, or int-2 amplification. C-myc amplification, and especially a high gene copy number (greater than 5 copies), was significantly related to early recurrence and death in breast cancer, a relationship seen in both the lymph-node-negative and node-positive subcategories. A particularly strong correlation with poor clinical outcome was seen in postmenopausal patients (p greater than 0.0005), an association which persisted in multivariate survival analysis. We conclude that the activation of c-myc is indeed associated with rapidly growing and progressive breast cancer. Gene amplification, on the other hand, is relatively infrequent and occurs mostly at low copy number, implying that tumors are heterogeneous with respect to cell clones harboring c-myc amplification. An immunohistochemical assessment would more accurately illustrate the importance of c-myc activation in human breast cancer. However, the obvious instability of the c-myc transcript and translate suggests that c-myc is not a suitable prognostic marker for routine purposes.

Adult↗
PubMed1992

The retinoblastoma gene in breast cancer: allele loss is not correlated with loss of gene protein expression.

The significance of the retinoblastoma gene (RB) in the development of human breast cancer remains unclear. In the present study, loss of heterozygosity (LOH) in RB was found in 26% of 90 informative primary breast tumors and was correlated to DNA nondiploidy, a high S-phase fraction, and LOH at chromosome 17p13.3. However, allele loss was not associated with loss of RB protein (pRB) expression. Low to absent levels of pRB were found in 15% of 73 immunoblot analyzed tumors, most of which manifested retained heterozygosity in RB. Conversely, tumors exhibiting LOH showed often high pRB expression. Our data suggest that RB may be involved in the pathogenesis of some breast tumors, as evidenced by the absence of pRB, but that this alteration is acquired by mechanisms other than the unmasking of a recessive mutation by allele loss. LOH in RB may be merely a stochastic event in the unstable genome of aneuploid, rapidly proliferating cells or, alternatively, reflect the presence of an adjacent tumor suppressor gene.

Adult↗