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  • 1
    Electronic Resource
    Electronic Resource
    The Rate of Breast-Conserving Surgery for Early Breast Cancer Is Not Influenced by the Surgical Strategy of Excisional Biopsy Followed by the Definitive Procedure (2001)
    Boston, MA, USA : Blackwell Science Inc
    The @breast journal 7 (2001), S. 0 
    Details
    ISSN: 1524-4741
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Increased emphasis on breast conservation and the primacy of the patient's preferences has led to the promotion and increased use of a two-step surgical strategy (definitive operation only after a final tissue diagnosis from a biopsy done on a previous visit) in the treatment of early breast cancer, with the assumption being that this is more conducive to the performance of breast-conserving surgery (BCS). We sought to test this by examining the effect of the surgical strategy (one-step versus two-step) on the operation performed (BCS versus mastectomy). A random sample of women with node-negative breast cancer diagnosed in 1991 in Ontario was drawn from the Ontario Cancer Registry database and matched to the Canadian Institute of Health Information and Ontario Health Insurance Plan databases (n = 643). This provided information on the timing and nature of all surgical procedures performed as well as patient, tumor, hospital, and surgeon characteristics. The surgical strategy was defined as either a one-step procedure (biopsy and definitive surgery performed at the same time) or a two-step procedure (surgical biopsy and pathologic diagnosis, followed by definitive surgery at a later date). The axillary lymph node dissection was used to define the definitive procedure. BCS was employed in 68% of patients, and this did not differ significantly between the one-step and two-step groups (66% versus 70%). Patients with palpable lesions had a significantly lower rate of breast conservation than those with nonpalpable lesions. Other variables associated with a lower rate of BCS were larger tumor size, presence of extensive ductal carcinoma in situ (DCIS), and central or multifocal tumors. The use of a one-step procedure was associated with a patient age of more than 50 years, a palpable mass, tumor size larger than 1 cm, previous fine needle aspiration (FNA) biopsy, absence of extensive DCIS, and surgery in an academic setting. Breast conservation was not affected by the surgical strategy used or the timing of the decision, but was associated with several accepted tumor factors. This study shows that, contrary to the opinion of some, there is a group of breast cancer patients in whom treatment in a one-step manner is appropriate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1524-4741.2001.007003158.x
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  • 2
    Electronic Resource
    Electronic Resource
    An individual patient-based meta-analysis of tamoxifen versus ovarian ablation as first line endocrine therapy for premenopausal women with metastatic breast cancer (1997)
    Springer
    Breast cancer research and treatment 44 (1997), S. 201-210 
    Details
    ISSN: 1573-7217
    Keywords: metastatic breast cancer ; tamoxifen ; ovarian ablation ; randomized trial ; meta-analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We performed a meta-analysis of randomized trials comparing tamoxifen to ovarian ablation carried out either by surgery or irradiation as first-line hormonal therapy for pre-menopausal women with metastatic breast cancer. Patients in all trials included were required to have measurable disease and to be currently menstruating or within 1 year of cessation of menses, and to have estrogen receptor (ER) positive or unknown disease (ER negative women were admitted to one of the studies). Individual patient data were obtained from the four studies identified and the results updated to June 1992. A total of 220 eligible patients were enrolled in the four trials. There was no difference in overall response rate between tamoxifen and oophorectomy across the four trials (p = 0.94, Mantel-Haenszel test). The odds reduction for progression was 14% ± 12% and for mortality 6% ± 13% in favour of tamoxifen, results which were not statistically significant (p = 0.32 and 0.72, respectively). Although the design of all four studies included a cross-over to the other therapy, only 54/111 patients receiving ovarian ablation and 34/109 patients receiving tamoxifen as primary therapy actually crossed over to the other arm at the time of disease progression. Response to initial treatment with tamoxifen was predictive of subsequent response to ovarian ablation (p 〈 0.05), and response to initial therapy with ovarian ablation was predictive of subsequent response to tamoxifen (p 〈 0.05). Support curves based on log-likelihood ratios revealed that this meta-analysis provides moderate evidence rejecting a 14% advantage for ovarian ablation compared to tamoxifen in terms of odds of disease progression. A 25% advantage for ovarian ablation with respect to odds of death is also rejected with moderate evidence. We conclude that the efficacy of tamoxifen appears to be similar to that of ovarian ablation by surgery or irradiation as first-line therapy for premenopausal, ER positive metastatic breast cancer, and is unlikely to be substantially inferior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005833811584
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  • 3
    Electronic Resource
    Electronic Resource
    A comparison of all-subset Cox and accelerated failure time models with Cox step-wise regression for node-positive breast cancer (1992)
    Springer
    Breast cancer research and treatment 22 (1992), S. 263-272 
    Details
    ISSN: 1573-7217
    Keywords: breast cancer ; prognostic factors ; Cox regression ; all-subset regression ; accelerated failure time models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Clinical studies usually employ Cox step-wise regression for multivariate investigations of prognostic factors. However, commercial packages now allow the consideration of accelerated failure time models (exponential, Weibull, log logistic, and log normal), if the underlying Cox assumption of proportional hazards is inappropriate. All-subset regressions are feasible for all these models. We studied a group of 378 node positive primary breast cancer patients accrued at the Henrietta Banting Breast Centre of Women's College Hospital, University of Toronto, between January 1, 1977, and December 31, 1986. 85% of these patients had complete prognostic factor data for multivariate analysis, and 96% of the patients were followed to 1990. There was evidence of marked departures from the proportional hazards assumption with two prognostic factors, number of positive nodes and adjuvant systemic therapy. The data strongly supported the log normal model. The all-subset regressions indicated that three models were similarly good. The variables 1) number of positive nodes, 2) tumour size, and 3) adjuvant systemic therapy were included in all three models along with one of three biochemical receptor variables 1) ER, 2) combined receptor (ER- PgR-; ER+ PgR-; ER- PgR+; ER+ PgR+; or 3) PgR. Better multivariate modeling was achieved by using quantitative prognostic factors, a check for appropriate underlying model-type, and all-subset variable selection. All-subset regressions should be considered for routine use with the many new prognostic factors currently under evaluation; it is very possible that there may not be a single model that is substantially better than others with the same number of variables.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01840839
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  • 4
    Electronic Resource
    Electronic Resource
    The rise of tamoxifen: Temporal and geographical trends of tamoxifen use in Ontario (1997)
    Springer
    Breast cancer research and treatment 43 (1997), S. 33-41 
    Details
    ISSN: 1573-7217
    Keywords: breast cancer ; health services research ; small-area analysis ; tamoxifen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: To describe the change in use oftamoxifen over time and across countries in Ontario.Methods: Data from the Ontario Drug Benefit (ODB)plan, Census Canada, and the Ontario Cancer Registry(OCR) were combined and analysed to determine ratesof tamoxifen use for females over 65 foreach county and the province overall, by year.Rates were analyzed by repeated measures ANOVA todetermine significance of changes over time. Consistency oftamoxifen use across counties was determined by theSpearman rank correlation coefficient, and overall variation betweencounties was described using three statistical techniques: Chi-squareanalysis, the extremal quotient (EQ), and the systematiccomponent of variation (SCV). Results: The number ofone-month tamoxifen prescriptions per incident case of breastcancer rose significantly from 13.51 in 1985 to20.54 in 1990 (p 〈 0.001) and to34.06 in 1992 (p=0.001). Viewed differently,the number of women over 65 receiving tamoxifenprescriptions per incident case of breast cancer changedfrom 1.91 in 1985 to 3.14 in 1990to 4.54 in 1992. Statistically significant variation inthe rate of tamoxifen prescribing was demonstrated betweenOntario counties in all three years by ChiSquared analysis (p 〈 0.0001). Both the EQand the SCV declined from 1985 to 1990,suggesting more uniform prescribing across the province. Littlechange in overall variation was seen between 1990and 1992. All counties over time tended toprescribe generic preparations more often and shifted from10 mg to 20 mg formulations. Conclusions: Thesignificant increase in the rate of tamoxifen useand trend towards more uniform prescribing across Ontariobetween 1985 and 1990 coincided with the publicationof two important documents outlining the benefits oftamoxifen in early breast cancer. Despite this trend,variation in tamoxifen use between counties remains. Therehas been little change in uniformity of prescribingsince 1990.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005736325626
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  • 5
    Electronic Resource
    Electronic Resource
    A randomized crossover trial of tamoxifen versus ovarian ablation for metastatic breast cancer in premenopausal women: A report of the National Cancer Institute of Canada Clinical Trials Group (NCIC CTG) trial MA.1 (1997)
    Springer
    Breast cancer research and treatment 44 (1997), S. 211-215 
    Details
    ISSN: 1573-7217
    Keywords: metastatic breast cancer ; premenopausal women ; ovarian ablation ; tamoxifen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We concluded a randomized crossover trial comparing tamoxifen 40 mg daily with ovarian ablation for treatment of metastatic breast cancer in premenopausal women. Objective responses (complete response (CR) plus partial response (PR)) were observed in 5/20 patients treated initially with tamoxifen and in 3/19 patients initially treated with ovarian ablation (p=0.69). Seven additional patients were stable (SD) on tamoxifen while five additional patients were stable after ovarian ablation, for CR + PR + SD rates of 12/20 (60%) for tamoxifen and 8/19 (42%) for ovarian ablation (p=0.34). Median time to disease progression was 184 days for tamoxifen and 126 days for ovarian ablation (p=0.40, logrank test, odds ratio for progression 0.71). Overall survival times were also similar: a median of 2.35 years for tamoxifen and 2.46 years for ovarian ablation (p=0.98, logrank test, odds ratio for death 1.07). Side effects from tamoxifen included hot flashes and menstrual abnormalities. With one exception, these toxicities were not sufficient to require dose reduction. In this small study, tamoxifen was associated with similar response rates, response durations, and survival times to those observed with ovarian ablation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005895813401
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    Paper (German National Licenses)
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