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Sylvia K Plevritis

Publications and source records attributed to Sylvia K Plevritis.

12 recordsLinked to original sources
PubMed2007

A natural history model of stage progression applied to breast cancer.

Invasive breast cancer is commonly staged as local, regional or distant disease. We present a stochastic model of the natural history of invasive breast cancer that quantifies (1) the relative rate that the disease transitions from the local, regional to distant stages, (2) the tumour volume at the stage transitions and (3) the impact of symptom-prompted detection on the tumour size and stage of invasive breast cancer in a population not screened by mammography. By symptom-prompted detection, we refer to tumour detection that results when symptoms appear that prompt the patient to seek clinical care. The model assumes exponential tumour growth and volume-dependent hazard functions for the times to symptomatic detection and stage transitions. Maximum likelihood parameter estimates are obtained based on SEER data on the tumour size and stage of invasive breast cancer from patients who were symptomatically detected in the absence of screening mammography. Our results indicate that the rate of symptom-prompted detection is similar to the rate of transition from the local to regional stage and an order of magnitude larger than the rate of transition from the regional to distant stage. We demonstrate that, in the even absence of screening mammography, symptom-prompted detection has a large effect on reducing the occurrence of distant staged disease at initial diagnosis.

Adult↗
PubMed2006

Cost-effectiveness of screening BRCA1/2 mutation carriers with breast magnetic resonance imaging.

CONTEXT: Women with inherited BRCA1/2 mutations are at high risk for breast cancer, which mammography often misses. Screening with contrast-enhanced breast magnetic resonance imaging (MRI) detects cancer earlier but increases costs and results in more false-positive scans. OBJECTIVE: To evaluate the cost-effectiveness of screening BRCA1/2 mutation carriers with mammography plus breast MRI compared with mammography alone. DESIGN, SETTING, AND PATIENTS: A computer model that simulates the life histories of individual BRCA1/2 mutation carriers, incorporating the effects of mammographic and MRI screening was used. The accuracy of mammography and breast MRI was estimated from published data in high-risk women. Breast cancer survival in the absence of screening was based on the Surveillance, Epidemiology and End Results database of breast cancer patients diagnosed in the prescreening period (1975-1981), adjusted for the current use of adjuvant therapy. Utilization rates and costs of diagnostic and treatment interventions were based on a combination of published literature and Medicare payments for 2005. MAIN OUTCOME MEASURES: The survival benefit, incremental costs, and cost-effectiveness of MRI screening strategies, which varied by ages of starting and stopping MRI screening, were computed separately for BRCA1 and BRCA2 mutation carriers. RESULTS: Screening strategies that incorporate annual MRI as well as annual mammography have a cost per quality-adjusted life-year (QALY) gained ranging from less than 45,000 dollars to more than 700,000 dollars, depending on the ages selected for MRI screening and the specific BRCA mutation. Relative to screening with mammography alone, the cost per QALY gained by adding MRI from ages 35 to 54 years is 55,420 dollars for BRCA1 mutation carriers, 130,695 dollars for BRCA2 mutation carriers, and 98,454 dollars for BRCA2 mutation carriers who have mammographically dense breasts. CONCLUSIONS: Breast MRI screening is more cost-effective for BRCA1 than BRCA2 mutation carriers. The cost-effectiveness of adding MRI to mammography varies greatly by age.

Adult↗
PubMed2006

A stochastic simulation model of U.S. breast cancer mortality trends from 1975 to 2000.

BACKGROUND: We present a simulation model that predicts U.S. breast cancer mortality trends from 1975 to 2000 and quantifies the impact of screening mammography and adjuvant therapy on these trends. This model was developed within the Cancer Intervention and Surveillance Network (CISNET) consortium. METHOD: A Monte Carlo simulation is developed to generate the life history of individual breast cancer patients by using CISNET base case inputs that describe the secular trend in breast cancer risk, dissemination patterns for screening mammography and adjuvant treatment, and death from causes other than breast cancer. The model generates the patient's age, tumor size and stage at detection, mode of detection, age at death, and cause of death (breast cancer versus other) based in part on assumptions on the natural history of breast cancer. Outcomes from multiple birth cohorts are summarized in terms of breast cancer mortality rates by calendar year. RESULT: Predicted breast cancer mortality rates follow the general shape of U.S. breast cancer mortality rates from 1975 to 1995 but level off after 1995 as opposed to following an observed decline. Sensitivity analysis revealed that the impact adjuvant treatment may be underestimated given the lack of data on temporal variation in treatment efficacy. CONCLUSION: We developed a simulation model that uses CISNET base case inputs and closely, but not exactly, reproduces U.S. breast cancer mortality rates. Screening mammography and adjuvant therapy are shown to have both contributed to a decline in U.S. breast cancer mortality.

Age Factors↗
PubMed2006

A comparative review of CISNET breast models used to analyze U.S. breast cancer incidence and mortality trends.

The CISNET Breast Cancer program is a National Cancer Institute-sponsored collaboration composed of seven research groups that have modeled the impact of screening and adjuvant treatment on trends in breast cancer incidence and mortality over the period 1975-2000 (base case). This collaboration created a unique opportunity to make direct comparison of results from different models of population-based cancer screening produced in response to the same question. Comparing results in all but the most cursory way necessitates comparison of the models themselves. Previous chapters have discussed the models individual in detail. This chapter will aid the reader in understanding key areas of difference between the models. A focused analysis of differences and similarities between the models is presented with special attention paid to areas deemed most likely to contribute substantially to the results of the target analysis.

Breast Neoplasms↗
PubMed2006

Impact of adjuvant therapy and mammography on U.S. mortality from 1975 to 2000: comparison of mortality results from the cisnet breast cancer base case analysis.

The CISNET breast cancer program is a consortium of seven research groups modeling the impact of various cancer interventions on the national trends of breast cancer incidence and mortality. Each of the modeling groups participated in a CISNET breast cancer base case analysis with the objective of assessing the impact of mammography and adjuvant therapy on breast cancer mortality between 1975 and 2000. The comparative modeling approach used to address this question allowed for a unique view into the process of modeling. Results shown here expand on those recently reported in the New England Journal of Medicine (Berry et al., N Engl J Med 2005;353:1784-92) by presenting mortality impact in several different ways to facilitate comparisons between models. Comparisons of each group's results in the context of modeling assumptions made during the process gave insight into how specific model assumptions may have affected the results. The median estimate for the percent decline in breast cancer mortality due to mammography was 15% (range of 8%-23%), and the median estimate for the percent decline in mortality due to adjuvant treatment was 19% (range of 12%-21%). A detailed discussion of the differences in modeling approaches and how those differences may have influenced the mortality results concludes the chapter.

Adult↗
PubMed2005

Effect of screening and adjuvant therapy on mortality from breast cancer.

BACKGROUND: We used modeling techniques to assess the relative and absolute contributions of screening mammography and adjuvant treatment to the reduction in breast-cancer mortality in the United States from 1975 to 2000. METHODS: A consortium of investigators developed seven independent statistical models of breast-cancer incidence and mortality. All seven groups used the same sources to obtain data on the use of screening mammography, adjuvant treatment, and benefits of treatment with respect to the rate of death from breast cancer. RESULTS: The proportion of the total reduction in the rate of death from breast cancer attributed to screening varied in the seven models from 28 to 65 percent (median, 46 percent), with adjuvant treatment contributing the rest. The variability across models in the absolute contribution of screening was larger than it was for treatment, reflecting the greater uncertainty associated with estimating the benefit of screening. CONCLUSIONS: Seven statistical models showed that both screening mammography and treatment have helped reduce the rate of death from breast cancer in the United States.

Adult↗
PubMed2005

Opinions of women with high inherited breast cancer risk about prophylactic mastectomy: an initial evaluation from a screening trial including magnetic resonance imaging and ductal lavage.

OBJECTIVE: Prophylactic mastectomy (PM) is often considered, but variably chosen by women at high inherited risk of breast cancer; few data exist on patient tolerance of intensive breast screening as an alternative to PM. We performed an evaluation of high-risk women's tolerance of a breast screening protocol using clinical breast examination, mammography, breast magnetic resonance imaging (MRI) and ductal lavage (DL), and of change in attitudes toward PM after screening. DESIGN: A questionnaire assessing tolerance of screening procedures and change in opinion towards PM was designed and administered to 43 study participants, after a median follow-up of 13 months. Responses were evaluated according to patient characteristics, including type of study-prompted interventions, BRCA mutation status, and prior history of cancer, via univariate analysis. RESULTS: Most patients [85.3% (68.9-95.1%)] were more opposed or unchanged in their attitudes towards PM after study participation, with only 14.7% (5.0-31.1%) less opposed (P = 0.017) despite a short-interval follow-up MRI rate of 71.7% and a biopsy rate of 37%. Lower rates of maximal discomfort were reported with mammogram [2.8% (0-14.5%)] and MRI [5.6% (0-18.7%)] than with DL [28.6% (14.6-46.3%)], with P = 0.035. CONCLUSIONS: Most high-risk women tolerated intensive breast screening well; they were not more inclined towards PM after participating. Future studies should prospectively evaluate larger numbers of high-risk women via multivariate analysis, to determine characteristics associated with preference for breast screening vs. PM.

Adult↗
PubMed2005

Ductal lavage of fluid-yielding and non-fluid-yielding ducts in BRCA1 and BRCA2 mutation carriers and other women at high inherited breast cancer risk.

OBJECTIVE: Nipple fluid production and atypical breast duct cells in women at high risk of breast cancer have been associated with further increased risk. Most publications on ductal lavage for cell collection report cannulating fluid-yielding ducts only. We report lavage of fluid-yielding and non-fluid-yielding ducts in women at high inherited breast cancer risk. METHODS: A pilot breast cancer screening study including ductal lavage was conducted in 75 women at high inherited risk, 56 (74.7%) of whom had BRCA1/2 mutations. Ductal lavage was attempted in any duct identifiable with a catheter. RESULTS: Ducts were successfully catheterized in 60 of 75 patients (80%). Successfully catheterized patients were younger (median age 41 versus 53 years, P = 0.0003) and more often premenopausal (51.7% versus 20%, P = 0.041). Thirty-one successfully catheterized patients [51.6%, 95% confidence interval (39.4-63.9%)] had non-fluid-yielding ducts only. Seventeen patients [28.3% (18.5-40.9%)] had atypical cells. Twelve of seventeen [70.6% (46.8-87.2%)] samples with atypia were from non-fluid-yielding ducts. Patients with non-fluid-yielding ducts (versus fluid-yielding ducts) were more likely to have had prior cancer (48.4% versus 17.2%, P = 0.014) or chemotherapy (45.2% versus 17.2%, P = 0.027); this was also true in patients with atypia from non-fluid-yielding ducts. CONCLUSION: Successfully lavaged women were younger and more often premenopausal. Atypical cells can be found in non-fluid-yielding ducts in patients at high inherited breast cancer risk. Non-fluid-yielding ducts, and atypia from non-fluid-yielding ducts, are more common in patients with prior cancer and chemotherapy. Larger studies are needed to identify risk factors and prognostic significance associated with atypia and non-fluid-yielding ducts in high-risk populations, and define their role as biomarkers.

Adult↗
PubMed2004

Breast magnetic resonance image screening and ductal lavage in women at high genetic risk for breast carcinoma.

BACKGROUND: Intensive screening is an alternative to prophylactic mastectomy in women at high risk for developing breast carcinoma. The current article reports preliminary results from a screening protocol using high-quality magnetic resonance imaging (MRI), ductal lavage (DL), clinical breast examination, and mammography to identify early malignancy and high-risk lesions in women at increased genetic risk of breast carcinoma. METHODS: Women with inherited BRCA1 or BRCA2 mutations or women with a >10% risk of developing breast carcinoma at 10 years, as estimated by the Claus model, were eligible. Patients were accrued from September 2001 to May 2003. Enrolled patients underwent biannual clinical breast examinations and annual mammography, breast MRI, and DL. RESULTS: Forty-one women underwent an initial screen. Fifteen of 41 enrolled women (36.6%) either had undergone previous bilateral oophorectomy and/or were on tamoxifen at the time of the initial screen. One patient who was a BRCA1 carrier had high-grade ductal carcinoma in situ (DCIS) that was screen detected by MRI but that was missed on mammography. High-risk lesions that were screen detected by MRI in three women included radial scars and atypical lobular hyperplasia. DL detected seven women with cellular atypia, including one woman who had a normal MRI and mammogram. CONCLUSIONS: Breast MRI identified high-grade DCIS and high-risk lesions that were missed by mammography. DL detected cytologic atypia in a high-risk cohort. A larger screening trial is needed to determine which subgroups of high-risk women will benefit and whether the identification of malignant and high-risk lesions at an early stage will impact breast carcinoma incidence and mortality.

Adult↗
PubMed2004

Simulation-based parameter estimation for complex models: a breast cancer natural history modelling illustration.

Simulation-based parameter estimation offers a powerful means of estimating parameters in complex stochastic models. We illustrate the application of these ideas in the setting of a natural history model for breast cancer. Our model assumes that the tumor growth process follows a geometric Brownian motion; parameters are estimated from the SEER registry. Our discussion focuses on the use of simulation for computing the maximum likelihood estimator for this class of models. The analysis shows that simulation provides a straightforward means of computing such estimators for models of substantial complexity.

Algorithms↗
PubMed2002

Ethical issues in contrast-enhanced magnetic resonance imaging screening for breast cancer.

Breast magnetic resonance imaging (MRI) screening has been shown to detect early breast cancer. The main challenge ahead for breast MRI screening is to prove its effectiveness in reducing breast cancer mortality. While this challenge is commonly viewed as a scientific, technological, and clinical one, it also carries ethical components. This article is concerned with the risks and benefits of MRI screening that should be explained to screening participants and discusses the evidence needed by policy makers who ultimately will determine a just allocation of health care resources to MRI breast cancer screening.

Breast Neoplasms↗