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Biomedical subjects

A J Coldman

Publications and source records attributed to A J Coldman.

83 records · Page 5Linked to original sources
PubMed1981

Steroid receptors in adjuvant hormonal therapy for breast cancer.

Using a computerized mathematical model the authors found that either a small [5%] or large [50%] hormone-dependent reduction in tumour cell population at the beginning of adjuvant chemotherapy for breast cancer greatly increases the probability fo achieving a cure. The fact that even a minor response to hormonal therapy early in the treatment of the tumor is effective underlines the importance of using estrogen receptors to to select potential responders in whom a cure is at least a strong theoretical possibility.

Breast Neoplasms↗
PubMed1980

Neuroblastoma: influence of age at diagnosis, stage, tumor site, and sex on prognosis.

A study of a consecutive series of 99 children with neuroblastoma seen at two major Toronto hospitals between 1951 and 1971 is reported. The children who were aged 24 months or less at diagnosis showed an overall two-year survival rate of 59 percent. Analysis, including fitting of a log-linear model, showed that increased probability of survival was associated with younger age at onset, nonadrenal site, and lower staging and the each of these factors acted independently. The sex of the child had no prognostic effect. This study thus extends earlier work by demonstrating the independent prognostic influence of site of tumor. The implications for treatment policy are discussed.

Actuarial Analysis↗
PubMed1979

Examining survival data.

This brief review presents a nonmathematical description of the methods used to describe the outcome of patient groups when the time to an event such as death or disease recurrence is of interest. Calculation of the product-limit, actuarial and relative survival curves is described and the underlying principles are explained. Two statistical tests frequently used in comparing survival curves (the generalized Wilcoxon and the log-rank or Mantel test) are described and an example of their use is given.

Epidemiologic Methods↗
PubMedDate not supplied

Yeast in blood cultures. Evaluation of factors influencing outcome.

Sixty episodes of candidemia occurring between January 1987 and September 1989 were retrospectively reviewed and the outcome was compared for three patient categories: neutropenic, postsurgical, and nonneutropenic nonsurgical. Because of increasing reports of resistant yeasts, minimal inhibitory concentrations (MICs) to amphotericin B (amB) were determined to examine its relationship to patient outcome. No significant differences between patient categories were found for selected risk factors, mortality, or species isolated, although there was a tendency for Candida tropicalis to occur in neutropenic patients. Statistical analysis using logistic regression showed that both an amB dose greater than 500 mg and a yeast MIC greater than 0.78 micrograms/ml were independent prognosticators of patient outcome.

Adult↗
PubMedDate not supplied

Improving the time to diagnosis after an abnormal screening mammogram.

INTRODUCTION: Five community-specific interventions to reduce the time to diagnosis after an abnormal breast screen have been evaluated. METHODS: Subjects with abnormal screening mammograms in 1998 were assessed through five community pilot projects (N = 1137) and a control random sample assessed elsewhere in BC (N = 1053). The number, types, dates and physician costs of breast-related interventions after an abnormal screen were compared between pilots and control. RESULTS: The median time to diagnosis for women without a biopsy was reduced from 23 days to 7 days (p = 0.001) in the pilot with facilitated referral to diagnosis. The median time to diagnosis for women with a biopsy was reduced from 57 days to 22-43 days in the pilots. Median physician costs per subject were lower (p = 0.02) in pilots that more frequently used core biopsy to obtain a diagnosis. CONCLUSIONS: Process changes can improve the time to diagnosis after an abnormal breast screen, with similar or lower physician costs per subject. Facilitating the referral process had the greatest impact.

Adult↗
PubMedDate not supplied

A mathematic model for relating the drug sensitivity of tumors to their spontaneous mutation rate.

A mathematic model has been developed relating the drug sensitivity of a tumor to its own spontaneous mutation rate towards phenotypic drug resistance. The proportion as well as the absolute numbers of resistant cells will increase with time and the fraction of resistant cells within tumor colonies of the same size with vary depending on whether mutation occurs as an early or late event. Analysis of the model indicates that the probability of the appearance of a resistant phenotype increases with the mutation rate. Furthermore, for any population of tumors with a non-zero mutation rate the likelihood of there being at least one resistant cell will go from a condition of low to high probability over a very short interval in the tumor's biologic history.

Antineoplastic Agents↗
PubMedDate not supplied

Compliance with the screening mammography program of British Columbia: will she return?

OBJECTIVE: To identify factors associated with compliance in the Screening Mammography Program of British Columbia (SMPBC). METHOD: Factors associated with rescreening within 18 months (annual compliers) and between 18 to 36 months later (late compliers) were identified in a cohort of SMPBC screenees using a self-administered questionnaire. RESULTS: Fewer than half of women initially screened within the SMPBC were annual compliers, nearly 40% not returning by 3 years. In women age 50+ years, annual compliers tended to have no prior mammography, no prior breast pain, a physician referral to SMPBC, and a normal initial SMPBC mammogram. Late compliers also tended to have no prior mammography, a physician referral, and a normal initial SMPBC mammogram. CONCLUSIONS: Several modifiable factors associated with compliance were identified: a physician referral to the program and possibly subsequent referral back to the program after workup for an abnormal mammogram.

Adult↗
PubMedDate not supplied

Variations in breast conservation surgery for women with axillary lymph node negative breast cancer in British Columbia.

A population-based study was conducted including all women diagnosed in British Columbia in 1991 with invasive node negative breast cancer (n = 942) in order to identify factors associated with variation in use of breast conserving surgery (BCS) and to determine if provincial practice guidelines were followed. Patient, disease, treatment and physician-specific information was abstracted from medical records and original source documents. 413 (44%) patients received BCS (51% and 23% in surgical candidates and non-candidates, respectively). Significant independent factors associated with BCS included patients' age, residence, family income, tumour size, tumour location, and extent of ductal carcinoma in-situ. Age and income had a significant interaction with stronger income effects in older women. A strong surgeon effect was observed which was not explained by measured surgeon attributes. Expansion of radiation treatment facilities may help address access issues. Further examination of the patient-physician relationship and of ways to assist patients in decision making is needed.

Aged↗