25 research outputs found
The incidence of cervical cancer among Chinese and caucasians in British Columbia
No full textCanadian Journal of Public Health844283-285CJPE
Using the Cancer Risk Management Model to Evaluate Colorectal Cancer Screening Options for Canada
No full textBackground: Several screening methods for colorectal cancer (CRC) are available, and some have been shown by randomized trials to be effective. In the present study, we used a well-developed population health simulation model to compare the risks and benefits of a variety of screening scenarios. Tests considered were the fecal occult blood test (FOBT), the fecal immunochemical test (FIT), flexible sigmoidoscopy, and colonoscopy. Outcomes considered included years of life gained, CRC cases and deaths prevented, and direct health system costs. Methods: A natural history model of CRC was implemented and calibrated to specified targets within the framework of the Cancer Risk Management Model (CRMM) from the Canadian Partnership Against Cancer. The CRMM-CRC permits users to enter their own parameter values or to use program-specified base values. For each of 23 screening scenarios, we used the CRMM-CRC to run 10 million replicate simulations. Results: Using base parameter values and some user-specified values in the CRMM-CRC, and comparing our screening scenarios with no screening, all screening scenarios were found to reduce the incidence of and mortality from CRC. The fobt was the least effective test; it was not associated with lower net cost. Colonoscopy screening was the most effective test; it had net costs comparable to those for several other strategies considered, but required more than 3 times the colonoscopy resources needed by other approaches. After colonoscopy, strategies based on the FIT were predicted to be the most effective. In sensitivity analyses performed for the FOBT and FIT screening strategies, FOBT parameter values associated with high-sensitivity formulations were associated with a substantial increase in test effectiveness. The FIT was more cost-effective at the 50 ng/mL threshold than at the 100 ng/mL threshold. Conclusions: The CRMM-CRC provides a sophisticated and flexible environment in which to evaluate CRC control options. All screening scenarios considered in this study effectively reduced CRC mortality, although sensitivity analyses demonstrated some uncertainty in the magnitude of the improvements. Where possible, local data should be used to reduce uncertainty in the parameters
A stochastic model for the resistance of tumor cells to cancer chemotherapeutic agents A.J. Coldman∗ and J.M. Goldie, Cancer Control Agency of British Columbia, British Columbia, Canada V5Z 4E6, USA
No full textA stochastic model for the resistance of tumor cells to cancer chemotherapeutic agents A.J. Coldman∗ and J.M. Goldie, Cancer Control Agency of British Columbia, British Columbia, Canada V5Z 4E6, USA
No full textThe impact of culture and sociological and psychological issues on Muslim patients with breast cancer in Pakistan
No full textThis is a non-final version of an article published in final form in Cancer Nursing, 32(4), 2009. The final published article is available from the link below.Breast cancer is the most common form of cancer in Muslim women in Pakistan. The impact of the initial diagnosis, culture, religion, and psychosocial and psychological aspects of the disease is not well established. This qualitative study examined the experience and coping strategies used by patients with breast cancer in relation to its impact on their physical, mental health, religious, and family issues. Thirty patients with breast cancer were interviewed. Data were analyzed using thematic analysis. The patient's experience of breast cancer focused on the range of emotions felt throughout the illness trajectory, the importance of religion and family support on coping strategies used to manage the adverse effects of chemotherapy, and also the financial concerns. This is the first study to examine Pakistani Muslim women's views on the lived experience of breast cancer. This article provides clarification of the voiced experiences of women with breast cancer. The data not only highlight the role of religion and family support as essential coping strategies but also emphasize the issues of isolation, aggression, and anger as common responses to chemotherapy. Unique features of this study are women's need to seek spiritual support for their illness and the overriding innate characteristic of maternal responsibility. These cultural features require further analysis and research
Estimation and Regularization Techniques for Regression Models with Multidimensional Prediction Functions
No full textBoosting is one of the most important methods for fitting
regression models and building prediction rules from
high-dimensional data. A notable feature of boosting is that the
technique has a built-in mechanism for shrinking coefficient
estimates and variable selection. This regularization mechanism
makes boosting a suitable method for analyzing data characterized by
small sample sizes and large numbers of predictors. We extend the
existing methodology by developing a boosting method for prediction
functions with multiple components. Such multidimensional functions
occur in many types of statistical models, for example in count data
models and in models involving outcome variables with a mixture
distribution. As will be demonstrated, the new algorithm is suitable
for both the estimation of the prediction function and
regularization of the estimates. In addition, nuisance parameters
can be estimated simultaneously with the prediction function
Using the Cancer Risk Management Model to Evaluate the Health and Economic Impacts of Cytology Compared with Human Papillomavirus DNA Testing for Primary Cervical Cancer Screening in Canada
No full textBackground: In Canada, discussion about changing from cytology to human papillomavirus (HPV) DNA testing for primary screening in cervical cancer is ongoing. However, the Canadian Task Force on Preventive Health Care has not yet made a recommendation, concluding that the evidence is insufficient. Methods: We used the cervical cancer and HPV transmission models of the Cancer Risk Management Model to study the health and economic outcomes of primary cytology compared with HPV DNA testing in 14 screening scenarios with varying screening modalities and intervals. Projected cervical cancer cases, deaths, colposcopies, screens, costs, and incremental cost-effectiveness were evaluated. We performed sensitivity analyses for HPV DNA test costs. Results: Compared with triennial cytology from age 25, 5-yearly HPV DNA screening alone from age 30 resulted in equivalent incident cases and deaths, but 55% (82,000) fewer colposcopies and 43% (1,195,000) fewer screens. At HPV DNA screening intervals of 3 years, whether alone or in an age-based sequence with cytology, screening costs are greater, but at intervals of more than 5 years, they are lower. Scenarios on the cost-effectiveness frontier were HPV DNA testing alone every 10, 7.5, 5, or 3 years, and triennial cytology starting at age 21 or 25 when combined with HPV DNA testing every 3 years. Conclusions: Changing from cytology to HPV DNA testing as the primary screening test for cervical cancer would be an acceptable strategy in Canada with respect to incidence, mortality, screening and diagnostic test volumes
Operationalising the collection of ethnicity data in studies of the sociology of health and illness
No full textIn response to the burgeoning interest in ethnic health issues and related published research, a number of
recent contributors have attempted to clarify or systematize the usage of overarching terminology like
'ethnicity', 'race', 'culture', and 'racism', including the development of guidelines. However, the operational
problems of how to collect ethnicity data in studies of the sociology of health and illness have not been
satisfactorily addressed. This paper explores conceptual issues, notably, the meanings of ethnic identity
and ethnic origin/ancestry; methodological approaches, including which dimensions to collect,
multidimensional versus global measures, and exclusive groups versus optional ethnicity; and also practical
issues such as method of assignment. The approach calls for a stronger development of the theoretical
understandings of ethnicity and work on how best ethnicity should be conceptualised and measured in the
different approaches to explaining ethnic inequalities in health
Clinical resistance to platinum chemotherapy in ovarian cancer
No full textPlatinum drugs are the most active agents in ovarian cancer. Their cytotoxicty results from DNA crosslinking. High tumour response rates are seen, but 80 % of patients
relapse. Major mechanisms of platinum resistance in patients remain to be established. We have studied DNA interstrand crosslinking and its repair in response to ex vivo treatment with cisplatin in forty patients with ovarian cancer using the single cell gel electrophoresis (comet) assay. Tumour cells from resected tumours or tumour and mesothelial cells from ascites were obtained from chemonaïve patients and those relapsing after platinum-based therapy. The average percent decrease in tail moment at the peak of crosslinking was 61.1% {\pm9.25} in 34 pre-chemotherapy patient samples following treatment with {100\mu}M cisplatin. In 14 post-chemotherapy patient samples it was 58.1% {\pm9.94}. The average percentage repair at 24 hours was 3.6% {\pm18.89} in prechemotherapy
patients and 44.6% {\pm43.4} for post-chemotherapy patients (p<0.001).
In 6 paired samples, before and after chemotherapy the average percentage repair at 24 hours was 7.2% {\pm12.64} increasing to 69.5% {\pm23.42} after chemotherapy. Differences in cell cycling, and cell signalling gene expression levels using microarray analysis was found, between pre- and post-chemotherapy patients. Real time PCR was also used to investigate the levels of ERCC1 (excision-related cross complementation group 1) in 3 of these paired patient samples, which was found to be increased by an average of 14.4% +/-0.8% in 3 post-chemotherapy samples.
In ten pre-chemotherapy and seven post-chemotherapy patient tumours incubated ex vivo with {50\mu}M melphalan, the percent decrease in tail moment at the peak of crosslinking was 41.4 {\pm11.2}, and 44.6 {\pm7.6}, respectively. 24 hours later the percentage repair was 3.1 {\pm25.6} for untreated and 2.8 {\pm26.3} for treated tumours. In conclusion, repair of DNA interstrand crosslinks appears to be an important mechanism of clinical platinum resistance in ovarian cancer. Repair of melphalan crosslinks is unaffected
