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Results for “NEOPLASM STATISTICS”

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At least 1,459 records · Page 81Linked to original sources
PubMed1992

[Natural history of minimal and occult breast cancers. Long term survival and mass screening].

It is commonly admitted that small breast cancer detection is usefull for mortality reduction. One must take care of both "lead time bias" and "length biased sampling". An aggressive screening could detect an increased number of prevalent cancers in young women. The annual screening of asymptomatic women could be modified in the future by some compromise strategies fixed on high risk women isolation.

Adult↗
PubMedDate not supplied

A statistical approach to detection of the primary cancer based on the site of neck lymph node metastases.

Preoperative differential diagnosis of a swelling in the neck is mandatory for a good therapeutic planning. Indiscriminate biopsy as first approach is to be disregarded, since it can compromise the result of a radical neck dissection in cases where a metastasis of epidermoid cancer is histologically recognized. A cervical biopsy is not to be performed until a complete HNT examination (including the thyroid and major salivary glands) has excluded the presence of a primary tumor in these regions. Since every localization of the head and neck malignancies shows rather fixed patterns in its lymphatic spreading, a correlation between site of T and particular localizations of N within the neck can be found. The knowledge of the probabilities that an adenopathy in a given region of the neck correlates with a primary tumor located in a given site of the body could strongly aid the physician in detecting the latter, following a rational statistically based approach. This study was performed applying Bayes theorem for probability calculus to the maps of distribution of metastases of tumors of different site in 3,700 patients who were taken into National Cancer Institute of Milan during 7 consecutive years. The results are gathered in tables and text-figures showing the great significance of some correlations, who become more evident when the adenopathies are multiple, but who usefully direct the physician also when the adenopathy is only one.

Adult↗
PubMed1985

[Comparative quantitative assessment of a carcinogenic effect taking intercurrent mortality into account].

The paper discusses the advantages offered by the statistical evaluation of experimental carcinogenic effect with due regard to mortality from concomitant pathology. The method used complex tables of contingents and analysis was carried out separately in 3 groups of tumors--independent of mortality, fatal and incidental ones. The method was compared with standard procedures which do not take care of the said mortality rate (table of contingents 2 X 2 and precise procedure of Fisher). The data on development of 1,2-dimethylhydrazine-induced tumors of the skin, uterus and ovaries in 5 strains of mice were used in the study.

Animals↗
PubMed1978

Clinical trial methodology.

A number of recent conferences have emphasized the importance of clinical trials methodology. The most significant of these was the one held in France in January, 1978. Much discussion centered around the use of matched historical controls from the same institution in comparison with randomized, prospectively controlled clinical trials. It was concluded that controlled clinical trials are required to answer comparative therapeutic questions in a convincing manner and that statistical advice is critical at all stages of such trials.

Clinical Trials as Topic↗
PubMed2004

Analyzing geographic patterns of disease incidence: rates of late-stage colorectal cancer in Iowa.

This study, using geocodes of the locations of residence of newly diagnosed colorectal cancer patients from the Iowa Cancer Registry, computed continuous spatial patterns of late-stage rates of colorectal cancer in Iowa. Variations in rates in intrahospital service regions were as great as interhospital service regions, shown by analysis of variance tests. Some of the spatial variations observed could be explained, using a general linear regression model on individual-level data, by spatial variations in attributes of individuals and their relationships to health resources. We show how this source of variation can be removed from the original map leaving a new map showing the remaining variation in late-stage rate not explained by these relationships. We argue that it would be more appropriate to organize prevention and control activities targeted at the areas with higher than expected late-stage rates shown on this map. The originality of this approach is in the integration of geocoded data from a cancer registry with methods of spatial analysis that provide considerable geographic detail in the cancer rate while controlling for rate stabilization and reliability due to the small number problem.

Colorectal Neoplasms↗
PubMed1999

Nodal staging of colorectal carcinomas from quantitative and qualitative aspects. Can lymphatic mapping help staging?

Retrospective data analysis was performed to determine the minimum number of lymph nodes required for the staging of colorectal carcinomas, and a prospective feasibility study was carried out to identify sentinel nodes in order to clarify whether these may predict the nodal status. From among 240 colorectal carcinoma specimens investigated between 1996 and 1998, 224 tumors were analyzed for their nodal status. Lymphatic mapping with vital patent blue dye injection into the peritumoral sub-serosal layer was performed in 25 patients. Blue nodes were identified by the pathologist in the unfixed specimen immediately after the resection of the bowel and were assessed separately. Of the 123 node-positive carcinomas, 40 had more than 3 nodes involved. The nodal positivity increased substantially when more than 6 nodes were assessed. The cumulative percentage analysis demonstrated that ideally 16 and 13 nodes should be obtained for the identification of any nodal involvement or the involvement of more than 3 nodes, respectively. Lymphatic mapping was successful in 24 patients (96%). Blue nodes were predictive of the nodal status in 19 cases (79%), and were the only sites of metastasis in 2 patients (15% of the node-positive cases). Lymphatic mapping with the vital blue dye technique does not seem to facilitate the staging of colorectal cancers, at least in our patient population with relatively large and deeply infiltrating tumors, and unless the technique is improved or other selective features of lymph nodes are found, all lymph nodes should be assessed. A minimum of 6 nodes, and an optimum of 16 nodes or more, are suggested from these series.

Adult↗
PubMed2006

Optimum parameters in a model for tumour control probability, including interpatient heterogeneity: evaluation of the log-normal distribution.

The heterogeneity of human tumour radiation response is well known. Researchers have used the normal distribution to describe interpatient tumour radiosensitivity. However, many natural phenomena show a log-normal distribution. Log-normal distributions are common when mean values are low, variances are large and values cannot be negative. These conditions apply to radiosensitivity. The aim of this work was to evaluate the log-normal distribution to predict clinical tumour control probability (TCP) data and to compare the results with the homogeneous (delta-function with single alpha-value) and normal distributions. The clinically derived TCP data for four tumour types-melanoma, breast, squamous cell carcinoma and nodes-were used to fit the TCP models. Three forms of interpatient tumour radiosensitivity were considered: the log-normal, normal and delta-function. The free parameters in the models were the radiosensitivity mean, standard deviation and clonogenic cell density. The evaluation metric was the deviance of the maximum likelihood estimation of the fit of the TCP calculated using the predicted parameters to the clinical data. We conclude that (1) the log-normal and normal distributions of interpatient tumour radiosensitivity heterogeneity more closely describe clinical TCP data than a single radiosensitivity value and (2) the log-normal distribution has some theoretical and practical advantages over the normal distribution. Further work is needed to test these models on higher quality clinical outcome datasets.

Breast Neoplasms↗