Guido Masarotto

Bio: Guido Masarotto is an academic researcher from University of Padua. The author has contributed to research in topics: Control chart & Statistical process control. The author has an hindex of 17, co-authored 42 publications receiving 1305 citations.

An Adaptive Exponentially Weighted Moving Average Control Chart

Abstract: Lucas and Saccucci showed that exponentially weighted moving average (EWMA) control charts can be designed to quickly detect either small or large shifts in the mean of a sequence of independent observations. But a single EWMA chart cannot perform well for small and large shifts simultaneously. Furthermore, in the worst-case situation, this scheme requires a few observations to overcome its initial inertia. The main goal of this article is to suggest an adaptive EWMA (AEWMA) chart that weights the past observations of the monitored process using a suitable function of the current “error.” The resulting scheme can be viewed as a smooth combination of a Shewhart chart and an EWMA chart. A design procedure for the new control schemes is suggested. Comparisons of the standard and worst-case average run length profiles of the new scheme with those of different control charts show that AEWMA schemes offer a more balanced protection against shifts of different sizes.

Different Features of Pulmonary Metastases in Differentiated Thyroid Cancer: Natural History and Multivariate Statistical Analysis of Prognostic Variables

Abstract: We studied 134 patients with differentiated thyroid cancer and pulmonary metastases. All were treated with total or near total thyroidectomy, radioiodine and L-thyroxine. The prognostic value of the following variables in three groups of patients were evaluated by univariate and multivariate analysis: age at diagnosis, sex, histologic type, tumor extension, cervical lymph node metastases, mediastinic metastases, presence of metastases in distant sites other than lungs (multiple distant metastases) and morphological (chest x-rays) and functional (131I uptake) features of lung metastases. Univariate analysis identified patient age (p < 0.0001), morphological and functional features of lung metastases (p < 0.0001), presence of multiple distant metastases (p < 0.0001) and histologic type (p = 0.04) as significant prognostic factors. Multivariate analysis showed only morphological (p = 0.0014) and functional (p < 0.0001) features of lung metastases and the presence of multiple distant metastases (p = 0.01) as significant and independent variables. The data show that early (pre-radiological) scintigraphic diagnosis and 131I therapy of lung metastases appear to be the most important elements in obtaining both a significant improvement in survival rate and a prolonged disease-free time interval in these patients.

Gaussian Copula Marginal Regression

Abstract: This paper identifies and develops the class of Gaussian copula models for marginal regression analysis of non-normal dependent observa- tions. The class provides a natural extension of traditional linear regression models with normal correlated errors. Any kind of continuous, discrete and categorical responses is allowed. Dependence is conveniently modelled in terms of multivariate normal errors. Inference is performed through a like- lihood approach. While the likelihood function is available in closed-form for continuous responses, in the non-continuous setting numerical approx- imations are used. Residual analysis and a specification test are suggested for validating the adequacy of the assumed multivariate model. Methodol- ogy is implemented in a R package called gcmr. Illustrations include simu- lations and real data applications regarding time series, cross-design data, longitudinal studies, survival analysis and spatial regression.

Distant metastases in differentiated thyroid cancer: long-term results of radioiodine treatment and statistical analysis of prognostic factors in 214 patients.

Abstract: Long-term results and statistical analysis of prognostic factors in a series of 214 patients with distant metastases from differentiated thyroid cancer (DTC) are reported here. These 214 were part of a total series of 1457 patients with DTC referred to our center from 1967 to 1987. All patients underwent surgery and 131-I therapy and were treated with TSH suppressive doses of thyroid hormones. After a mean follow-up of 7.3 years including clinical, scintigraphic, radiological and laboratory investigations, 24.4% of patients were alive without disease, 36.5% alive with disease, 1.8% dead without disease and 37.3% dead with disease. One of the main factors influencing the survival in our series was 131-I uptake (RIU) by metastatic tissue. No case of complete remission of disease was observed among patients with nonfunctioning metastases. Another important factor was the site of metastases, patients with bone metastases having the worst prognosis. The patient's age at diagnosis represented another important factor for survival; patients over 40 years, particularly those over 60 years had a bad prognosis. A clear interrelation was found among the factors advanced age, nonfunctioning metastases and bone metastases. Patients with these last clinical features were considered to be at high risk and generally had a fatal outcome. Another significant prognostic factor revealed by univariate analysis was the histologic type. Patients with follicular tumor showed a poorer prognosis in comparison to papillary tumor. When multivariate analysis was applied, the factors age at diagnosis, site of metastases and RIU proved to have a significant influence on survival, but not the histologic type. Lastly, the relative rate of males was higher in the group of patients with metastases in comparison to the whole series of DTC patients. Despite this, the factor sex did not influence survival.

Increasing incidence of thyroid cancer in the United States, 1973-2002.

Abstract: ContextIncreasing cancer incidence is typically interpreted as an increase in the true occurrence of disease but may also reflect changing pathological criteria or increased diagnostic scrutiny. Changes in the diagnostic approach to thyroid nodules may have resulted in an increase in the apparent incidence of thyroid cancer.ObjectiveTo examine trends in thyroid cancer incidence, histology, size distribution, and mortality in the United States.MethodsRetrospective cohort evaluation of patients with thyroid cancer, 1973-2002, using the Surveillance, Epidemiology, and End Results (SEER) program and data on thyroid cancer mortality from the National Vital Statistics System.Main Outcome MeasuresThyroid cancer incidence, histology, size distribution, and mortality.ResultsThe incidence of thyroid cancer increased from 3.6 per 100 000 in 1973 to 8.7 per 100 000 in 2002—a 2.4-fold increase (95% confidence interval [CI], 2.2-2.6; P .20 for trend). Virtually the entire increase is attributable to an increase in incidence of papillary thyroid cancer, which increased from 2.7 to 7.7 per 100 000—a 2.9-fold increase (95% CI, 2.6-3.2; P<.001 for trend). Between 1988 (the first year SEER collected data on tumor size) and 2002, 49% (95% CI, 47%-51%) of the increase consisted of cancers measuring 1 cm or smaller; 87% (95% CI, 85%-89%) consisted of cancers measuring 2 cm or smaller. Mortality from thyroid cancer was stable between 1973 and 2002 (approximately 0.5 deaths per 100 000).ConclusionsThe increasing incidence of thyroid cancer in the United States is predominantly due to the increased detection of small papillary cancers. These trends, combined with the known existence of a substantial reservoir of subclinical cancer and stable overall mortality, suggest that increasing incidence reflects increased detection of subclinical disease, not an increase in the true occurrence of thyroid cancer.

Papillary and follicular thyroid carcinoma.

Abstract: Papillary and follicular thyroid carcinomas are among the most curable of all cancers. However, some patients are at high risk of recurrence or even death from their cancer. Most of these patients can be identified at the time of diagnosis using well-established prognostic indicators. The extent of initial treatment and follow-up should therefore be individualized. The early discovery of persistent and recurrent disease is based on the combined use of serum thyroglobulin determination and of total body scanning with 131I. The recent availability of recombinant human thyroid stimulating hormone has greatly improved the quality of the patient's life during follow-up. Treatment of recurrences is based mainly on surgery and 131I treatment.