Suk-Bok Kang

Preservation of lymphatic drainage from arm in breast cancer surgery: is it safe?.

Abstract #201 Purpose: Sentinel lymph node biopsy (SLNB) for breast cancer was introduced to prevent the high morbidity seen with Axillary lymph node dissection (ALND). Although multiple comparison studies have confirmed that SLNB consistently has lower morbidity and lymphedema rates than ALND; it is still clinically significant ranging from 0∼13%. The aim of this study was to confirm the feasibility of the technique, so called Axillary reverse mapping (ARM), and to test the hypothesis that arm lymphatics are never involved by the metastatic process of breast cancer.
 Methods: We reviewed prospectively maintained database of 129 patients who operated for primary breast cancer since June 2007. Sentinel lymph nodes (SLNs) were identified by using a radiolabeled isotope (TC99m-phytate or human serum albumin). Under general anesthesia, 2.5∼3 mL of blue dye was injected in the upper inner arm along the medial intramuscular groove of ipsilateral arm in order to locate the draining lymphatics or lymph node from the arm. We then proceeded as usual with the SLNB or ALND. During axillary procedure, we take the blue node (ARM node) and SLN (hot node), and both were sent to pathology department for frozen section analysis. If SLNs were positive, ALND was performed and axillary contents were sent to pathology. Histological results of ARM node were compared with that of the other nodes of the SLNB or ALND.
 Results: The mean age of patients was 48.3 years old (rang 27∼73). Surgeries included 41 mastectomies, 80 breast conserving surgeries and eight skin sparing mastectomies with immediate reconstruction. Of the 129 procedures, 81 were in SLNB (62.8%), 43 SLNB+ALND (33.3%), and five ALND. One hundred one of 129 (78.3%) blue ARM nodes were identified in the axilla. The average number of removed ARM node was 1.5 (range 1∼5). In 19 of 96 SLNB cases, the ARM nodes were hot, yielding 18.9% of concordance rate between ARM node and SLN. Among these 19 cases, seven ARM nodes contained metastasis. In one SLNB case, the metastatic ARM node was not hot. In all five ALND cases, ARM nodes were identified and one of five ARM nodes was positive for metastasis. Thus, ARM node metastasis rate of identified ARM node during ARM procedure was 8.9% (9/101).
 Conclusion: According to our study, it is thought that lymphatic drainage from arm share common lymphatic channel in axilla with lymphatic flow from breast. Therefore, intentional preservation of lymphatics or lymph node drained from arm during performing axillary surgery in breast cancer could be a dangerous one. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 201.

Estimation for the Half Logistic Distribution under Progressive Type-II Censoring

In this paper, we derive the approximate maximum likelihood estimators(AMLEs) and maximum likelihood estimator of the scale parameter in a half-logistic distribution based on progressive Type-II censored samples. We compare the proposed estimators in the sense of the mean squared error for various censored samples. We also obtain the approximate maximum likelihood estimators of the reliability function using the proposed estimators. We compare the proposed estimators in the sense of the mean squared error.

Estimation in an Exponentiated Half Logistic Distribution under Progressively Type-II Censoring

In this paper, we derive the maximum likelihood estimator(MLE) and some approximate maximum likelihood estimators(AMLEs) of the scale parameter in an exponentiated half logistic distribution based on progressively Type-II censored samples. We compare the proposed estimators in the sense of the mean squared error(MSE) through a Monte Carlo simulation for various censoring schemes. We also obtain the AMLEs of the reliability function.

Estimation for the Half Logistic Distribution Based on Double Hybrid Censored Samples

Many articles have considered a hybrid censoring scheme, which is a mixture of Type-I and Type-II censoring schemes. We introduce a double hybrid censoring scheme and derive some approximate maximum likelihood estimators(AMLEs) of the scale parameter for the half logistic distribution under the proposed double hybrid censored samples. The scale parameter is estimated by approximate maximum likelihood estimation method using two different Taylor series expansion types. We also obtain the maximum likelihood estimator(MLE) and the least square estimator(LSE) of the scale parameter under the proposed double hybrid censored samples. We compare the proposed estimators in the sense of the mean squared error. The simulation procedure is repeated 10,000 times for the sample size n = 20(10)40 and various censored samples. The performances of the AMLEs and MLE are very similar in all aspects but the MLE and LSE have not a closed-form expression, some numerical method must be employed.

Estimation for the Double Rayleigh Distribution Based on Multiply Type-II Censored Samples

In this paper, we derive the approximate maximum likelihood estimators of the scale parameter and the location parameter in a double Rayleigh distribution based on multiply Type-II censored samples. We compare the proposed estimators in the sense of the mean squared error for various censored samples.

Estimation of the parameters in a Pareto distribution by jackknife and bootstrap method

Abstract In this paper, we propose the jackknife estimator, the generalized jackknife estimator, and the minimum risk estimator (MRE) of parameters in a Pareto distribution. The MRE’s can be derived by minimizing the mean square error among the class of estimators which include some estimators as special cases. We consider the bootstrap estimator by using the proposed estimators. We can conclude that the jackknifing is effective in reducing bias for the estimators of the scale and the shape parameters and the MRE’s are more efficient than the other estimators of the scale and the shape parameters in the sense of the mean square error.

AMLEs for Rayleigh Distribution Based on Progressive Type-II Censored Data

In this paper, we shall propose the AMLEs of the scale parameter and the location parameter in the two-parameter Rayleigh distribution based on progressive Type-II censored samples when one parameter is known. We also propose the AMLEs of the two parameters in the Rayleigh distribution based on progressive Type-II censored samples when two parameters are unknown. We simulate the mean squared errors of the proposed estimators through Monte Carlo simulation for various censoring schemes.

Entropy Estimation of Generalized Half-Logistic Distribution (GHLD) Based on Type-II Censored Samples

This paper derives the entropy of a generalized half-logistic distribution based on Type-II censored samples, obtains some entropy estimators by using Bayes estimators of an unknown parameter in the generalized half-logistic distribution based on Type-II censored samples and compares these estimators in terms of the mean squared error and the bias through Monte Carlo simulations.

An Estimation of the Entropy for a Double Exponential Distribution Based on Multiply Type-II Censored Samples

In many life-testing and reliability studies, the experimenter might not always obtain complete information on failure times for all experimental units. Multiply Type-II censored sampling arises in a life-testing experiment whenever the experimenter does not observe the failure times of some units placed on a life-test. In this paper, we obtain estimators for the entropy function of a double exponential distribution under multiply Type-II censored samples using the maximum likelihood estimation and the approximate maximum likelihood estimation procedures. We compare the proposed estimators in the sense of the mean squared errors by using Monte Carlo simulation.

Bayesian Estimators Using Record Statistics of Exponentiated Inverse Weibull Distribution

The inverse Weibull distribution(IWD) is a complementary Weibull distribution and plays an important role in many application areas. In this paper, we develop a Bayesian estimator in the context of record statistics values from the exponentiated inverse Weibull distribution(EIWD). We obtained Bayesian estimators through the squared error loss function (quadratic loss) and LINEX loss function. This is done with respect to the conjugate priors for shape and scale parameters. The results may be of interest especially when only record values are stored.