HIV estimation using population-based surveys with non-response: A partial identification approach.

HIV estimation using data from the demographic and health surveys (DHS) is limited by the presence of non-response and test refusals. Conventional adjustments such as imputation require the data to be missing at random. Methods that use instrumental variables allow the possibility that prevalence is different between the respondents and non-respondents, but their performance depends critically on the validity of the instrument. Using Manski's partial identification approach, we form instrumental variable bounds for HIV prevalence from a pool of candidate instruments. Our method does not require all candidate instruments to be valid. We use a simulation study to evaluate and compare our method against its competitors. We illustrate the proposed method using DHS data from Zambia, Malawi and Kenya. Our simulations show that imputation leads to seriously biased results even under mild violations of non-random missingness. Using worst case identification bounds that do not make assumptions about the non-response mechanism is robust but not informative. By taking the union of instrumental variable bounds balances informativeness of the bounds and robustness to inclusion of some invalid instruments. Non-response and refusals are ubiquitous in population based HIV data such as those collected under the DHS. Partial identification bounds provide a robust solution to HIV prevalence estimation without strong assumptions. Union bounds are significantly more informative than the worst case bounds without sacrificing credibility.

Change in outbreak epicentre and its impact on the importation risks of COVID-19 progression: A modelling study.

BACKGROUND: The outbreak of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) that was first detected in the city of Wuhan, China has now spread to every inhabitable continent, but now the attention has shifted from China to other epicentres. This study explored early assessment of the influence of spatial proximities and travel patterns from Italy on the further spread of SARS-CoV-2 worldwide. METHODS: Using data on the number of confirmed cases of COVID-19 and air travel data between countries, we applied a stochastic meta-population model to estimate the global spread of COVID-19. Pearson's correlation, semi-variogram, and Moran's Index were used to examine the association and spatial autocorrelation between the number of COVID-19 cases and travel influx (and arrival time) from the source country. RESULTS: We found significant negative association between disease arrival time and number of cases imported from Italy (r = -0.43, p = 0.004) and significant positive association between the number of COVID-19 cases and daily travel influx from Italy (r = 0.39, p = 0.011). Using bivariate Moran's Index analysis, we found evidence of spatial interaction between COVID-19 cases and travel influx (Moran's I = 0.340). Asia-Pacific region is at higher/extreme risk of disease importation from the Chinese epicentre, whereas the rest of Europe, South-America and Africa are more at risk from the Italian epicentre. CONCLUSION: We showed that as the epicentre changes, the dynamics of SARS-CoV-2 spread change to reflect spatial proximities.

Activation of TRPA1 nociceptor promotes systemic adult mammalian skin regeneration.

Adult mammalian wounds, with rare exception, heal with fibrotic scars that severely disrupt tissue architecture and function. Regenerative medicine seeks methods to avoid scar formation and restore the original tissue structures. We show in three adult mouse models that pharmacologic activation of the nociceptor TRPA1 on cutaneous sensory neurons reduces scar formation and can also promote tissue regeneration. Local activation of TRPA1 induces tissue regeneration on distant untreated areas of injury, demonstrating a systemic effect. Activated TRPA1 stimulates local production of interleukin-23 (IL-23) by dermal dendritic cells, leading to activation of circulating dermal IL-17-producing γδ T cells. Genetic ablation of TRPA1, IL-23, dermal dendritic cells, or γδ T cells prevents TRPA1-mediated tissue regeneration. These results reveal a cutaneous neuroimmune-regeneration cascade triggered by topical TRPA1 activators that promotes adult mammalian tissue regeneration, presenting a new avenue for research and development of therapies for wounds and scars.

Refusal bias in HIV data from the Demographic and Health Surveys: Evaluation, critique and recommendations.

Non-response is a commonly encountered problem in many population-based surveys. Broadly speaking, non-response can be due to refusal or failure to contact the sample units. Although both types of non-response may lead to bias, there is much evidence to indicate that it is much easier to reduce the proportion of non-contacts than to do the same with refusals. In this article, we use data collected from a nationally representative survey under the Demographic and Health Surveys program to study non-response due to refusals to HIV testing in Malawi. We review existing estimation methods and propose novel approaches to the estimation of HIV prevalence that adjust for refusal behaviour. We then explain the data requirement and practical implications of the conventional and proposed approaches. Finally, we provide some general recommendations for handling non-response due to refusals and we highlight the challenges in working with Demographic and Health Surveys and explore different approaches to statistical estimation in the presence of refusals. Our results show that variation in the estimated HIV prevalence across different estimators is due largely to those who already know their HIV test results. In the case of Malawi, variations in the prevalence estimates due to refusals for women are larger than those for men.

Aging Suppresses Skin-Derived Circulating SDF1 to Promote Full-Thickness Tissue Regeneration.

Physicians have observed that surgical wounds in the elderly heal with thinner scars than wounds in young patients. Understanding this phenomenon may reveal strategies for promoting scarless wound repair. We show that full-thickness skin wounds in aged but not young mice fully regenerate. Exposure of aged animals to blood from young mice by parabiosis counteracts this regenerative capacity. The secreted factor, stromal-derived factor 1 (SDF1), is expressed at higher levels in wounded skin of young mice. Genetic deletion of SDF1 in young skin enhanced tissue regeneration. In aged mice, enhancer of zeste homolog 2 (EZH2) and histone H3 lysine 27 trimethylation are recruited to the SDF1 promoter at higher levels, and pharmacologic inhibition of EZH2 restores SDF1 induction and prevents tissue regeneration. Similar age-dependent EZH2-mediated SDF1 suppression occurs in human skin. Our findings counter the current dogma that tissue function invariably declines with age and suggest new therapeutic strategies in regenerative medicine.

Shrinkage empirical likelihood estimator in longitudinal analysis with time-dependent covariates--application to modeling the health of Filipino children.

The method of generalized estimating equations (GEE) is a popular tool for analysing longitudinal (panel) data. Often, the covariates collected are time-dependent in nature, for example, age, relapse status, monthly income. When using GEE to analyse longitudinal data with time-dependent covariates, crucial assumptions about the covariates are necessary for valid inferences to be drawn. When those assumptions do not hold or cannot be verified, Pepe and Anderson (1994, Communications in Statistics, Simulations and Computation 23, 939-951) advocated using an independence working correlation assumption in the GEE model as a robust approach. However, using GEE with the independence correlation assumption may lead to significant efficiency loss (Fitzmaurice, 1995, Biometrics 51, 309-317). In this article, we propose a method that extracts additional information from the estimating equations that are excluded by the independence assumption. The method always includes the estimating equations under the independence assumption and the contribution from the remaining estimating equations is weighted according to the likelihood of each equation being a consistent estimating equation and the information it carries. We apply the method to a longitudinal study of the health of a group of Filipino children.

Efficient parameter estimation in longitudinal data analysis using a hybrid GEE method.

The method of generalized estimating equations (GEEs) provides consistent estimates of the regression parameters in a marginal regression model for longitudinal data, even when the working correlation model is misspecified (Liang and Zeger, 1986). However, the efficiency of a GEE estimate can be seriously affected by the choice of the working correlation model. This study addresses this problem by proposing a hybrid method that combines multiple GEEs based on different working correlation models, using the empirical likelihood method (Qin and Lawless, 1994). Analyses show that this hybrid method is more efficient than a GEE using a misspecified working correlation model. Furthermore, if one of the working correlation structures correctly models the within-subject correlations, then this hybrid method provides the most efficient parameter estimates. In simulations, the hybrid method's finite-sample performance is superior to a GEE under any of the commonly used working correlation models and is almost fully efficient in all scenarios studied. The hybrid method is illustrated using data from a longitudinal study of the respiratory infection rates in 275 Indonesian children.

Testing intergroup concordance in ranking experiments with two groups of judges.

Across many areas of psychology, concordance is commonly used to measure the (intragroup) agreement in ranking a number of items by a group of judges. Sometimes, however, the judges come from multiple groups, and in those situations, the interest is to measure the concordance between groups, under the assumption that there is some within-group concordance. In this investigation, existing methods are compared under a variety of scenarios. Permutation theory is used to calculate the error rates and the power of the methods. Missing data situations are also studied. The results indicate that the performance of the methods depend on (a) the number of items to be ranked, (b) the level of within-group agreement, and (c) the level of between-group agreement. Overall, using the actual ranks of the items gives better results than using the pairwise comparison of rankings. Missing data lead to loss in statistical power, and in some cases, the loss is substantial. The degree of power loss depends on the missing mechanism and the method of imputing the missing data, among other factors.

Bayesian designs with frequentist and Bayesian error rate considerations.

So far, most Phase II trials have been designed and analysed under a frequentist framework. Under this framework, a trial is designed so that the overall Type I and Type II errors of the trial are controlled at some desired levels. Recently, a number of articles have advocated the use of Bayesian designs in practice. Under a Bayesian framework, a trial is designed so that the trial stops when the posterior probability of treatment is within certain prespecified thresholds. In this article, we argue that trials under a Bayesian framework can also be designed to control frequentist error rates. We introduce a Bayesian version of Simon's well-known two-stage design to achieve this goal. We also consider two other errors, which are called Bayesian errors in this article because of their similarities to posterior probabilities. We show that our method can also control these Bayesian-type errors. We compare our method with other recent Bayesian designs in a numerical study and discuss implications of different designs on error rates. An example of a clinical trial for patients with nasopharyngeal carcinoma is used to illustrate differences of the different designs.

A semiparametric two-component "compound" mixture model and its application to estimating malaria attributable fractions.

Malaria remains a major epidemiologic problem in many developing countries. Malaria is defined as the presence of parasites and symptoms (usually fever) due to the parasites. In endemic areas, an individual may have symptoms attributable either to malaria or to other causes. From a clinical viewpoint, it is important to correctly diagnose an individual who has developed symptoms so that the appropriate treatments can be given. From an epidemiologic and economic viewpoint, it is important to determine the proportion of malaria-affected cases in individuals who have symptoms so that policies on intervention program can be developed. Once symptoms have developed in an individual, the diagnosis of malaria can be based on the analysis of the parasite levels in blood samples. However, even a blood test is not conclusive as in endemic areas many healthy individuals can have parasites in their blood slides. Therefore, data from this type of study can be viewed as coming from a mixture distribution, with the components corresponding to malaria and non-malaria cases. A unique feature in this type of data, however, is the fact that a proportion of the non-malaria cases have zero parasite levels. Therefore, one of the component distributions is itself a mixture distribution. In this article, we propose a semiparametric likelihood approach for estimating the proportion of clinical malaria using parasite-level data from a group of individuals with symptoms. Our approach assumes the density ratio for the parasite levels in clinical malaria and nonclinical malaria cases can be modeled using a logistic model. We use empirical likelihood to combine the zero and nonzero data. The maximum semiparametric likelihood estimate is more efficient than existing nonparametric estimates using only the frequencies of zero and nonzero data. On the other hand, it is more robust than a fully parametric maximum likelihood estimate that assumes a parametric model for the nonzero data. Simulation results show that the performance of the proposed method is satisfactory. The proposed method is used to analyze data from a malaria survey carried out in Tanzania.

Screening chest imaging studies are not effective in the follow-up of breast cancer patients.

PURPOSE: To determine the utility of chest imaging after adjuvant therapy for breast cancer in detection of recurrent disease. PATIENTS AND METHODS: This is a retrospective review of 786 patients diagnosed with early stage breast cancer between 1996-1998 at Memorial Sloan Kettering Cancer Center. 250 of these patients had a chest radiograph or CT scan performed greater that one year after their original diagnosis. Patients were stratified as to whether the chest imaging study was ordered for screening or to evaluate symptoms. RESULTS: 533 chest imaging studies were performed: 397 (74%) chest radiographs and 136 (26%) CT scans. Ten (4%) patients developed metastatic breast cancer. Two patients (0.8%) were found to have metastatic disease by chest radiographs: one (0.4%) was symptomatic and one was not. The remaining eight patients had a negative chest x-ray within one year. No patients were found to have metastatic disease by chest CT. A 2nd primary cancer was found in three patients (1.2%) all of whom had a negative chest x-ray in the past year. There were 20 abnormal radiology studies: 2 true positive (2/20 = 10%) and 18 false positive (18/20 = 90%). CONCLUSIONS: Within this duration of follow-up, we conclude that chest imaging is of limited value for asymptomatic patients with a history of breast cancer and has a high false positive rate.

Adrenocortical adenoma and carcinoma: histopathological and molecular comparative analysis.

We compared histomorphological features and molecular expression profiles of adrenocortical adenomas (ACAd) and carcinomas (ACCa). A critical histopathological review (mean, 11 slides per patient) was conducted of 37 ACAd and 67 ACCa. Paraffin-embedded tissue cores of ACAd (n = 33) and ACCa (n = 38) were arrayed in triplicate on tissue microarrays. Expression profiles of p53, mdm-2, p21, Bcl-2, cyclin D1, p27, and Ki-67 were investigated by immunohistochemistry and correlated with histopathology and patient outcome using standard statistical methodology. Median follow-up period was 5 years. Tumor necrosis, atypical mitoses, and >1 mitosis per 50 high-power fields were factors that were highly specific for ACCa (P <.001). Number (0 to 4) of unfavorable markers [Ki-67 (+), p21 (+), p27 (+), mdm-2(-)] expressed was significantly associated with mitotic activity and morphologic index (i.e., number of adverse morphologic features) and highly predictive of malignancy (P <.001). Ki-67 overexpression occurred in 0 ACAd and 36% ACCa (P <.001) and was significantly associated with mitotic rate and unfavorable morphologic index (P <.001). Tumor necrosis, atypical mitoses, >5 mitoses per 50 high-power fields, sinusoidal invasion, histologic index of >5, and presence of more than two unfavorable molecular markers were associated significantly with metastasis in ACCa. Well-established histopathologic criteria and Ki-67 can specifically distinguish ACCAd from ACCa. Tumor cell proliferation (Ki-67) correlates with mitotic activity and morphologic index. Tumor morphology is a better predictor of metastatic risk in ACCa than current immunohistochemistry-detected cell cycle regulatory and proliferation-associated proteins.

Factors influencing treatment patterns of breast cancer patients age 75 and older.

PURPOSES: To retrospectively determine the factors influencing treatment decisions in older breast cancer patients at a single center. EXPERIMENTAL DESIGN: 216 patients age > or = 75 seen in post-treatment follow-up between January, 1997 and June, 2000 were identified in the Memorial Sloan-Kettering breast cancer database. Eligible patients were > or = 75 years old at diagnosis, had a diagnosis of stage I, II, or III breast cancer, and received their follow-up care at Memorial Sloan Kettering Cancer Center. A retrospective chart review was performed. Patients were stratified by: (1) prognostic factors (age (75-79 or > or = 80), Charlson comorbidity score, tumor size, nodal status, stage, ER, PR, creatinine, albumin, hemoglobin, and liver function tests), (2) local treatment (lumpectomy, axillary lymph node dissection (AxLND), radiation (XRT), modified radical mastectomy (MRM)) and (3) systemic treatment (tamoxifen, chemotherapy). Combined local treatment was defined as (a) lumpectomy, AxLND, XRT or (b) MRM, AxLND, XRT (if tumor > or = 5 cm or > or = 4+ lymph nodes). RESULTS: 96 patients were eligible for this study: 46 patients (75-79 years); 50 patients (> or = 80 years). The majority of patients (74%) were treated with lumpectomy but those > or = 80 were less likely to receive XRT (94% age 75-80; 45% age >80; P<0.01). Patients > or = 80 were also less likely to receive AxLND (94% age 75-79; 62% age > or = 80; P<0.01). A logistic regression model identified two independent prognostic variables for not receiving combined local treatment: increased age (P<0.01) and increased comorbidity score (P=0.01). Increased age did not correlate with increased comorbidity (P=0.48). 5.2% of patients received adjuvant chemotherapy (all age <80). 83% of ER positive patients received tamoxifen (89% age 75-79; 79% age >80). CONCLUSION: We hypothesize that both comorbidity and age play a significant role in influencing treatment decisions in the older breast cancer patient but these two variables are not necessarily correlated. Prospective studies are needed to determine the relative impact of these variables.

Antifibrinolytic therapy and perioperative blood loss in cancer patients undergoing major orthopedic surgery.

BACKGROUND: Aprotinin has been reported to reduce blood loss and transfusion requirements in patients having major orthopedic operations. Data on whether epsilon amino-caproic acid (EACA) is effective in this population are sparse. METHODS: Sixty-nine adults with malignancy scheduled for either pelvic, extremity or spine surgery during general anesthesia entered this randomized, double-blind, placebo-controlled trial, and received either intravenous aprotinin (n = 23), bolus of 2 x 10(6) kallikrein inactivator units (KIU), followed by an infusion of 5 x 10(5) KIU/h, or EACA (n = 22), bolus of 150 mg/kg, followed by a 15 mg/kg/h infusion or saline placebo (n = 24) during surgery. Our goal was to determine whether prophylactic EACA or aprotinin therapy would reduce perioperative blood loss (intraoperative + first 48h) >30% when compared to placebo. RESULTS: The mean age of the study population was 52 +/- 17 yr. The groups did not differ in age, duration of surgery, perioperative blood loss or number of packed erythrocyte units transfused. When compared to the placebo group, the two treated groups had a significantly lower D-Dimer level immediately after surgery, P < 0.01. CONCLUSIONS: Under the conditions of this study, we were unable to find a clinical benefit to using aprotinin or EACA to reduce perioperative blood loss or transfusion requirements during major orthopedic surgery in cancer patients.

Tissue microarray molecular profiling of early, node-negative adenocarcinoma of the rectum: a comprehensive analysis.

PURPOSE: Early-stage adenocarcinoma of the rectum treated with curative intent has a favorable overall prognosis; however, 20%-30% of the patients recur, and the majority ultimately die of disease. Recurrence and tumor-related mortality may be attributable to molecular abnormalities in primary tumors accounting for their more aggressive biological behavior. This study evaluates such molecular phenotypes with regard to cell cycle regulation and proliferation and determines their significance for patient outcome. EXPERIMENTAL DESIGN: One hundred patients with primary T(2-3), N(0) adenocarcinoma of the rectum uniformly treated by surgery alone were studied. Core biopsies of pathological specimens were assembled on tissue microarrays, and expression of p53, mdm-2, p21, Bcl-2, p27, cyclin D1, and Ki-67 was analyzed by immunohistochemistry. Molecular profiles were correlated with disease-free (DFS) and disease-specific survival (DSS). RESULTS: Despite previously described prognostic relevance of some of the investigated molecules in analyses where different stages of colorectal cancer were included, none of the cell cycle-regulatory or proliferation-related markers was associated with recurrence or survival. However, patients with tumors demonstrating down-regulation of p27, a cyclin-dependent kinase inhibitor and tumor suppressor gene associated with development of metastases, showed a trend toward reduced DFS and DSS (P = 0.06 and P = 0.07, respectively). CONCLUSIONS: In this homogeneous group of patients with early-stage, node-negative adenocarcinoma of the rectum uniformly treated by surgery alone, the investigated cell cycle-regulatory and proliferation-associated proteins appear to have no prognostic significance. However, down-regulation of p27 appears to be associated with a trend toward reduced DFS and DSS, which suggests further investigation of other p27-related pathways potentially relevant for metastatic disease.

Primary adult soft tissue sarcoma: time-dependent influence of prognostic variables.

PURPOSE: To define prognostic factors for postrelapse survival and their time-dependent influence for adult soft tissue sarcoma (STS). PATIENTS AND METHODS: We analyzed 2,123 patients with completely resected localized primary STS treated from 1982 to 1999. Variables studied included tumor site, size, depth, grade, and resection margin but not treatment other than resection. Landmark time frames were used to assess the influence of disease-free interval (DFI) on disease-specific survival (DSS). DSS was estimated with the Kaplan-Meier method. Univariate and multivariate analyses were performed using log-rank test and the Cox proportional hazards regression model. Time-dependent stepwise regression analysis evaluated the time-dependent influence of each variable. RESULTS: Two thirds of recurrences developed within 2 years of initial resection. Tumor size (P <.001), grade (P <.001), and microscopic resection margin (P <.001) independently predicted DSS for all STS. Size and grade independently predicted early (DFI 3 years) DSS. Risk of tumor-related death was the same across all sites 3 years postresection and decreased significantly for extremity/trunk STS when DFI exceeded 3 years (P <.001). Influence of initial high-risk factors for tumor-related mortality in extremity/trunk STS decreased by 40% 3 years postresection, but their influence over DSS for non-extremity/trunk sites remained constant over time. Likelihood of complete resection after recurrence (all sites) increased with DFI (9% and 33% for DFI < 6 and > 36 months, respectively). CONCLUSION: Tumor size, grade, and resection margin predict outcome for completely resected STS, and their influence for DSS is time- and site-dependent. The influence of prognostic factors changes over the natural history of extremity/trunk STS. Time to recurrence exerts significant influence over complete resection rates for recurrent disease.

Conventional hemangiopericytoma: modern analysis of outcome.

BACKGROUND: Hemangiopericytoma (HPC) is a rare vascular tumor, and pathologic distinction from synovial sarcoma and solitary fibrous tumor is a significant problem due to shared histologic features. In the current report the authors defined the clinical behavior and prognosis for patients with HPC. METHODS: Between July 1982 and February 1998, 62 patients with a diagnosis of primary, recurrent, or metastatic HPC were identified from a prospectively maintained database. The pathology of all cases for which material was available (57 cases) was re-reviewed for histologic confirmation of the HPC diagnosis. Using strict pathologic criteria, including immunohistochemistry and electron microscopy, tumors from 25 of 57 patients qualified for the diagnosis of conventional hemangiopericytoma; those tumors formed the basis of the current report. Survival was determined by the Kaplan-Meier method. RESULTS: At the time of initial presentation, 19 patients had primary tumors, 3 had locally recurrent disease, and 3 had metastatic disease. The most frequent anatomic sites for HPC were the extremities, the pelvis, and the head and neck, accounting for 80% of the total cases. The median followup (n = 25) was 49 months (range, 1 to 160 months). The two and five year overall survival rates (n = 25) were 93% and 86% respectively. The disease-specific survival was 86% at last followup. Patients undergoing complete resection (n = 16) showed a 100% median survival at 60 months. CONCLUSIONS: At present, complete tumor resection for patients with conventional HPC is recommended. However, considering the favorable outcome in this disease, the authors caution against performing operations that may potentially cause loss of function or are limb threatening.

Soft tissue sarcoma brain metastases. Prevalence in a cohort of 3829 patients.

BACKGROUND: Brain metastases from soft tissue sarcoma (STS) are uncommon. To the authors' knowledge limited information is available regarding the influence of the initial STS site, the significance of parenchymal versus leptomeningeal metastases, and the role of surgical resection. METHODS: STS patients evaluated between July 1982 and March 1999 who presented with or developed brain metastases were identified from a prospective database. Association between factors was determined using the Fisher exact test. Survival was estimated using the Kaplan-Meier method. The influence of factors on the endpoint (disease specific survival [DSS]) was analyzed using the log-rank test. Significance was defined at P < or = 0.05. RESULTS: A total of 3829 STS patients were evaluated during the study interval; 21 patients presented with and 19 patients subsequently developed brain metastases, accounting for < 1% (40 of 3829 patients) of the total patient group. The STS presentation status for this group of patients (n = 40) included 15 patients with primary STS, 1 patient with local recurrence, and 24 patients with metastatic disease. The most frequent types of STS metastasizing to the brain were leiomyosarcoma (eight patients), liposarcoma (five patients), rhabdomyosarcoma (four patients), and malignant fibrous histiocytoma (MFH) (four patients). Fourteen other sarcoma types were determined in the remaining 19 patients. Of the 19 patients who developed subsequent brain metastases, 18 had lung metastases as the immediate prior site of disease. The median overall follow-up for the 40 patients was 14 months (range, 1-128 months); for survivors (n = 5), the median overall follow-up was 18 months. During follow-up, 34 patients died of disease and 1 patient died of other causes. Brain metastasectomy was performed in 27 of the 40 patients and was highly associated with the initial site of STS; 20 of the 27 patients who underwent resection versus 2 of the 13 patients who did not undergo resection initially had extremity or trunk STS (P < 0.001). No association was observed between parenchymal versus leptomeningeal site of metastases and any outcome factor. The 1-year and 2-year overall DSS for the 40 patients was 55% and 25%, respectively, with a median survival of 15 months. The 1-year and 2-year postmetastasis survival rates were 34% and 20%, respectively, with a median survival of 7 months. Metastasectomy (n = 27) was associated with an improved median postmetastasis survival (9.6 months vs. 2.7 months for unresected patients; P < 0.01). The 2-year postmetastasis survival was 27% for those patients who underwent resection and 0% for the unresected patients. CONCLUSIONS: Although brain metastases from STS are rare, vigilance is warranted. Symptomatic patients should be examined neurologically and investigated thoroughly for metastases. Surgical resection may be an appropriate treatment for selected patients; however, survival is dismal.

Hürthle cell carcinoma: a 60-year experience.

BACKGROUND: The aim of this study was to define the clinical behavior and prognostic indicators of outcome in Hürthle cell cancer (HCC). METHODS: Diagnosis was confirmed for 56 patients with HCC treated between 1940 and 2000, who form the basis of this study. Primary end points were relapse-free survival (RFS) and disease-specific survival (DSS). Data were analyzed with the Kaplan-Meier method and by log-rank test. RESULTS: The extent of thyroid resection did not predict outcome. Recurrence was a significant predictor of tumor-related mortality. Significant adverse predictors of RFS and DSS were degree of invasion, size >4 cm, extrathyroidal extension, and initial nodal or distant metastases. The most significant predictor of outcome was extent of invasion. Eight-year RFS values for low- and high-risk groups were 100% and 24%. Corresponding rates of 8-year DSS were 100% and 58%. CONCLUSIONS: Widely invasive HCC is an aggressive malignancy that identifies patients who are at high risk for recurrence and tumor-related death. Patients with HCC have a prognosis that is reliably predicted by degree of invasion, tumor size, extrathyroidal disease extension, and initial nodal or distant metastasis. Recurrence portends a poor outcome. High-risk patients and those with recurrence should be considered for adjuvant therapy.