Hub and spoke framework for study of surgical centralization within United States health systems

BACKGROUND

Hospital consolidation into health systems has mixed effects on surgical quality, potentially related to degree of surgical centralization at high-volume (hub) sites. We developed a novel measure of centralization and evaluated a hub and spoke framework.

METHODS

Surgical centralization within health systems was measured using hospital surgical volumes (American Hospital Association) and health system data (Agency for Healthcare Research and Quality). Hub and spoke hospitals were compared using mixed effects logistic regression and system characteristics associated with surgical centralization were identified using a linear model.

RESULTS

Within 382 health systems containing 3022 hospitals, system hubs perform 63% of cases (IQR 40-84%). Hubs are larger, in metropolitan and urban areas, and more often academically affiliated. Degree of surgical centralization varies ten-fold. Larger, multistate, and investor-owned systems are less centralized. Adjusting for these factors, there is less centralization among teaching systems (p ​< ​0.001).

CONCLUSIONS

A hub-spoke framework applies to most health systems but centralization varies significantly. Future studies of health system surgical care should assess the contributions of surgical centralization and teaching status on differential quality.

Incidence and Risk Factors for Incidental Cancer on Melanoma Wide Excisions

INTRODUCTION

Cancer patients and survivors have a high risk of developing additional malignancies. Patients who undergo melanoma excision often have sun-damaged skin and are predisposed to concurrent and subsequent skin cancers. The unexpected finding of an incidental cancer on melanoma wide excisions can require further surgery and delays adjuvant treatment. We aimed to determine the incidence and risk factors for incidental skin cancers in patients who had surgical excision of melanoma.

METHODS

Our single-center retrospective study analyzed all patients diagnosed with primary melanoma at our institution from July 1, 2019 through June 30, 2020. We included patients with localized cutaneous melanoma who underwent surgical excision and had relevant pathology data available. Descriptive statistics and univariate analyses were performed on the demographic, clinical, and pathological data collected. We analyzed differences between the groups with and without incidental cancer to ascertain risk factors using chi-squared tests and Wilcoxon rank sum tests. Dunn's tests with Bonferroni correction were performed for multiple pairwise comparisons.

RESULTS

There were 642 patients who met the criteria for inclusion, of whom 13 (2.0%) had incidental cancers identified on a pathologic assessment. Six (46%) had incidental squamous cell carcinoma and seven (54%) had basal cell carcinoma. With regard to management of incidental cancer, three (23%) patients required additional surgery for margin re-excision. Risk factors for incidental cancers in melanoma excision included older age (median 79 versus 62 y, P < 0.001), male sex (P = 0.042), and primary tumor location in the head/neck region relative to trunk (P < 0.01) or extremity (P < 0.01) primary sites.

CONCLUSIONS

Although the frequency of incidental findings on melanoma excision is low, certain patients are at a greater risk including older male individuals with head/neck melanomas. These findings can be used to improve preoperative counseling of at-risk patients when melanoma excision is planned.

Burden of Care for Patients With In-Transit Melanoma

INTRODUCTION

Patient burden of cancer care can be significant, especially for cancers like melanoma where patients are living longer, even with advanced disease. The purpose of this study is to compare the burden of treatment of melanoma patients with in-transit metastases (ITM). There are multiple treatment options for ITM, but no standard due to lack of large cohort comparative studies; thus, the anticipated burden of care may influence therapy choice.

METHODS

Included patients had in-transit melanoma without distant metastasis and were managed at our institution from July 1, 2015 through December 31, 2020 using a combination of surgery, systemic, intralesional, and radiation therapy. We compared treatment burden, (number of treatments, clinic visits, inpatient hospital days, and distance traveled) and response rates using Kruskal-Wallis and chi-squared tests. Recurrence-free survival and estimated charges were exploratory endpoints.

RESULTS

There were 42 patients who met the inclusion criteria. As initial treatment, patients had surgery (n = 20), surgery with adjuvant (n = 6), systemic (n = 9), and intralesional therapy (n = 2). Surgery had the lowest treatment burden (median of 1 treatment, 3 clinic visits, and 0 inpatient days) while surgery with adjuvant systemic therapy had the highest burden (median of 13 treatments, 12 clinic visits, and 0 inpatient days). Systemic, intralesional, and radiation therapy were used more often for recurrent ITM. Travel distance (P = 0.88) and response rates did not statistically differ between the four options for first line therapy (P = 0.99). At a median follow-up time of 8.8 mo, 22 (52%) of the cohort required more than 1 therapy to manage recurrent or progressive disease and 14 (33%) progressed to distant disease.

CONCLUSIONS

Treatment of in-transit melanoma is associated with high burden of care and often requires multiple therapies, even with maximally effective first treatment choice. Factors evaluated in this study may be used to set expectations of treatment course for newly diagnosed patients and may aid in patients' decisions on therapy selection.

The efficacy of immune checkpoint blockade for melanoma in-transit with or without nodal metastases - A multicenter cohort study

PURPOSE

Guidelines addressing melanoma in-transit metastasis (ITM) recommend immune checkpoint inhibitors (ICI) as a first-line treatment option, despite the fact that there are no efficacy data available from prospective trials for exclusively ITM disease. The study aims to analyze the outcome of patients with ITM treated with ICI based on data from a large cohort of patients treated at international referral clinics.

METHODS

A multicenter retrospective cohort study of patients treated between January 2015 and December 2020 from Australia, Europe, and the USA, evaluating treatment with ICI for ITM with or without nodal involvement (AJCC8 N1c, N2c, and N3c) and without distant disease (M0). Treatment was with PD-1 inhibitor (nivolumab or pembrolizumab) and/or CTLA-4 inhibitor (ipilimumab). The response was evaluated according to the RECIST criteria modified for cutaneous lesions.

RESULTS

A total of 287 patients from 21 institutions in eight countries were included. Immunotherapy was first-line treatment in 64 (22%) patients. PD-1 or CTLA-4 inhibitor monotherapy was given in 233 (81%) and 23 (8%) patients, respectively, while 31 (11%) received both in combination. The overall response rate was 56%, complete response (CR) rate was 36%, and progressive disease (PD) rate was 32%. Median PFS was ten months (95% CI 7.4-12.6 months) with a one-, two-, and five-year PFS rate of 48%, 33%, and 18%, respectively. Median MSS was not reached, and the one-, two-, and five-year MSS rates were 95%, 83%, and 71%, respectively.

CONCLUSION

Systemic immunotherapy is an effective treatment for melanoma ITM. Future studies should evaluate the role of systemic immunotherapy in the context of multimodality therapy, including locoregional treatments such as surgery, intralesional therapy, and regional therapies.

Increased concentrations of chlordane in adipose tissue from non-Hodgkin's lymphoma patients compared with controls without a malignant disease

Chlordane is a pesticide which is lipophilic, bioaccumulates, and may cause immunological impairment in exposed subjects. The aim of this study was to determine the concentrations of chlordane and its metabolites in cases with NHL and surgical controls without a malignant disease. Adipose tissue was obtained from the abdominal wall and analysis was performed using gas chromatograph coupled to mass spectrometer. The study included 27 NHL cases of the B-cell type and 17 controls. Significantly increased concentrations were found in NHL patients versus (vs) controls of trans-nonachlor, mean 98.9 vs 47.0, range 24.9-389 vs 16.3-88.2 ng/g lipid (p = 0.002), cis-nonachlor, mean 17.1 vs 7.4, range 4.1-68.3 vs 1.7-13.6 (p = 0.010), oxy-chlordane, mean 39.7 vs 24.5, range 8.5-144 vs 8.9-49.0, (p = 0.028) nonachlor III, mean 18.4 vs 8.7, range 6.3-67.6 vs 3.0-19.3 (p = 0.002) and sum of chlordanes, 180 vs 92.8, range 48.3-678 vs 37.0-164 ng/g lipid (p = 0.002). For cases with a concentration higher than the median for all subjects significantly increased odds ratios (OR) and 95% confidence intervals (CI) were calculated for trans-nonachlor (OR = 4.1, CI = 1.1-15), nonachlor LII (OR = 6.5, CI = 1.7-25), and sum of chlordanes (OR = 4.1, CI = 1.1-15); median concentrations were 61.2, 11.3, and 119 ng/g lipid, respectively.

Quantitative trait loci on chromosomes 3 and 17 influence phenotypes of the metabolic syndrome

Recent research has emphasized the importance of the metabolic cluster, which includes glucose intolerance, dyslipidemia, and high blood pressure, as a strong predictor of the obesity-related morbidities and premature mortality. Fundamental to this association, commonly referred to as the metabolic syndrome, is the close interaction between abdominal fat patterning, total body adiposity, and insulin resistance. As the initial step in identifying major genetic loci influencing these phenotypes, we performed a genomewide scan by using a 10-centiMorgan map in 2,209 individuals distributed over 507 nuclear Caucasian families. Pedigree-based analysis using a variance components linkage model demonstrated a quantitative trait locus (QTL) on chromosome 3 (3q27) strongly linked to six traits representing these fundamental phenotypes [logarithm of odds (lod) scores ranged from 2.4 to 3.5]. This QTL exhibited possible epistatic interaction with a second QTL on chromosome 17 (17p12) strongly linked to plasma leptin levels (lod = 5.0). Situated at these epistatic QTLs are candidate genes likely to influence two biologic precursor pathways of the metabolic syndrome.

Estimation of antigen-responsive T cell frequencies in PBMC from human subjects

A new method for estimating the frequency of antigen-responsive T cells, using a cell proliferation assay, is described. In this assay, the uptake of tritiated thymidine by peripheral blood mononuclear cells which have been exposed to antigen, is measured for each well on a microtiter plate. Whereas this assay is generally used as part of a limiting dilution assay, here we estimate the frequency of responding cells using a single, carefully chosen cell density. The traditional analysis of such data uses a cut-off to separate wells which contain no responding cells and wells which contain at least one responding cell. The new method uses the scintillation count to estimate the number of responding cells for each well on the plate. We do this by fitting a two-stage model, the first stage being a Poisson model with antigen-specific frequency parameters, and the second stage a linear model with plate-specific parameters.

Nitrogen catabolite regulation of proline permease in Saccharomyces cerevisiae. Cloning of the PUT4 gene and study of PUT4 RNA levels in wild-type and mutant strains

The proline permease gene PUT4 has been cloned. Nitrogen-source regulation ('ammonia sensitivity') of this and at least two other amino-acid permeases is believed to occur at two distinct levels, i.e. permease synthesis and permease activity. Therefore, PUT4 transcription/messenger stability was examined in the ammonia- and proline-grown wild type as well as in mutant strains supposedly affected at only one or at both of these levels. We report transcript-level repression of proline permease synthesis in ammonia-grown cells. Repression is lifted at this level in gdhCR, gln1ts and gdhA mutants which exhibit pleiotropically derepressed permease and catabolic enzyme activities. On the other hand, the npi1 and npi2 mutations, formerly called mut2 and mut4, relieve an inactivation process which seems only to affect permeases. These mutations do not affect the detected PUT4 RNA level. The only known positive factor in proline permease regulation, the nitrogen permease reactivator protein Npr1, is believed to counteract the inactivation process on derepressing media. This protein appears to have an additional, indirect effect on PUT4 transcription/messenger stability: it would actually mediate repression via its activating effect on ammonia uptake.

Occurrence and role of phosphoenolpyruvate carboxykinase in procyclic Trypanosoma brucei brucei glycosomes

Phosphoenolpyruvate carboxykinase (EC 4.1.1.32) was detected in a particulate fraction of Trypanosoma brucei brucei procyclic culture form. It requires ADP rather than GDP for activity in the direction of carboxylation and is located in the glycosomes. Since phosphoenolpyruvate can serve to furnish ATP for glycolysis and can promote 3-phosphoglycerate or 1,3-bisphosphoglycerate formation without simultaneous alpha-glycerophosphate production, we suggest that the glycosomal phosphoenolpyruvate carboxykinase-malate dehydrogenase tandem contributes to ATP regeneration and NADH re-oxidation in the glycosome, and regulates alpha-glycerophosphate production.

Oxygen and nitrate in utilization by Bacillus licheniformis of the arginase and arginine deiminase routes of arginine catabolism and other factors affecting their syntheses

Bacillus licheniformis has two pathways of arginine catabolism. In well-aerated cultures, the arginase route is present, and levels of catabolic ornithine carbamoyltransferase were low. An arginase pathway-deficient mutant, BL196, failed to grow on arginine as a nitrogen source under these conditions. In anaerobiosis, the wild type contained very low levels of arginase and ornithine transaminase. BL196 grew normally on glucose plus arginine in anaerobiosis and, like the wild type, had appreciable levels of catabolic transferase. Nitrate, like oxygen, repressed ornithine carbamoyltransferase and stimulated arginase synthesis. In aerobic cultures, arginase was repressed by glutamine in the presence of glucose, but not when the carbon-energy source was poor. In anaerobic cultures, ammonia repressed catabolic ornithine carbamoyltransferase, but glutamate and glutamine stimulated its synthesis. A second mutant, derived from BL196, retained the low arginase and ornithine transaminase levels of BL196 but produced high levels of deiminase pathway enzymes in the presence of oxygen.

Structure and function of ornithine carbamoyltransferases

The reaction catalyzed by ornithine carbamoyltransferase can participate in either the anabolism or the catabolism of arginine. The carbamoylation of ornithine, yielding citrulline, is involved in the biosynthetic sequence; the reverse reaction, the phosphorolysis of citrulline, is the second step of the arginine deiminase pathway. The ornithine carbamoyltransferases of a number of microorganisms which can fulfil both of these functions have been studied in this work. This group of organisms was found to possess two distinct ornithine carbamoyltransferases. The functions of these enzymes were surmised by determining the type of genetic regulation to which they were subjected. The kinetic properties of these various enzymes have been determined. All of them, regardless of the role they play in the cell, catalyze both the synthesis and arsenolysis of citrulline. The anabolic transferase of Pseudomonas is the only enzyme which displays functional irreversibility. A comparison of the quaternary structure of these transferases was performed and reveals interesting features in relation to the metabolic function of these enzymes. All well-characterized anabolic enzymes have low molecular weights (from 150000--105000) and are likely to be trimers. Catabolic enzymes, with the exception of those of Bacillus licheniformis and Halobacterium salinarium, display much higher molecular weights and more elaborate quaternary structure. The properties of these two groups of transferases are discussed in relation to their metabolic role in the cells.