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Biomedical subjects

Steven L Chen

Publications and source records attributed to Steven L Chen.

11 recordsLinked to original sources
PubMed2006

Chemokine receptor CXCR4 expression in patients with melanoma and colorectal cancer liver metastases and the association with disease outcome.

OBJECTIVE: To determine the role of chemokine receptor (CR) expression in patients with melanoma and colorectal cancer (CRC) liver metastases. SUMMARY BACKGROUND DATA: Murine and in vitro models have identified CR as potential factors in organ-specific metastasis of multiple cancers. Chemokines via their respective receptors have been shown to promote cell migration to distant organs. METHODS: Patients who underwent hepatic surgery for melanoma or CRC liver metastases were assessed. Screening cDNA microarrays of melanoma/CRC cell lines and tumor specimens were analyzed to identify CR. Microarray data were validated by quantitative real-time RT-PCR (qRT) in paraffin-embedded liver metastases. Migration assays and immunohistochemistry were performed to verify CR function and confirm CR expression, respectively. RESULTS: Microarray analysis identified CXCR4 as the most common CR expressed by both cancers. qRT demonstrated CXCR4 expression in 24 of 27 (89%) melanoma and 28 of 29 (97%) CRC liver metastases. In vitro treatment of melanoma or CRC cells with CXCL12, the ligand for CXCR4, significantly increased cell migration (P < 0.001). Low versus high CXCR4 expression in CRC liver metastases correlated with a significant difference in overall survival (median 27 months vs. 10 months, respectively; P = 0.036). In melanoma, low versus high CXCR4 expression in liver metastases demonstrated no difference in overall survival (median 11 months vs. 8 months, respectively; P = not significant). CONCLUSIONS: CXCR4 is expressed and functional on melanoma and CRC cells. The ligand for CXCR4 is highly expressed in liver and may specifically attract melanoma and CRC CXCR4 (+) cells. Quantitative analysis of CXCR4 gene expression in patients with liver metastases has prognostic significance for disease outcome.

Adult↗
PubMed2006

More extensive nodal dissection improves survival for stages I to III of colon cancer: a population-based study.

OBJECTIVE: To determine whether analyzing more lymph nodes in colon cancer specimens improves survival. SUMMARY BACKGROUND DATA: Increasing the number of lymph nodes analyzed has been reported to correlate with improved survival in patients with node-negative colon cancer. METHODS: The Surveillance, Epidemiology, and End Results database was queried for all patients undergoing resection for histologically confirmed colon cancer between the years 1988 and 2000. Patients were excluded for distant metastases or if an unknown number of nodes was sampled. The number of nodes sampled was categorized into 0, 1 to 7, 8 to 14, and > or =15 nodes. Survival curves constructed using the Kaplan-Meier method were compared using log rank testing. A Cox proportional hazard model was created to adjust for year of diagnosis, age, race, gender, tumor grade, tumor size, TNM stage, and percent of nodes positive for tumor. RESULTS: The median number of lymph nodes sampled for all 82,896 patients was 9. For all stages examined, increasing nodal sampling was associated with improved survival. Multivariate regression demonstrated that patients who had at least 15 nodes sampled as compared with 1 to 7 nodes experienced a 20.6% reduction in mortality independent of other patient and tumor characteristics. CONCLUSIONS: Adequate lymphadenectomy, as measured by analysis of at least 15 lymph nodes, correlates with improved survival, independent of stage, patient demographics, and tumor characteristics. Currently, most procedures do not meet this guideline. Future trials of adjuvant therapy should include extent of lymphadenectomy as a stratification factor.

Aged↗
PubMed2006

Radiofrequency ablation of hepatic metastases from colorectal cancer: are newer generation probes better?

Second-generation radiofrequency ablation (RFA) probes and their successors have more power, shorter ablation times, and an increased area of ablation compared with the first-generation probes used before 2000. We examined whether the use of the newer probes has improved the clinical outcome of RFA for hepatic metastases of colorectal cancer at our tertiary cancer center. Of 160 patients who underwent RFA between 1997 and 2003, 52 had metastases confined to the liver: 21 patients underwent 46 ablations with the first-generation probes and 31 patients underwent 58 ablations with the newer probes. The two groups had similar demographic characteristics. At a median follow-up of 26.2 months, patients treated with the newer probes had a longer median disease-free survival (16 months vs 8 months, P < 0.01) and a lower rate of margin recurrence (5.2% vs 17.4%); eight patients had no evidence of disease and one patient was alive with disease. By contrast, of the 46 patients treated with the first-generation probes, 2 patients had no evidence of disease and 1 patient was alive with disease. Newer-generation probes are associated with lower rates of margin recurrence and higher rates of disease-free survival after RFA of hepatic metastases from colorectal cancer.

Aged↗
PubMed2006

Treatment disparities in Hispanic rectal cancer patients: a SEER database study.

Although Hispanics demonstrate a low overall incidence of rectal cancer, mortality rates have not decreased relative to non-Hispanic whites. To determine if this was in part due to racial disparities in care, we compared rates of neoadjuvant therapy and sphincter-preserving surgery between Hispanics and non-Hispanic whites diagnosed with rectal cancer using the Surveillance, Epidemiology, and End Results (SEER) database. The study population was comprised of 2,573 Hispanics (55.4% male) and 28,395 non-Hispanic whites (56.6% male). Rates of neoadjuvant radiation were 13.5 per cent for Hispanics compared with 10.4 per cent for non-Hispanic whites (P < 0.001). In a Cox proportional hazards model adjusting for nodal status, tumor size, and T stage, non-Hispanic whites were significantly less likely to have received neoadjuvant therapy (hazard ratio, 0.72; P < 0.001; 95% confidence interval 0.63-0.83). Rates of sphincter preservation were 67 per cent for Hispanics and 70 per cent for non-Hispanic whites (P = 0.003). Non-Hispanic whites were significantly more likely to have received a sphincter-preserving operation than Hispanics (hazard ratio, 1.076; P = 0.019; 95% confidence interval 1.02-1.27). We conclude that Hispanics are significantly more likely to receive neoadjuvant therapy but are less likely to receive sphincter-sparing operations for rectal cancer compared with non-Hispanic whites. Further studies are required to assess the impact of these treatment disparities on patient outcome.

Aged↗
PubMed2004

An academic health center cost analysis of screening mammography: creating a financially viable service.

BACKGROUND: The current study sought to determine the institutional financial impact of a screening mammography (SM) program in the context of an integrated cancer center. METHODS: Using administrative databases, 10,048 women were identified as receiving screening mammograms in fiscal year 1999 and the first one-half of fiscal year 2000. The utilization of breast care resources was followed for an average of 1208 days. The University of Michigan cost accounting system was then used to determine overall margin (revenues-total costs) and contribution margin (revenues-actual costs) of the SM program, as well as other breast care services. RESULTS: The percentage of variable costs to total costs for the SM program was 24%. The overall facility losses in the breast care line were $1.7 million with a positive contribution margin of $2.0 million. The annual yield of nonscreening/diagnostic mammographic procedures was 0.9%. All types of radiologic activity failed to cover their total costs, but did provide a positive contribution margin. Overall margins for surgery procedures were approximately even, and adjuvant medical and radiotherapy services were net positive. Modeling helped to identify overhead limits necessary to achieve margin targets associated with increased activity. CONCLUSIONS: The current study showed that SM programs are unlikely to succeed financially without careful selection of those screened to increase the yield of diagnostic and therapeutic procedures. Based on favorable contribution margins, SM programs were viable when viewed as incremental business.

Adult↗
PubMed2004

Hospital costs associated with surgical complications: a report from the private-sector National Surgical Quality Improvement Program.

BACKGROUND: The National Surgical Quality Improvement Project (NSQIP) has reduced morbidity rates in Veterans Affairs Hospitals. As the NSQIP methods move to private-sector hospitals, funding responsibilities will shift to the medical center. The objective of the current study was to calculate hospital costs associated with postoperative complications, because reducing morbidity may offset the costs of using the NSQIP. STUDY DESIGN: Patient data were obtained from a single private-sector center involved in the NSQIP from 2001 to 2002 (n=1,008). Cost data were derived from the hospital's internal cost-accounting database (TSI; Transitions Systems Inc). Total hospital costs associated with both minor complications and major complications were calculated. Multiple linear regression was used to determine the cost of each type of complication after adjusting for patient characteristics. RESULTS: Rates of minor complications (6.3%, 64 events) and major complications (6.6%, 67 events) were similar. Median hospital costs were lowest for patients without complications (4,487 dollars) compared with those with minor (14,094 dollars) and major complications (28,356 dollars) (p<0.001). After adjusting for differences in patient characteristics, major complications were associated with an increase of 11,626 dollars (95% CI, 9,419 dollars to 13,832 dollars; p<0.001). Minor complications were not associated with increased costs in the adjusted analysis. CONCLUSIONS: Given the substantial costs associated with major postoperative complications, reducing morbidity may provide sufficient cost savings to offset the resources needed to participate in the private-sector expansion of the NSQIP.

Adult↗
PubMed2003

The added cost of urgent cholecystectomy to health systems.

BACKGROUND: The purpose of this study is to assess the cost and reimbursement differential between elective and urgent laparoscopic cholecystectomy. STUDY DESIGN: All visits for laparoscopic cholecystectomy (ICD-9 Code 51.23) to the University of Michigan Health System were reviewed for 1997 to 2001 (n = 752). Data were obtained from the University of Michigan Data Warehouse. Patients were grouped into urgent and elective cases, and further subgrouped into complicated and uncomplicated cases based on Diagnostic Related Group (DRG) coding. RESULTS: Total costs were determined for 13 distinct facility cost centers with average costs greater than $10 per case. Reimbursement was also assessed. Total costs were approximately 90% higher in urgent cases. The largest contributors to increased costs were nursing care and pharmacy costs. The emergent group experienced a pre-operative delay to surgery of 1.8 days. Reimbursement was similar for both elective and urgent patients when stratified by complicated and uncomplicated DRGs. CONCLUSIONS: The urgency of the operation significantly elevates the costs and resource consumption associated with laparoscopic cholecystectomy. These cost differences should also be recognized when setting reimbursement premiums under risk-bearing systems, such as Medicare Diagnosis Related Group reimbursement. Consideration for including urgent operation as a comorbidity should be assessed.

Cholecystectomy, Laparoscopic↗
PubMedDate not supplied

Lymphatic mapping and sentinel node analysis: current concepts and applications.

Since the introduction of sentinel node biopsy in 1990 as a minimally invasive surgical technique for the diagnosis of melanoma lymphatic metastases, the number of applications has expanded. We review applications and the current status of sentinel node biopsy in melanoma, breast, colon, gastric, esophageal, head and neck, thyroid, and lung cancer. Variations on techniques specific to each organ are explained, and the current role of sentinel node biopsy in diagnosis and treatment is discussed.

Breast Neoplasms↗