A comparison of 12-gene colon cancer assay gene expression in African American and Caucasian patients with stage II colon cancer.

BACKGROUND: African American (AA) colon cancer patients have a worse prognosis than Caucasian (CA) colon cancer patients, however, reasons for this disparity are not well understood. To determine if tumor biology might contribute to differential prognosis, we measured recurrence risk and gene expression using the Oncotype DX® Colon Cancer Assay (12-gene assay) and compared the Recurrence Score results and gene expression profiles between AA patients and CA patients with stage II colon cancer. METHODS: We retrieved demographic, clinical, and archived tumor tissues from stage II colon cancer patients at four institutions. The 12-gene assay and mismatch repair (MMR) status were performed by Genomic Health (Redwood City, California). Student's t-test and the Wilcoxon rank sum test were used to compare Recurrence Score data and gene expression data from AA and CA patients (SAS Enterprise Guide 5.1). RESULTS: Samples from 122 AA and 122 CA patients were analyzed. There were 118 women (63 AA, 55 CA) and 126 men (59 AA, 67 CA). Median age was 66 years for AA patients and 68 for CA patients. Age, gender, year of surgery, pathologic T-stage, tumor location, the number of lymph nodes examined, lymphovascular invasion, and MMR status were not significantly different between groups (p = 0.93). The mean Recurrence Score result for AA patients (27.9 ± 12.8) and CA patients (28.1 ± 11.8) was not significantly different and the proportions of patients with high Recurrence Score values (≥41) were similar between the groups (17/122 AA; 15/122 CA). None of the gene expression variables, either single genes or gene groups (cell cycle group, stromal group, BGN1, FAP, INHBA1, Ki67, MYBL2, cMYC and GADD45B), was significantly different between the racial groups. After controlling for clinical and pathologic covariates, the means and distributions of Recurrence Score results and gene expression profiles showed no statistically significant difference between patient groups. CONCLUSION: The distribution of Recurrence Score results and gene expression data was similar in a cohort of AA and CA patients with stage II colon cancer and similar clinical characteristics, suggesting that tumor biology, as represented by the 12-gene assay, did not differ between patient groups.

Dual intervention to improve pathologic staging of resectable lung cancer.

BACKGROUND: Detection of lymph node metastasis is of immense prognostic value in patients with resectable non-small cell lung cancer (NSCLC), but routine pathologic nodal staging is suboptimal. To determine the impact on the rate of detection of nodal metastasis, we tested dual intervention with a prelabeled lymph node specimen collection kit to improve intraoperative node dissection and a fastidious gross dissection of the lung resection specimen for intrapulmonary lymph nodes. METHODS: We matched dual-intervention cases with controls staged using standard surgical specimen collection and pathologic examination protocols. Controls were hierarchically matched for extent of resection, laterality, surgeon, pathologist, and T stage. All statistical comparisons were made with exact conditional logistic regression, to account for the matched case-control design. RESULTS: One hundred dual-intervention cases were matched with 100 controls. The dual interventions resulted in approximately a 3-fold increase in the number of lymph nodes examined and the number of lymph nodes with metastasis detected; they also increased the proportion of patients with lymph node metastasis from 21% to 35% (p = 0.02). There were strong trends toward higher aggregate stage distribution, and eligibility for postoperative adjuvant chemotherapy in the dual-intervention cases. CONCLUSIONS: The combination of interventions improved the thoroughness and accuracy of pathologic nodal staging. A prospective randomized trial to test the survival impact of the dual interventions is warranted.