Clinical Utility of a Fully Automated Microsatellite Instability Test with Minimal Hands-on Time

BACKGROUND: Microsatellite instability (MSI) analysis is becoming increasingly important in many types of tumor including colorectal cancer (CRC). The commonly used MSI tests are either time-consuming or labor-intensive. A fully automated MSI test, the Idylla MSI assay, has recently been introduced. However, its diagnostic performance has not been extensively validated in clinical CRC samples.METHODS: We evaluated 133 samples whose MSI status had been rigorously validated by standard polymerase chain reaction (PCR), clinical next-generation sequencing (NGS) cancer panel test, or both. We evaluated the diagnostic performance of the Idylla MSI assay in terms of sensitivity, specificity, and positive and negative predictive values, as well as various sample requirements, such as minimum tumor purity and the quality of paraffin blocks.RESULTS: Compared with the gold standard results confirmed through both PCR MSI test and NGS, the Idylla MSI assay showed 99.05% accuracy (104/105), 100% sensitivity (11/11), 98.94% specificity (93/94), 91.67% positive predictive value (11/12), and 100% negative predictive value (93/93). In addition, the Idylla MSI assay did not require macro-dissection in most samples and reliably detected MSI-high in samples with approximately 10% tumor purity. The total turnaround time was about 150 minutes and the hands-on time was less than 2 minutes.CONCLUSIONS: The Idylla MSI assay shows good diagnostic performance that is sufficient for its implementation in the clinic to determine the MSI status of at least the CRC samples. In addition, the fully automated procedure requires only a few slices of formalin-fixed paraffin-embedded tissue and might greatly save time and labor.

Prognostic Factors of Stage II Rectal Cancer / 대한소화기학회지

BACKGROUND/AIMS: We aimed to verify the prognostic factors of stage II rectal cancer and the effect of radiation therapy on the survival and local recurrence rate. METHODS: This study was undertaken in 202 patients who underwent curative resection of rectal cancer and confirmed to be stage II between July 1989 and December 1996. Univariate and multivariate (Cox's model) analyses of survival were employed to identify prognostic factors. Statistical significance was assigned by p value of <0.05. RESULTS: Overall recurrence occurred in 32 patients. Four patterns of recurrence were observed: hematogenous recurrence in 17 patients, local recurrence in 11, peritoneal seeding in two and simultaneous hematogenous and local recurrence in two cases. Overall 5-year survival rate was 85.6% and 5 year disease free survival rate was 82.8%. There was no significant difference in local recurrence rate and survival according to radiation therapy or location of cancer. In multivariate analysis, the number of harvested lymph node was only a prognostic factor. CONCLUSIONS: The number of harvested lymph nodes has prognostic value in stage II rectal cancer. Postoperative radiation therapy should be considered for stage II rectal cancer with poor prognostic factors although radiation did not decrease local recurrence rate in present study.