In:
Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 37, No. 4_suppl ( 2019-02-01), p. 215-215
Abstract:
215 Background: In light of recent FDA approval of anti-PD-1 therapy for microsatellite unstable (MSI-H) or mismatch repair deficient (dMMR) solid tumors, identifying patients with dMMR tumors has become increasingly important. While screening for dMMR and MSI-H in colorectal cancer (CRC) is recommended, this screening is less commonly done for extracolonic gastrointestinal (GI) tumors. At Stanford Comprehensive Cancer Institute (SCCI), all GI cancer patients have been universally screened for dMMR via immunohistochemistry since January 2016. Methods: In this study, we undertook a retrospective review of all GI cancer patients screened for dMMR between January 2016 to December 2017. Data on patient characteristics, germline and tumor sequencing, and tumor characteristics were collected and reported. Results: A total of 1543 GI malignancies were screened for dMMR at SCCI during the study period. Colorectal (n = 711), pancreatic (n = 264), gastric (n = 159), and gastro-esophageal (n = 137) cancer were amongst the most frequently screened tumors. dMMR was detected in 7.1% of all GI malignancies. We detected the highest prevalence of dMMR in colorectal (69/711, 9.7%), followed by gastric (15/159, 9.4%), pancreatic (18/264, 6.8%), and gastro-esophageal cancer (6/137, 4.4%). Lynch syndrome was the most common etiology for dMMR in CRC patients (39.4%), double somatic (confirmed or possibly) mutations were most common in pancreatic cancer (44.4%), and somatic MLH1 hypermethylation was the most common etiology in gastric (73.3%) and gastro-esophageal cancer (100%). Conclusions: Given the relatively high incidence of dMMR in GI malignancies, we strongly recommend screening all GI malignancies. Of note, we found higher than previously reported rates of dMMR within pancreatic cancer. Our results also suggest that while rare, double somatic mismatch repair mutations may be a significant pathway causing dMMR in pancreatic cancer.
Type of Medium:
Online Resource
ISSN:
0732-183X
,
1527-7755
DOI:
10.1200/JCO.2019.37.4_suppl.215
Language:
English
Publisher:
American Society of Clinical Oncology (ASCO)
Publication Date:
2019
detail.hit.zdb_id:
2005181-5
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