Abstract 3291
Background
Microsatellite instability (MSI) is thought to be a marker of immunogenicity and better prognosis in colorectal cancer (CRC). However, the mechanism by which MSI confers a survival advantage is not well known and there is a range of results reported in the literature.
Methods
A systematic literature search of original studies was performed on Ovid searching Medline, Embase, Cochrane Library, CINAHL, Clinical Trials databases from inception of database to current. Data extracted included age, stage, MSI-H, MSS and MSI-L, proximal (right) vs. distal (left), colon vs. rectal, BRAF status, type of MSI or IHC test used, incidence of Lynch within cohort. The primary endpoint was survival (overall survival (OS), disease/relapse free survival (DFS) and disease (cancer) specific survival DSS). Statistical analysis was performed using RevMan Ver 5.3 Cochrane Collaboration.
Results
From 11,747 studies, 117 met the inclusion criteria (n = 100,257; MSI-H n = 12,263, (MSI-H 12.2%). Overall, MSI was associated with improved OS (OR 0.80 (0.71, 0.91). When stratified by stage, there was no difference in OS in stage I and IV, but a protective effect in stage II (OR 0.69 (0.51, 0.92)) and III (0.70 (0.54, 0.91)) CRC. By age, there was benefit in studies where reported median age < 60 (OR 0.66 (0.54,0.82)) but not ≥ 60. There was no difference in OS between MSI-L and MSS. In studies including only mucinous/signet cell/poor differentiation, there was no difference in OS. In both right and left colon, MSI status was associated with improved OS, but not in the rectum. MSI status was associated with improved DFS (HR 0.75 (0.66, 0.84)), but there was no difference in DSS (HR 0.78 (0.60, 1.03)), and this was seen in all stages (I-IV).
Conclusions
MSI is associated with improved overall survival in stage II and III colorectal cancer. Improved prognosis is seen in younger patients, in both right and left sided colon cancer, but evidence is limited in rectal cancer. MSI was associated with less relapse, but was not associated with cancer specific survival at any stage.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
5747 - The routine use of sentinel lymph node biopsy in high risk DCIS lesions is not justified
Presenter: Fanny Preat
Session: Poster Display session 2
Resources:
Abstract
1837 - Oncological impact of re-excision for positive margin status after breast conserving surgery in invasive breast cancer
Presenter: Kenjiro Jimbo
Session: Poster Display session 2
Resources:
Abstract
4347 - Pneumonitis and fibrosis after breast cancer radiation.
Presenter: Jarle Karlsen
Session: Poster Display session 2
Resources:
Abstract
2280 - Prognosis of mastectomy with reconstruction after neoadjuvant chemotherapy: a nationwide study in Korean Breast Cancer Society
Presenter: Sungmin Park
Session: Poster Display session 2
Resources:
Abstract
804 - A negative prognosis of radiotherapy-induced lower lymphocyte to monocyte ratio in patients with breast cancer
Presenter: Chang-ik Yoon
Session: Poster Display session 2
Resources:
Abstract
2701 - Patient data to monitor clinical patterns in early and advanced breast cancer in Europe
Presenter: Francesco Giusti
Session: Poster Display session 2
Resources:
Abstract
1437 - A critical appraisal of quality indicators of breast cancer treatment in Belgium
Presenter: Didier Verhoeven
Session: Poster Display session 2
Resources:
Abstract
1534 - Predictors of adherence among post-menopausal women receiving adjuvant endocrine therapy for breast cancer in Ontario, Canada
Presenter: Phillip Blanchette
Session: Poster Display session 2
Resources:
Abstract
4363 - Evaluation of endocrine therapy and patients preferences in early breast cancer: results of Elena study
Presenter: Emilia Montagna
Session: Poster Display session 2
Resources:
Abstract
2679 - Baseline Quality of life (QoL) and chemotherapy related toxicities (CRT) in localized breast cancer (BC) patients (pts): the French multicentric prospective CANTO cohort study
Presenter: Idlir Licaj
Session: Poster Display session 2
Resources:
Abstract