Background: Differences between the features of primary cancer and matched metastatic cancer have recently drawn attention in research. This study investigated the concordance in microsatellite instability (MSI) and mismatch repair (MMR) status between primary and corresponding metastatic colorectal cancer (CRC). Methods: Consecutive patients with metastatic CRC who had both primary and metastatic tumors diagnosed at our institution in January 2008 through December 2016 were identified. Immunohistochemistry was used to test the MMR status of both primary and matched metastatic tumors, and PCR analysis was performed to test MSI in patients with deficient MMR (dMMR) status. Results: A total of 369 patients were included. Of the 46 patients with MSI-high primary tumors, 37 (80.4%) also had MSI-high metastatic tumors, whereas 9 (19.6%) had microsatellite stable (MSS) metastatic tumors. A high concordance was found in patients with liver, lung, or distant lymph node metastases. Interestingly, the discrepancy was more likely to be limited to peritoneal (5/20) or ovarian (4/4) metastasis (chi-square test, P<.001). These organ-specific features were also found in the pooled analysis. Along with the change of MSI-high in primary cancer to MSS in metastatic cancer, lymphocyte infiltration decreased significantly (P=.008). However, the change did not influence survival; the median overall survival of MSI-high and MSS metastatic tumors was 21.3 and 21.6 months, respectively (P=.774). The discrepancy rate was 1.6% for patients with proficient MMR primary tumors. Conclusions: For patients with dMMR primary tumors, the concordance of MSI and MMR status in primary CRC and corresponding metastatic cancer is potentially organ-specific. High concordance is found in liver, lung, and distant lymph node metastases, whereas discrepancy is more likely to occur in peritoneal or ovarian metastasis. Rebiopsy to evaluate MSI-high/dMMR status might be needed during the course of anti–PD-1 therapy in cases of peritoneal or ovarian metastasis.
Wen-Zhuo He, Wan-Ming Hu, Fang Wang, Yu-Ming Rong, Lin Yang, Qian-Kun Xie, Yuan-Zhong Yang, Chang Jiang, Hui-Juan Qiu, Jia-Bin Lu, Bei Zhang, Pei-Rong Ding, Xiao-Jun Xia, Jian-Yong Shao, and Liang-Ping Xia
Zi-Xian Wang, Hao-Xiang Wu, Ming-Ming He, Ying-Nan Wang, Hui-Yan Luo, Pei-Rong Ding, Dan Xie, Gong Chen, Yu-Hong Li, Feng Wang, and Rui-Hua Xu
Background: Previous meta-analyses have suggested primary tumor location as a predictive factor for efficacy of anti–epidermal growth factor receptor (EGFR) therapies in patients with metastatic colorectal cancer (mCRC). However, the recent phase III TAILOR trial addressing this issue was not included in those analyses. This meta-analysis incorporated data from the TAILOR trial to evaluate the efficacy of chemotherapy plus anti-EGFR agents (cetuximab [Cet] or panitumumab [Pani]) versus chemotherapy alone for RAS wild-type (wt) right- and left-sided mCRC. Patients and Methods: A PubMed-based literature search was conducted to identify randomized controlled trials (RCTs) studying the additional efficacy of Cet/Pani in combination with chemotherapy versus chemotherapy alone in RAS wt left- and right-sided mCRC. Study-level pooled analyses of hazard ratios (HRs) for overall survival (OS) and progression-free survival (PFS) and odds ratios (ORs) for objective response rate (ORR) were performed. Results: Three first-line RCTs (CRYSTAL, PRIME, and TAILOR) and one second-line RCT (20050181) were included. Significant OS benefits from Cet/Pani were observed in the left-sided (HR, 0.76; 95% CI, 0.66–0.86) but not right-sided subgroups (HR, 0.99; 95% CI, 0.78–1.27). However, the addition of Cet/Pani to chemotherapy significantly improved PFS and ORR in both the left-sided (HR, 0.70; 95% CI, 0.57–0.86, and OR, 3.28; 95% CI, 1.95–5.51, respectively) and right-sided subgroups (HR, 0.76; 95% CI, 0.59–0.99, and OR, 1.78; 95% CI, 1.08–2.93, respectively). Conclusions: The addition of Cet/Pani to chemotherapy significantly benefits PFS and ORR in patients with RAS wt right-sided mCRC, indicating that anti-EGFR therapies may remain an option for selected patients.