Outcomes of isolated distant lymph node metastases in colorectal cancer.

84 Background: The optimal management of isolated distant lymph node metastases (IDLNM) in metastatic colorectal cancer (mCRC) is not clearly established. Small case series and prior data from the TRACC (Treatment of Recurrent and Advanced Colorectal Cancer) registry support the use of radical treatment with curative intent (local resection, chemo-radiation or stereotactic radiotherapy), which may lead to better outcomes in mCRC patients with IDLNM. Aims: This study investigates the clinical characteristics and outcomes of mCRC patients with IDLNM treated with systemic therapies plus locoregional therapy with curative intent versus systemic therapies with palliative intent. Methods: Clinical data were collected and reviewed from the TRACC registry, a prospective, comprehensive registry for mCRC from multiple tertiary hospitals across Australia from 01/07/2009 to 30/06/2020. Clinicopathological characteristics, treatment modalities and survival outcomes were analyzed in patients with IDLNM and compared to patients with other organ metastases. Fisher exact test was used for significance tests and Kaplan Meier curves for survival analyses. Results: Of 3408 mCRC patients with a median follow-up of 38.0 months, 93 (2.7%) were found to have IDLNM. Compared to mCRC with other organ metastases, patients with IDLNM were younger (mean age: 62.1 vs 65.6 years, p=0.0200), more likely to have metachronous disease (57.0% vs 38.9%, p=0.0005), be KRAS wild-type (74.6% vs 53.9%, p=0.0012) and BRAF mutant (12.9% vs 6.2%, p=0.0100). There was no overall survival difference between with IDLNM and those with other organ metastases (median OS 27.24 vs 25.92 months, p=0.2300). Twenty-four patients (25.8%) with IDLNM received treatment with curative intent, with a trend towards improved overall survival compared to those with other organ metastases treated with curative intent (73.5 vs 62.7 months, p=0.8200). Amongst mCRC patients with IDLNM, those who received treatment with curative intent had a significantly better overall survival than those treated with palliative intent (73.5months vs 23.2 months, p=0.0070). Conclusions: Our findings suggest that there are differences in the patterns of presentation of IDLNM and other organ metastases. Radical treatment with curative intent options should be considered for mCRC patients with IDLNM where appropriate.