Abstract 506P
Background
Causing almost 900.000 deaths a year in 2019, colorectal cancer (CRC) represents world´s fourth leading cancer related death. Up to 50 % of patients show metastases at diagnosis or develop them later. Liver represents the most common intra-abdominal and lung the most common extra-abdominal site of metastasis. Metastatic pattern, organ involvement and its association with mutation of molecular markers and location of primary tumor have been linked with survival in recent studies. We aim to describe the prognostic information of metastases distribution in distinct clinical settings.
Methods
2915 Patients diagnosed with colorectal adenocarcinoma treated at three different Austrian oncological centers from 2006 to 2019 were evaluated retrospectively. 1079 patients with metastatic disease were eligible for analysis. Primary endpoint was overall survival (OS) regarding site of metastasis (lung, liver, peritoneum only or others) compared to the rest of the population (ROP).
Results
Overall, lung only metastasis was associated with the most favorable outcome (30.7 months, p < 0.001). In the multimodal treatment group (systemic therapy plus metastasectomy) OS was 39.7 months in lung only (p = 0.008) and 27.1 months in liver only metastases (p = 0.02). Receiving best palliative care, median OS of 14.6 months for lung only (p = 0.002) was associated with best survival rates. In contrast, no significant prognostic correlation was found in patients treated by systemic treatment alone. Lung only metastases were associated with rectum as primary cancer (17.8 %, p < 0.001), metachronous metastasis pattern (23.9 vs. 6.6 %, p = 0.01) and RAS mutation (12 vs. 7 %, p = 0.01), whereas liver only metastasis was associated with synchronous metastasis only (44.6 vs. 28.6 %, p < 0.001). The majority (65.8-81 %) of patients retained their initial metastatic pattern during the course of the disease.
Conclusions
OS in mCRC depends on site of metastasis at diagnosis and the clinical setting, with lung only showing most favorable outcomes compared to other organs. Metastasis pattern at diagnosis remains unchanged in the majority of patients during the course of disease and shows prognostic relevance depending on treatment modality.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Holger Rumpold.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.