The varied clonal trajectory of liver and lung metastases of colorectal cancer

Abstract

Background: The liver and lungs are the most common sites of colorectal cancer (CRC) metastases. Their involvement can take five different clinical scenarios: lung metastases only, liver metastases only, lung metastases before liver metastases, liver metastases before lung metastases and simultaneous lung and liver metastases. Using clinical and morphological data we studied the clonal trajectory of these scenarios. Materials and methods: A total of 465 (CRC) patients with 7952 liver and 6406 lung metastases were evaluated. Metastases clinical route was deciphered from metastases number, timing, and linear/parallel ratio (LPR)- a computerized parameter used for deducing clonal trajectories. LPR of +1 suggest pure linear dissemination and −1 pure parallel. Results: Lung-only metastases: high percentage of metachronous disease with a long lead time and a low LPR suggest parallel dissemination. Liver-only metastases: Rare metachronous disease with a short lead time, and a high LPR suggest linear spread. Lung-before-liver metastases: rare solitary metastasis, a median gap of 21 months between the organs, high lung and low liver LPRs suggest linear progression to the lungs and parallel dissemination to the liver. Liver-before-lung metastases: low liver and high lung LPRs and a median gap of 16.5 months between the organs suggest parallel dissemination to the liver and linear spread from the liver to the lungs. Simultaneous liver and lung metastases: rare solitary metastasis and similar and high LPRs suggest simultaneous linear progression to both organs. Conclusions: CRC metastases have different dissemination trajectories in different clinical scenarios. This information can potentially impact on clinical management.

Keywords

• Liver metastases
• Lung metastases
• Clonal origin