Background: Few studies report the incidence of metastatic patterns in colorectal cancer. Furthermore, little is known about dynamic aspects of these metastases during the course of disease.
Methods: This retrospective cohort study involved 385 patients who received anti-tumor treatment at our institution (Department of Medical Oncology, University Hospital Grosshadern, Ludwig-Maximilians-University Munich, Germany) for metastatic colorectal adenocarcinoma between 2007 and 2014. We reviewed all available imaging results of these patients to document the presence and detailed localization of metastases.
Results: Most of the evaluated patients were initially diagnosed with metastases in the liver (70%), followed by the lungs (24%), distant lymph nodes (16%), and peritoneum (15%), besides rare anatomical sites (<5%). Colon and rectal cancer as well as synchronous and metachronous metastases differed with regard to the pattern of individual metastatic sites. The median time to first progressive disease (PD) with new metastases was 12.6 months. The time intervals between first and second as well as second and third PD with new metastases were comparable with 10.5 and 10.8 months, respectively. At initial diagnosis, the mean number of metastatic sites was 1.4 and increased to 2.6 at the third PD with new metastases. For patients with initially one metastatic site, the mean number increased to 2.2.
Conclusion: The present analysis provides detailed information on the pattern and evolution of colorectal cancer metastases over time. Thus, it may establish the basis for prospective future research in this field.
Keywords: Development of metastases; Incidence; Localization; Metachronous metastases; Metastatic colorectal cancer; Synchronous metastases.