Search

Simple Summary: Controlled clinical trials are one of the most important sources of medical knowledge, but their results are not always identical to those observed later in normal day-to-day practice. Therefore, real-world studies are needed to investigate those differences. The targeted agents cetuximab and panitumumab, combined with chemotherapy, are an effective treatment for metastatic colon cancer, provided that certain mutations have not occurred in cancer cells (namely activating mutations in KRAS, NRAS or BRAF genes). Recently, it was found that the outcomes of the aforementioned therapy differ depending on which part of the colon the tumour originates from. We conducted a real-world study on 842 patients treated at 16 cancer centres. The study confirmed that metastatic cancer that originated in the right part of the colon has a lower response to cetuximab or panitumumab-based treatment. Anti-EGFR antibodies combined with chemotherapy doublets are a cornerstone of the upfront treatment of colorectal cancer. RAS and BRAF mutations are established negative predictive factors for such therapy. The primary tumour located in the proximal colon has recently emerged as another negative predictive factor. We have conducted a retrospective multicentre study to collect data on real-world population characteristics, practice patterns, and outcomes in patients with metastatic colorectal cancer treated in a first-line setting with either cetuximab or panitumumab in combination with either FOLFOX or FOLFIRI chemotherapy. The presented analysis focuses on the impact of the primary tumour location. 126 of 842 patients analysed (15.0%) had proximal primary. It was associated with a lower BMI at diagnosis, mucinous histology, and peritoneal metastases. It was also associated with inferior treatment outcomes in terms of response ratio: 59.4% vs. 74.22% (odds ratio [OR] 0.51, 95% CI 0.33–0.78, p = 0.010), and median depth of response: −36.7% vs. −50.0% (p = 0.038). There was only a borderline non-significant trend for inferior PFS in patients with proximal tumours. OS data was incomplete. The presented analysis confirms the negative impact of tumour sidedness on the efficacy of an upfront anti-EGFR-chemotherapy combination and provides valuable data on real-world population characteristics. [ABSTRACT FROM AUTHOR]