The effects of primary tumour location on patients with all stages of colorectal cancer

Purpose: the aim of this study was to examine the effects of tumor localization in early and advanced stage colon cancer patients. materials and methods: this retrospective study enrolled 249 primary colorectal cancer (crc) patients at medical oncology department of adnan menderes university between 2013-2017. results: in early stage, left sided tumors were significantly more common in males (p=0.027). in right sided tumours recurrence developed earlier in female patients (p=0.043) and female sex young age were unfavorable prognostic factors for the relapse time. positive and unknown ras mutation status were found to be unfavorable prognostic factors for both side. in metastatic stage, patients with ras mutant left sided tumors lived longer than ras negative patients (49.0 vs 25.5 months respectively, p<0.001). in right sided tumors anti-egfr agents provided longer os and pfs than anti vegf agents;11 and 1.8 months respectively. in left sided tumors, there was no difference, only pfs was longer with anti-vegfr agents (13 months vs 6.3 months). in ras positive patients, os and pfs were longer with anti-vegfr treatment in the left side tumors (os 49.0 months vs 30.6 months pfs, 13.2 months vs 7.2 months, p=0.784). conclusions: in our study, the efficacy results of the treatment which was given according to the primary tumor location were not compatible with the literature. primer tumor location is a transition period for understanding of molecular subtypes for the colon cancer. the on-going studies of genomic differences between right and left sided tumors will be able to better clarify the biologic explanation of the observed difference.