Colorectal cancer (CRC) represents a major public health concern as it is the third most frequently diagnosed cancer and the fourth cause of cancer-related mortality worldwide . The ﬁve-year survival rate is around 64.9% for all stages, while in metastatic cases, it only reaches 13.1% .~Approximately 26% of CRCs are diagnosed at stage IV among patients aged younger than 50 years, compared with 23% in those aged 50 to 64 years and 19% among those aged 65 years and older. Overall survival (OS) among patients younger than 50 years (68%) is similar to that in those 50 to 64 years (69%) because of a later stage at diagnosis.~Obesity is associated with an increased incidence of CRC . In recent studies body mass index (BMI) was prognostic for overall survival and progression free survival. That is risk of progression and/or death was greatest for low BMI; risk decreased as BMI increased. BMI was not predictive of treatment effect . Cachexia and associated poor performance status have previously been identiﬁed as negative prognostic factors in patients with CRC.~Tumor sidedness is an independent prognostic factor in patients with early and metastatic CRC as left-sided primaries have improved outcomes. sidedness also represents a powerful predictor of benefit from anti epidermal growth factor receptor[EGFR] inhibitors therapies in patients with RAS wild-type metastatic CRC (mCRC) .~The mainstay of treatment of mCRC includes cytotoxic chemotherapy with the addition of a molecularly targeted agent . The cytotoxic regimens that are usually used include a combination of oxaliplatin or irinotecan with a fluoropyrimidine, in addition to targeted agents such as [EGFR] inhibitors for patients with RAS wild-type mCRC or vascular endothelial growth factor inhibitors .
To determine progression free survival (PFS) and overall survival (OS) in metastatic colorectal cancer in relation to age, BMI and tumor sidedness, describing their predictive influence on systemic therapy outcome.