Age, Body Mass Index and Tumor Sidedness in Metastatic Colorectal Cancer Patients as Predictive Factors for Systemic Therapy Outcome

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 .