BACKGROUND: Previous reports have described differences in biology and outcome for colorectal cancer based on whether the primary is right or left sided. Further division by right, left, and rectum or even exact primary site has also been explored. Possible differences in response to biological agents have also been reported based on side of primary lesion. METHODS: We explored the South Australian registry for metastatic colorectal cancer to assess if there were any differences in patient characteristics, prognostic markers, and treatment received and outcomes based on whether the primary was right or left sided. We also explored if differences exist based on left colon and rectum and by exact primary site. RESULTS: Two thousand nine hundred seventy-two patients were analyzed. Thirty-five percent had a right-sided primary. The median overall survival for the entire group right versus left was 9.6 versus 20.3 months (P <.001). Multivariate analysis confirmed side of primary as an independent prognostic factor. For the group that had active therapy, defined as chemotherapy (6 metastasis resection), median overall survival was right, 18.2 months; and left, 29.4 months (P <.001). Importantly, we found no suggestion of major differences if left side was divided by left colon and rectum, and trends by individual site still supported a left and right division. CONCLUSIONS: Patients with a right-sided primary have more negative prognostic factors and indeed have inferior outcomes compared with those with a left-sided primary. Our data with further breakdown by exact site still favor a simple left-versus-right division moving forward for metastatic colorectal cancer. Cancer 2015;121:830-5.

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The treatment of patients with metastatic CRC continues to progress with modern medical and surgical developments. Important insights into the current patterns of care and clinical outcomes for metastatic CRC are provided by these data. In addition, this registry provides a feasible and useful database for the evaluation of current treatments established as best evidence in this population.

BACKGROUND. Life expectancy is increasing, and more patients are presenting with cancer at an advanced age (≥80 years). Optimal management for this group of patients has not been well defined. METHODS. The South Australian Clinical Registry for Metastatic Colorectal Cancer (mCRC) collects data on all patients diagnosed since February 2006 in South Australia. The authors examined cancer characteristics, treatments administered, and outcomes for patients aged ≥80 years compared with patients aged <80 years. RESULTS Data from 2314 patients were evaluable, and 29.2% of these patients were aged ≥80 years. The majority had moderately differentiated tumors. Poorly differentiated tumors were reported in fewer patients aged ≥80 years (20.1% vs 26.1%; P < .005). Overall, 28.1% of patients aged ≥80 years received chemotherapy, and 74.2% received single‐agent fluoropyrimidines as first‐line treatment. By comparison, 68.2% of patients aged <80 years received chemotherapy, 74.3% received combination chemotherapy, and 25.7% received single‐agent fluoropyrimidine as first‐line treatment. No treatment was received by 38.2% of patients aged ≥80 years compared with 11.4% of those aged <80 years. Participation in clinical trials was lower in patients aged ≥80 years (2% vs 13%). The median survival was worse for patients aged ≥80 years (8.2 months vs 19.2 months; P < .001), and the median survival of patients who received chemotherapy was 19.0 months for those aged ≥80 years and 22.3 months for those aged <80 years (P = .139). Patients who did not receive treatment had a poor median survival regardless of age (2.6 months for patients aged ≥80 years vs 2.7 months for patients aged <80 years). CONCLUSIONS. Patients aged ≥80 years were less likely to receive intervention for their metastatic colorectal cancer and had poorer survival. The survival of selected patients aged ≥80 years who received chemotherapy was similar to the survival of those aged <80 years despite the receipt of single‐agent therapy. Patients aged ≥80 years with metastatic colorectal cancer are less likely to receive intervention for their disease and have poorer survival. Survival for selected patients aged ≥80 years who receive chemotherapy is similar to the survival of patients aged <80 years despite the receipt of single‐agent therapy. Cancer 2013. © 2012 American Cancer Society.