Primary Tumor Resection and Multimodality Treatment for Patients with Metastatic Colon Cancer.

Background: Although controversial, recent data suggest a benefit associated with primary tumor resection (PTR) in metastatic colon cancer (mCC) patients. However, utilization of the various management strategies over time relative to surgery, in particular multimodality treatment (MMT), as well as the impact of age on treatment remains unclear.

Study Design: Historical cohort study of mCC patients in the National Cancer Data Base (1998-2009). Temporal trends in treatment utilization (chemotherapy, PTR alone, MMT) were evaluated. Using a landmark approach, the association between treatment, age, and risk of death was evaluated with multivariable Cox regression, including interaction.

Results: Among 103,100 mCC patients, PTR decreased 50.1 % during the study period, whereas MMT and chemotherapy increased 27.4 and 104.8 %, respectively (trend test, p < 0.001). Patients aged ≥75 years were the only group for whom PTR alone was the most common intervention over time and performed more commonly (33.8 %) than MMT (23.8 %) in the most recent study year. Relative to MMT, risk of death was higher for all other management strategies. The sequence of PTR and chemotherapy (reference-surgery first) did not affect risk of death (chemotherapy first-1.05 [0.95-1.15]), as long resection was a part of MMT (PTR alone-1.16 [1.08-1.23]). Patient age did not impact the relative benefit associated with competing management strategies.

Conclusions: Although the benefit associated with PTR in mCC patients is a function of MMT, PTR alone remains a common management strategy among older patients. Given the aging U.S. population, exploring provider biases and patient preferences may be necessary to optimize management of mCC patients.