Importance: With the advent of effective modern chemotherapeutic and biologic agents, primary tumor resection for patients with stage IV colorectal cancer (CRC) may not be routinely necessary.
Objective: To evaluate the secular patterns of primary tumor resection use in stage IV CRC in the United States.
Design, setting, and participants: A retrospective cohort study using data from the National Cancer Institute's Surveillance, Epidemiology, and End Results CRC registry. Demographic and clinical factors were compared for 64,157 patients diagnosed with stage IV colon or rectal cancer from January 1, 1988, through December 31, 2010, who had undergone primary tumor resection and those who had not. Rates of primary tumor resection and median relative survival were calculated for each year. Joinpoint regression analysis was used to determine when a significant change in trend in the primary tumor resection rate had occurred. Logistic regression analysis was used to assess factors associated with primary tumor resection.
Main outcomes and measures: Difference in primary tumor resection rates over time.
Results: Of the 64,157 patients with stage IV CRC, 43,273 (67.4%) had undergone primary tumor resection. The annual rate of primary tumor resection decreased from 74.5% in 1988 to 57.4% in 2010 (P<.001), and a significant annual percentage change occurred between 1998-2001 and 2001-2010 (-0.41% vs -2.39%; P<.001). Factors associated with primary tumor resection were age younger than 50 years, female sex, being married, higher tumor grade, and presence of colon tumors. Median relative survival rate improved from 8.6% in 1988 to 17.8% in 2009 (P<.001); the annual percentage change was 2.18% in 1988-2001 and 5.43% in 1996-2009 (P<.001).
Conclusions and relevance: The majority of patients with stage IV CRC had undergone primary tumor resection but, beginning in 2001, a trend toward fewer primary tumor resections was seen. Despite the decreasing primary tumor resection rate, patient survival rates improved. However, primary tumor resection may still be overused, and current treatment practices lag behind evidence-based treatment guidelines.