Trends in Diagnosis and Treatment of Metastatic Cancer in the United States

Metastatic cancer has historically been considered fatal; however, there is a paucity of evidence characterizing the epidemiology of incidence, treatment, and outcomes in these patients.

Incidence rates, annual percent change (APC), descriptive epidemiological statistics, and odds ratios for survival were calculated using registry data from the Surveillance, Epidemiology, and End Results (SEER) and the National Cancer Database (NCDB), 1998 to 2015.

There were a total of 1,055,860 patients with metastatic cancer. The most frequent primary cancers were lung (42.6%), colorectal (9.5%), and ovarian (5.5%). Metastatic lung and colorectal cancer incidence decreased, APC: -1.57 (P<0.001) and APC: -1.48 (P<0.001), respectively; metastatic pancreatic cancer incidence increased, APC: 0.62 (P=0.001). The use of local therapies decreased for almost all sites, and the use of systemic therapies increased across multiple sites: single-agent chemotherapy in kidney (2.54% increase/year), female breast (1.14% increase/year), and prostate cancer (1.08% increase/year); multiagent chemotherapy, most notably in pancreas (2.23% increase/year), uterus (1.81% increase/year), and colorectal cancer (1.54% increase/year). Increased utilization of immunotherapy was observed across the majority of sites, most notably in melanoma (2.14% increase/year). Patients diagnosed from 2006 to 2010 had 17.4% higher odds of surviving at least 60 months compared with 1998 to 2002.

In this study, metastatic disease has been shown to have unique epidemiological patterns, and survival has improved. Continued research on metastatic disease is important in understanding and addressing the distinct health concerns of this population.