Neuroendocrine tumor epidemiology: contrasting Norway and North America

The National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program has proven to be a significant resource in US neuroendocrine tumor (NET) epidemiology. Norway also holds a robust and detailed cancer registry: the Norwegian Registry of Cancer (NRC).

SEER NET data were compared with corresponding NRC data in the time period 1993 to 2004 to determine whether there are differences in NET epidemiology between Norway and the United States.

The SEER and NRC reported 17,312 and 2030 NETs, respectively. The overall Caucasian SEER NET incidence was 4.44, compared with 3.24 in the NRC. In the SEER white subset, bronchopulmonary NETs were the most common (incidence = 1.42; 32% of all NETs), compared with small intestinal NETs in the NRC (0.81; 26%). A marked increase in SEER NET incidence (37%-40%) was observed in the period 2000 to 2004, compared with 1993 to 1997; an even more pronounced increase (72%) was seen in the NRC. African Americans exhibited a remarkably high overall NET incidence of 6.50; furthermore, among African Americans, rectal NETs were most common (1.65; 27%). Small intestinal NET incidence was approximately 30% higher in men compared with women in all populations. The highest 5-year survival rates were for rectal NETs (74%-88%) in both databases, whereas prostatic NETs had the worst outcome (0%-23%). At diagnosis, NETs were localized in 27% to 46% of patients.

NET incidence in the US Caucasian population and in Norway is similar, but considerably higher ( approximately 50%) among African Americans. NETs have been regarded as indolent tumors; however, the 5-year survival is only approximately 55%.