MORE INTENSIVE COLORECTAL CANCER SCREENING FOR OBESE SMOKERS: THE IMPACT OF LIFE EXPECTANCY

Purpose: To determine whether obese current smokers should be screened more intensively for colorectal cancer (CRC) than the general population given their increased risk for CRC and other cause mortality. Offering more intensive screening of CRC to high risk individuals based on risk factors such as a high body mass index (BMI) and smoking, may be beneficiary. However, the presence of such risk factors may also limit the benefits of intensifying CRC screening, because the same risk factors also affect the risk for other important diseases such as lung cancer and cardiovascular disease.

Method: We used the MISCAN-Colon micro-simulation model to estimate costs and effects of colonoscopy screening in obese current smokers and in the general population for screening schedules with different screening ages, number of screens in a life time and screening intervals. From these model outcomes, we determined the optimal CRC screening schedule from a cost-effectiveness perspective for obese current smokers and for the general population. For the obese smokers we conducted this analysis with two alternative life tables: 1) with the average US life table; 2) risk factor specific life table. This latter table has been derived from National Health and Examination Survey (NHANES) and NHNANES linked- mortality.

Result: When accounting for survival that is specific for obese smokers, obese smokers and the general population should be offered the same amount of screening: 4 screenings, starting at 50 with an interval of 8 years. If obese current smokers would not be at increased risk for other cause mortality, they should be offered considerably more screening: 6 screenings at a 6-year interval starting at 50.

Conclusion: From a cost-effectiveness point of view the impact of risk factors on other cause mortality should not be ignored when individualizing screening decisions based on risk factors, because this will result in overestimation of benefits and therefore in too intensive screening recommendations in e.g. obese current smokers.