Substance use is a barrier to people receiving all appropriate preventive health services such as cancer screenings or flu shots, U.S. researchers suggest. Dr. Karen Lasser, a primary care physician at Boston Medical Center and an associate professor of medicine at Boston University School of Medicine who was the lead author of a study on the issue, identified unhealthy substance use as a risk factor for not receiving all appropriate preventive health services. "Persons with unhealthy substance use  for alcohol, from risky use to dependence; for drugs, from any illicit drug use, including prescription drugs to dependence represent a high-risk 'pocket' of people who under-utilize preventive care," Lasser said in a statement. The researchers analyzed data from 4,804 women eligible for mammograms, 4,414 eligible for Pap smears, 7,008 were eligible for colorectal cancer screenings and 7,017 people eligible for influenza vaccination. All patients were screened for unhealthy substance use. The findings, published in BMJ Open, found among the nearly 10,000 patients eligible for one or more of the preventive services, 10 percent screened positive for unhealthy substance use. For example, 83.3 percent of women who had no substance use had mammograms versus 75.4 percent of women with unhealthy substance use.