A study published in 2007 suggested that the act of performing a Pap smear produces an inflammatory cytokine response, which may initiate immunologic clearance of HPV, therefore reducing the risk of cervical cancer. Women that had even a single Pap smear in their history had a lower incidence of cancer. "A statistically significant decline in the HPV positivity rate correlated with the lifetime number of Pap smears received."[29]