The Obama administration is kicking off a nationwide ad campaign urging seniors to take advantage of free preventive services such as cancer screenings made possible in Medicare by the new healthcare law. The campaign -- featuring television and radio ads in English and Spanish -- comes on the heels of a new report showing that less than one in six Medicare beneficiaries have taken advantage of the new benefit since President Obama signed the law last year. The new law includes numerous provisions to encourage more preventive care, which many health experts believe is critical to controlling long-term health costs. Among the services available to Medicare beneficiaries without any cost-sharing are mammograms, bone density tests and prostate cancer screenings. Seniors are also able to see their doctor for an annual wellness visit without being billed a copay.