Pain is a highly prevalent, complex, debilitating symptom for cancer patients. Pain management is an essential component of cancer care. Adequate pain management can significantly improve health-related quality of life for patients. However, there are substantial disparities in access to adequate pain management especially among underserved and underprivileged populations. Meanwhile, the opioid epidemic is a serious public health crisis, and there have been many policy efforts to curb opioid misuse. One important policy change is the rescheduling of hydrocodone from Schedule III to Schedule II in 2014 by the United States Drug Enforcement Administration. However, prior literature has shown mixed evidence on the actual overall impacts of this policy, as patients could either receive non-opioid pharmacotherapy (e.g. nonsteroidal anti-inflammatory drugs, antidepressants, muscle relaxant, anticonvulsants) or stronger opioids as replacements for hydrocodone. Additionally, few studies examined the impact on pain management strategies and outcomes among cancer patients, who may face potentially higher barriers to adequate pain management. Further, how the policy change affects underserved and underprivileged groups is largely unknown. We propose to use national cancer registry data linked with Medicare claims (SEERMedicare) to comprehensively examine the effects of the rescheduling of hydrocodone on older lung cancer patients with a special focus on underserved and underprivileged groups. The proposed study is well in line with the R21 RFA calling for research that utilizes Centers for Medicare and Medicaid Services (CMS) administrative data to study pain management strategies and outcomes, including underserved and underprivileged groups. We will address the following aims: Aim 1. Examine the change in opioid and nonopioid pharmacotherapy use among older lung cancer patients before and after the rescheduling of hydrocodone from Schedule III to Schedule II. Aim 2. Compare the adequacy of pain management in terms of prevalence of service use consistent with inadequate pain management among older lung cancer patients before and after the rescheduling. Aim 3. Examine potential disparities in the use of medications for pain management and service use consistent with inadequate pain management among older lung cancer patients dually eligible for both Medicare and Medicaid and among patients in racial/ethnic minority groups. The proposed study will provide important insights to guide policy efforts and clinical practice aimed at improving pain management and reducing disparities in cancer patients.