This study tests if adding the chemotherapy drug **lomustine** to the usual treatment of **temozolomide** and **radiation therapy** helps treat a type of brain cancer called **glioblastoma**, which has **MGMT methylation** (a specific gene change). Chemotherapy drugs like lomustine and temozolomide aim to stop tumor growth by killing cells or stopping them from spreading. Radiation therapy uses high-energy rays to kill and shrink tumors. Participants will be randomly placed in one of two groups: one receiving just temozolomide and radiation, and the other receiving lomustine as well.

• **Study Length:** Treatment lasts about 6 cycles, with each cycle being 28 or 42 days.
• **Follow-up Visits:** After completing treatment, follow-up visits occur every few months.
• **Potential Risks:** As with any cancer treatment, there may be side effects, which will be monitored.

Participants need to be 18-70 years old with specific health criteria. Tumor tissue and specific tests are required for entry. Pregnant individuals or those with certain health conditions may not be eligible. Always discuss with your doctor to understand if this study is right for you.