This study looks at how radiotherapy, a treatment using high-energy rays to kill cancer cells, affects certain blood cells in patients with cancer. These cells include myeloid-derived suppressor cells (MDSCs), T cells, and extramedullary erythroid precursor cells. The study will help understand how the numbers of these cells change before and after treatment and how these changes relate to how well the treatment works.

• **Eligibility**: Adults over 18 with specific cancers, such as breast or lung cancer, who need radiotherapy.
• **Commitment**: Must be willing and able to take blood tests.
• **Exclusion**: People with mental illness, autoimmune diseases, or other serious health issues can't join.

This study aims to provide information to develop better cancer treatment plans. Participants will need to sign a consent form to join. Understanding these changes could lead to new ways to improve cancer treatment in the future.