A case report: Secondary cancers due to oncological treatment modalities

Background: Breast cancer (BC) is one of the most common cancers worldwide. In recent years, numerous non-chemotherapy agents have been developed for BC treatment, including targeted agents, new hormonal therapies, and immunotherapies. However, despite the widespread use of these agents, chemotherapies are still an important cornerstone in BC treatment. Similarly, serious de-escalation studies in radiotherapy use have been conducted in recent years. These two treatment modalities, which we frequently use in the treatment of BC due to their effectiveness, may also have serious side effects. Case Presentation: In this article, I will present a case of multiple myeloma (MM) and myxofibrosarcoma (MFS) that occurred many years later in a patient who completed adjuvant chemotherapy and radiotherapy for BC. MM has developed due to previous chemotherapy and MFS has developed due to previous radiotherapy. Conclusion: We usually treat our cancer patients with chemotherapy or radiotherapy to prolong their lives. In addition to the benefits we provide, may negatively affect the lifetime and quality of life by causing the development of metachronous secondary cancers in some patients. In this case report, I will present the "ironic" side of oncology science and treatment.