Sequential approach in the treatment of small cell lung carcinoma

Introduction: A 60-year-old woman was diagnosed in August 2023 with extensive-stage small cell lung cancer, after presenting with severe, asymptomatic hyponatremia secondary to paraneoplastic syndrome of inappropriate antidiuretic hormone (SIADH). Imaging revealed mediastinal lymphadenopathy and metastatic spread to the liver and bones. Case report: She started first-line treatment with carboplatin, etoposide, and atezolizumab (IMpower133 regimen), achieving a partial response with resolution of hepatic and bone lesions. This was followed by consolidative mediastinal radiotherapy and prophylactic cranial irradiation. She continued on atezolizumab maintenance until May 2024, when disease progression was noted in the liver, adrenal gland, and lymph nodes. A rechallenge with carboplatin-etoposide was initiated but was unsuccessful, with further hepatic and bone progression after four cycles. The patient was not eligible for clinical trial enrollment due to a history of prior breast cancer. In September 2024, third-line weekly paclitaxel was started but showed no response. Following further progression, she began irinotecan (180 mg/m² every two weeks) in December 2024, which she continues at present, pending reassessment. She also received palliative radiotherapy to the iliac crest for symptomatic bone disease. Conclusion: Recurrent episodes of SIADH have persisted throughout treatment, requiring close monitoring and supportive care.