The Efficacy of Immunotherapy in Long-Term Survival in Non-Small Cell Lung Cancer (NSCLC) Associated with the Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)

Abstract

Introduction: The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause of hyponatremia in cancer patients, occurring most frequently in patients with small cell lung cancer. However, this syndrome occurs extremely rarely in patients with non-small cell lung cancer. The results of the clinical trials have revealed that immuno-oncological therapies are effective for long periods of time, providing hope for long survival and with a good quality of life.

Case presentation: We present the case of a female patient who was 62 years old at the time of diagnosis in 2016 who underwent surgery for a right pulmonary tumor (pulmonary adenocarcinoma) and subsequently underwent adjuvant chemotherapy. The patient had a left inoperable mediastinohilar relapse in 2018, which was treated using polychemotherapy The patient also had an occurrence of progressive metastasis and a syndrome of inappropriate antidiuretic hormone secretion (SIADH) in 2019 for which immunotherapy was initiated. The patient has continued with immunotherapy until the time this study began to be written (April 2023), the results being the remission of hyponatremia, the clinical benefits and long-term survival.

Discussion: The main therapeutic option for SIADH in cancer patients is the treatment of the underlying disease, and its correction depends almost exclusively on a good response to oncological therapy. The initiation of immunotherapy at the time of severe hyponatremia occurrence led to its remission as well as the remission of the other two episodes of hyponatremia, which the patient presented throughout the evolution of the disease, demonstrating an obvious causal relationship between SIADH and the favorable response to immunotherapy.

Conclusions: Each patient must be approached individually, taking into account the various particular aspects. Immunotherapy proves to be the innovative treatment that contributes to increasing the survival of patients with metastatic non-small cell lung cancer and to increasing their quality of life.

Keywords: immunotherapy; long-term survival; non-small cell lung cancer; syndrome of inappropriate antidiuretic hormone secretion.

Figure 1

Chest CT, January 2019: some of the previous adenopathy’s were dimensionally reduced (in the aorto-pulmonary window, from 18 mm short axis to 14 mm short axis) but others had increased (left inferior bronchus, from 12/16 mm to 22/27 mm), with a newly appeared adenopathy in the prevascular space of 14/17 mm.

Figure 2

Chest CT, August 2021: bilateral pulmonary nodules to be monitored and mediastinal adenopathy.

Figure 3

Abdominal CT, August 2021: a hepatic lesion of the V segment.

Figure 4

Abdominal CT, August 2021: bilateral adrenal nodules suspicious for secondary determinations.

Figure 5

Chest CT, March 2022: dimensional progression and pulmonary secondary determinations.

Figure 6

Abdominal CT, March 2022: liver metastases.

Figure 7

Abdominal CT, March 2022: adrenal secondary determinations, the occurrence of abdominal adenopathy (retroperitoneal and mesenteric) and newly occurring peritoneal carcinomatosis.

Figure 8

Brain CT, February 2023: appearance of a nodule in the right cerebellar parenchyma suspicious for a secondary lesion.

Figure 9

Chest CT, February 2023: numerical and dimensional progression of secondary lung lesions.

Figure 10

Abdominal CT, February 2023: progression of secondary liver lesions.

Figure 11

Abdominal CT, February 2023: disappearance of secondary splenic lesions and peritoneal carcinomatosis lesions, dimensional regression of the secondary peritoneal lesion in the left hypochondrium.