# A Case of Spontaneous Regression of Primary Tumor after Adrenalectomy for Primary Lung Cancer with Synchronous Adrenal Metastasis

## TL;DR

A patient with lung cancer and adrenal metastasis showed spontaneous regression of the primary tumor after surgery for the adrenal lesion.

## Contribution

This case report documents a rare instance of spontaneous regression of non-small cell lung cancer following adrenalectomy.

## Key findings

- The primary lung tumor was pathologically absent after surgical removal of the adrenal metastasis.
- Postoperative imaging showed a reduction in the size of the primary tumor.
- The patient remained recurrence-free for 5 months after surgery.

## Abstract

Adrenal metastasis from primary lung cancer is relatively common, occurring in approximately 5%–10% of clinical cases. Long-term survival can be achieved through surgical resection of adrenal metastases in addition to primary lesions. Spontaneous regression of cancer is defined as the partial shrinkage or complete disappearance of cancer following no treatment or treatment considered ineffective against cancer. Spontaneous regression of non-small cell lung cancer (NSCLC) is rare. Here, we describe a case of NSCLC with adrenal metastasis, in which the primary tumor exhibited spontaneous regression and was pathologically absent following surgical treatment of the metastatic lesion.

A 59-year-old male patient was referred to our department with elevated carcinoembryonic antigen levels and an abnormal opacity on chest CT. Contrast-enhanced CT revealed a 2-cm lesion in the right upper lobe of the lung and a 4.5-cm mass in the right adrenal gland. Bronchoscopic biopsy confirmed non-small cell carcinoma (cT1bN0M1b, cStage IVA). As the adrenal metastasis was considered oligometastatic based on 18F-fluorodeoxyglucose PET/CT and head MRI, surgical resection of both the primary lung lesion and the adrenal metastasis was planned. Laparoscopic right adrenalectomy was performed, and histological examination confirmed adrenal metastasis from lung cancer. Postoperatively, no new metastases were detected, and CT demonstrated a reduction in the size of the primary lesion. Robot-assisted right upper lobectomy with lobe-specific nodal dissection was subsequently performed. Pathological examination revealed no malignant findings in the resected right upper lobe. The patient was discharged without complications and remains recurrence-free 5 months after surgery.

This report presents a case of primary lung cancer with adrenal metastasis in which the primary tumor underwent spontaneous regression and was pathologically absent following surgical treatment of the metastasis.