Spontaneous regression of FDG/PET positive lung adenocarcinoma in an elderly man.

Spontaneous cancer regression, either partial or complete, is a rare phenomenon, particularly in patients with lung cancer. The present paper is the case report of an elderly lung cancer patient aged 80 who exhibited spontaneous regression of the primary lesion, without receiving any treatment. Spontaneous regression commenced two years after obtaining pathological specimens by transbronchial biopsy from the pulmonary lesion. It is interesting that the tumor lesion had a strong uptake (standardized uptake value max: 26.3) in ¹⁸fluorodeoxyglucose positron-emission tomography before biopsy and that the regression occurred after a long interval after the biopsy, and that the regression developed in an elderly man. It is unknown why spontaneous regression was observed in this case and what kind of mechanism was involved in the phenomenon. Even in the elderly, as observed in our case, spontaneous regression can occur. The patient should be closely followed up to monitor the clinical course of such an unusual phenomenon.