Metachronous esophageal squamous cell carcinoma suspected as a second malignancy arising at the site of post-radiotherapy for esophageal adenocarcinoma.

Esophageal cancer is a prevalent malignancy with high mortality rates worldwide, often warranting aggressive treatment modalities, such as chemoradiotherapy or radiotherapy. Although these treatments are effective, they can predispose patients to secondary malignancies, posing challenges for long-term management. Here, we present a case report detailing the development and management of secondary malignancies following radiotherapy for esophageal adenocarcinoma. A 78-year-old man presented with symptoms resulting in the diagnosis of esophageal adenocarcinoma with multiple lung metastases. Complete remission was achieved through chemotherapy with docetaxel, cisplatin, and S-1, followed by intensity-modulated radiation therapy. Seven years later, surveillance revealed a squamous cell carcinoma at the post-radiotherapy site; however, endoscopic resection was deemed challenging owing to fibrotic changes. Photodynamic therapy (PDT) with talaporfin sodium was administered, resulting in complete response without complications. This case highlights the potential for secondary malignancies following radiotherapy for esophageal adenocarcinoma and the efficacy of PDT as salvage therapy. This report underscores the importance of vigilant post-treatment surveillance and the need for tailored management strategies. Future research should focus on understanding the mechanisms of radiation-induced carcinogenesis, evaluating the long-term outcomes of PDT, and developing preventive strategies to enhance patient care and outcomes.