Case:
The patient was a Japanese man with no known abnormalities at birth. By the age of 5 years, he was observed to be prone to sunburn, but the cause was unknown at that time. At the age of 30 years, a skin lesion on his face was resected and diagnosed as keratoacanthoma. He was subsequently diagnosed as having XP based on his clinical symptoms but had lived for a further 30 years without avoiding UV exposure. He had no medical history other than XP, no known allergies, and had never smoked.
After XP was diagnosed, numerous skin lesions were resected, all of which were diagnosed as squamous cell carcinoma (SCC). Skin grafting or local flap reconstruction was occasionally required after these resections. Cryotherapy was administered periodically for a basal cell carcinoma on the left ala of the nose that relapsed repeatedly [Figure 1]. At the age of 36 years, the lesion on the left ala of the nose was treated by proton beam therapy, and at 56 years, a metastasis to the left orbit was treated by radiotherapy with a total of 54 Gy.
At the age of 60 years, computed tomography (CT) and positron emission tomography scan (PET) revealed multiple metastases to the mediastinum, pleura, liver, bones, and tongue base. Irinotecan, which is approved in Japan for skin cancer, was selected as first-line chemotherapy. At the time of a total of four doses of irinotecan (100mg/m2) at weekly intervals, CT shown that all lesions were in an increasing trend, and we decided that irinotecan was ineffective. After discussion in a multidisciplinary team meeting, it was decided that he should be treated using the therapeutic strategy for recurrent or metastatic head and neck squamous cell carcinoma (RM-HNSCC). A previous report suggested that platinum agents such as cisplatin were highly toxic in patients with XP [10]. Therefore, 5-fluorouracil, carboplatin, and cetuximab were administered as second-line chemotherapy with a considerable reduction of the dose of carboplatin. However, progression of bone metastases was observed after one course. Therefore, we have decided to started n nivolumab, the anti-PD-1 monoclonal antibody, as third-line chemotherapy.