Fanconi's anemia and clinical radiosensitivity -: Report on two adult patients with locally advanced solid tumors treated by radiotherapy

Background: Patients with Fanconi's anemia (FA) may exhibit an increased clinical radiosensitivity of various degree, although detailed clinical data are scarce. We report on two cases to underline the possible challenges in the radiotherapy of FA patients. Case Report and Results: Two 24- and 32-year-old male patients with FA were treated by definitive radiotherapy for Locally advanced squamous cell head and neck cancers. In the first patient, long-term tumor control could be achieved after delivery of 67 Gy with a - in part - hyperfractionated split-course treatment regimen and, concurrently, one course of carboplatin followed by salvage neck dissection. Acute toxicity was marked, but no severe treatment-related Late effects occurred. 5 years Later, additional radiotherapy was administered due to a second (squamous cell carcinoma of the anus) and third (squamous cell carcinoma of the head and neck) primary, which the patient succumbed to. By contrast, the second patient experienced fatal acute hematologic toxicity after delivery of only 8 Gy of hyperfractionated radiotherapy. While the diagnosis FA could be based on flow cytometric analysis of a Lymphocyte culture in the second patient, the diagnosis in the first patient had to be confirmed by hypersensitivity to mitomycin of a fibroblast cell Line due to complete somatic Lymphohematopoietic mosaicism. In this patient, phenotype complementation and molecular genetic analysis revealed a pathogenic mutation in the FANCA gene. The first patient has not been considered to have FA until he presented with his second tumor. Conclusion: FA has to be considered in patients presenting at young age with squamous cell carcinoma of the head and neck or anus. The diagnosis FA is of immediate importance for guiding the optimal choice of treatment. Radiotherapy or even radiochemotherapy seems to be feasible and effective in individual cases.