In the treatment of early-stage tongue cancer, brachytherapy has been considered a good indication of the point of preserving shape and function. In recent years, the number of long-term survivors after radiotherapy has increased, and secondary cancers in the irradiated field have begun to attract attention. Herein, we report here on two cases of radiation-induced cancer of the tongue developing after brachytherapy.
Case I: A 59-year-old woman who had undergone brachytherapy for right tongue cancer 20 years earlier, and had passed without recurrence in the intervening period presented with. She felt a burning sensation on her tongue, and was diagnosed by biopsy as having squamous cell carcinoma.
Case II: A 48-year-old woman had undergone brachytherapy for left tongue cancer 22 years earlier. She underwent neck dissection and postoperative radiotherapy for delayed emergence of regional recurrence 5 months after the brachytherapy. She had had no recurrence in the intervening period since then until her present visit when a physical examination revealed induration at the left tongue margin, and she was diagnosed by biopsy as having squamous cell carcinoma.
It is extremely difficult to distinguish between late recurrence and radiation-induced cancer in cases presenting with secondary cancers after radiotherapy. In these two cases described above, the secondary cancers developed within the irradiation field of the radiotherapy administered for primary cancer, and there was no evidence of cancer in other tissues between primary cancer and the current secondary cancer. Therefore, we considered that it might be more appropriate to diagnose it as radiation-induced cancer rather than as late recurrence or field carcinogenesis. Although the local control rate of brachytherapy for early-stage tongue cancer is comparable to that following surgical treatment, long-term follow-up is necessary because of the possibility of secondary cancer developing in the irradiation field, as in the cases reported herein.
