BAOJ Medical and Nursing Radiation Induced Squamous Cell Carcinoma of the Tongue after Hodgkin Disease treatment: Case Report and Literature Revue

Radiation-induced tumors of the tongue, secondary to radiation therapy for Hodgkin's disease are rare. Some authors reported a recent increase in the incidence of this rare complication, especially because of the improved prognosis and survival of patients after radiotherapy. Precise pathogenic mechanisms of radiationinduced carcinomas are poorly understood. However diagnosis criteria are well established. Treatment options must be discussed and adapted to the patient profile. Surgery in irradiated tissue is challenging, with limited treatment options with chemotherapy and radiotherapy.


Introduction
Radiation therapy is a major weapon in the treatment of Hodgkin disease especially when it reaches Head and neck location [1]. Hodgkin lymphoma (HL) represents approximately 4% of all lymphomas of the head and neck, and most of these neoplasms involve lymph nodes [1]. Extranodal involvement by HL, including Waldeiyer ring, is rare [1,2].The occurrence of radiation-induced carcinomas in the tongue is a very rare complication of radiotherapy [3]. With improved oncologic outcomes, post-irradiation carcinomas are increasingly seen in long-term survivors with an estimated risk of up to 0.3% [4]. The spectrum of radiation induced tumours include soft tissue sarcoma, osteosarcoma, squamous cell carcinoma (SCC), leukaemia, and neuroendocrine carcinomas, which may developed in the head and neck, oesophagus, lung, or stomach [5].We report herein case of squamous cell carcinoma of the tongue occurring thirteen years after completion of radiotherapy for primary Hodgkin lymphoma of the ring of Waldeiyer.

Case Presentation
A 65-year-old Arabic male presented with ulceration and swelling of the right side edge of the tongue base. A primary Hodgkin's disease of Waldeiyer's ring treated 14 years before presentation marks his medical history. It was stage II Hodgkin lymphoma that was managed successfully by 4 months of chemotherapy according to the ABVD regimen (Doxorubicin 25mg/m 2 Bleomycin 10 mg/m 2 Vinblastine 6 mg/m 2 Dacarbazine 375 mg/m 2 day 1 and day 15), followed by radiotherapy using gamma photons of 1, 25 Mv energy, delivered by a Cobalt 60 machine, at a total dose of 36 Gy, 2 Gy by fraction, in four weeks, with two opposed fields including the base of the tongue. Magnetic Resonance Imaging of the oral cavity showed a mass of 1.5 cm diameter on the right edge of the tongue base with extension to adjacent structures ( Figure 1 staged T1N0M0. After amultidisciplinarystaffa surgical resection was performed with safe margins without lymphadenectomyas long as it was a small and well-lateralized tumor and considering the difficulty of this procedure in an irradiated tissue. After a follow-up of 18 months the patient is free of recurrence at local or distant site, without significant morbidity.

Epidemiology and Pathogenesis
The carcinogenic effects of ionizing radiation have been described in several publications. The exact mechanisms in tumor genesis remain poorly known [6]. Secondary tumors occurring in irradiated tissues are rare [6]. In published series, their frequency varies between 0.15 and 0.75% [5,6]. All tissue types can be processed by irradiation, although the radio sensitivity varies with the type of irradiated organ [7]. In the upper aero digestive tract, oral cavity and oropharynx are the most affected, with a high incidence of carcinoma of the base of the tongue [5]. There is no histological evidence to confirm the origin of the radiation-induced tumors [7].Ionizing radiation causes damage to healthy tissue included in the radiation field. Some authors identified the specific stem cells in the lingual epithelium that maintain keratinized epithelial cells long-term and that can regenerate them on injury [8]. On irradiation-induced injury, the stem cells rapidly start proliferating and can regenerate injured epithelial tissue [8].
Several risk factors appear to influence the occurrence of these secondary tumors. In particular the radiation dose which is a variable parameter depending on the irradiated organs, the type of chemotherapy that appears to potentiate the effect of radiation therapy, young age (children are especially sensitive to radiation oncogenesis), and a genetic predisposition to multiple tumors [9]. An inverse relationship between the radiation dose and solid cancers latency period is about to be established for secondary cancers of the tongue [9].

Diagnosis
The diagnosis is established by criteria established by Cahan et al. In 1948 [10] and revised by Murray et al. in 1999 [11]. A history of radiotherapy for cancer, an asymptomatic latency period of several years, the occurrence of tumor in the irradiation field, and histological evidence of the secondary tumor [12]. Complete remission of the primary tumor is also necessary to establish this diagnosis [9]. All of these items are found in our patient.

Management
Therapeutic approaches are often limited. Surgery is the only curative method, when it is possible. The difficulty of surgery in irradiated areas is known, but doable if the tumor is diagnosed at an early stage and also if the surgeon is experienced. In advanced stages, chemotherapy may have a place, although the tumor responses in irradiated areas remain poor [13].In these cases the prognosis is also poor, and the median survival doesn't exceed a few months.

Conclusion
Herein we presented the case of a patient presented with radiationinduced carcinoma of the tongue. This event is very uncommon making almost impossible to perform prospective clinical trials specifically designed to compare different treatment approaches. Surgery is the mainstay of treatment. A close follow up of irradiated patients is the only way for an early diagnosis of this serious complication.

Consent
"Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal."