RADIATION-INDUCED ORPHARYNGEAL CANCER - A LONG-TERM SEQUELAE OF INTRAORAL RADIUM IMPLANT

Australian Journal of Oto-Laryngology, Jun 2004 by Choo, J C, Shaw, C L

It is well known that external beam radiotherapy to the head and neck region can result in acute and chronic toxicities. A rare long-term complication of radiation treatment is the radiation-induced malignancies and these are more likely to occur when external beam radiotherapy is given to the head and neck region in childhood. However the incidence of permanent radium implant induced head and neck malignancy is unknown. We report an unusual case of radium induced oropharyngeal carcinoma which highlights the potentially serious sequelae ol'permanent radium implant left in situ.

Key words: radium, radiation-induced, oropharyngeal neoplasms, second primary neoplasms, head and neck neoplasms

Introduction

Primary head and neck malignancy is usually managed with single modality therapy (surgery or radiotherapy alone) or combined therapy (surgery and radiotherapy with or without adjuvant chemotherapy), depending on disease, patient and treatment factors. The potential acute and chronic toxicities of radiation therapy to the head and neck region are well known. These include mucositis, xerostomia, radiodermatitis, osteoradionecrosis and carotid stenosis.1,2,3,4 External beam radiation-induced tumours in the head and neck region are rare, accounting for less than 1% of head and neck tumours.5 Skin cancer, thyroid cancer, osteosarcoma, fibrosarcoma and squamous cell carcinoma4,5,6,7,8,9 are amongst the cancers which can be induced by radiation. We report an unusual case of radiation-induced tonsillar squamous cell carcinoma 34 years after intraoral radium seeds were implanted for the treatment of previous tongue cancer.

Case Report

A 63 year-old male nursing home resident with cerebral palsy and severe kyphoscoliosis was referred to the Otolaryngology Unit in 2003 with several months history of progressive throat pain, dysphagia and extremely poor oral intake secondary to a right-sided clinically T4N0 ulcerating tonsillar squamous cell carcinoma. The patient did not have a history of smoking or alcohol use. He had a past history of right-sided tongue squamous cell carcinoma in 1969 treated with the insertion of 21 radon seeds. It is unclear if these radon seeds were subsequently removed. A year later he underwent right neck dissection for the treatment of neck recurrence. Hc was subsequently followed up for 7 years without signs of recurrence. He was well until several months prior to his current presentation. Clinically, the patient had an extensive ulcerating tonsillar tumour involving the right-sided soft palate, posterior buccal mucosa and posterior tongue base.

The patient underwent palliative endoscopic transoral laser debulking of the tumour. Two small metallic foreign bodies (radium implants) were discovered at the inferior portion of the tumour mass within the right tongue base muscle (Figure 1). Histology showed an extensive ulcerated moderately to poorly differentiated squamous cell carcinoma with muscle invasion.

Post-operative recovery was uneventful. The patient was discharged to the nursing home under the care of the palliative care team.

Discussion

Multiple primary head and neck tumours are not uncommon, with 8.5 to 40% of cases10,11,12,13,14 found to be complicated by the development of second primary tumours. They can present either synchronously or metachronously. The particular frequency with which multiple primary tumours complicate head and neck tumours supports the field cancerization theory.15 Fields with diameters of over seven centimetres have been described in head and neck mucosa, and these fields often remain after initial therapy of the index tumour and have been proposed to lead to new cancers.16 A review of literature found the longest recorded time interval between the first primary malignancy and the development of the second malignancy is 28 years.17 The most important risk factors for developing a second head and neck malignancy are still nicotine and alcohol use in excess.17 Although the second cancer in this report falls within a seven centimetre range of the initial tumour and its appearance could be consistent with field cancerization, the patient in our case developed the second malignancy 34 years after the first malignancy and had no history of nicotine or alcohol consumption. The unprecedented duration and the absence of significant risk factors make it unlikely to be a typical second primary. The history of permanent radium implants therefore strongly suggests that the second cancer may be radiation-induced.

It is well recognized that radiation is carcinogenic. Both environmental and therapeutic radiation has been linked with radiation-induced malignancies. There is an increase in childhood thyroid cancer after exposure to the atomic bomb detonations in Japan and Chernobyl reactor incident.18 Radium industry workers and radium dial painters were found to have an increased incidence of osteosarcoma, fibrosarcoma,9 and carcinoma of the paranasal sinuses and mastoid air cells.9,19 A review involving 2500 patients with head and neck cancer attributed 0.70% of the cancers to previous therapeutic irradiation.5 Previous neck irradiation was associated with an estimated absolute risk of 4.4 excess thyroid cancers per 10.000 person years per Gy.20 The risk was greatest for young children and almost all were papillary thyroid cancers of the solid/follicular type.20 The use of radium-224 in the treatment of bone tuberculosis and ankylosing spondylitis in the 1940s and 1950s has contributed significantly to the increase of bone sarcomas,8,21 and malignancies of the breast, thyroid, liver, kidney, bladder and soft tissue.22 Radium-226 used to treat skin haemangioma in the 1930s to 1960s was found to have significantly increased the risk of subsequent gliomas, meningiomas23 and thyroid and other endocrine gland cancers.24 Radiotherapy to the scalp for tinea capitis was found to have increased the risk of skin cancer.6 Radiotherapy to the head, neck and chest was found to increase the risk of breast cancer25 and possibly increase the risk of parotid gland tumour26. Nasopharyngeal radium irradiation for otitis serosa in children and barotrauma in airmen and submariners in the 1940s to 1970s was found to have increased the risk of head and neck basal cell carcinoma27 and other head and neck tumours.28