Endoscopic Transoral Laser Resection For Radiotherapy Failure For Base Of Tongue Cancer

Introduction

Carcinoma of the base of tongue usually presents at a relatively advanced stage due to the subtle non specific initial symptoms which can mimic various benign conditions. The presence of normal lymphoid tissue and the infiltrative nature of the disease make the diagnosis even more challenging. Once diagnosed, the usual treatment is radiotherapy with or without chemotherapy. Surgical resection is usually reserved for non responders as open resection of the tongue base is associated with severe morbidity in relation to speech and swallowing. However, conservative endoscopic laser can be used to salvage post radiotherapy recurrent or residual tumors with minimal morbidity for selective patients.

Case Report

A 75 year old gentleman presented to our OPD with complaints of dysphagia, odynophagia and pain in left ear for the last 3 months. On palpation, there was pain and induration over the left side of the base of tongue. Cervical lymph nodes were not palpable. CT scan showed an infiltrative growth involving left side of the base of tongue extending to the vallecula and the encroaching onto the lateral pharyngeal wall (cT3N0M0). No significant lymph nodes were evident on CT scan. Biopsy was confirmatory for a moderately differentiated squamous cell carcinoma.

The patient received IMRT (70 Gy in 35 fractions) over a period of 6 weeks. After the completion of radiotherapy, his symptoms regressed but did not disappear, after 3months rigid laryngoscopy with biopsy was done which confirmed the residual disease ,which was confirmed by biopsy. The CT scan of neck & thorax revealed lesion on the left BOT 2x2cm with no evidence of metastasis. The patient then underwent endoscopic trans oral laser resection of the lesion over the base of tongue which was margin negative on final histopathology. The patient is on regular follow up for six months post surgery. He has no evidence of disease at present. His morbidity is minimal with mild impairment in articulation and no difficulty in swallowing.

Discussion

The base of the tongue is one of the most unfavorable sites for endoscopic laser surgeries. Firstly, it is extremely difficult to achieve adequate access to this region with sufficient exposure of all the areas that are involved by the tumor. Secondly, the differentiation between tumor and healthy tissue is particularly difficult due to the presence of lingual tonsils. For adequate exposure, the use of distending oropharyngoscopes is largely recommended. Continuous repositioning of the oropharyngoscope is required which demands a lot of patience and experience by the surgeon. An intermittent assessment of the wound should be performed by digital palpation and the use of a 30 degree or a 70 degree endoscope. Intraoperative frozen section can be a very handy tool in determining the margins of the resection.

Side effects of laser resection are significantly lower as compared to an open surgery. Post operative pain is surprisingly low. Hemorrhages can occur but is extremely low in experienced hands. Functional disturbances like impairment in swallowing and transient aspiration usually follow extensive resections. Finally the patient is spared of a temporary tracheotomy which is required in most open resections.

A study was conducted at Department of Otolaryngology,RushUniversityMedicalCenter,Chicago,USA. By Camp AA et al to determine survival and functional results in patients who underwent transoral laser excision of base of tongue squamous cell carcinoma. Of the 71 patients treated, one (1.4%), nine (12.7%), seven (9.9%), and 54 (76.1%) were stage I, II, III, and IV, respectively, at diagnosis. At 24 months, overall survival was 90 percent; disease-specific survival was 94 percent. Locoregional recurrence occurred in 10 percent. The study concluded transoral laser excision offers an acceptable treatment approach in terms of survival and quality of life for patients with base of tongue squamous cell carcinoma.

In a study conducted by Grant DG et al at the Department of Otorhinolaryngology-Head and Neck Surgery, Mayo Clinic, USA to determine the oncologic and functional outcomes of transoral laser(TLM) microsurgery in the treatment of persistent, recurrent, and second primary squamous cell carcinoma of the tongue base, it was found to be a rational and effective treatment in appropriately selected patients with persistent, recurrent, or second primary tongue base cancer. The low morbidity and mortality and shortened duration of hospitalization associated with TLM make it an attractive therapeutic alternative.