Treatment

Treatment modalities presented in the literature have included radiotherapy alone, surgical resection, preoperative irradiation and surgery, surgery followed by radiotherapy, and occasional supplemental chemotherapy.

The ideal surgical approach to squamous cell carcinoma of the head and neck includes the external auditory canal and temporal bone in en bloc resection with the immediate adjacent tissues having the highest probability of lymphatic spread. The goal of surgical resection is to remove all tumor, as noted in the standard approach to squamous cell carcinoma of the head and neck, and to create the least amount of surgical morbidity and mortality with the best reasonable chance of 5-year or better survival. In some cases there may be a justification for a less than ideal surgical resection in order to provide relief of pain and a reasonable quality of life in the patient's last months to 1 year.

The literature during the past 40 years gives some insight into the ability to achieve the goals presented above. Boland4 in 1963 presented the results of megavolt irradiation and felt that better than 50% of patients could be cured. This included T1 lesions as defined by Arriaga et al.3 In 1975 Wang5 reported about 50% cure rate of T1 lesions but believed that lesions beyond the external canal are not successful with radiotherapy alone. Wang and Doppke6 reported on osteoradionecrosis of the temporal bone given postoperatively at doses of > 6000 to 6500 rad.

Lewis7 is credited by most investigators as presenting the best opportunity of en bloc resection of the temporal bone. He has also presented the largest series of cases in the literature. He advocated total en bloc resection of the temporal bone followed by radiotherapy. He had an overall 5-year survival rate of 28%. Arena8 presented his modifications of the en bloc temporal bone resection, emphasizing the need for neurosurgical assistance to achieve total removal of the temporal bone. He noted that, in those cases in which the primary was not controlled, survival was less than 6 months.

Neely and Forrester,9 in 1982, presented a temporal bone study to determine the feasibility of en bloc temporal bone resection, including the lateral wall of the bony carotid canal and jugular bone. These investigators noted the advisability of removing all pneumatized spaces when the tumor had invaded beyond the external canal. The ability to remove all of the air cell system without violation was remote.

Goodwin and Jesse,10 in 1980, found that the survival rate for 35 patients with deep involvement of the squamous cell carcinoma was 28%. The reason for failure was incomplete resection of disease. Go et al.11 presented the results of 16 cases of temporal bone resection noting that failures occurred because of incomplete resection of disease. There were positive margins on the surgical specimen.

Graham et al.12 presented two cases of temporal bone resection, including the carotid artery. Sataloff et al.13 presented an additional two patients with resection of the carotid artery and cranial nerves VI through XII and noted that there still was inadequate resection of the primary disease.

Willging and Pensak,14 in 1991, presented their experience using temporal bone resection for squamous cell carcinoma of the temporal bone. These investigators emphasized early diagnosis and radical treatment. Imaging studies may be helpful in defining the extent of disease and limits of resection. They noted that inclusion of the petrous apex in an en bloc resection does not add to survival but significantly increases morbidity.

In 1987, Kinney and Wood15-17 presented their experience of 30 cases of temporal bone malignancy. Based on the experience of Crabtree et al.18 an external auditory canal resection, with further removal of all tumor as needed using frozen section margin control. Most patients were given full postoperative radiotherapy. The survival rate for external canal lesions, T1 of Arriaga et al.,3 was 91%. T2 lesions survival rate was 72%. T3 and T4 lesions was 45%. As noted by Arena,8 those cases not controlled died within 12 months.

The treatment algorithm for squamous cell carcinoma of the external auditory canal and temporal bone has evolved with some modifications. The high index of suspicion and early diagnosis remain the best prognostic tools in this disease.

Very limited lesions with low malignancy histology, such as verrucous carcinoma with no bone involvement, can be treated with a sleeve canal resection with or without split-thickness skin graft, depending on the size of the lesion. Radiotherapy is usually unnecessary during the postoperative period.

Recognizing the high incidence of tumor violation in the best designed en bloc temporal bone resection, this technique is not currently employed for primary treatment modality. Patients presenting with squamous cell carcinoma in an open mastoid cavity or who have undergone previous radiotherapy will be considered for attempted en bloc temporal bone resection.

Patients with T1 and T2 preoperative-stage lesions will be offered a lateral temporal bone resection with incontinuity removal of the superficial lobe of the parotid gland. If the lesion is anterior medial in the external canal, the deep lobe of the parotid gland may be removed. Level 2 and 3 lymph nodes are sampled for frozen-section evaluation to determine the need for formal radical neck dissection.

If the lesion is stage T3 or T4, the same protocol is offered as for T1 and T2, followed by removal of all positive and adjacent normal tissue in piecemeal fashion. If disease extends anteriorly into the glenoid fossa, the entire anatomic fossa is drilled out to the dura of the middle fossa, middle meningeal artery, and V3 as needed. The mandibular condyle, masseter, and pterygoid muscles may be removed.

The entire labyrinth, cochlea, facial nerve, and petrous apex may be removed. The entire mastoid middle fossa tegmen and posterior fossa dural plate may be resected. Dura is resected and grafted as needed. Squamous cell carcinoma rarely penetrates the dura but will track along the dura and must be resected.

The carotid artery can be removed from its bony canal and the external sheath stripped or carotid resection with bypass may be performed. Sacrifice of cranial nerves IX, X, and XI may be accomplished. All decisions are based on frozen-section control, often 20 to 30 samples in one case.

At present, all patients with CT evidence of bone involvement or histologic evidence of bone involvement, will be given full therapy postoperative radiotherapy. This is done in consultation with the radiation oncologist and will include the neck as considered necessary.

Recognizing the difficulties with late osteoradionecrosis of the temporal bone including bone death and cerebral spinal fluid leaks, the middle ear transformer is sacrificed in all cases for which irradiation will be given. This means that the operative field will be covered by vascularized soft tissue and skin. The original attempts to obliterate this site with sternocleidomastoid mastoid muscle have not been successful. The temporalis muscle with its anterior blood supply is useful for covering limited canal resections. Regional flaps or vascularized free flaps may be used particularly in those cases of auriculectomy and dural resection with grafts.

Appropriate cranial nerve rehabilitation to protect the eye, airway, and swallowing are also performed. Control of cerebrospinal fluid (CSF) and prevention of infection are concurrently employed.

Primary malignancies of the temporal bone are extremely rare. These would include rhabdomyosarcoma, aggressive middle ear adenoma, and adenocarcinoma of the endolymphatic sac. Current treatment of rhabdomyosarcoma consists of chemo-therapy and radiotherapy. Surgery is used only to reduce the bulk size of the tumor.

Aggressive middle ear adenoma19 may be considered a form of adenocarcinoma or a benign papillary adenoma. The treatment is aggressive total removal of all tumor. It is advisable to plan a second-look operation about 1 year after the primary operation to ensure total removal.

Adenocarcinoma of the endolymphatic sac20 is rare, and the diagnosis may not be apparent until the tumor has been violated. Aggressive total removal as advocated for T3 and T4 squamous cell carcinoma lesions of the external auditory canal followed by full-therapy irradiation would be given.

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