Malignant Tumors of the Temporal Bone

Since temporal bone cancer is so rare, measuring specific etiologic factors for cancers in this area is very difficult. However, fair-skinned whites are more prone to nonmelanomatous skin cancers in other areas, especially areas exposed to ultraviolet radiation. A genetic predisposition to skin cancer may also exist, manifested as the development of skin cancers in sites not exposed to sunlight as well as sun-exposed areas. Chronic otitis media and cholesteatoma are common in patients with temporal bone cancers and have been implicated as etiologic factors.[6, 7] Chronic suppurative otitis media and the resulting chronic inflammation may lead to squamous metaplasia. Human papillomavirus has been implicated in squamous cell carcinomas of the middle ear.[8] Lim et al (2000) reported a series of temporal bone cancers in 7 patients who had undergone radiotherapy for nasopharyngeal carcinoma.[9] These patients had a particularly poor outcome.

The complex anatomy of the temporal bone makes tumor spread difficult to predict. Tumors of the skin around the auricle may extend along the soft tissues of the neck and ear. The soft tissues are a poor barrier against tumor spread, and eventually the tumors may extend along the conchal bowl and into the EAC. The cartilage of the EAC provides minimal resistance to tumor spread. The fissures of Santorini, foramen of Huschke, and bony-cartilaginous junctions are a source of direct access to the periparotid tissues and temporomandibular joint.

Cancer in the external auditory meatus can invade posteriorly through the soft tissue into the retroauricular sulcus over the mastoid cortex. The bony canal is more resistant to cancer extension; however, erosion through the posterior bony canal provides access to the mastoid cavity. Tumor growth medially along the EAC can extend through the tympanic membrane and bony tympanic ring, allowing invasion into the middle ear. Once a tumor enters the middle ear, the hard bone of the otic capsule provides a more effective barrier against tumor spread.

In the middle ear or mastoid, tumors spread easily via the eustachian tube, round and oval windows, neurovascular structures, and extensive air spaces of the mastoid cavity. The eustachian tube and neurovascular structures of the middle ear are potential means of tumor spread beyond the temporal bone to the infratemporal fossa, nasopharynx, or neck.

Aggressive tumors can erode through the tegmen tympani or mastoid into the middle or posterior fossa. The sigmoid sinus may become involved. The dura, although somewhat resistant to invasion, portends a grave prognosis if involved. The facial nerve and the stylomastoid foramen are metastatic routes to the soft tissues of the neck and the parotid. Proximal extension along the facial nerve leads toward the inner ear and posterior fossa. Leonetti et al (1996) offer an excellent review of the invasion patterns of temporal bone cancer.[10]

Nodal metastasis is uncommon in early disease but may occur in 10-20% of cases of advanced disease.[11, 6] The lymphatic drainage of the auricle and EAC extends anteriorly to the periparotid lymph nodes and parotid gland.[12] Drainage may also occur to the jugular chain or nodes overlying the mastoid. Lymphatic drainage of the medial EAC and middle ear is to the retropharyngeal nodes or deep jugular nodes. The lymphatic drainage of the inner ear is unknown.

Distant metastasis is rare.

Patients with cancer of the temporal bone most often present when aged 60 years or older, although any age group, including children, can be affected. Common presenting symptoms include chronic otalgia, otorrhea, bleeding, and hearing loss. Physical findings include otorrhea, a mass lesion, facial swelling, facial paresis, and other cranial nerve (CN) deficits. Patients often present after many years of symptoms. In a series from the authors' institution, the average time from the onset of symptoms to the time of primary treatment for cancer was 3.9 years.[11] Nodal disease is present in 10-20% of patients.[11, 6] Symptoms and signs of temporal bone lesions are summarized as follows:

• Otalgia (80-85%)

• Otorrhea (40-75%)

• Facial paralysis (25%)

• Hearing loss (45-80%)

• Tinnitus (8-10%)

• Vertigo

• Auricular lesion

• External canal mass (10%)

• Parotid mass (19%)

• Skin lesions

• CN V, IX, I, XI deficits (30%)

The aforementioned study by Song et al found that in cases of temporal bone metastasis, facial palsy and hearing loss were the most frequent otologic symptoms, with each occurring in 30.5% of patients.[3]

Physical examination in cases of temporal bone cancer should include inspection of the pinna, EAC, and middle ear for ulcers, mass lesions, soft tissue swelling or induration, old scars (eg, previously excised skin cancers may have been forgotten by the patient), and otorrhea. Perform a thorough CN examination. Close inspection for facial weakness is crucial. Perform audiography if hearing loss is suspected. As always, perform a complete head and neck examination. The patient's general medical condition should also be evaluated because it may greatly impact treatment options and outcome.

In general, all patients who are medically able should undergo surgical treatment. Primary radiation is ineffective for curative treatment; however, in the most extreme cases in which contraindications to surgery are serious deterrents to surgery, palliative radiation and chemotherapy may be offered.

The temporal bone is a complex structure comprised of 3 parts: the squamous, tympanic, and petrous portions. The squamous portion of the temporal bone forms a small portion of the bony EAC, the zygomatic process (and mandibular fossa), and a portion of the mastoid process. It has a superior portion that protects the temporal lobe and articulates with the parietal and occipital bones. The tympanic portion forms most of the bony canal and the posterior wall of the mandibular fossa. The middle ear is a space between the squamous and temporal portions laterally and the petrous portion medially. The petrous portion of the temporal bone contains the otic capsule and the internal auditory canal.

The EAC extends from the concha to the tympanic membrane. The lateral cartilaginous portion meets the bony portion at a bony-cartilaginous junction located about one third of its total length from the lateral aspect. The anterior cartilaginous wall contains small cartilage defects filled with connective tissue called fissures of Santorini, which are direct routes of tumor spread into the periparotid tissues. Within the bony portion is another potential route for tumor extension at the foramen of Huschke, a defect of the tympanic ring located inferiorly. The anterior wall of the canal is closely associated with the temporomandibular joint, and the anterior-inferior wall is close to the parotid gland.

The temporal bone contains or abuts many vital structures, including the internal carotid artery, jugular bulb, cavernous sinus, and sigmoid sinus. A thin layer of bone separates the middle ear and mastoid cavities from the middle and posterior fossae dura. Other important structures that lie within the temporal bone include the ossicles, the cochlea, and the eustachian tube and the cochlear, vestibular, facial, trigeminal, caroticotympanic, chorda tympani, and petrosal nerves.

In general, no contraindications specific to tumors of the temporal bone exist; all patients who are medically able should undergo surgical treatment. However, advanced tumors with intracranial invasion have a grave prognosis, and treatment should probably be limited to palliation with less extensive (and less morbid) surgical procedures.

Routine preoperative testing includes CBCs, electrolyte level tests, renal function tests, liver function tests, and coagulation studies (if warranted based on the patient's history of bleeding and current medications).

See the list below:

• CT scanning of the temporal bone and neck: A physical examination alone cannot adequately evaluate the extent of tumor extension beyond the pinna. Specific radiographic information is crucial for accurate preoperative staging. Obtain a fine-cut (1 mm) high-resolution CT scan of the temporal bone. The radiologist should evaluate the study specifically for EAC erosion, middle ear involvement, otic capsule erosion, mastoid involvement, jugular fossa erosion, carotid canal erosion, tegmen erosion, and posterior fossa involvement. The facial nerve, stylomastoid foramen, temporomandibular joint, parotid gland, and infratemporal fossa should also be carefully examined.

• MRI: CT scanning may be unreliable to differentiate fluid and inflamed mucosa from a tumor in the middle ear and mastoid, especially when no bony erosion is present to raise the suspicion for the presence of a tumor. In addition, spread along fascial planes and neurovascular structures can be very difficult to detect. In these situations, MRI with gadolinium enhancement can be helpful because it better delineates soft tissue interfaces.

• Chest radiography: If the histology indicates squamous cell carcinoma, obtain plain radiographs or CT scans of the chest to rule out metastasis.

• CT scanning of the chest, abdomen, or pelvis: CT scanning of the chest, abdomen, or pelvis is not necessary unless the biopsy specimen of the temporal bone tumor reveals a tumor with a known propensity for metastasis. This type of tumor includes melanoma, adenocarcinoma, lymphoma, and renal cell carcinoma.

• Carotid angiography with balloon occlusion Xenon test: If the carotid artery is suspected to be involved, angiography with ipsilateral balloon occlusion Xenon testing is performed to demonstrate the adequacy of cerebral blood flow from the contralateral carotid artery. Special attention is also given to the venous outflow phase to determine the adequacy of the contralateral sigmoid/jugular system in case the surgery requires sacrifice of the sigmoid sinus or internal jugular vein.

See the list below:

• Audiometry: An audiogram is obtained prior to performing any major procedure on the ear or temporal bone. Audiograms provide baseline hearing thresholds for future comparison.

• Electrocardiography

See the list below:

• Biopsy: Obtain a biopsy to determine whether the lesion in the ear is benign or malignant. A needle biopsy can be performed if most of the mass is subcutaneous or in the parenchyma of the parotid gland. A staging mastoidectomy is not appropriate.

Although CT scanning provides important preoperative staging information, systematic pathologic evaluation of the specimen is crucial for staging and treatment. For example, if pathologic evidence of bony invasion or soft tissue spread is found but was not predicted by findings on preoperative imaging studies, the stage may be adjusted and adjuvant therapy considered.

The surgeon should personally orient the surgical tissue for the pathology team. The pathologist should then examine multiple sections of key elements (eg, bony EAC, facial canal, otic capsule, tympanic ring, bony-cartilaginous junction). The soft tissue margins at the stylomastoid foramen, infratemporal fossa, and facial nerve (if resected) should be detailed. Also, mucosal samples of the middle ear and mastoid should be specifically examined.

Staging systems are intended to help classify patients preoperatively into groups whereby decisions regarding treatment may be made on the basis of comparison to previously treated patients with similar tumor characteristics (ie, the stage). To date, no staging system for temporal bone malignancies is universally accepted. Several factors impede the process of developing a staging system, including the rarity of the tumors, the impossibility of evaluating disease extent by physical examination alone, and the unreliability of radiographic studies to determine the extent of disease in certain situations.

Many authors have proposed staging systems concurrent with a review of patient series from major institutions; however, the small number of patients per group, the disparity of staging criteria, the diversity in management protocols, and the use of nonstandardized surgical nomenclature prohibits meaningful comparison of outcomes. In addition, some patients are reportedly classified into groups with variability in histology types and sites of tumor origin, which further confounds analysis of outcome by stage.

Numerous staging systems have been proposed; however, to date, no universally accepted staging system for temporal bone cancers exists. A staging system for squamous cell cancers of the EAC proposed by the University of Pittsburgh has been shown useful and has gained support in the literature.[13, 14, 15, 10, 6, 16] This staging system is based on clinical, radiologic, and pathologic findings. In general, tumors that are limited to the EAC are defined as early disease, and those that extend beyond the external canal to invade the surrounding soft tissues, the middle ear, the mastoid, or CNs are recognized as advanced disease.

In the original staging system proposed by Pittsburgh, lesions were defined as follows:[13]

• T1 - Tumor limited to the EAC without bony erosion or evidence of soft tissue involvement

• T2 - Tumor with limited EAC bone erosion (not full thickness) with limited (< 0.5 cm) soft tissue involvement

• T3 - Tumor eroding the osseous EAC (full thickness) with limited (< 0.5 cm) soft tissue involvement or tumor involving the middle ear, mastoid, or both

• T4 - Tumor eroding the cochlea, petrous apex, medial wall of the middle ear, carotid canal, or jugular foramen of dura; or with extensive soft tissue involvement (>0.5 cm), such as involvement of the temporomandibular joint or stylomastoid foramen; or with evidence of facial paresis

The Pittsburgh staging system has become widely applied in case reports of temporal bone cancer.[6, 17]

The Pittsburgh staging system was modified by the authors after further review of patients from an extended series.[11] In the modified staging system, facial nerve weakness is considered a criterion for a T4 lesion. The authors observed that facial nerve paresis did not occur in lesions otherwise classified as limited T1, T2, or T3 lesions. Involvement of the facial nerve would be otherwise classified as T4 based on the anatomical area of involvement, including the medial wall of the middle ear (horizontal segment), extensive bony erosion within mastoid (vertical segment), or involvement of stylomastoid foramen. In the T4 group, survival was similar between patients with and without facial paralysis (unpublished). A few reports have used the modified staging system.[18]

Nodal involvement and stage can be classified as it is for other cancers of the head and neck.

• N1 - Single ipsilateral lymph node, size less than 3 cm

• N2 - Single ipsilateral node, size 3-6 cm

• N2b - Multiple ipsilateral nodes, all less than 6 cm

• N2c - Bilateral or contralateral nodes, all less than 6 cm

• N3 - Nodes involved greater than 6 cm

Cancer is staged as follows:

• Stage 0 - Tis N0 M0

• Stage I - T1 N0 M0

• Stage II - T2 N0 M0

• Stage III - T3 N0 M0, T1 N1 M0, T2 N1 M0, T3 N1 M0

• Stage IV - T4 N0 M0, T4 N1 M0, any T N2 M0, any T N3 M0, any T any N M1

Primary radiation is ineffective for curative treatment. In the most extreme cases in which contraindications to surgery are serious deterrents to an operation, palliative radiation and chemotherapy may be offered. The literature supports a beneficial effect of adjunctive radiation on survival, but no well-controlled studies have been performed. Postoperative radiation treatment may be indicated in advanced disease. Most authors advocate full course postoperative radiation to stage T3 or T4 tumors as defined by the University of Pittsburgh staging system. Some authors also recommend radiation for T2 disease.[4]

The literature supports a beneficial effect of postoperative radiation on survival.[6, 11] The temporal bone and neck should be treated with 50-60 Gy for tumors staged T3 and T4. Radiation may also be indicated for smaller lesions.

Preoperative chemotherapy was reviewed by Nakagawa et al in a retrospective series of patients treated with preoperative chemoradiation or with chemoradiation alone).[19] Four of 8 patients treated with chemoradiation (5-flourouracil or a fluoropyrimidine complex during external beam radiation with a dose of 40Gy), followed by chemotherapy in one case, were free of disease at 24-47 months. Pemberton et al reported 53% cancer-specific survival of 123 patients treated with radiotherapy alone (55 Gy).[20]

A study by Noda et al indicated that nivolumab, an immune checkpoint inhibitor used against platinum-refractory metastatic or recurrent head and neck squamous cell carcinoma, has some therapeutic effect in temporal bone squamous cell carcinoma. The drug was administered to nine patients in whom recurrent or residual temporal bone squamous cell carcinoma was found following platinum-including chemotherapy and/or chemoradiotherapy. The investigators determined that one patient showed a partial response, two had stable disease, and four demonstrated progressive disease, with the size having not been assessed in two cases. Moreover, the 1-year overall survival rate was greater in the patients on nivolumab than in five patients who were not treated with the agent (33.3% vs 20.0%, respectively).[21]

Based on a retrospective study and literature review of patients with temporal bone paragangliomas, Prasad et al recommended that elderly patients with advanced forms of these tumors be managed with a wait-and-scan approach, with radiotherapy reserved for the treatment of fast-growing tumors. In the study, among patients with class C or D tumors who underwent wait-and-scan management, the investigators found that the tumor remained stable in 22 of 24 patients who were followed up for less than 3 years and that the paraganglioma remained stable or regressed in 10 of 12 patients who were followed up for 3-5 years. In addition, the tumor remained stable or regressed in five of 11 patients who were followed up for more than 5 years.[22]

A literature review, Prasad and colleagues stated, revealed no conclusive evidence that radiotherapy is an effective primary modality for the treatment of either class C or D temporal bone paragangliomas.[22]

In general, all patients who are medically able should undergo surgical treatment. The optimal surgery removes all of the cancer en bloc because positive margins are associated with poor survival rates.[5] The resection procedures that can be performed for the temporal bone include a modified lateral temporal bone resection, lateral temporal bone resection, subtotal temporal bone resection, and total temporal bone resection. The specific procedures and nomenclature vary among surgeons. Adjunctive surgical procedures, including neck dissection, parotidectomy, and craniotomy, should be performed when indicated. Advanced tumors with intracranial invasion have a grave prognosis, and treatment should probably be limited to palliation with less extensive (and less morbid) surgical procedures.

Determination of tumor stage and medical status assists the surgeon in surgical planning. The goal should be complete tumor removal with preservation of CNs and other vital structures whenever possible. Preoperative planning includes mapping of disease extent by both clinical and radiographic evaluation. Tumor encroachment to the region of the internal carotid artery, sigmoid sinus, or jugular vein requires further investigation such as balloon test occlusion with xenon/CT scan (demonstrating the integrity of the contralateral cerebral artery) or angiography with venous phase (to determine dominance of the cerebral outflow). Consultation with a neurosurgeon may be necessary if involvement of the dura is suspected. The patient's medical status plays a major role in his or her tolerance of a long surgical procedure, postoperative recovery, healing, and postoperative rehabilitation.

Management of the primary site

Hirsch and Chang have described the operative procedures in detail and the indications based on the location and stage of the tumor.[23] Medina (1990) described several modifications of the lateral temporal bone dissection (LTBR) based on the location of disease.[24]

A modified LTBR removes the EAC and leaves the uninvolved tympanic membrane intact. This type of resection is appropriate for tumors originating in the concha without involvement of the EAC.

The LTBR includes resection of the EAC, tympanic membrane, malleus, and incus. The boundaries are the middle ear cavity and stapes medially, the mastoid cavity posteriorly, the epitympanum and zygomatic root superiorly, the temporomandibular joint (TMJ) capsule anteriorly, and the medial tympanic ring or infratemporal fossa (ITF) inferiorly. The lateral margin depends on the extent of spread. The otic capsule and facial nerve are preserved. The LTBR is appropriate for T1 and T2 tumors.

The LTBR begins with a long, postauricular incision extending from the temporal fossa into the neck. If the pinna is to be preserved, a second incision is made within the concha lateral to the lesion. If the pinna is to be resected, a preauricular incision is incorporated to the postauricular incision allowing the pinna and surrounding skin to be included in the specimen. A cortical mastoidectomy is performed and the facial nerve identified. Bone removal is extended into the zygomatic root and to the digastric ridge. An extended facial recess is made, and the incudostapedial joint is separated. The facial recess is continued inferiorly and anteriorly lateral to the facial nerve, but medial to the annulus, until the specimen is attached only at the anterior canal bony wall at the level of the temporomandibular capsule. An osteotome is used to separate the bony specimen. The parotidectomy is performed en bloc.

A subtotal temporal bone resection (STBR) is performed when invasion medial to the tympanic membrane or into the mastoid (T3 disease) is evident. In this case, the medial margin may be obtained in a piecemeal fashion, usually with a drill. The specimen includes the LTBR with additional dissection of the otic capsule and the medial bony wall of the middle ear and mastoid. The margins of resection are the sigmoid sinus and posterior fossa dura posteriorly, middle fossa dura superiorly, internal carotid artery anteriorly, jugular bulb inferiorly, and petrous apex medially. Based on the extent of tumor spread, dissection may include the condyle of the mandible, the facial nerve, dura, sigmoid sinus, and contents of the infratemporal fossa. The carotid artery is skeletonized and becomes the medial margin.

Tumor involvement of the jugular bulb requires ligation of the inferior jugular vein and proximal control of the sigmoid sinus. The facial nerve is traditionally sacrificed, with the proximal margin taken in the labyrinthine or internal auditory canal segment. However, the surgeon may elect to preserve the nerve if no indication of nerve involvement exists. The medial extent of dissection at the level of the otic capsule depends on the depth of involvement and is done piecemeal. Tumor extension into the protympanum, eustachian tube, or carotid artery is addressed with an infratemporal fossa dissection. The temporalis muscle is reflected and the zygomatic arch removed. The mandibular condyle is resected. The dissection proceeds based on the extent of disease but may include identification of the pterygoid plate, the mandibular nerve (V3), and the horizontal carotid artery and may include a temporal craniotomy.

A total TBR can be used to address T4 disease. However, this procedure is associated with significant morbidity and may not significantly improve survival in these cases of advanced disease. The total TBR includes the STBR with the additional resection of the petrous apex. The internal carotid artery may be isolated, mobilized, and preserved or resected. The sigmoid sinus, jugular vein, carotid artery, dura and CNs are removed as indicated by the extent of the tumor.

Management of the parotid and temporomandibular joint

The intraparotid lymph nodes are a first echelon drainage site for cancers of the EAC and middle ear. An adequate anterior margin for the temporal bone resection routinely involves resection of the parotid gland, temporomandibular joint, and condyle. Resection of these soft tissues will also address minimal soft tissue extension beyond the temporal bone. Ideally, this is performed en bloc with the temporal bone. A superficial parotidectomy is performed with preservation of the facial nerve for T1 and T2 tumors. When the facial nerve is resected for more advanced lesions, a total parotidectomy may be performed.

Management of the neck

Although metastasis to the neck is uncommon in limited cancers of the temporal bone, neck dissections are routinely performed. With more extensive cancers, dissection of the neck offers staging and provides control of the great vessels and exposure to the skull base. However, the presence of metastasis is associated with a poor prognosis, and neck dissection does not improve survival.[11, 6]

Management of the dura and brain

Although involvement of the dura and brain portend for a poor prognosis, an aggressive approach includes resection of the dura and a small volume of the temporal lobe with a healthy margin.

Reconstruction

Facial nerve grafting is usually not performed in the presence of a malignant lesion. Management of facial nerve paralysis may include CN XII to VII grafting, cross facial grafting, and static procedures. Extensive resections may result in large soft tissue defects. A temporalis muscle flap can be used to fill small to medium defects. The pedicled myocutaneous trapezius flap is an excellent option for reconstruction of the soft tissue and skin defect. The pectoralis flap has limited distant reach to the resected margin. The rectus abdominus free flap and radial forearm flap are particularly suited for the area. Dural defects should be repaired primarily or with graft reconstruction.

Postoperative care consists of monitoring wound complications, flap viability, intracranial complications, and complications of CN deficits. If the dura was resected and repaired, the wound should be observed for a cerebrospinal fluid leak. Supportive care for dizziness, nausea, and vertigo is needed when the otic capsule is entered during the resection. Eye care should be instituted if postoperative facial paralysis develops or if the facial nerve is resected. Resection of CN X requires swallowing and vocal fold rehabilitation and observation for aspiration or airway complications. If the temporomandibular joint was removed, the mandible should be mobilized early to prevent contralateral dysfunction.

Complications of treatment depend on the extent of resection and the use of adjunctive radiation. Postoperative hearing loss, facial nerve paralysis, vertigo, and other CN deficits (eg, CN V, VII, VIII, IX, X, XI) may occur. Dural resection may predispose to cerebral spinal fluid leaks, meningitis, or intracranial complications. Significant complications can result from trauma to or resection of the carotid artery. Radiation has known complications of fibrosis of soft tissues, destruction of salivary gland tissue, osteoradionecrosis of the temporal bone, and possibly central nervous system effects if the field of radiation extends to intracranial tissues.

Prognosis is related to the primary site, the histologic type, and treatment.[25, 26] The outcome of treatment for early stage tumors is favorable, with most series reporting an 80-100% survival rate. Later stage cancers after adequate surgery and radiation treatment have a survival between 50% and 80%. Advanced lesions have a poor prognosis despite aggressive treatment, with 2-year survival of 0-40%.[11, 6] Salvage surgery after an incomplete resection is associated with a poorer prognosis compared to a definitive procedure in an undisrupted field.[6] A mastoidectomy or limited excision performed by an outside institution prior to referral complicates preoperative assessment and staging, disrupts margins, and forces the surgeon to operate in an inflamed field with interrupted landmarks. Positive margins, nodal disease, dural involvement, and advanced disease are associated with poorer survival.[11, 6]

A retrospective study by Komune et al of outcomes and prognostic factors in temporal bone squamous cell carcinoma found the 5-year disease-specific survival rate to be higher in stage T1 to T3 cases than in patients with stage T4 tumors, the rates being 100% (T1), 92% (T2), 86% (T3), and 51% (T4). No correlation was found between poor survival and extension of the tumor to the middle ear cavity, as occurred in 13 of 17 stage T3 cases.[27]

Another study by Komune et al found, through univariate Cox regression analysis, that in patients with temporal bone squamous cell carcinoma, a poor prognosis is associated with high ratios of neutrophils to lymphocytes and platelets to lymphocytes, a low ratio of lymphocytes to monocytes, a Glasgow Prognostic Score of 2, and a Systemic Inflammation Score of 2. Thus, the report indicated a link between inflammation-based prognostic markers and survival in temporal bone squamous cell carcinoma.[28]

A study by Hongo et al indicated that in temporal bone squamous cell carcinoma, the tumor’s immune microenvironment can help to predict prognosis. For example, the investigators reported an association between a high density of CD8+ tumor-infiltrating lymphocytes (TILs) and a complete response to chemoradiotherapy. On the other hand, a poorer prognosis was associated with expression of programmed death ligand 1 (PD-L1) (1% or more) and a high density of Foxp3+ TILs.[29]

A study by Marioni et al indicated that in patients with advanced, aggressive temporal bone squamous cell carcinoma, the risk for tumor recurrence after postoperative radiotherapy is increased in those with a primary tumor classification of 4, a pathologic grade of 2 or 3, and dura mater involvement.[30]

The optimal management of temporal bone cancer remains unclear because of continued debate regarding staging, the utility of preoperative radiographic evaluation, the extent and nomenclature of surgical procedures, and the use of adjuvant radiation. The limited number of cases of temporal bone malignancies at each individual institution precludes definitive conclusions regarding the optimum protocol for management. The future of improved treatment strategies lies in a multi-institutional effort to adopt a staging system and develop prospective trials.