International Journal of Otolaryngology and Head & Neck Surgery, 2013, 2, 221-227
Published Online November 2013 (http://www.scirp.org/journal/ijohns)
http://dx.doi.org/10.4236/ijohns.2013.26046
Open Access IJOHNS
Survival in Primary Carcinoma of the External and
Middle Ear Is Strongly Dependent on Stage at Diagnosis
Toru Ugumori1, Jun Hyodo2, Naohito Hato1, Kiyofumi Gyo1
1Departmentof Otolaryng ology, Ehime University, Toon, Japan
2Department of Otolaryngol ogy, Takanoko Hospital, Matsuyama, Japan
Email: ugumorit@m.ehime-u.ac.jp
Received July 8, 2013; revised August 5, 2013; accepted September 2, 2013
Copyright © 2013 Toru Ugumori et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Conclusion: Early-stage detection of temporal bone carcinoma improves the survival rate. When detected at an ad-
vanced stage, predicted prognosis is poor even with a combination of surgery, radiotherapy and chemotherapy. Objec-
tives: We evaluated treatment strategies and survival rates in cases of carcinomas of the external and middle ear.
Method: Retrospective review of patients treated at Ehime Un iversity Hospital during the 32 years from 1977 to 2008.
Subjects were 41 patients, consisting of 21 men and 20 women with a mean age of 63.2 years. Modified Pittsburgh
staging system: stage I in 11 cases (27%), stage II in 4 (10%), stage III in 6 (15%) and stage IV in 20 (49%). Histop a-
thology: squamous cell carcinoma (SCC) in 35 cases, adenoid cystic carcinoma (ACC) in 3, and adenocarcinoma (AC)
in 3. Thirty-eight patients were treated by surgery. Radiation was added postoperatively in 23 patients. Three patients
wer e t r ea t ed b y che moradiotherapy. Results: The survival rate of carcinomas detected at an advanced stage was poor with
a disease-specific 5-year survival rate of 100% in early-stage disease (stage I and II) versus 20.8% in stage III and
27.5% in stage IV disease, irrespective of histopathology of the tumor.
Keywords: Survival; Staging; External Auditory Canal; Middle Ear
1. Introduction
Primary carcinoma of the external and middle ear is a
rare disease entity which affects 0.8 - 6 per million of
population per year [1]. It occurs most frequently in peo-
ple aged 50 - 70 years, with equal gender distribution [2].
The initial presenting symptoms are non-specific, and
diagnosis therefore tends to be delayed. When detected at
an advanced stage, predicted prog nosis is poor, ev en with
a combination of surgery, radiotherapy and chemother-
apy. By histological subtype, squamous cell carcinoma
(SCC) accounts for approximately 90% of all primary
malignant tumors of the temporal bone [3]. Complete
surgical resection with a clear margin is a generally ac-
cepted therapeutic modality, but this is often difficult as
temporal bone carcinomas are often found in the ad-
vanced stage. Adjunct radiotherapy and chemotherapy
are recommended in cases with incomplete resection,
although large-scale clinical evidence concerning their
effects is lacking, mainly because of the rarity of the dis-
ease. At present, no universal consensus on optimal
treatment of temporal bone carcinoma has yet to be es-
tablished.
Here, we reviewed 41 patients with primary temporal
bone carcinomas treated in our hospital over the past 32
years. The aim of this paper was to evaluate treatment
strategies and survival rates of our patients, particularly
in relation to tumor stage.
2. Material and Methods
The study was conducted by retrospective review of
medical records. Subjects were 41 consecutive patients
with primary temporal bone carcinoma who were treated
in our hospital between 1977 and 2008. The Patients and
lesion characteristics are listed in Table 1. Tumor grade
was classified using the modified Pittsburgh staging sys-
tem [4] (Table 2). According to th e system, in total, there
were 11 T1, 4 T2, 6 T3, and 20 T4 in our study (Table 3 ),
which were corresponding to 11 stage I (T1N0M0), 4
stage II (T2N0M0), 6 stage III (T3N0M0), and 20 stage
IV (T4N0M0/T4N1M0) tumors. So we state the T classi-
fication as a stage here. Cervical lymph node metastasis
was found only in one patient, while involvement of the
T. UGUMORI ET AL.
222
dura mater was seen in 14 patients, mandibular joint in
10, parotid gland in 8, sigmoid sinus in 4, cochlea in 2,
facial nerve in 2, and carotid artery in 1, when involved
sites were counted separately. These cases were all clas-
sified as stage IV. No distant metastases were seen pre-
operatively, although three patients subsequently died of
lung metastasis. Three types of surgical procedure were
employed [4]: 1) Local resection (LR; so-called sleeve
resection), 2) Lateral temporal bone resection (LTBR;
some radical mastoidectomy), 3) Subtotal temporal bone
resection (STBR). The standard surgical protocol and
number of patients was displayed in Table 4. After re-
moval of the tumor, the orifice of the ear canal was kept
open to allow the observation of possible local recur-
rence in postoperative follow-up. For patients with tu-
mors extending to the parotid g land or causing metastasis
to neck lymph nodes, parotidectomy and/or neck dissec-
tion was done in addition to subtotal TBR. As the inci-
dence of temporal bone ACC and AC is low and no treat-
ment strategy has yet been established, treatment was
done by the same protocol as that for SCC [5]. Details of
ACC and AC cases are summarized in Table 5 . Twenty-
four patients with stage III or IV disease in whom tumor
resection was considered incomplete under went subse-
quent adjuvant radiotherapy. Radiation was started 2 to 4
weeks after surgery, with total radiation dose set to 66
Gy. We did not use anticancer agents until 1983, after
which chemoradiotherapy was started in consenting pa-
tients using one of three anticancer agents, namely cis-
platin in combination with adjuvant radiotherapy in one
patient with stage IV disease; TS-1® (tegafur-gimeracil-
oteracil potassium) in seven patients; and 5FU® (fluorou-
racil) in two patients. The three SCC patients who did not
Table 1. Patients and lesion characteristics.
No. of patients 41
Age (range), y 63.2 (31 - 87)
Sex, men/women 21/20
Primary site
Right 23
Left 18
External auditory canal 29
Middle ear 11
Unknown 1
Histopathology
Sqamous cell car cinoma 35
Adenoid cystic carcinoma 3
Adenocarcinoma 3
Table 2. Moody’s modified Pittsburgh staging system.
Factor Descr ipti on/di stin g uishin g fea tur es/c har act eri stic s
T classification
T1 Limited to the external auditory canal without bo n y erosion or evidence of soft tissue involvement
T2 Limited to the external auditory canal with bone erosion (not full-thickness) or limited soft tissue involvement (<5 mm)
T3 Erosion through the osseous exter nal auditory canal (full thickness) with limited soft tissue involvement (<5 mm), or
tumor involving the middle ear and/or mastoid
T4 Erosion of the cochlea, p e t rous apex, medial wall o f t h e middle ear, car ot id c a na l, jugular forame n , or dura; or tumor
with extensive soft tissu e i n v ol v e ment (>5 mm, such as involvement of the temporomandibular joint or st yloid process);
or evidence of facial paresis
N classification
N0 No regional nodes identified
N1 Single metastatic regional node <3 cm in size
N2a Single ipsilateral metastatic node 3 - 6 cm in size
N2b Multiple ipsilateral metastatic lymph nodes
N2c Contralateral metastatic lymph node
N3 Metastatic lymph node >6 c m in size
Overall stage
I T1 N0
II T2 N0
III T3 N0
IV T4 N0
IV T1 - T4 N+
Open Access IJOHNS
T. UGUMORI ET AL. 223
Table 3. TNM staging.
TNM staging No. of patients Percentage
Size of tumor (T)
T1 11 27%
T2 4 10%
T3 6 15%
T4 20 49%
Lymph node metastasis (N)
N0 40 98%
N1 1 2%
Distant metastasis (M)
M0 41 100%
M 0 0%
Clinical stage
I 11 27%
II 4 10%
III 6 15%
IV 20 49%
Table 4. Types of surgery.
Surgery Specimen resected No. of patients
LR Skin of external auditory canal 6
LTBR En bloc removal of externalauditory canal, tympanicmembrane, malleus, and incus optional: parotid,
mandibularcondy l e, infratemporal fossa, or neck dissection 9
STBR LTBR plus otic capsule optional: facial nerve, supe rior and posterior dura, or sigmoid sinus 17
LR indicates local resection; LTBR, la teral temporal bone resectio n; S TBR, subtotal temporal bone resection.
Table 5. Patient data for cases of adenoidcystic carcinoma (ACC) and adenocarcinoma (AC).
No. Age (yr),
gender Histology T Lymph
node/metastasis Tumor
extension/invasion Surgical
procedure Radiation/
Chemotherapy Outcome Follow-up
period
1 40, F AC 1 -/- - Sleeve resection- CR 55 mo
2 66, M AC 4 -/- Middle ear, ICA Partial TBR - dead (8 mo)
3 81, F AC 4 -/- Dura mater, mandibular jointPartial TBR - dead (19 mo)
4 75, F ACC 2 -/- Canal bone erosion Lateral TBR - CR 55 mo
5 31, F ACC 2 -/- Canal bone erosion Lateral TBR - CR 88 mo
6 48, F ACC 4 -/- Middle ear, mandibular jointPartial TBR - dead (33 mo)
ICA: internal carotid artery; TBR: temporal bone resection; CR: complete remission.
undergo surgery were treated with 66 Gy of radiation
plus TS-1 chemotherapy. Postoperative follow-up pri-
marily consisted of careful otoscopic observation. Scar
tissue after surgery or radiation often became indurated
and was difficult to distinguish from recurrence, necessi-
tating repeated biopsy and/or CT examination when any
recurrence was suspected. Median follow-up period for
the 22 survivors was 59 months (range, 19 - 115 months).
Disease-specific survival rates were calculated by the
Kaplan-Meier method and the results were analyzed by
the log-rank test. In this study, p values less than 0.05
were regarded as statistically significant.
3. Results
Presenting symptoms of temporal bone carcinoma varied,
with otorrhea in 28 patients, otalgia in 24, hearing loss in
19, facial palsy in 9, ear itching in 8, tinnitus in 7, feeling
of ear fullness in 6, bleeding in 3, and ear tumor in 2.
Importantly, 25 of 41 patients had a history of chronic
Open Access IJOHNS
T. UGUMORI ET AL.
224
otitis media or recurrent external otitis, suggesting that
continuous external or middle ear inflammation might be
a predisposing factor to temporal bone carcinoma. Post-
operative recurrence occurred in 55.3% (21/38) of pa-
tients, all of whom had stage III or IV disease. Survival
rates were closely related to carcinoma stage. In early
(stage I and II) disease, disease-specific 5-year survival
rate was 100%, versus 20.8% in stage III and 27.5% in
stage IV disease (Figure 1). On univariate analysis,
Clinical stage (p < 0.0001) and Tumor site (p = 0.036)
were found to be significant prognostic factors (Table 6).
Final outcomes did not significantly differ by differences
in tumor histopathology, with overall 5-year survival
rates of 54.8% in SCC (n = 35), 66.7% in ACC (n = 3),
and 33.3% in AC (n = 3). Rather, survival rate depended
on tumor stage. Of the three patients who did not un-
dergo surgery, two subsequently died of carcinoma,
while one is still alive and in a tumor-free condition. In
summary, 22 of 39 patients were still alive at 5 years
after diagnosis, of whom 18 were tumor-free and 4 had
static disease, while 17 died of temporal bone carcinoma.
The remaining two patients died of condition s not related
to carcinoma, namely cerebral hemorrhage and heart
failure in one each.
Figure 1. Kaplan-Meier survival curves for patients with external and middle ear carcinoma.
Table 6. Univariate analysis of various potential prognostic factors for disease-specific survival.
Univariate analysis
Variable No. of patients 5-y DSS rate (%) p
Clinical stage
Stage I and II 15 100%
Stage III and IV 26 26% <0.0001
Treatment modality
Surgery 15 73% 0.26
Surgery + RT 14 48%
Surgery + RT + Chemo 8 13% 0.097
Tumor site
External auditory canal 29 64%
Middle ear 11 33% 0.036
Gender
Female 20 53%
Male 21 54%
0.98
Age (y)
<65 20 50%
>65 21 59%
0.62
D
SS = Disease-specific survi val; RT = Radiothe r apy; Chem o = Chemotherapy .
Open Access IJOHNS
T. UGUMORI ET AL. 225
4. Discussion
Prognosis of temporal bone carcinoma is generally good
when detected at an early stage. However, early detection
is often difficult, mainly due to the absence of pathog-
nomonic signs or symptoms related to this disease. A
slowly worsening or treatment-resistant lesion in the ear
canal might be one key to suspect carcinoma. Kuhel et al.
[2] analyzed the clinical data of 442 patients described in
the literature and reported that otorrhea (61%), otalgia
(51%), and a mass in the external ear canal (37%) were
the most common symptoms of temporal bone carcinoma.
Yin et al. [6] analyzed the complaints of 95 patien ts with
temporal bone SCC and reported that the main symptoms
were otorrhea in 42.1%, otalgia in 24.2%, bloody otor-
rhea in 15.8%, and tumor in the ear canal in 11.6%. In
most of Yin’s patients, otorrhea persisted for longer than
20 years, suggesting that long- lasting inflamma tio n in the
ear might be a cause of temporal bone carcinoma. As
pointed out by Varyberg [7], otalgia described as a dull
and deep-seated pain might be a second key to suspect
carcinoma. As otorrhea and otalgia are common com-
plaints in otitis media, most such patients do not co nsider
ear carcinoma, resulting in a delay in diagnosis. Further,
a mass in the external ear canal might be misdiagnosed
as an aural polyp or inflammatory granu lation, indicating
the necessity of histological study before a diagnosis of
temporal bone carcinoma can be confirmed. The current
treatment strategy for temporal bone carcinoma remains
controversial, mainly due to the rarity of the disease.
Complete surgical resection with a clear margin is ideal,
but often difficult or impossible, particularly in patients
with aggressive invasion to the surrounding structures.
Prognosis in such cases is very poor. In our cases, inva-
sion to the dura mater was noted in 14 patients and to the
sigmoid sinus in 4. All but two of these patients finally
died of cancer metastasis to the brain or lung. Although
the main lesion was removed by subtotal TBR, complete
elimination of cancer cells invading into the dura mater
or brain vessels appears impractical, even with the addi-
tion of postoperative chemoradiotherapy. We did not
employ total TBR, as the procedure has greater morbidity
without superior survival rates [7]. Recently, Su gimoto et
al. [8] reported a histological study showing that epithe-
lial-mesenchymal transition was highly expressed in
cancer tissue with poor prognosis, and concluded that
vimentin, a marker of epithelialmesenchymal transition,
can be used to predict the prognosis of temporal bone
carcinoma. Radiation is an important tool in the treat-
ment of temporal bone carcinoma. Several authors have
recommended radiation therapy for the treatment of mid-
dle ear carcinoma, showing that overall 5-year survival
rate was as high as 41% [9,10]. Gurgel et al. [11] re-
ported a poor prognosis with radiation treatment alone,
with 5-year survival rates in 215 patients of 74.4% by
surgery, 9.1% by radiation, and 20.1% by surgery plus
radiation, and accordingly disagreed with this recom-
mendation. As pointed out by Gacek et al. [12] and
Spector [13], once the tumor invades the middle ear, ra-
diation therapy alone was curative in less than 23% of
cases. Pfreundner et al. [14] noted that tumors extending
beyond the surgical margins require radiation doses in
excess of 66 Gy, since tumors recurred in regions re-
ceiving less than 66 Gy. Tumor cells at the surgical mar-
gins were hypoxic and therefore had decreased sensitiv-
ity to radiation. In our hospital, direct beam radiation of
66 Gy was routinely applied to lesions by packing the
surgical defect with dimethyliso-propylazulene-ointment
gauze to facilitate the tumor’s sensitivity to radiation.
Chemotherapy is also an important tool in the treatment
of the head and neck carcinoma. At present, however, the
effects of chemotherapy on this carcinoma have yet to be
established [15]. Nakagawa et al. [15] administered anti-
cancer agents (5-fluorouracil or TS-1®) postoperatively
to enhance radiation therapy, and reported a 5-year sur-
vival rate for T3 and T4 lesions of 80% and 35%, respec-
tively. Recently, Ueda [16] reported the clinical effects
of super-selective intra-arterial infusion chemotherapy
were combined with radiotherapy for the treatment of
external ear carcinoma. They tentatively applied th is pro-
cedure to four patients and obtained complete remission
in all cases with minor toxic effects. At present, however,
the effects of this combined procedure in patients with
advanced stage disease remain unclear. In our three pa-
tients considered unsuitable for surgery owing to inva-
sion to the internal carotid artery or jugular vein, chemo-
therapy using TS-1 was combined with radiotherapy; two
patients subsequently died of carcinoma while one pa-
tient with stage 4 SCC remains alive in a cancer-free
condition. Tumor stage is an important factor in predict-
ing the prognosis of temporal bone carcinoma. Yin et al.
[6] re- ported that overall 5-year survival rate was 100%
in early-stage disease; while it was 67.2% for stage III
and 29.5% for stage IV. In their review of the literature,
Varyberg and Sataloff [7] reported that survival rates in
combination treatment with surgery and radiation ranged
from 75% to 100% for T1 and T2 lesions, 35% to 50%
for T3 lesions, and 12.5% to 35% for T4 lesions. Histo-
pathology of the tu mor is also associated with prognosis.
According to Gurgel et al. [11], 5-year survival rates of
middle ear carcinoma were 23.9% for SCC, 65.0% for
AC, 60.0% for other carcinoma, and 38.6% for non-car-
cinoma. In the present study, a statistical difference could
not be observed among the three groups owing to the
limited number of patients. Other factors reported to be
associated with decreased survival rates were facial pa-
ralysis, positive surgical margins, advanced age, moder-
ate-to-severe pain, dural involvement and lymph node
metastasis, etc. For example, treatment failure rates were
Open Access IJOHNS
T. UGUMORI ET AL.
226
34% in patients with mild facial paralysis, 50% with
moderate paralysis, and 62% with complete paralysis
[17,18]. In our cases, facial paralysis was noted in nine
patients, seven of whom died of carcinoma. As pointed
out by Varyberg and Sataloff [7], treatment failure was
mostly due to local recurrence. To improve the survival
rate, initial surgery should be aggressive, as it offers the
greatest chance for cure [19], and survival is reported to
be better with more extensive surgery [20]. This is tech-
nically difficult, as the temporal bone locates closely to
vital structures such as the brain, brainstem, cranial
nerves and major vessels. In conclusion, external and
middle ear carcinoma is curable when detected at an ear-
ly stage. In cases extending deep into the middle ear or
occurring in the middle ear cavity, prognosis is poor even
with combination treatment with surgery plus chemora-
diotherapy. Improving the survival rate in temporal bone
carcinoma requires that treatment is started at an early
stage.
REFERENCES
[1] S. E. Kinney and B. G. Wood, “Malignancies of the Ex-
ternal Ear Canal and Temporal Bone: Surgical Tech-
niques and Results,” Laryngoscope, Vol. 97, No. 2, 1987,
pp. 158-164.
http://dx.doi.org/10.1288/00005537-198702000-00006
[2] W. I. Kuhel, C. R. Hume and S. H. Selesnick, “Cancer of
the External Auditory Canal and Temporal Bone,” Oto-
laryngologic Clinics of North America, Vol. 29, No. 5,
1996, pp. 827-852.
[3] P. M. Stell and M. S. McCormick, “Carcinoma of the
External Auditory Meatus and Middle Ear. Prognostic
Factors and a Suggested Staging System,” The Journal of
Laryngology & Otology, Vol. 99, No. 9, 1985, pp. 847-
850. http://dx.doi.org/10.1017/S0022215100097796
[4] S. A. Moody, B. E. Hirsch and E. N. Meyers, “Squamous
Cell Carcinoma of the External Auditory Canal: An Eva l u a-
tion of a Staging System,” American Journal of Otolar-
yngology, Vol. 21, No. 4, 2000, pp. 582-588.
[5] C. H. Chang, M. T. Shu, J. C. Lee, Y. S. Leu, Y. C. Chen
and K. S. Lee, “Treatments and Outcomes of Malignant
Tumors of External Auditory Canal,” American Journal
of Otolaryngology, Vol. 30, No. 1, 2009, pp. 44-48.
http://dx.doi.org/10.1016/j.amjoto.2008.02.007
[6] M. Yin, K. Ishikawa, K. Honda, T. Arakawa, Y. Harabu-
chi, T. Nagabashi, et al., “Analysis of 95 Cases of Squamous
Cell Carcinoma of the External and Middle Ear,” Auris
Nasus Larynx, Vol. 33, No. 3, 2006, pp. 251-257.
http://dx.doi.org/10.1016/j.anl.2005.11.012
[7] M. Varyberg and R. T. Sataloff, “Hearing Loss. Chapter
21. Squamous Cell Carcinoma of Temporal Bone,” R. T.
Sataloff and J. Sataloff, Eds., Taylor & Francis, New
York/London, 2005, pp. 545-571.
[8] H. Sugimoto, M. Ito, M. Hatano, S. Kondo, S. Suzuki and
T. Yoshizaki, “Roles of Epithelial-Mesenchymal Transi-
tion in Squamous Cell Carcinoma of the Temporal Bone,”
Otology & Neurotology, Vol. 32, No. 3, 2011, pp. 483-
487. http://dx.doi.org/10.1097/MAO.0b013e31820d9654
[9] L. S. Pemberton, R. Swindell and A. J. Sykes, “Primary
Radical Radiotherapy for Squamous Cell Carcinoma of
the Middle Ear and External Auditory Canal: An Histori-
cal Series,” Journal of Clinical Oncology, Vol. 18, No. 5,
2006, pp. 390-394.
http://dx.doi.org/10.1016/j.clon.2006.03.001
[10] A. R. Birzgalis, A. O. Keith and W. T. Farrington, “Ra-
diotherapy in the Treatment of Middle Ear and Mastoid
Carcinoma,” Clinical Otolaryngology and Allied Sciences,
Vol. 17, No. 2, 1992, pp. 113-116.
http://dx.doi.org/10.1111/j.1365-2273.1992.tb01055.x
[11] R. K. Gurgel, L. H. Karnell and M. R. Hansen, “Middle
Ear Cancer: A Population-Based Study,” Laryngoscope,
Vol. 119, No. 10, 2009, pp. 1913-1917.
http://dx.doi.org/10.1002/lary.20202
[12] R. R. Gacek and M. Goodman, “Management of Malig-
nancy of the Temporal Bone,” Laryngoscope, Vol. 87, No.
10, 1977, pp. 1622-1634.
http://dx.doi.org/10.1288/00005537-197710000-00003
[13] J. G. Spector, “Management of Temporal Bone Carcino-
mas: A Therapeutic Analysis of Two Groups of Patients
and Long-Term Followup,” Otolaryngology-Head and
Neck Surgery, Vol. 104, No. 1, 1991, pp. 58-66.
[14] L. Pfreundner, K. Schwager, J. Willner, K. Baier, K.
Bratengeier, F. X. Brunner, et al., “Carcinoma of the Ex-
ternal Auditory Canal and Middle Ear,” International
Journal of Radiation Oncology*Biology*Physics, Vol. 44,
No. 4, 1999, pp. 777-788.
[15] T. Nakagawa, Y. Kumamoto, Y. Natori, H. Shiratsuchi, S.
Toh, Y. Kakazu, S. Shibata, T. Nakashima and S. Ko-
mune, “Squamous Cell Carcinoma of the External Audi-
tory Canal and Middle Ear: An Operation Combined with
Preoperative Chemoradiotherapy and a Free Surgical
Margin,” Otology Neurotology, Vol. 27, No. 2, 2006, pp.
242-249.
http://dx.doi.org/10.1097/01.mao.0000190463.88873.3d
[16] Y. Ueda, T. Kurita, Y. Matsuda, S. Ito a nd T. Naka shima,
“Superselective, Intra-Arterial, Rapid Infusion Chemo-
therapy for External Auditory Canal Cartinoma,” The
Journal of Laryngology & Otology, Vol. 123, No. S31,
2009, pp. 75-80.
http://dx.doi.org/10.1017/S0022215109005143
[17] J. E. Medina, A. O. Park, G. L. Neely, et al., “Lateral
Temporal Bone Resection,” American Journal of Surgery,
Vol. 160, No. 4, 1990, pp. 427-433.
http://dx.doi.org/10.1016/S0002-9610(05)80559-8
[18] R. T. Sataloff, D. L. Myers, L. D. Lowry and J. R.
Spiegel, “Total Temporal Resection for Squamous Cell
Carcinoma,” Otolaryngology-Head and Neck Surgery,
Vol. 96, No. 1, 1987, pp. 4-14.
[19] M. Ito, M. Hatano and T. Yoshizaki, “Prognostic Factors
for Squamous Cell Carcinoma of the Temporal Bone:
Extensive Bone Involvement or Extensive Soft Tissue In-
volvement?” ActaOto-Laryngologica, Vol. 129, No. 11,
2009, pp. 131-139.
Open Access IJOHNS
T. UGUMORI ET AL.
Open Access IJOHNS
227
http://dx.doi.org/10.3109/00016480802642096
[20] S. Prasad and I. P. Janecka, “Efficacy of Surgical Treat-
ments for Squamous Cell Carcinoma of the Temporal
Bone: A Literature Review,” Otolaryngology-Head and
Neck Surgery, Vol. 110, No. 3, 1994, pp. 270-280.
http://dx.doi.org/10.1016/S0194-5998(94)70769-3