Total resection is recommended due to the rare
malignant potential of CBTs. Resection can be
technically difficult in patients with a larger tumor
size and, particularly, in cases with Shamblin type 3.
Detection of the tumor when it is of small size results
in favorable surgical outcomes, whereas a scarce
number of clinical symptoms in the early period may
lead to the establishment of the diagnosis of these
tumors in the long-term when they reach larger sizes.
In this study, almost half of the patients had tumors
larger than 4 cm. Surgical risk is higher in patients
with Shamblin type 3 CBTs and, particularly, in
cases with large tumoral masses. We believe that
the major challenge in CBT management is the late
referral of patients to surgery due to the difficulties
in diagnosis.
Histopathological analysis of the tumor reveals a
weak malignant potential in 5% of glomus tumors.
Therefore, malignancy is defined only by the presence
of distant metastases.[10] In this study, any evidence of
malignancy was not found in the follow-up period
of patients. There is a familial predisposition in
7 to 9% of the cases.[2] In this study, family history
was obtained in only four (7.27%) patients. In this
series, 35 women (63.6%) and 20 men (36.6%) were
included. Bilateral CBTs were seen in 10% of the
cases. In this report, these rates are consistent with
the literature (9.1%) (Figure 3).[2]
Figure 3: Computed tomography image showing bilateral
carotid body tumors.
The risk of cranial nerve paralysis has been
reported at a rate of 10 to 40% in surgical resection of
CBTs.[11,12] Therefore, the risk of serious complications
after surgical treatment appears to be an important
factor in decision-making for each individual patient.
In our study, this rate was 18.2%.
Surgery is the definitive treatment method in the
management of CBTs, but conservative approaches
or radiotherapy can be also used in these patients.[13]
Despite the satisfactory results of the early grade of
tumors, Shamblin type 3 tumors and tumors larger
than 4 cm remain challenging cases for surgeons.
Some attempts have been considered to facilitate
surgery and reduce the associated complications. In
the 1980s, considering the tumor receiving the blood
supply from the ECA, devascularization of the ECA
was suggested.[14,15] Contrary to this assumption, in our experience, ligation of the ECA does not often
reduce blood loss and does not facilitate dissection of
the bifurcation.
Preoperative embolization before CBT surgery
has become to be a current trend to reduces tumor
size, surgical bleeding, and resection related
complications.[16] However, the effectiveness of
embolization is still controversial.[17] With the
advances in endovascular surgery and prevalent use
of coated stents, the collaterals of the tumor fed from
the ECA have been bypassed, leaving the tumor to
shrink or even disappear. These limited case reports
suggest that without the use of intra-arterial gel
foams, the risk of peri-procedural stroke may be
reduced.[14] However, these techniques are rarely
used. In our study, we did not use any of the
aforementioned techniques.
Although external radiotherapy is still a
controversial treatment option, it can be used in patients
in whom CBTs cannot be surgically removed.[18,19]
It has been demonstrated that radiotherapy slows
down or temporarily stops tumor growth, but it is
not a curative approach.[19] In addition, in inoperable
elderly patients and patients with multisystemic
disease, considering the slow growth rates of their
CBTs, watchful waiting or external radiotherapy may
be a more appropriate treatment method.[20,21] The
long-term results of this treatment have not been
shown, yet. Although radiotherapy is an appropriate
approach for elderly patients, it is not a sufficient
treatment for the young age group.[22,23] In our seven
patients, radiotherapy was used due to inadequate
resection or disease recurrence.
In the treatment of Shamblin type 1 and 2 CBTs,
removal of the tumor with careful subadventitial
dissection is preferred. In type 3 tumors,
reconstruction of the ECA or ICA may be required.
If massive bleeding occurs in type 3 tumors, the
mass can be removed by clamping the arteries and,
in the event of further damage occurring during the
procedure, vascular reconstruction may be indicated.
While eight of our patients required reconstruction,
in three cases, ECA was ligated due to bleeding.
Surgical removal of the tumor should be definitely
preferred in patients with Shamblin type 3 tumors,
and in patients under 50 years of age with long life
expectancy.[4,24]
This study has several limitations that are inherent
due to the retrospective design. We were unable to perform preoperative embolization to any patient
during our study period. In particularly, the high
complication rates in Shamblin type 3 class patients
may indicate the need for pre- or intraoperative
devascularization strategies in this patient group.
In addition, the low number of Shamblin type 3 patients
in the study period may have caused the complication
rates in this patient group to be overestimated.
In conclusion, we believe that Shamblin type 1
and type 2 tumors can be treated safely with surgery
and, since type 3 tumors are associated with high
cranial nerve damage and high complication rates,
a special attention is required during surgery, and
radiotherapy would be a treatment alternative in cases
with recurrent tumors and metastases.
Declaration of conflicting interests
The author declared no conflicts of interest with respect
to the authorship and/or publication of this article.
Funding
The author received no financial support for the research
and/or authorship of this article.
){kind=link}
){kind=link}
){kind=link}
){kind=link}
){kind=link}
){kind=link}
){kind=link}