Chondrosarcomas (CSs) are malignant bone tumors which develop as a cartilaginous differentiation of primary mesenchymal cells. It is the second most frequently seen malignant tumor of the bone after osteosarcoma and rarely (1% - 12%) observed in head and neck (HN) region. In this region, it has been reported frequently in larynx, maxilla and skull base and rarely seen in nasal cavity [1] .

Primary treatment of HN CSs is radical surgery [2] . Neck dissection is not recommended because of low rates of regional lymph node involvement (5.6%) [1] . However, in surgically unresectable cases, chemotherapy and radiotherapy are main components of treatment. Some authors assert that since CSs are not a radiosensitive tumor, radiotherapy has no place in primary and adjuvant therapy [3] ; however, some of them suggest that radiotherapy provides acceptable outcomes [4] [5] . Besides, some authors think that different radiotherapy techniques such as Intensity Modulated Radiation Therapy (IMRT) or Proton Beam Radiation Therapy may yield diverse treatment outcomes [6] [7] . In this report, a patient with a diagnosis of inoperable low-grade CSs arising from nasal septum, which was treated using HT device, was presented.

A 71-year-old female patient consulted to outpatient clinic of Ear-Nose and Throat in 2013 with complaints of difficult nasal breathing, nasal stuffiness for nearly 10 years, gradual worsening of vision of the right eye and diplopia for 6 months. Anterior rhinoscopic examination detected a mass completely filling the nasal cavity. MRI of the patient demonstrated a mass in the left nasal cavity, extending into anterior cranial fossa, basis cranii, right orbita and left ethmoidal sinus with hypointense intensity on T1-weighted and heterogenous intensity on T2 weighted contrast-enhanced images (Figure 1). The mass contained irregular calcifications. Histopathological examination of the biopsy material excised from nasal cavity revealed tumoral mass formed by atypical chondrocytes demonstrating nuclear hyperchromasia and binucleationin the chondroid matrix, which was reported as low-grade CSs (Figure 2). Before initiation of

external radiotherapy visual field examination performed by the clinic of Eye Diseases, disclosed decreased visual acuity of the right eye and diplopia. The patient was evaluated in our clinic, treatment using HT device was decided. Tumor volume, clinical target volume and critical organs were contoured. Extreme proximity of the tumor to vital organs such as optic nerve, optic chiasm and brain and its invasion into the right orbita and skull base made treatment planning process complicated. For better protection of critical organs; treatment plan was prepared using a Simultaneous Integrated Boost technique (Figure 3). Treatment planning of the patient was created using HT planning system (Accuray Inc., Madison, USA). In this planning a field width of 2.5 cm, a pitch of 0.287 and a modulation factor of 2.0 were used during optimization and dose calculation (Table 1). The patient was treated to 64 Gy in 32 fractions using HT device.

Control examination performed at 3 Month after radiotherapy demonstrated that visual acuity of the patient’s right eye and diplopia recovered almost complete. Partial regression in the dimensions of the lesion was observed on MRI obtained at 6 Month, while a marked regression was detected in the dimensions of the lesion on MRI obtained at 18 Month (Figure 4). The patient is still followed up by us and at control examination in June 2015 the patient did not report any complaint.

Chondrosarcomas are locally aggressive tumors, which rarely metastasize, and symptoms may change according to the size and location of the tumor. In localized HN CSs nodal and distant metastasis is rare [8] . CSs originating from nasal septum may generally manifest nonspecific symptoms as nasal obstruction, epistaxis, nasal discharge, in advanced cases with invasion into skull base, it may lead to symptoms of diplopia, proptosis, facial pain, headache, cranial nerve deficits, loss of vision and otalgia [9] [10] . Our patient complained of nasal obstruction gradually increasing for nearly 10 years and decreased visual acuity of the right eye persisting for the last 6 months and diplopia. In cases with CSs arising from nasal septum, as it is seen in our patient, disease

progresses with nonspecific symptoms so diagnosis can be made only after onset of marked eye symptoms following invasion of the skull base or clinical signs signifying involvement of cranial nerves.

Surgical resection was accepted as a standard treatment for the treatment of head and neck CSs. Type of surgery depends on the histological grade, spread and location of the tumor. The objective of surgery is to perform gross total resection so as to obtain a tumor-free surgical margin. However, in tumors involving skull base, achievement of tumor-free surgical margin could not be ensured in most of the cases [11] [12] .

Effectiveness of radiotherapy in these patients as a monotherapy has been reported and applicability of radiotherapy has been indicated if radical surgery is the only curative alternative [8] . In conclusion radiotherapy can be used for postsurgical residues, palliation of unresectable tumors or patients not suitable for major surgery. Also our patient was considered as an inoperable case because of tumor invasion into the right orbita and skull base, so radiotherapy was applied.

Various arguments exist about CSs localized on HN region. Since this tumor slowly progresses and consists of cartilage and connective tissue, it has a low level of radiosensitivity and it is considered relatively radioresistant. We also know that these types of tumors have smaller α/β ratios and yield a quadratic and delayed response to radiotherapy.

In our case, although clinical improvement was detected at an early time from treatment, radiological response manifested itself on MRI obtained at 18 month with marked regression in the dimensions of the lesion (Figure 4). As a result, radiotherapy is frequently used for cases not amenable to surgical excision or cases with surgical margin positivity. In a study by Sahgal et al. the researchers followed up 18 patients with CS treated with IG-IMRT method and reported 5-year overall survival and local control rates as 87.8% and 88.1%, respectively [6] .

IG-IMRT method using HT enables treatment of the patients. As another modality of External Beam Radiation Therapy, Proton Beam Radiation Therapy, which utilizes therapeutic effects of accelerated proton particles, is used successfully in the treatment of the tumors of paranasal sinus and skull base. In the future, Intensity Modulated Proton Therapy (IMPT) technique can enable the treatment of head, neck and skull base tumors [7] .

In our study, we performed in patients with diagnosis of low-grade CS of head and neck region who have not any chance of surgery because of its close vicinity to critical organs; we recommend application of IG-IMRT method using HT device.

The English in this document has been checked by at least two professional editors, both native speakers of English.

Basaran, H., Koca, T., Karaca, S., Kılınc, O.E., Karauc, F.G., Özdemir, O., Kuduban, O., Tatar, A. and Şipal, S. (2016) Treatment of Massive Low- Grade Chondrosarcoma of Nasal Septum with Helical Tomotherapy: A Case Report. International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 5, 263-269. http://dx.doi.org/10.4236/ijmpcero.2016.54026