**7.3 Radiotherapy**

It has been stated that conventional osteosarcoma is relatively resistant to RT; however, RT may have the positive effect of reducing the rate of local recurrence [41, 42].

Generally, radiotherapy (RT) is indicated only in HNOS patients who have close or positive resection margins [6], as the combined treatment of surgery and radiotherapy has shown to have impact on local control and on disease-free survival on HNOS

### **Figure 9.**

*Appearance 6 months after treatment (surgery and chemotherapy) of patient presented in* **Figure 1***, a 35-year-old female with a maxillary chondroblastic osteosarcoma.*

### *Perspective Chapter: Osteosarcomas of the Head and Neck DOI: http://dx.doi.org/10.5772/intechopen.107456*

patients with unknown or close margins [10]. However, its impact on overall survival has evidenced conflicting results [43].

Guadagnolo et al. studied on 119 patients, of which 92 underwent surgery alone and in the other 27 cases surgery was followed by RT [10]. They revealed on a multivariate analysis that only the margin status predicted overall survival. Analysis by resection margin status demonstrated that the combined use of surgery and 55–60 Gy dose radiotherapy was superior to surgery alone and could improve overall survival (80 vs. 31%) and disease-free survival (80 vs. 35%) in patients with positive or uncertain margins. Moreover, the addition of adjuvant RT did not improve local control for those with negative margins but did improve local control for those with positive or uncertain margins, concluding that this high-risk group is inclined to get the best results, while no advantage is expected for patients with negative margins. However, the rates of RT-associated complications were 40% and 47% at 5 years and 10 years, respectively, and severe RT complications were observed in five (19%) of 27 patients.

In addition, while the evidence supports the use of RT in patients with positive or uncertain surgical margins, the role of combined adjuvant chemoradiotherapy is not established [10]. Some experts alternatively offer chemoradiation, typically with concurrent cisplatin as a radiosensitizer [41], extrapolating from the treatment approach used for squamous cell carcinoma of the head and neck. However, since there are limited data to support the use of chemoradiation in HNOS, the decision to use it should be made in a multidisciplinary setting. If both adjuvant chemotherapy and RT are being used, some groups chose to delay RT until the end of adjuvant chemotherapy.

The optimal dose for RT on HNOS is probably similar to that used for carcinomas and is the one commonly reported to be used in different series.

The use of heavy-particle radiation such as proton beam or carbon ion therapy is promising, particularly in patients with unresectable HNOS [44]. Proton therapy may offer some benefit to those with skull base lesions, allowing to reduce the dose to the eye and central nervous system, decreasing the risk of long-term complications [6].

There is also concern for increased risk of long-term complications of adjuvant chemotherapy and radiotherapy, including development of secondary malignancies [5, 10].

In summary, key points in the treatment of HNOS:

• The treatment for HNOS cannot be extrapolated directly from that of OS in extremities, due to substantial differences in its biological behavior.

The rationale of implementing neo/adjuvant chemotherapy is always questioned as it has a notoriously lower rate of distant metastasis, and the need for a complete resection becomes increasingly important as it has greater failure due to local recurrence.

