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Technical advances and pitfalls in head and neck radiotherapy.

Parvathaneni U, Laramore GE, Liao JJ - J Oncol (2012)

Bottom Line: However, these benefits come with a serious and sobering price.Proton therapy has a theoretical physical advantage over photon therapy due to a lack of "exit dose".The purpose of this article is to review the literature, discuss the salient issues and make recommendations that address the gaps in knowledge.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, University of Washington, Seattle, WA 98195, USA.

ABSTRACT
Intensity Modulated Radiotherapy (IMRT) is the standard of care in the treatment of head and neck squamous cell carcinomas (HNSCC) based on level 1 evidence. Technical advances in radiotherapy have revolutionized the treatment of HNSCC, with the most tangible gain being a reduction in long term morbidity. However, these benefits come with a serious and sobering price. Today, there is a greater chance of missing the target/tumor due to uncertainties in target volume definition by the clinician that is demanded by the highly conformal planning process involved with IMRT. Unless this is urgently addressed, our patients would be better served with the historically practiced non conformal radiotherapy, than IMRT which promises lesser morbidity. Image guided radiotherapy (IGRT) ensures the level of set up accuracy warranted to deliver a highly conformal treatment plan and should be utilized with IMRT, where feasible. Proton therapy has a theoretical physical advantage over photon therapy due to a lack of "exit dose". However, clinical data supporting the routine use of this technology for HNSCC are currently sparse. The purpose of this article is to review the literature, discuss the salient issues and make recommendations that address the gaps in knowledge.

No MeSH data available.


Related in: MedlinePlus

Typical beam arrangement applied for treating HNSCC of oropharynx with HRT on left using opposed lateral beams treating the primary site and upper cervical nodal regions compared with multiple beam angle arrangements employed for IMRT on right. The opposed beams do not treat through the oral cavity or the posterior scalp, and hence mucositis, is not seen in the lips and anterior oral cavity. With IMRT mucositis may be seen in the lips as well as hair loss which is observed in the posterior scalp.
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fig2: Typical beam arrangement applied for treating HNSCC of oropharynx with HRT on left using opposed lateral beams treating the primary site and upper cervical nodal regions compared with multiple beam angle arrangements employed for IMRT on right. The opposed beams do not treat through the oral cavity or the posterior scalp, and hence mucositis, is not seen in the lips and anterior oral cavity. With IMRT mucositis may be seen in the lips as well as hair loss which is observed in the posterior scalp.

Mentions: The most prevalent and a highly distressing long-term complication after radiotherapy for HNSCC is xerostomia [4]. In addition to a subjective perception of a dry mouth that is unpleasant for most, lack of saliva also makes it difficult to speak, swallow, taste, chew, and wear dentures. It may contribute to nutritional deficiencies, predisposing to painful mucosal fissures and ulcerations, and adversely affects oral health, promoting dental caries, and the consequential dental extractions may contribute to osteoradionecrosis. Xerostomia is associated with significant deterioration in the patient's quality of life [4]. In selected patients IMRT can successfully spare the salivary glands mitigating these debilitating effects of xerostomia. Prospective randomized clinical trials [1–3] have demonstrated that IMRT is significantly superior to HRT in sparing parotid glands and the consequential recovery of salivary function, reducing the incidence of xerostomia with marked improvements in associated quality of life. IMRT can also spare other normal structures such as cochlea, oral mucosa, temporomandibular joint, and mandible [5, 6]. IMRT is expected to reduce the frequency of osteoradionecrosis [7] and may decrease dysphagia by reducing the doses delivered to pharyngeal constrictor muscles [8]. Although IMRT allows for better conformity of the high-dose region to the tumor, it does so at the expense of delivering low doses to a greater volume of normal tissue. This “low dose spill” into nontarget structures may result in unexpected and unintuitive short-term toxicity from IMRT including alopecia and acute mucositis in locations that were not in the beam pathways of HRT due to the multiple beam angle arrangements employed for IMRT as seen in Figure 2. Nausea from dose to brain stem (area postrema) and increased acute fatigue compared to HRT have also been reported with IMRT [1, 9]. There is a theoretical long-term risk of increased radiation-induced secondary malignancies due to the greater whole body integral dose from this “low dose spill” [10].


Technical advances and pitfalls in head and neck radiotherapy.

Parvathaneni U, Laramore GE, Liao JJ - J Oncol (2012)

Typical beam arrangement applied for treating HNSCC of oropharynx with HRT on left using opposed lateral beams treating the primary site and upper cervical nodal regions compared with multiple beam angle arrangements employed for IMRT on right. The opposed beams do not treat through the oral cavity or the posterior scalp, and hence mucositis, is not seen in the lips and anterior oral cavity. With IMRT mucositis may be seen in the lips as well as hair loss which is observed in the posterior scalp.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3369487&req=5

fig2: Typical beam arrangement applied for treating HNSCC of oropharynx with HRT on left using opposed lateral beams treating the primary site and upper cervical nodal regions compared with multiple beam angle arrangements employed for IMRT on right. The opposed beams do not treat through the oral cavity or the posterior scalp, and hence mucositis, is not seen in the lips and anterior oral cavity. With IMRT mucositis may be seen in the lips as well as hair loss which is observed in the posterior scalp.
Mentions: The most prevalent and a highly distressing long-term complication after radiotherapy for HNSCC is xerostomia [4]. In addition to a subjective perception of a dry mouth that is unpleasant for most, lack of saliva also makes it difficult to speak, swallow, taste, chew, and wear dentures. It may contribute to nutritional deficiencies, predisposing to painful mucosal fissures and ulcerations, and adversely affects oral health, promoting dental caries, and the consequential dental extractions may contribute to osteoradionecrosis. Xerostomia is associated with significant deterioration in the patient's quality of life [4]. In selected patients IMRT can successfully spare the salivary glands mitigating these debilitating effects of xerostomia. Prospective randomized clinical trials [1–3] have demonstrated that IMRT is significantly superior to HRT in sparing parotid glands and the consequential recovery of salivary function, reducing the incidence of xerostomia with marked improvements in associated quality of life. IMRT can also spare other normal structures such as cochlea, oral mucosa, temporomandibular joint, and mandible [5, 6]. IMRT is expected to reduce the frequency of osteoradionecrosis [7] and may decrease dysphagia by reducing the doses delivered to pharyngeal constrictor muscles [8]. Although IMRT allows for better conformity of the high-dose region to the tumor, it does so at the expense of delivering low doses to a greater volume of normal tissue. This “low dose spill” into nontarget structures may result in unexpected and unintuitive short-term toxicity from IMRT including alopecia and acute mucositis in locations that were not in the beam pathways of HRT due to the multiple beam angle arrangements employed for IMRT as seen in Figure 2. Nausea from dose to brain stem (area postrema) and increased acute fatigue compared to HRT have also been reported with IMRT [1, 9]. There is a theoretical long-term risk of increased radiation-induced secondary malignancies due to the greater whole body integral dose from this “low dose spill” [10].

Bottom Line: However, these benefits come with a serious and sobering price.Proton therapy has a theoretical physical advantage over photon therapy due to a lack of "exit dose".The purpose of this article is to review the literature, discuss the salient issues and make recommendations that address the gaps in knowledge.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, University of Washington, Seattle, WA 98195, USA.

ABSTRACT
Intensity Modulated Radiotherapy (IMRT) is the standard of care in the treatment of head and neck squamous cell carcinomas (HNSCC) based on level 1 evidence. Technical advances in radiotherapy have revolutionized the treatment of HNSCC, with the most tangible gain being a reduction in long term morbidity. However, these benefits come with a serious and sobering price. Today, there is a greater chance of missing the target/tumor due to uncertainties in target volume definition by the clinician that is demanded by the highly conformal planning process involved with IMRT. Unless this is urgently addressed, our patients would be better served with the historically practiced non conformal radiotherapy, than IMRT which promises lesser morbidity. Image guided radiotherapy (IGRT) ensures the level of set up accuracy warranted to deliver a highly conformal treatment plan and should be utilized with IMRT, where feasible. Proton therapy has a theoretical physical advantage over photon therapy due to a lack of "exit dose". However, clinical data supporting the routine use of this technology for HNSCC are currently sparse. The purpose of this article is to review the literature, discuss the salient issues and make recommendations that address the gaps in knowledge.

No MeSH data available.


Related in: MedlinePlus