10 General Aspects of Head and Neck Brachytherapy

General Aspects of Head and Neck Brachytherapy

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THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 30/01/2019

5.1.2. Regional Nodal status should be determined in all cases. Clinical examination and CT/MRI imaging is helpful in classifying patients into a group of clinically-negative (cN0) and clinically-positive necks (cN+). Since the predictive ability of clinical-radiological assessment is limited, the majority of cN0 patients with deeply invasive lesions will require a surgical assessment of nodal status. A few cN0 cases may be spared froma surgical exploration if the tumor is superficial (i.e, invasion beyond the lamina propria of 2mm or less) or if the probability of nodal spread calculated as a function of location, size and grade is minimal (i.e, <5%).

be evaluated by an experienced anesthesiologist in the clearance visit prior to implantation. Precautions to maintain the patency of the airway in case of bleeding at insertion, at removal or due to postimplant edema are mandatory. Since most implants are performed under general anesthesia in an anesthesiologist-controlled scenario, bleeding during catheter insertion should rarely compromise the airway. However, extensive implants located in the posterior oral cavity or the oropharynx can cause life-threatening edema and bleeding during the postimplant period or at removal and precautionary measures such as a temporary tracheostomymay be required. Some radiation oncologists use an individual silk thread tied to each of the catheters implanted and secured with tape at the patient´s lip commissure to facilitate implant removal in case of emergency. 6.1. Brachytherapy alone Brachytherapy alone remains an acceptable mode of treatment in a) intact T1 and small T2 tumours with low risk of lymph node involvement that are located in areas of functional importance (lip, commisure, vestibulumnasi ,etc.) or b) cosmetic relevance such as the periorificial zone (eyelids, pinna, ears, etc.). Ninety percent of the cases described above are locally controlled after LDR/PDR doses of 60–70 Gy with hourly doses in the 0.4–0.7 Gy range [9] . These results underline the similar efficacy of brachytherapy compared to surgery in node-negative T1-T2 cancers. In addition, c) exclusive HN BT can also be a reasonable option for advanced lip tumors. Brachytherapy alone should also be considered when there exists a d) medical contraindication for radical surgery or e) in cases of small lesions (< 3cm) arising in a previously irradiated field with dose and volume adjustments aimed to minimize potential complications derived from cumulative dose. The combination of EBRT or chemoradiation and brachytherapy for HN tumors follows the same principles applied in other tumor sites treated with combined modality therapy such as advanced cervical cancer. Brachytherapy is used as a boost one or two 2 weeks after the completion of EBRT or cisplatin-based chemoradiation. If brachytherapy is used as a boost, the overall treatment time should be kept similar to that elapsed with external irradiation alone (preferrably within 7 weeks). Combined EBRT and brachytherapy is an acceptable mode of treatment in a) patients unsuitable for surgery with intact clinical T1-2N0 tumors that present a substantial risk of lymph node involvement or in b) advanced T3-4 and/or N+ tumors that would require surgical resections with functional or cosmetic impact (i.e. cheek, base of tongue, etc.) provided that the residual lesion after EBRT is accessible and can be adequately covered with a HN BT implant. Combined EBRT and brachytherapy may also be a reasonable treatment option in c) patients who may require high radiation doses that are precluded by the proximity of the lesion to dose-sensitive structures such as the swallowing apparatus [10]. In these later cases, a benefit of a brachytherapy boost over an EBRT 6.2.BrachytherapycombinedwithExternal Irradiation or Chemoradiation 6. CLINICAL INDICATIONS OF HN BT

5.2. Metastatic workup 5.2.1. Baseline assessment

Most tumors considered for HNBT alone (cT1, 2-N0) will require at least a chest CT to rule out lung metastases or a second cancer. Patients withmore advanced disease (cT3, 4 and/or N+) in whom HN BT is being considered as a boost after EBRT or patients with recurrent lesions may require a more extensive workup including FDG-PET/CT.

5.3. Non-oncological assessment 5.3.1. Dental care

An evaluation of oral hygiene and dental status should always be made by a odontologist well trained in head and neck oncology. Mandibular panoramic radiographs or CT are indicated and provide information about the height and the structure of the mandible as well as radiographic evidence of bone destruction [8]. Teeth with caries should be restored. Teeth with deep caries or poor periodontal support must be removed and complete healing obtained before starting radiotherapy, although this would require at least two weeks and must be counterbalanced with the oncological status of the patient. 5.3.2. Nutritional assessment An evaluation of the patient nutritional status needs to be made by a nutritionist before HN BT as in any other head and neck patient that is being evaluated to receive irradiation. Some patients may have a recent history of weight loss induced by tumor-related dysphagia. In the most severe cases, a high calorie hypercaloric diet, dietary supplements and hyperhydration must be done before brachytherapy. Parenteral feeding may be an option in severe cases of malnourishment. In average cases, care must be taken in scheduling an adequate oral/feeding tube intake during the duration of brachytherapy and during the subsequent weeks until the swallowing function returns to normal. Percutaneous gastrostomy may be an option to allow outpatient management in patients who do not tolerate feeding tubes and in whom return to adequate oral intake is presumably long. 5.3.3. Airway assessment and protection As mentioned before, HNBT requires a preimplantation evaluation of the status of the airway due to anesthetic needs, risk of hemorrhage during catheter insertion or at removal and risk of postimplant edema leading to impaired ventilation. Most implants in the head and neck area benefit fromnasotracheal intubation because traditional orotracheal intubation, although manageable, may limit maneuverability within the oral cavity and the oropharynx. If this is the case, nasotracheal intubation must