Th e aim of adjuvant radiotherapy is to improve locoregional control and survival following surgi- cal resection. Th e addition of radiotherapy follow- ing surgery compared with surgery alone has shown improved locoregional control rates (Mishra et al ., 1996 ; Lavaf et al. , 2008 ). Studies have identifi ed a number of primary tumour and lymph node patho- logical features which are associated with increased risk of locoregional recurrence; these may be classi- fi ed as ‘intermediate’ and ‘high’ risk features as shown in Table 11.7 .
Most centres in the UK currently use a total dose of 60 Gy in 30 fractions given over 6 weeks. A boost dose (typically of 5–6 Gy) is used at some centres in patients with either positive primary tumour margins and/or extracapsular spread (ECS) of nodal disease. Adjuvant radiotherapy should start within 5 weeks of surgery, as overall treatment time from the date of surgery to completion of adjuvant radiotherapy (< 11 weeks ver- sus > 13 weeks) has been shown to reduce local control from 76% to 38% (Ang et al ., 2001 ).
Concurrent cisplatin with postoperative radiother- apy showed 12% and 10% improvement in locoregional control, 11% and 9% improvement in disease-free
Table 11.7 Pathological risk factors for recurrence following head and neck cancer surgery
Factor Intermediate-risk factors High-risk factors
Primary tumour factors Advanced tumour (T) stage (T3/T4) Close margin (defi ned as tumour present < 5 mm and > 1 mm from resection margin)
Perineural invasion
Lymphovascular space invasion
Positive margin (defi ned as tumour present at or < 1 mm from resection margin)
Lymph node factors Two or more positive lymph nodes Nodes greater than 3 cm
Multiple lymph node level involvement
Extracapsular spread (ECS) of nodal disease
11: Management of cancer of the head and neck
anatomical approach to outlining is used. Alternatively, these regions can be included in CTV2 and/or can be omitted altogether if a purely geometric (or volumetric) approach to outlining is used.
Step 3: Delineate elective clinical target volume
(CTV2)
Th is volume varies with the site of the primary and the status of the neck and usually consists of unin- volved at-risk nodal levels in the neck (unilateral or bilateral) to be treated to a prophylactic dose. Levels Ib to Vb are irradiated in most node-positive cases and other lymph node levels are included in CTV2 depending on which nodal level(s) are involved, as shown in Table 11.8 . In a node-negative neck, selec- tive neck irradiation is considered when the risk of involvement is more than 15–20% and usually includes level II–IV in most subsites, but can vary with site of primary.
Step 4: Delineate organs at risk (OAR)
Th e OARs are classifi ed as serial and parallel organs. Serial organs such as spinal cord and brain- stem are routinely outlined in all head and neck tumours with others (optic chiasm, optic nerves) outlined as required depending upon the site of the primary and the extent of treatment fi elds. Parallel organs such as parotids and mandible are routinely outlined with other areas/structures (oral cavity, larynx, oesophagus, lacrimal gland, retina) on a patient-by-patient basis.
Step 5: Create planning target volume (PTV) and
planning risk volume (PRV)
Th e PTV/PRV is generated geometrically by the planning system and the margin used varies from centre to centre to ensure adequate CTV coverage. Th e magnitude of this volume depends upon accur- acy of the immobilisation systems, day-to-day set-up Patients lie supine with appropriate head rest and
knee support. A fi ve-point immobilisation system is normally used which includes head, neck and both shoulders. Th e position of the chin is normally neutral and the shoulders are kept as low as possible. Patients undergo a planning CT scan in the treatment position with the thermoplastic shell usually with intravenous contrast to aid accurate delineation of targets. CT slice thickness varies between 2 and 4 mm .
Target volume delineation
Target delineation requires a detailed knowledge of cross-sectional anatomy. With the use of multiple dose levels to treat diff erent regions, it is important to name each volume according to an agreed departmental protocol. Th e delineation process can be staged in fi ve steps both in the defi nitive and postoperative setting. Th e steps detailed here are for two dose levels, CTV1 (high dose) and CTV2 (prophylactic dose).
Target delineation in the primary/defi nitive setting Step 1: Delineate gross tumour volume (GTV)
Th is includes outlining both primary tumour (GTVp) and all involved nodes (GTVn). Th e primary is outlined with the knowledge of all available infor- mation (diagnostic imaging (CT, MRI and PET-CT if available) and clinical examination fi ndings including pan endoscopy, the best modality to assess the mucosal extent of disease.
Co-registration of diagnostic images (CT, MRI or PET-CT) with planning CT aids in delineating the GTV accurately.
Step 2: Delineate clinical target volume (CTV1) Th is CTV includes the GTVp and GTVn with a 1 cm isotropic expansion in all directions, adjacent high-risk regions and whole involved nodal level(s) in the neck and is delineated using the following steps. • Add a 1 cm isotropic margin in all directions to
GTV primary and GTV nodes. A 1.5 cm margin may be used around poorly defi ned primary tumours (e.g. in the tongue base).
• Edit out natural tissue planes (bone, air cavities and fasciae).
• Include the entire involved nodal level(s) according to the consensus guidelines as in Table 11.3 .
• CTV1 may be extended to include adjacent high-risk regions (e.g. parapharyngeal spaces; remaining oropharynx/larynx, etc.) if an
Table 11.8 Prophylactic neck irradiation for head and neck cancers
Level involved
Levels to include in prophylactic dose
Any level (I to IVa) Level Va and Vb
II Ib and VII b (retrostyloid nodes) IVa and/or V (Va and
Vb)
IVb (medial supraclavicular group) and Vc (lateral supraclavicular group)
Step 3: Delineate elective clinical target volume (CTV2)
Th is includes all uninvolved nodal levels in the dissected neck and other at-risk nodal levels as in Table 11.9 .
Steps 4 and 5 are the same as those in the defi nitive setting described above .
Setting objectives/constraints and order of priorities Th is step is essential for inverse planning and is required to achieve an optimal plan. An objective is a parameter desired to be met where compromise may be an option, while a constraint is a parameter that must be met where compromise is not an option. A planning risk volume is added to all OARs, and priorities are individualised for each patient.
Normally constraints to serial OARs are set at the highest priority and the maximum dose to these organs cannot exceed a predetermined level, even to achieve PTV coverage (there are exceptions to this). Th e next priority is to achieve PTV coverage, followed by object- ives for dose to the parotid gland and other OARs. On occasions, the dose to the parotid gland on the unin- volved contralateral neck is prioritised at the expense of the PTV coverage. Table 11.9 shows the dose con- straints for various OARs in the head and neck region with the respective endpoints. Th e accepted standard level of risk is 5% complication rate at 5 years (TD-5/5). Planning
All patients undergoing radical radiotherapy are con- formally planned usually in a single phase (forward or inverse planned) and most centres in the UK now use intensity-modulated radiotherapy (IMRT) to treat a majority of curative intent head and neck cancer patients. Intensity modulation is delivered using a step variation and is normally between 3 and 5 mm, grown
isotropically in all directions. Each CTV is grown to create respective PTV and all serial OAR are grown to create respective planning risk volume (PRV). Target delineation in the postoperative setting
Th e following steps are a guide to delineate target volumes in this setting and are based on the general principles of radiotherapy in the defi nitive setting. Th e postoperative histology report and intraoperative fi ndings aid in outlining the at-risk regions accurately. Step 1: Re-create preoperative primary and nodal
gross tumour volume (‘GTVp’ and ‘GTVn’)
Th e position of the primary and involved node(s) is re-created on the planning CT scan. Th e accuracy of this step is improved with the aid of co-registration of diagnostic scans (CT, MRI and/or PET-CT). Th e vol- umes are labeled ‘GTVp’ and ‘GTVn’.
• Edit ‘GTVp’ and ‘GTVn’ as necessary, based on the postoperative change in anatomy.
• Add 1- to 1.5-cm isotropic margin in all directions to ‘GTVp’ to create CTVp.
• Add 1-cm isotropic margin in all directions to ‘GTVn’ to create CTVn.
Step 2: Delineate clinical target volume (CTV1) Th is clinical target volume includes the primary and nodal tumour bed with a margin and all patho- logically involved nodal levels.
• Edit the volumes CTVp and CTVn for anatomical barriers such as bone, fascia and air.
• Extend CTVn to include all pathologically involved nodal levels according to the consensus guidelines.
• Extend this volume to include seromas and any other postoperative changes.
Table 11.9 Radiation dose constraints for organs at risk
OAR Dose Endpoint
Spinal cord PRV Max 48 Gy Myelopathy
Brainstem PRV Max 54 Gy Necrosis
Optic nerve PRV Max 50 Gy Neuropathy
Optic chiasm PRV Max 50 Gy Visual loss
Retina PRV Max 45 Gy Scotomas/visual fi eld loss
Lens PRV Max 8 Gy Cataract
11: Management of cancer of the head and neck
and 12% at 3 years) experience long-term feeding tube dependence aft er treatment, which has reduced con- siderably in the current IMRT era to less than 5% at 2 years.
Increasing treatment conformality, reducing radio- therapy dose and substituting chemotherapy with biological agents are all being investigated as ways to reduce the long-term consequences of treatment on swallowing.
Management of acute reactions
Skin : unguentum is used for the aff ected areas (patchy moist desquamation) while continuing with regular moisturising cream (e.g. Epaderm®) to the unaff ected regions. Confl uent desquamation needs a moist wound management system such as Intrasite Gel®, a topical application that helps to maintain the moisture and aids in wound debridement or alternatively a polymem dressing when there is a large area of skin ulceration.
Mucous membrane : all patients develop mucositis (oral and/or pharyngeal) during the course of radio- therapy, the severity varying from patient to patient. Th e management consists of:
• maintaining scrupulous oral hygiene by brushing the teeth twice with soft brush and rinsing the mouth regularly with saline;
• Caphosol® mouth rinse (calcium and phosphate
ions) can prevent and reduce the duration and pain of oral mucositis;
• benzydamine mouth wash, a topical, non-steroidal anti-infl ammatory drug with analgesic and anaesthetic properties to control pain;
• systemic analgesics according to the WHO pain ladder;
• topical mucoprotectant such as Gelclair®, MuGard®, Episil®;
• treat super-added infection (bacterial or fungal) if present;
• avoid smoking, alcohol and certain foods (citrus, spicy, hot and hard);
• avoid chlorhexidine mouth wash, as this may inhibit the re-growth of the mucosa.
Xerostomia : artifi cial saliva preparations can be used to help with this symptom (AS Saliva Orthana®, Gladosane®, Biotène® oral balance gel).
Odynophagia : analgesics according to the WHO pain ladder and the use of soft , pureed diet and sup- plements (given orally or via nasogastirc and/or and shoot technique or more recently using dynamic
volumetric-modulated arc therapy (VMAT).
Table 11.10 shows an example of PTV objectives that are normally used to assess a plan quantitatively.