40Radiotherapy dose fractionation Third edition
6.
Head and neck cancer
Background
Intensity-modulated radiotherapy (IMRT) is the accepted standard radiotherapy for
patients undergoing primary and adjuvant radiotherapy for head and neck squamous cell
carcinomas; exceptions are T1/T2N0 glottic cancer and the use of low-dose palliative
radiotherapy. The international standard for denitive treatment remains 70 Gray (Gy) in
daily fractions of 2 Gy over seven weeks, although altered fractionation regimens have been
widely used. In the UK, many centres have adopted 65–66 Gy in 30 fractions over six weeks
as a standard regimen. Most centres employ a simultaneous integrated boost technique
with IMRT to treat all target volumes and elective lymph node regions to varying dose levels
in each fraction (rather than the use of multiple phases or a matched neck eld). This has
led to altered fractionation regimens for either high-dose or elective treatment volumes.
1
T1/2N0 glottic carcinoma
Hypofractionated regimens are recommended.
2
A randomised trial demonstrated the
superiority of modest hypofractionation with 2.25 Gy per fraction and, in large retrospective
series, fraction sizes of ≥2.25 Gy compared favourably with other reported series.
2–4
Several
UK series have reported high rates of local control with shorter more hypofractionated
schedules including 50–52.5 Gy in 16 fractions over three weeks for T1 disease and 55 Gy
in 20 fractions for T1 and T2 disease.
5–8
Hyperfractionated schedules have not shown a
signicant improvement compared with conventional fractionation.
9
Recommendations
63 Gy in 28 fractions over 5.5 weeks (Grade B)
50 Gy in 16 fractions over 3 weeks (T1 disease only) (Grade C)
55 Gy in 20 fractions over 4 weeks (Grade C)
The types of evidence and the grading of recommendations used within this review are based on
those proposed by the Oxford Centre for Evidence-based medicine.
10
Role of modied fractionation in head and neck squamous cell
carcinoma (HNSCC) (non-nasopharyngeal)
A meta-analysis of 15 trials of altered fractionation without chemotherapy in non-
nasopharyngeal head and neck squamous cell carcinoma (predominantly oropharynx
and larynx cancers) showed a modest benet in overall survival (3.4% at ve years)
and local control (6.4% at ve years).
11
The overall survival benet was mainly seen
with hyperfractionation (8.2% at ve years) although these schedules are dicult to
implement and are not widely used (Level 1a).
10
The Danish Head and Neck Cancer
Group (DAHANCA) regimen of six fractions per week showed an improvement of 10% in
ve-year locoregional control in patients treated without chemotherapy with transiently
increased acute toxicity.
12
In the meta-analysis the overall survival benet of acceleration
without a total dose reduction was 2% at ve years, and 1.7% at ve years with a total dose
reduction.
11
There was no benet of altered fractionation for patients age >70 years old
(Level 1b).
10,11
41Radiotherapy dose fractionation Third edition
Elective lymph node and mucosal doses with IMRT
A biological equivalent dose (EQD2) of 50 Gy in 25 fractions is a standard dose to electively
treat lymph node regions. Although there is no direct evidence of the need for higher doses
for microscopic disease, some centres favour the use of an additional ‘intermediate’ risk
higher elective dose, such as a biological equivalent to 60 Gy in 30 fractions, to regions
deemed to be at higher risk of harbouring disease, particularly radiologically equivocal
areas for nodal disease (Level 4).
10,13
In the management of head and neck carcinomas of unknown primary, commonly used
mucosal doses are the biological equivalent of 50–60 Gy in 25–30 fractions.
14–17
Several
series have suggested that doses at the lower end of this dose range are associated with
very low rates of subsequent emergence of a mucosal primary (Level 4).
10,15–17
To incorporate elective lymph node and mucosal doses into a single phase IMRT plan, two
approaches to dose fractionation can be adopted: i) accept moderate hypofractionation to
sites of known disease while retaining a conventional fraction size (1.8–2 Gy) for elective
lymph node treatment or ii) retain a conventional fraction size to known disease and deliver
a reduced fraction size to the elective lymph node regions (for example, 1.5–1.6 Gy). An
increasing number of series suggest that elective lymph node irradiation may be safely
delivered with a reduced fraction size (Level 4).
11,18
Recommendations
For elective nodal treatment using IMRT with a matched lower neck technique:
50 Gy in 25 fractions over 5 weeks to the matched neck (Grade C)
Elective treatment within the IMRT plan, the following dose levels
areappropriate:
54 Gy in 30 fractions over 6 weeks (Grade C)
56–57 Gy in 35 fractions over 7 weeks (Grade C)
60 Gy in 30 fractions over 6 weeks or 63 Gy in 35 fractions over 7 weeks may be
additionally used for ‘intermediate’ risk regions (Grade D)
The types of evidence and the grading of recommendations used within this review are based on
those proposed by the Oxford Centre for Evidence-based medicine.
10
Radiotherapy alone for early stage (I/II) oropharynx/hypopharnx/larynx
cancer (excluding T1/2 glottic carcinoma)
Single modality treatment with surgery or radiotherapy is the standard of care. The relative
merits of conventional versus altered fractionation remain unclear. IMRT with modest
acceleration has shown high rates of local control with low rates of late toxicity.
19
Patients
with early stage disease accounted for >50% of patients in the DAHANCA 6 and 7 trial
which demonstrated a substantial benet of shortening overall treatment time without
reduction in total dose (66–68 Gy in 33–34 fractions delivered at ve versus six fractions
per week).
12
In a meta-analysis, there was no clear benet for altered fractionation for the
subgroup with stage I/II disease (Level 1a).
10,11
42Radiotherapy dose fractionation Third edition
Recommendations
Stage I/II oropharynx, hypopharynx or non-glottic larynx cancer:
70 Gy in 35 fractions over 7 weeks (Grade C)
65–66 Gy in 30 fractions over 6 weeks (Grade C)
66 Gy in 33 fractions or 70 Gy in 35 fractions, 6 fractions per week over 6 weeks (Grade B)
The types of evidence and the grading of recommendations used within this review are based on
those proposed by the Oxford Centre for Evidence-based medicine.
10
Radiotherapy with concomitant chemotherapy for stage III/IVa/b
HNSCC (excluding nasopharyngeal carcinoma)
Radiotherapy with concurrent cisplatin is the current standard of care for the denitive
management of stage III/IV patients <70 years of age with adequate performance
status.
20
The international standard schedule is 70 Gy in 35 fractions.
20
Although not
directly compared, a modestly hypofractionated schedule of 65–66 Gy in 30 fractions
has been adopted as standard practice in a number of UK trials and centres.
21
There has
been considerable interest in combining perceived benets of altered fractionation with
concurrent chemotherapy. However, the Radiation Therapy Oncology Group (RTOG)
0129 trial compared 72 Gy in 42 fractions delivered over six weeks with two cycles of
concurrent chemotherapy with a standard arm of 70 Gy in 35 fractions over seven weeks
with three cycles of concurrent chemotherapy with no dierence seen between the arms.
22
The three arm Groupe d’Oncologie Radiothérapie Tête et Cou (GORTEC) 99-02 phase
III trial compared 70 Gy in 35 fractions over seven weeks with three cycles of concurrent
chemotherapy with 70 Gy over six weeks with two cycles of concurrent chemotherapy and
a very accelerated radiotherapy alone arm of 64.8 Gy in 3.5 weeks; there was no benet of
modest acceleration with concurrent chemotherapy while the accelerated radiotherapy
alone arm was inferior (Level 1b).
10,23
These data support a hypothesis that concurrent
cisplatin may suppress tumour repopulation during radiotherapy, leading to a lower than
expected tumour biologically equivalent dose with modestly accelerated schedules.
24
Reported outcomes for hypofractionated IMRT schedules with concomitant chemotherapy
(65 Gy in 30 fractions over six weeks or 55 Gy in 20 fractions over four weeks) do not as yet
support this hypothesis (Level 2b).
10,21,25
In patients with oropharyngeal cancer, the tumour human papilloma virus (HPV) status
has been identied as a strong and independent prognostic factor for survival.
26
In the
anticipation of robust evidence from ongoing de-escalation studies, radiotherapy dose and
fractionation for HPV positive oropharyngeal carcinomas should be no dierent to that for
HPV negative oropharyngeal tumours (Grade D).
10
Recommendations
Radiotherapy with concomitant chemotherapy:
70 Gy in 35 fractions over 7 weeks (Grade A)
65–66 Gy in 30 fractions over 6 weeks (Grade C)
The types of evidence and the grading of recommendations used within this review are based on
those proposed by the Oxford Centre for Evidence-based Medicine.
10
43Radiotherapy dose fractionation Third edition
Radiotherapy alone for stage III/IVa/b HNSCC (excluding
nasopharyngeal carcinoma)
The meta-analysis does not show a benet of concomitant chemotherapy in patients >70
years old (Level 1a).
10,20
Concomitant chemotherapy or cetuximab may not be appropriate
for some patients <70 years old due to co-morbidity, tness or patient choice. Altered
fractionation is an option for t patients <70 years old treated with radiotherapy alone with
superior local control and no increase in late toxicity; meta-analysis of altered fractionation
studies did not show a benet for alterated fractionation in patients ≥70 years old
(Level1a).
10,11,12,27
Recommendations
Radiotherapy without concomitant radiotherapy:
66 Gy in 33 fractions or 70 Gy in 35 fractions, 6 fractions per week, over 6 weeks (Grade A)
70 Gy in 35 fractions over 7 weeks (Grade B)
65–66 Gy in 30 fractions over 6 weeks (Grade C)
The types of evidence and the grading of recommendations used within this review are based on
those proposed by the Oxford Centre for Evidence-based Medicine.
10
Postoperative radiotherapy
There are few studies of radiation dose with postoperative radiotherapy with or without
chemotherapy. Historical studies suggest that for adjuvant radiotherapy alone, patients
with extracapsular extension benetted from doses of 63 Gy and for other patients there
was no benet >57.6 Gy (Level 2b).
10,28
Adjuvant doses of 60–66 Gy in 30–33 fractions were
used in the RTOG and European Organisation for Research and Treatment of Cancer
(EORTC) trials investigating the role of concurrent chemotherapy.
29,30
A pooled analysis
identied subgroups with close/positive margins and/or extracapsular spread as beneting
from concurrent cisplatin (Level 2a).
10,31
Based on limited evidence of a dose-eect in the
adjuvant setting, a dose of 66 Gy in 33 fractions is considered standard in the presence of
high-risk pathological ndings, and 60 Gy in 30 fractions is widely used in the absence of
high-risk features.
32,33
Doses equivalent to 50–54 Gy in 2 Gy per fraction are commonly used
for lower risk areas at risk of microscopic disease (Level 4).
10,33
Recommendation
Postoperative radiotherapy:
60 Gy in 30 fractions over 6 weeks (Grade B)
A dose of up to 66 Gy in 33 fractions over 6.5 weeks may be delivered to high-risk
subvolumes (areas surrounding extracapsular spread and/or positive/close margins)
(Grade B)
The types of evidence and the grading of recommendations used within this review are based on
those proposed by the Oxford Centre for Evidence-based Medicine.
10
44Radiotherapy dose fractionation Third edition
Nasopharyngeal carcinoma
Radiotherapy alone is used for early stage nasopharyngeal carcinoma.
34
For locally
advanced disease, conventionally fractionated radiotherapy combined with chemotherapy
is currently recommended. RTOG phase 2 trials have used a high, intermediate and elective
three dose level approach of 70 Gy, 59.4 Gy and 54 Gy in 33 fractions (Level 2b).
10,35
A case
series of altered fractionation using 65 Gy in 30 fractions with an elective dose level of 54 Gy
in 30 fractions has reported disease outcomes and toxicity (Level 4).
10,36
Doses biologically
equivalent to 50–60 Gy in 2 Gy per fraction are commonly used to treat at-risk sites.
34
Recommendations
Nasopharyngeal cancer:
70 Gy in 35 fractions over 7 weeks (Grade A)
70 Gy in 33 fractions over 6.5 weeks (Grade B)
65 Gy in 30 fractions over 6 weeks (Grade C)
The types of evidence and the grading of recommendations used within this review are based on
those proposed by the Oxford Centre for Evidence-based Medicine.
10
Palliative radiotherapy schedules
Palliative radiotherapy is used in a very heterogenous group of patients, and may range
from the use of a single fraction to stop bleeding/fungation to the use of high doses to
achieve longer-term disease control while accepting that a cure is not possible. Decisions
with regard to palliative radiotherapy dose fractionation take into account symptoms,
disease extent and co-morbidity. When higher doses are delivered, three-dimensional (3D)
conformal radiotherapy or IMRT are often required due to proximity to critical structures.
There is no consensus for palliative radiotherapy for locally advanced head and neck
cancer.
37
Recommendations
E
xamples of appropriate dose fractionations include:
40 Gy in 10 fractions over 4 weeks ‘split course’ (Level C)
38
*
24 Gy in 3 fractions over 3 weeks (Level C)
39
20 Gy in 5 fractions over 1 week (Level C)
40
14 Gy in 4 fractions which may be repeated 2 further times every 4 weeks (Level C)
41
The types of evidence and the grading of recommendations used within this review are based on
those proposed by the Oxford Centre for Evidence-based Medicine.
10
*Please note this recommendation was corrected on 2 December 2020 from 8 Gy in 3 fractions over three
weeks (Level C). It had been previously updated on 20 November 2020 from the original schedule which
incorrectly stated 21 Gy in 3 fractions over 3 weeks (Level C).
45Radiotherapy dose fractionation Third edition
Re-irradiation
Re-irradiation with curative intent can be an option for selected patients with limited local
recurrence or new primary disease who are unsuitable for surgical treatment/decline
surgery. Re-irradiation may also be considered following salvage surgery with adverse
histological features (for example, positive margins, extracapsular spread). Patient
selection, choice of dose fractionation and dose constraints are individualised dependent
on the extent of recurrence, time from previous radiotherapy, sequalae of prior treatment,
proximity to organs at risk, performance status, co-morbidity and nutritional status.
Radiotherapy target volumes are limited to high-risk areas only and do not include elective
regions. Ideally the aim should be to deliver a dose equivalent of ≥60 Gy in 2 Gy per fraction,
although the dose may need to be reduced on an individual basis if organ at risk tolerances
are exceeded.
40,41
Hyperfractionation with bi-daily irradiation at approximately 1.2 Gy per
fraction can be considered (Grade C).
10,41
The use of concomitant radiosensitising agents
should only be used with extreme caution.
46Radiotherapy dose fractionation Third edition
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