Trial Information

Effectiveness of Adjuvant Radiotherapy in Patients With Oropharyngeal and Floor of Mouth Squamous Cell Carcinoma and Concomitant Histological Verification of Singular Ipsilateral Cervical Lymph Node Metastasis (pN1-state)

Background

Prevailing curative intended therapeutic strategies combine radical resection of the tumor
mass with a safety margin followed by radiation of the original tumor site and adjacent
locoregional lymphatic drainage areas. To date selection of the individual therapeutic
pattern is essentially guided by pre- and post-therapeutic TNM staging parameters.
Exceptionally for advanced tumors postoperative radiotherapy and optional combination with
(radiosensitizing) chemotherapeutic agents is favorable and recommended. Interdisciplinary
guidelines stated the following detailed recommendations for application of adjuvant
radiation therapy:

- non in sano resection if reoperation is impossible (R1-, R2-status)

- primary tumor status > pT2 and pN2, pN3

- extranodular spread of the disease

- lymphangiosis carcinomatosa

- facultative: pN1 According to these recommendations postoperative radiotherapy of
advanced tumors is feasible while for small tumors indication for adjuvant therapy
depends on further parameters like the pN findings. Here verification of more than one
singular lymph node metastasis (pN2) leads to additional radiotherapy. In tumors with a
diameter less than 4 cm (T1, T2) and concomitant verification of a single lymph node
metastasis no explicit therapeutic recommendation is offered to date displaying
radiation an optional complement for these cases. Meta-Analysis revealed only a few
studies taking this special group of patients into account stating adjuvant
radiotherapy an additional risk factor for overall survival, however small patient
numbers, inhomogeneous group distribution and ambiguous risk factors exhibited a
significant bias.

The methodological key problems which had to be addressed in the protocol were the
following:

- extremely different treatment arms with strong preferences for one or the other therapy
arm

- low number of eligible patients per center

- Inclusion criterion (pN1) including a pathological diagnosis and surgical treatment
with possible differences

- Radiation treatment as one arm with special need for quality control Thus the idea of
presenting this paper is, to discuss how these specific issues were taken care of.

Methods/Design Study Design The study is designed as a non-blinded, prospective, randomized
controlled clinical trial.

Study objectives Objective of the clinical study will be the investigation of two different
patient collectives (irradiated/unirradiated) with pT1/2 primary and verification of a
singular ipsilateral lymph node metastasis in parallel design in order to evaluate a
possible significant benefit of radiation therapy. Investigation of further biological
parameters will be concomitantly performed to assess a possible prediction of tumor
progression and to evaluate surrogate markers of radioresistance. The following null
hypothesis forms the basis of the present study: Radiation therapy will have no influence on
the overall survival in patients with pT1/2, pN1 primary tumor. Secondary outcome variables
include incidence and time to tumor relapse (locoregional relapse, lymph node involvement
and metastatic spread), Quality of life as reported by EORTC (QLQ-C30 with H&N 35 module)
and time from operation to orofacial rehabilitation.

Patients

Males and females with histological verified diagnosis of a primary squamous cell carcinoma
of the oral cavity or the oropharynx are eligible. Inclusion criteria are as follows:

- maximum tumor diameter less than 4 cm in the pathohistological specimen irrespective of
histological grading (pT1 or pT2)

- concomitant histological verification of a singular ipsilateral lymph node metastasis
less than 3cm in diameter (pN1) without penetration of the lymph node´s capsule and
without presence of lymphangiosis carcinomatosa

- radical resection of the tumor within adequate resection margins (R0)

- written informed consent from the patient

- adequate performance status ECOG Index ≤ 2 Patients with an age less than 18 and
pregnant women are to be excluded. Further criteria of exclusion are reported drug
addiction or intake of remedies with potential influence on compliance or impaired
judgment. In addition patients with mental disorders or conceivable physical, familial
or job related embarrassments which may preclude the patient to realize the study
schedule. Moreover patients with physical impairment by inadequate treatment of
derailed diseases e.g. untreated diabetes mellitus or acute heart insufficiency
(ECOG-Index >2).

Study interventions Radiotherapy should begin within 6 weeks after the last surgical
intervention, whereas a minimal postoperative healing period of at least 8 days should be
respected. Causes for delay of intervention are to be documented. Application of
radiotherapy defines group 1 versus the non irradiated group (group 2).

Surgical treatment The primary is considered radically resected if macroscopic and
histologic evaluation approved resection margins without tumor residuals (R0 status). For
surgical proceeding a safety margin of at least 1cm is established. For surgical
considerations of lymph node resection the tumor localization is divided in level I (below
occlusional plane) and level II (above occlusional plane) respecting pre-, postcanine or
retromolar finding in addition. Classification of cervical regions follows the
recommendations of Robbins from 2002. Hence, the neck is divided into 6 different sections.

Ipsilateral N0 state of cervical lymph nodes Pre- and postcanine localized tumors of level I
require a selective neck dissection of the cervical level 1-3. In level I tumours of the
retromolar triangle selective neck dissection of ipsilateral level 1-5 is proceeded. In
level II tumors no selective neck dissection is considered.

Contralateral N0 state No neck dissection is performed Ipsilateral N1- N2 state For
retromolar localized level I tumors a modified radical neck dissection is performed. If the
tumor is localized pre- or postcanine intraoperative frozen sections of level 1 lymph nodes
are evaluated. Positive intraoperative results lead to modified radical resection of level
1-5 lymph nodes. In case of negative results resection of the lymph nodes within level 1-3
is affiliated. Negative instantaneous sections in level II tumors require no lymph node
dissection. All metastatic affection of level II-III lymph nodes necessitates modified
radical neck dissection.

Contralateral N1-N2 state Instantaneous section is performed for level 1 lymph nodes.
Modified radical neck dissection is performed in positive, resection of level 1-3 lymph
nodes is conducted in negative results. Metastases spread in level 2-3 lymph nodes acquire
modified radical neck dissection.

Lymph node therapy of midline tumors Midline tumors may require bilateral resection of lymph
node echelons at risk. Bilateral modified neck dissection is performed for staging purposes
if indicated. Contralateral lymph node dissection of the level 1-3 in precanine localized
tumors is mandatory.

Technical conditions and practical execution of radiation therapy Radiotherapy is performed
by photons of 4 to10 MeV or/and electrons of 6 to 15 MeV maximum energy. Individual 3
dimensional dose distribution calculation is mandatory and has to be made on the basis of a
postoperative native computer tomogram. All patients are to be treated while immobilized by
a custom made face mask made of thermoplast or equivalent. Clinical target volume definition
compasses the original tumor site with a safety margin of 2 cm in each direction.

Floor of mouth, anterior tongue Irradiation of the anterior two third of the tongue as well
as the anterior floor of mouth is irradiated by lateral opposing beams, while the maxilla is
separated by insertion of a bite block.

Oropharynx, buccal plane, soft palate confined to one side For tumors of the buccal plane,
the tonsilla, the soft palate and the retromolar triangle two types of planning target
volume may be applied.

In case of negative contralateral cervical nodes an ipsilateral target volume for the
primary is defined including the lymph nodes of group IB, IIA and IIB. Irradiation technique
recommended is a two wedge fields typically angulated by 90 to 120 degrees. The ipsilateral
node levels III-V are treated by an anterior portal down to clavicle. The contralateral neck
is spared.

Tumors of the lateral and dorsal pharyngeal wall and their lymphatic drainage (levels II,
III, IV and V) are irradiated bilaterally with opposing beams. Irrespective of technique
used 3 D conformal dose shaping is highly recommended.

Dosage and fractionation Target volume definition and dosage has to be performed according
to the rules of ICRU report 50. At the primary tumor site and at involved lymph node levels
a total dose of 59.4 Gy in 33 fractions within 45 days is scheduled. At electively
irradiated volumes a total dose of 50.4 Gy in 28 fractions is scheduled. All fractions of
1.8 Gy each are given five times per week. In case of machine break down an additional
fraction per week is recommended with an at least 6 h interval between two fractions on the
same day or on Saturday. Total treatment duration (including planned/unplanned
interruptions) is to be documented in days. Any patient must be available for intent to
treat analysis.

Instead of the classical portal arrangements and dose distributions intensity modulated
radiotherapy using an inverse calculation algorithm may be used in experienced centers. Dose
constraints for normal tissues are at the discretion of the participating centers. Dose
specification according to the RTOG protocol H 0022 is recommended. Details are given in a
standard operation procedure.

Follow-Up Recruitment phase will be 4 years with physical examination, ECOG index, and
quality of life questionnaire will be performed 3, 6 and 12 months after end of radiation.
Further follow up will be performed annually up to 5 years to obtain sufficient clinical
data.

Randomization and Sample Size The present study setup consists of a two armed randomized
controlled trial (RCT) as primary study aim. Patients rejecting their participation to a
randomized approach and preference to a certain procedure (radiation/no radiation) will be
included into a prospective observational study after given informed consent. This parallel
constructed observational trial will be performed with a maximum of consistency to treatment
and observation compared to the RCT. In case of positive attendance the patients will be
randomized, stratified by the criteria of adequate lymph node therapy (yes/no) as formulated
by the DOESAK. Randomization to both groups (radiation group/control group) will be 1 to1.
Patients will be recruited over a period of 4 years and follow-up will be annually until the
trial ends, i.e. at least for 5 years for each patient. Sample size calculation will be
performed for the two-sided log rank test at a significance level of 5%. Assuming an
exponential distributed survival with survival probabilities after 5 years of 45% within the
control group and of 55% within the radiation group (results observed from the DOESAK
collective) and a drop-out rate of 5% per year, 280 patients per group are required to
detect a significant difference in overall survival with a power of 70%. In case of impaired
patient recruitment within the randomized trial, it is intended to recruit at least 280
patients per group in the observational study.

Analysis of RCT and observational trial

Initiation of this trial is only arguable with a realistic chance of statistical evaluation
of an adequate count of randomized patients. Hence an intermediate assessment of attendance
to randomization will be performed after the first and the second year of recruitment. If
less than 5% of patients agreed to randomization within the first and 10% within the second
year RCT will be stopped and the study is continued solely as observational trial (see table
1). Intermediate assessment is performed with presumption of accelerating involvement to
achieve a minimum of 20% randomized patients after the recruitment phase. As consequence to
the study design two different collectives (randomized collective/ collective with preferred
form of therapy) will exist. The following scenarios of analysis are possible:

1. If a sufficient number of patients was randomized, treatment comparison will be
performed within the randomized collective. The non-randomized collective will be used
to evaluate the external validity of observed treatment effects.

2. If no sufficient number of patients could be randomized, all recruited patients will be
analyzed. Descriptive comparison of treatment groups will be performed for all baseline
variables. All analyses will be performed with adjustment to baseline variables
affecting survival. Results have to be interpreted with respect to any group
differences in baseline variables.

Outcome measurements Primary clinical endpoint Overall survival Secondary clinical endpoints
Incidence of tumor relapse

- Time to occurrence of lymphatic metastases

- Time to occurrence of local relapse

- Time to occurrence of distant metastases

- Tumor related death due to local tumor progression or metastatic spread Life quality

- Time to provisional orofacial rehabilitation

- Time from operation to first intermediate prosthesis intake

- Time from operation to definitive prosthesis application

- Life Quality report (EORTC QLQ-C30 with H&N 35 module)

Overall survival will be evaluated in a Cox proportional hazard model with treatment and
adequate lymph node therapy (yes/no) as covariates. Further covariates may be considered if
they affect survival.