GUIDELINES FOR THE MANAGEMENT OF SKULL BASE TUMOURS. Version: 1 AngCN-SSG-BC6

Transcription

1 GUIDELINES FOR THE MANAGEMENT OF SKULL BASE TUMOURS Version: 1 Ref: AngCN-SSG-BC6

2 CONTENTS Page No 1 Introduction Imaging Other investigations Referral Accepting referrals MDT Meeting Vestibular Schwannoma / Acoustic Neuroma Management Policy Surveillance Surgery Radiotherapy Single fraction radiosurgery Fractionated conformal radiotherapy Neurofibromatosis Type Surveillance Surgery RT -Treatment Planning Immobilisation Imaging Planning Target Volume Dose Prescription Implementation Glomus Tumours Treatment Policy Surgical management Radiotherapy Treatment Planning Target Volume Dose Prescription Implementation... 9 Page 2 of 13

3 7 Chordoma / Chondrosarcoma Treatment Policy Radiotherapy Treatment Planning Target Volume Dose Prescription Implementation Squamous Cell Carcinoma (SCC) of the Temporal Bone Diagnosis Management APPENDICES Appendix A: Document Management and Approval Page 3 of 13

4 1 Introduction These protocols represent the treatment policy for skull base tumours and are intended as guidance to those working within the Anglia Cancer Network. While every effort has been made to ensure that the guidelines are accurate and unambiguous it must be emphasised that constant modifications will be necessary. These protocols should only be used to give an indication of current management. We do not guarantee the accuracy of these protocols and do not accept any liability if they are used outside of the Anglia Cancer Network. 2 Imaging MR imaging is a highly sensitive investigation for the identification of skull base tumours. All patients with a suspected skull base tumour must have an MRI scan that as a minimum includes T1, T2 and T1 with gadolinium. If a skull base tumour is identified using a screening MR protocol, patients should be asked to return for a full investigation protocol. 2.1 Other investigations In order to speed up referral to the designated skull base unit, it is advised that further investigation is not performed. MR imaging is made available via Link for discussion at the skull base MDT. 3 Referral By the nature of patient symptoms, there is often significant delay referring patients to the skull base MDT for definitive treatment. GP referral to the local ENT Dept, MR imaging, follow up appointment to inform the patient of the diagnosis and then referral to the skull base MDT can bring patients very close to or past the 18 week target. With this in mind, it is essential that once a diagnosis has been made, urgent review and then referral be organised. Rare malignant tumours of the skull base should be referred via the 2 week cancer pathway to the skull base MDT. Patients must be referred to a member of the skull base team by letter that is both posted and faxed. The referral is then passed on to the skull base MDT coordinator for an appointment to be booked in the next clinic. All investigations must be completed and on the Addenbrooke s PACS or Link System by the Wednesday evening on the week of the skull base MDT. 3.1 Accepting referrals When receiving the initial referral the MDT coordinator should record patient name, age, referring team details, patient location, history and co-morbidities. The MDT coordinator should ask that all films be sent via the image link or by CD by the Wednesday evening on the week of the skull base MDT. Page 4 of 13

5 The MDT coordinator should then pass all new patient details to the Skull Base Fellow for preparation of the skull base MDT. It is the responsibility of the Skull Base Fellow to forward patient details to the neuroradiologist in good time so that he can prepare the images for the meeting the following morning. 3.2 MDT Meeting The skull base MDT meeting occurs on Friday morning from am weeks 2 & 4 of the month. All cases referred over the previous 14 days are discussed and a management plan agreed. Patient details are presented by the skull base fellow or nominated deputy in his absence. A video link with the Oncology teams in Ipswich and Norfolk & Norwich enable a clear treatment plan at both the skull base centre and local oncology units. All enquiries should initially be directed to the MDT Coordinator or Clinical Nurse Specialists. 4 Vestibular Schwannoma / Acoustic Neuroma 4.1 Management Policy For patients diagnosed with vestibular Schwannoma there are a number of management strategies available: 4.2 Surveillance Vestibular Schwannomas are often diagnosed when small, before compression of the brainstem. These tumours are usually slow growing and a watch wait rescan policy can be adopted. Regular surveillance scans adopting a clear rescan protocol is essential until patient age dictates no further scans are required. If tumour growth does occur, another treatment option can be adopted without significant change in patient morbidity. 4.3 Surgery Surgery is an excellent treatment, provided complete excision is achieved without undue morbidity. Surgery achieves complete excision in over 97% of patients and surgical mortality or serious intracranial adverse event is below 1%. The main concern to patients is the risk of facial nerve injury (Appendix H). The possibility of facial weakness increases with increasing tumour size. For small tumours, the risk is below 5%. For tumours over 3cm, the risk increases to between 20 and 30%. Hearing preservation surgery is possible if patients have useful pre-operative hearing which is regarded as better than 70% speech discrimination and pure tone average threshold below 30dB. Hearing preservation surgery should only be considered if the patient regards hearing preservation as a major surgical objective and the tumour is medially placed within the internal auditory meatus. Page 5 of 13

6 Patients can expect a post-operative recovery period of between 6 weeks to 3 months. Persistent imbalance especially in the elderly can be a problem. Surgical excision is performed in two defined patient groups: Large tumours where radiotherapy is not an option and if left risks serious morbidity/mortality. Smaller growing tumours where the patient does not want further observation and does not want radiotherapy. 4.4 Radiotherapy Radiotherapy is an alternative to surgery and can be delivered in two ways: Single fraction radiosurgery (Gamma Knife) Fractionated conformal radiotherapy Single fraction radiosurgery For small ( 3cm) laterally placed lesions, stereotactic radiosurgery is an excellent choice. At present patients seeking an opinion on radiosurgery should be referred to a Gamma Knife Centre (Royal London or Sheffield) Fractionated conformal radiotherapy For larger lesions and those lesions adjacent to or compressing the brain stem fractionated conformal radiotherapy is a worthwhile treatment. Ideally to reduce PTV margins (normal tissue irradiated) patients should be immobilised in the relocatable SRT frame, however a shell can be used if more appropriate. For patients who have useful hearing this option may preserve hearing. However radiotherapy is designed to stabilize the tumour and will not remove the lesion, so patients will require an active follow up plan. Published results for fractionated radiotherapy suggest excellent efficacy and low morbidity (Fuss et al). 5 Neurofibromatosis Type 2 Neurofibromatosis type 2 (NF2) is an autosomal dominant condition characterised by multiple benign intracranial tumours usually centred on the auditory nerve. Patients with NF2 are at a greater risk of multiple cranial nerve deficits. Patients are referred to a unit specialising the management of this complex condition. Funding for the management of this condition is from the National Commissioning Group (NCG) 5.1 Surveillance It is important to maintain cranial nerve function if at all possible. With this in mind, surveillance is usually adopted until intervention is necessary either because of persistent tumour growth or profound/total hearing loss or other cranial nerve deficit that requires intervention. Page 6 of 13

7 5.2 Surgery Surgery is the treatment of choice if there is evidence of persistent tumour growth or significant cranial nerve deficit. Total tumour removal with preservation of residual cranial nerve function is important. Hearing implants can restore a degree of hearing loss in certain, well defined cases. Radiotherapy: Single dose radiosurgery is currently the only option funded by the NCG. Gamma knife is offered at the only designated centre in Sheffield. It is usually offered to patients that have a rapidly growing tumour in an only hearing ear or after failed surgery. Chemotherapy: Chemotherapeutic agents have recently been used to some effect for the control aggressive uncontrolled disease. Bevacizumab is currently funded by the NCG for patients who fulfil strict inclusion criteria. 5.3 RT -Treatment Planning Immobilisation Relocatable SRT head frame patients who are Performance Status (PS) 0 with good upper jaw dentition Perspex beam direction shell - supine Imaging Neuro CT planning scan with IV contrast - 1mm slices throughout the brain MRI - with 2mm contiguous slices for T1W+Gd sequence CT: MR co-registration - to T1W+Gd sequence Planning Conformal radiotherapy planning use of personalised shielding blocks or mmlc Target Volume GTV: the enhancing lesion as demonstrated on T1W + Gd MR sequence CTV: = GTV PTV: This margin should be grown isotropically with the planning software. Stereotactic frame CTV - PTV margin is 0.3cm. Beam Direction Shell - the standard CTV - PTV margin is 0.5cm. Critical normal structures: these should be outlined including the eyes, lenses, brain stem and the pituitary. Page 7 of 13

8 5.3.5 Dose Prescription 50Gy/30# Implementation Always measure eye TLDs for future reference. Take portal films or images as per protocol. Please see Appendix H for the Vestibular Schwannoma Assessment diagram. 6 Glomus Tumours 6.1 Treatment Policy The decision between surgery and radiotherapy may be difficult and needs to be considered individually. The most important factor dictating treatment choice is residual lower cranial nerve function. Sudden loss of lower cranial nerve function can be catastrophic, resulting in persistent aspiration requiring a tracheotomy, poor voice and difficulty feeding resulting n the placement of a PEG. Planning management must therefore always take into account lower cranial nerve function. 6.2 Surgical management Total surgical excision should be the treatment of choice for small Fisch type A or B tumours centred either on the promontory of the cochlea or within the middle ear. These tumours are often not involving the jugular bulb and there is little risk to lower cranial nerve function. Patients main complaint is conductive hearing loss and pulsatile tinnitus, which often resolve after surgical excision. Total surgical excision should also be considered if patients present with slowly progressive complete vagal and glossopharyngeal palsy. The progressive loss of lower cranial nerve function often enables the patient to adapt to that loss and manage to eat and drink without significant aspiration. Surgical tumour removal is unlikely to cause further significant loss of function although the risk to other cranial nerves including VII, VIII, XI should always be considered. Partial surgical excision should be considered for patients who have lower cranial nerve function and debilitating symptoms for example pulsatile tinnitus. Partial tumour removal, leaving a remnant centred on the jugular bulb offers symptomatic relief with a low risk lower cranial function. Postoperative radiotherapy is then advised for control of tumour remnant. 6.3 Radiotherapy Radiotherapy has the advantage of very low toxicity, but the disadvantages that the tumour remains and late tumour regrowth occurrence or second tumours can occur. The risk of this is very low. Page 8 of 13

9 Local control rates are reported to be high after radiotherapy, with moderate doses, in the range 90-93% (Springate et al 1990, 1991). In one report, the majority of patients noted symptomatic relief of tinnitus after radiation, but objective neurological deficits usually remained unchanged or showed only partial improvement (Powell et al 1992) Treatment Planning Use a beam-direction shell or stereotactic radiotherapy frame, depending on circumstances. For tumours with any significant extension into the neck, the SRT frame is not suitable. Use CT planning, with IV contrast, which show glomus tumours quite well. CT slices spacing is normally The CT should cover the whole head to allow the possibility of noncoplanar beams (and NTCP calculations), and must extend low enough in the neck to cover the inferior extent. For large, low lesions a mouth bite may be useful. CT: MR image co-registration is often valuable, and may be essential. Some additional localisation information is often available from the angiogram Target Volume Plan conformally, usually with CT: MR co-registration. The CTV is essentially the GTV, with or without an allowance for uncertainty in localisation and co-registration. Always review the CT at bone window settings. The standard CTV - PTV margin for patients in a shell is 0.5 cm, while for patients in the stereotactic frame the margin is 0.3 cm. This margin should be grown tropically with the planning software. Outline critical normal structures, including the pituitary, the eyes, the parotid glands, brain stem etc Dose Prescription 50 Gy / 30 # at 1.67 Gy/# 1 phase. In exceptional circumstances consider a slightly higher dose, of 55 Gy / 33 # Implementation Always measure eye TLDs for future reference. Take portal films or images as per protocol. Very occasional patients experience nausea, especially when the brain stem is irradiated. This is usually manageable with 5-HT3 antagonists. Patients rarely require steroids. Page 9 of 13

10 7 Chordoma / Chondrosarcoma 7.1 Treatment Policy Aim for maximum surgical resection. Follow with referral for proton therapy via the National Proton Group (leedsth-tr.protonncg@nhs.net). If not suitable for proton therapy for high dose stereotactic radiotherapy or Image Guided Radiotherapy. 7.2 Radiotherapy Treatment Planning Use the stereotactic radiotherapy frame. Use CT planning, with IV contrast, and slice spacing of Always scan the whole head, for improved DRRs and NTCP calculations, though spacing may be larger outside the target region. CT: MR image co-registration is essential Target Volume Plan conformally, with CT: MR co-registration. Treat in 2 phases. For Phase 1, the CTV is essentially the pre-op GTV, with or without an allowance for uncertainty in localisation. For Phase 2, the CTV is the post-op GTV. Add the stereotactic frame PTV margin of 0.3 cm. Outline critical normal structures, including the pituitary, the eyes and lenses, and often the optic nerves and chiasm. Grow these into PRVs. For further planning details see below Dose Prescription This is very individual. Aim for Gy, optimising physical planning and fractionation Implementation Always measure eye TLDs for future reference. Take portal films or images as per protocol. Page 10 of 13

11 8 Squamous Cell Carcinoma (SCC) of the Temporal Bone SCC of the temporal bone is rare. It usually presents with a painful bloody discharge from the ear. 8.1 Diagnosis It is important to forward histology slides to the skull base MDT for review by the Skull Base pathologist. This enables confirmation of diagnosis and grade. Pre-operative MR of the head and neck as well as CT of the head, neck, chest and abdomen are required before surgical planning. 8.2 Management SCC of the temporal bone can invade adjacent structures for example the temporomandibular joint, dura and brain. Management is centered on the need to achieve complete macroscopic surgical excision of the tumour followed by radiotherapy. Factors favouring good treatment outcome: Well or moderately differentiated histological grade No involvement of the brain No 0 disease Involvement of the facial nerve is the factor that best predicts the need to perform either a lateral or total temporal bone resection. Both surgical procedures require the removal of the head of the mandible and glenoid. Facial nerve preservation rates are high following lateral temporal bone resection. The reconstructive surgical team performs free flap repair of the surgical defect. It is rare for the pinna to be preserved as it is almost always infiltrated with tumour. The patient is admitted onto the Plastic Surgical ward for post-operative monitoring of the free-flap before discharge. Post-operative radiotherapy is planned by the local oncology team. Page 11 of 13

12 9 APPENDICES 9.1 Appendix A: Document Management and Approval These Guidelines have been approved by the Network Board in December 2010 and as follows: The Skull Base SMDT Lead Clinician Name: Mr Patrick Axon Organisation: CUHFT The Brain CNS SSG Chair Name: Sarah Jefferies Organisation: CUHFT The AngCN Medical Director Name: Rory Harvey The AngCN Chair Name: Paul Watson Organisation: Anglia Cancer Network Organisation: Anglia Cancer Network Document management Document ratification and history Approved by: Network Board, Patrick Axon, Rory Harvey and Paul Watson. Date approved: December 2010 Date placed on electronic library: December 2010 Reviewed and Review period: 1 year Authors: Patrick Axon and Neil Donnelly, SMDT Chair and Deputy Chair Document Owner: Anglia Cancer Network Tel: Version number as approved and published: 1 Unique identifier no.: AngCN-SSG-BC6 For clinical comments / amendments to the guidelines, please contact: Clinical Panel Name Hospital Tel. No Patrick Axon Addenbrookes Patrick.axon@addenbrookes.nhs.uk Neil Donnelly Addenbrookes Neil.donnelly@addenbrookes.nhs.uk Sarah Jefferies Addenbrookes sarah.jefferies@addenbrookes.nhs.uk For copies of guidelines, please refer to the Anglia Cancer Network website: Page 12 of 13

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