Tumour Treatment
Treatment options vary widely depending of course on the type of tumour involved, but also factors such as the type of symptoms the tumour may be causing, the age of the patient, the presence of other health conditions, and the individual patient’s own expectations, concerns, and wishes.
In general a careful appraisal needs to be made to determine what the treatment options are and in making recommendations as to the best option in the individual case. The skill of the surgeon should be measured not just on what they achieve in the operating room but perhaps even more so on the care, thoughtfulness, and judgement they can bring when considering all of these issues in the pre-operative consultations and planning, and the honesty with which they discuss these issues with the individual patient.
Further, it is often best to discuss an individual case in a so-called MDT or multi-disciplinary team meeting. This is a conference between care givers involved in looking after patients with brain tumours including doctors specialising in surgery, radiology, neurology, radiation oncology, medical oncology, and pathology, as well as nursing and allied health, and allows options to be discussed and various expert opinions to be sought to work out the best treatment in the individual case.
i) Surveillance
Sometimes the best thing to do is just to keep an eye on things. If a tumour is small, thought to be benign or low grade, incidentally found, or causing no symptoms it may be best left alone to avoid the down sides of any intervention. This may involve periodic MRI check-ups to be sure that the tumour is not growing, or only growing very slowly. For many of the benign lesions people may be very able to live the normal course of their lives without the tumour ever causing them a problem. If the tumour is seen to be growing on follow-up scans then this may trigger the need for something more to be done.
ii) Biopsy
Like tumours elsewhere in the body it is possible to perform a biopsy of a tumour in the brain with the purpose of obtaining a small amount tissue for the pathologist to make a diagnosis. Once the diagnosis is made it may then allow better choices between further treatment options.
However, there are limitations to performing a biopsy. Some of these relate to the tumour itself which may not be the same throughout its entirety or may be difficult to localise. Taking a small specimen therefore may lead to misleading results (e.g. a “non-diagnostic” biopsy where the pathologist is unable to tell the exact diagnosis, or “sample error” where the biopsy may suggest the tumour is only low grade if the sample taken “misses” some other part of the tumour which is high grade).
Further, the biopsy may require a full general anaesthetic whereby an operation is performed to access the tumour but to then only remove a small part of it. Once the diagnosis is made, a second operation under another general anaesthetic may be needed since for many of the different types of tumours that occur there can be very real advantages in removing as much of the tumour as possible. Accordingly, biopsy may be most suited to situations where more formal resection is thought to be either not warranted or not advisable.
iii) Surgical Resection
For many brain tumours surgical resection is an initial and critical step in their treatment. In certain situations complete removal of a benign or low grade lesion may be curative and all that is required. In others, the overall response to treatment including the effectiveness of the adjuvant therapies can be enhanced by removing as much of the tumour as possible.
However, for gliomas it is generally not possible to remove all of the tumour since at a microscopic level cells can infiltrate the normal brain and may not show up on the scans. For tumours elsewhere in the body such as bowel, breast, skin, etc. the surgeon may look to take a wide margin of apparently normal tissue in order to try and remove the tumour completely. In the brain however the approach is exactly the opposite whereby the surgeon tries to minimise any damage to the surrounding normal brain. Where possible attempts are made to achieve a so-called gross total resection (or volumetric resection) meaning that the area of abnormality as seen on the MRI has been largely removed, but in all likelihood there will still be tumour cells left behind.
If tumours are too extensive there may be value in a sub-total resection to reduce the overall tumour volume and the pressure it may be causing on surrounding structures (so-called mass effect). Further, although controversies still exist in the field, increasingly studies suggest that the more of a tumour that can be safely removed the better the overall prognosis. Hence there can be value performing generous sub-total resection even if a gross total resection may not be possible.
Nonetheless, one of the down sides of more aggressive surgery aimed at removing as much of the tumour as possible is the increased risk involved, particularly if there are unwanted effects on the surrounding normal and functional brain. In areas of the brain that are known to be highly functional (so-called eloquent areas) this may limit the ability to remove the tumour in order to reduce the risk of stroke-like setbacks from the surgery. The same studies that suggest an improved outcome with more extensive tumour removal also show that this benefit is lost if the patient experiences a significant neurological setback.
Many modern technologies exist to improve the safety and precision of surgery and thereby help to achieve more maximal resections. These include:
- aMagnified vision and especially the operating microscope allow significantly enhanced visualisation and illumination of the operative field that is a critical step in improving the safety of surgery and the preservation of important traversing structures such as arteries and nerves. The use of the operating microscope is one of the major advances in neurosurgery techniques over the last half century.
- Equipment that can safely delivery energy to emulsify or dissect through tumours including bipolar cautery, laser, and more commonly high energy ultrasound with a device known as the cavitronic ultrasonic surgical aspirator (or CUSA for short) can help develop tissue planes, reduce trauma to surrounding critical structures, and increase the ability to remove tumours with greater fidelity and safety.
- Neuronavigation using techniques known as stereotaxy allow real time feedback on sophisticated equipment to precisely identify where in the brain and within the tumour itself the surgery is being performed. The pre-operative MRI scan and other imaging can be uploaded onto the navigation workstation which is the co-registered to the patient’s anatomy immediately prior to the operation commencing. During the procedure a video screen displays the exact location at which the operation is being performed, and in some situations this can also be displayed in a “heads up” view on the operating microscope. This information helps interpret the direct operative findings since something that looks very distinct or different on the MRI scan may in fact be very similar to normal brain to direct or magnified vision and touch.
- Intraoperative imaging, especially the use of the intraoperative MRI (or iMRI) machine, allows a way to check how the degree of resection is proceeding while the patient is still under the anaesthetic, allowing surgical plans to be adjusted and neuronavigation systems to be updated with new data. Often, as surgery proceeds, there can be movement or so-called “brain shift” as the volume of tumour is reduced. By updating the stereotaxy machine with intraoperative imaging the neuronavigation accuracy is maintained, similar to a GPS road map being updated for road closures or real time traffic conditions. The iMRI can also be used to map out important nerve fibre tracks that may be in the vicinity of the tumour and need to be preserved.
- Cortical mapping with direct electrode stimulation can help identify surgical no-go zones such as parts of the brain that are involved with movement or speech etc. Although in the right situation this can be useful the downside is that the procedure needs to be done under local anaesthetic with the patient awake during the cortical mapping and often being asked to perform task such as speaking, moving, or reporting any sensory sensations that the stimulation produces.
iv) Adjuvant therapy
- Radiotherapy – For many types of tumour radiotherapy can be an effective treatment either to add to on top of surgery or as a stand alone option. Modern planning and delivery techniques using sophisticated equipment and based on detailed MRI scans can be used to help target treatment with the aim to increase the effect of the radiation on the tumour itself and reduce any unwanted side effects on adjacent structures. These techniques include changes to the type of radiation used and sophisticated ways to target the radiation beam precisely where it needs to be concentrated known as stereotactic radiotherapy. In some specific situations a single one-off treatment without the need for anaesthesia or surgery may be all that is required and can be performed as an outpatient without the need for any overnight or longer hospital stay.
- Chemotherapy – The development of new drugs and prescription regimes has meant that chemotherapy now has a major role to play in the treatment of certain types of brain tumours where previously this option may have been more limited. Furthermore, many of these new drugs can be given in tablet form and are generally well tolerated so the patients can receive this treatment as an outpatient. Often, drugs may be prescribed in cycles involving a pattern of a period of treatment followed by a period of observation and repeated depending on the individual circumstances of the case.
- Immunotherapy – This type of treatment involves using the body’s own defence mechanisms to treat the tumour either by directly enhancing the immune reaction itself or by unmasking those tumour cells that have developed ways to hide from the immune system. By making the abnormal cells visible again they can be recognised as abnormal and killed. For some tumours, e.g. metastatic melanoma, immunotherapies have truly revolutionised the ability to control and in some cases eliminate tumours in the brain. For primary brain tumours various vaccine related strategies have been developed but remain at a research stage.
- Combined treatment – In many situations the best treatment of a particular tumour may involve using a combination of the above methods, sometimes one after another or sometimes concurrently. For certain types of tumours we have learned that giving chemotherapy at the same time as radiotherapy is more effective than giving these treatments one after the other.
- Other drug treatments – In addition to treating the tumour itself various drugs can be used to work on the effects of the tumour on the surrounding brain. Steroid medications such as dexamethasone can be effective at reducing oedema or swelling in the brain that can occur as a result of the tumour or its treatment, and medications to stop or prevent epileptic seizures may be necessary in those situations where the risk of seizures may be high.
- Support – Dealing with a diagnosis of a brain tumour and undergoing treatment is an emotionally difficult and stressful time for patients and their families. Various support strategies exist to help people manage these stressors including practical assistance from social workers with issues such as income support, restrictions on driving, accommodation needs, etc, as well as support groups with people who have had similar experiences. Also, opportunities to contribute to research programmes exist in which some patients also find meaning that helps them as they progress through the journey from diagnosis to treatment and recovery.
