Introduction to Technology
Photodynamic Diagnosis of Bladder Cancer
Photodynamic diagnosis of Bladder Cancer Explained
Photodynamic diagnosis of bladder cancer, or fluorescence cystoscopy, assists in the diagnosis and treatment of non-muscle invasive bladder cancer by helping to identify tumour that may otherwise have been missed using conventional white light Cystoscopy. The current standard for the initial treatment of non-muscle invasive bladder cancer is the transurethral resection of bladder tumour, or TURBT. This surgical procedure involves the insertion of an instrument called a resectoscope into the bladder to carry out an initial visual endoscopic examination or cystoscopy during which tumour is visually located and resected.
Photodynamic diagnosis of bladder cancer or PDD is a supplement to the existing, standard TURBT, assisting in the diagnostic and treatment elements of the procedure. The standard technique involves an initial cystoscopy with white light before the resection. However, with PDD, tissue fluorescence is utilised to assist in the visual identification of tumour, as it better enables the distinction between tumour and normal bladder lining. A photo-sensitising chemical is first instilled into the bladder and when the standard white light is switched to blue light, lesions and suspicious areas can be seen that may not have been seen with standard white light cystoscopy. This ability helps to ensure a more comprehensive resection of tumour from the bladder. Additionally, more lesions and suspicious areas can sometimes be seen that would be appropriate for biopsy and further histological analysis. A more complete assessment of the extent of disease and risk stratification may also result, allowing a more effective management patients post operatively.
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The Technology in Use
The initial step in utilising PDD is to install a photo-sensistising chemical known as hexaminolevulinate (Hexvix ®) into the bladder via a catheter for a minimum of 1 hour pre operatively; the bladder is then emptied after the 1st hour and the surgery can start within the following hour. The instillation of Hexvix ® leads to red fluorescence by tumour tissue when blue light is used.
A PDD-assisted transurethral resection of bladder tumour (TURBT) is similar to the standard procedure, with the exception that some modification is required to the equipment already in theatre: a blue light enabled camera system and endoscope, a blue light source, light cable, and a switch to allow change-over between white light and blue light during the procedure are required. The equipment is such that both white light and blue light cystoscopy can be utilised during the TURBT. The normal mode of use is to carry out initial investigation and resection using white light and then switch over to blue light in order to see any remaining lesions not found under white light or to confirm additional suspicious areas for resection or biopsy. The surgeon can repeatedly switch between white light (to resect) and blue light (to investigate) as required. Patients are then managed as per current standard TURBT protocols.
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What problems does it solve?
Over the past eight years, inpatient admissions for cancer have risen by 25% and bed days are rising by 1% per year, according to the Cancer Commissioning Toolkit (2008). Streamlining bladder surgery by introducing the PDD not only improves overall quality of life for patients, but can further assist in reducing the admissions and overall length of stay for bladder cancer patients. Introducing the procedure can also lead to a reduction in the on-going demands on healthcare services (e.g. adjuvant therapies can begin straight after initial surgery) and the wider socioeconomic impact (such as the ability to work due to a second surgical procedure).
A more thorough resection of tumour at the initial TURBT may allow some patients to be moved to a lower risk state by reducing 'recurrence' of the disease. Reduction in recurrence equates to reduced numbers of procedures required for these patients - both TURBT and cystodiathermy with associated in-patient bed days, and outpatient check cystoscopies - freeing up resources for use elsewhere. A more complete visualisation of tumour may also enable identification of disease at higher risk of recurrence or progression. This would enable more appropriate and timely treatment for such patients, which would result in earlier placement of a patient on a more appropriate high risk management pathway before the disease progresses.
Decreasing the number of bed days as a result of implementing the diagnostic technique can help to achieve a vision set out in the Cancer Reform Strategy (2010) which advocates that more can be done to decrease the number of inpatient bed days. The Cancer Reform Strategy (2010) states that "inpatient bed days could be reduced by at least 20%. If this level of reduction were achievable across the NHS, there would be a potential efficiency gain of about £190 million, representing approximately 8.1% of the cancer inpatient budget" (£2.332 billion in 2007/08. Source: HES analysis in the Cancer Commissioning Toolkit).
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Clinical and Patients Benefits
The availability of PDD which is concurrent with transurethral resection of bladder tumour (TURBT) offers the potential to streamline the number of subsequent surgeries undertaken for primary bladder cancer each year, with length of stay savings of up to 0.24 days per patient (this will vary depending on local protocols). This would equate to a saving of approximately 2,116 bed days in the UK over a five year period and would remove the inefficiencies associated with unnecessary follow-up protocol post-operatively.
Recurrence of non-muscle invasive bladder cancer is common, occurring in up to 60 - 70% of cases. One of the reasons for this is that standard white-light cystoscopy does not always identify all tumour present in the bladder. This undetected tumour is, therefore, not removed at the time of the initial TURBT, but will appear as a 'recurrence' at a later time. This is thought to be the case in 40 - 60% of TURBTs. As PDD enables the visualisation of tumour that may not have been identified with white-light cystoscopy, it has been found to lead to a reduction in 'recurrence' through unresected tumour by improving the thoroughness of the initial TURBT.
Additionally, better visualisation of tumour at the initial TURBT, may lead to earlier identification of disease at higher risk of recurrence or progression e.g. carcinoma in situ. This facilitates the earlier onset of a more intensive treatment pathway, the need for which may not have been identified until later during bladder surveillance. The presence of carcinoma in situ places a patient in a high risk category for progression to muscle-invasive disease, and usually indicates the need for a more appropriate intensive management pathway. Carcinoma in situ is well known to be difficult to visualise with standard, white-light cystoscopy, but is much more easily seen with PDD.
Click to access the Evidence Base section of this How to Why to guide.
Providers of the Technology
Whilst it is not NTAC's role to recommend specific manufacturers, a single supplier of the photo-sensitiser agent to run the PDD technique is currently only commercially available from GE Healthcare. At the point of publication, the hardware that compliments the agent is available from Karl Storz, R Wolf and Olympus.
The Procurement Section of this How to Why to Guide explains all of the details surrounding the options available to Trusts when purchasing this technology and any associated consumables.
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