Superficial Basal Cell Carcinoma Treatment With Topical Photodynamic Therapy With Fractionated 5-aminolevulinic Acid 20% Versus Two Stage Methylaminolevulinate

• Basal cell carcinoma throughout the world

Skin cancer is the most common form of cancer, with basal cell carcinoma (BCC) being the most common form of all skin cancers, and the incidence is still rising.1,2 Of all types of BCC, superficial basal cell carcinoma (sBCC), is the histopathologic subtype with the fastest growing incidence, especially on the trunk in younger patients.3-5 It is a common health problem and although there is no chance of metastasis it can lead to more aggressive forms of BCC with the ability to cause serious local destruction.

• Treatment options

The DBC (diagnose behandel combinatie) cost price, the amount received for diagnostic and treatment of one BCC, for surgical excision is partly free negotiable between each hospital and health insurances. Only the DBC cost price of patients whose health insurance has no contract with the hospital is public for everyone. This leads to around 18 million euro (based on a cost price of 400.00 euro for 44,000 new BCCs per year) that is yearly spent on the surgical treatment of BCC in the Netherlands and cost will only increase in future with the growing incidence.6 For most BCC subtypes the only effective treatment is surgery but for sBCC other non-invasive treatments like photodynamic therapy (PDT) are suitable. It is well accepted in today's dermatologic practice that surgical excision can be considered as over-treatment for sBCC.7-9 PDT is superior to surgical excision in primary sBCC of any size in low-risk sites.9 As a consequence unnecessary anaesthesia and incisions are avoided thereby preventing side-effects, such as scars, haematomas or functional disruption, and healthy tissue is preserved. MAL is a worldwide registered agent for the use of topical PDT in sBCC while 5-ALA is not registered in the European Union. In the Netherlands both fractionated 5-ALA 20% and MAL PDT in 2 sessions are used as treatment for sBCC. Although there are studies showing the effectiveness of both treatment regimens, the effectiveness, costs and patient preferences have never been studied in a prospective randomised trial.

• Developments in treatment: photodynamic therapy

PDT has become increasingly implemented in standard care for sBCC in the last years.8-10 Nowadays, in the Maastricht University Medical Centre, about 60% of patients are treated with PDT. Similar situations are found in the Erasmus MC Rotterdam and the VieCuri Medical Centre Venlo/Venray. On national level, around two thirds of patients are treated with MAL PDT in 2 sessions and one third with fractionated 5-ALA 20% PDT. This distribution is historically determined and not based on evidence based research.

• 5-ALA 20% PDT versus MAL PDT

There are only a few randomised controlled studies on treatment of the most common skin cancer.11 Choice of PDT treatment with fractionated 5-ALA 20% or MAL in 2 sessions often depends on the experience and choice of the physician or the availability of the precursor in a hospital. World-wide, most studies are performed with MAL and it has been accepted as the standard of care in PDT.12 However, according to the literature, the effectiveness in terms of clearance rates is in different studies lower for MAL in two sessions compared to fractionated 5-ALA 20% PDT: 79% versus 97% intention to treat (ITT) after one year in sBCC.13,14 Contra dictionary, MAL has the theoretical benefit of being more and faster absorbed in the cell than 5-ALA 20% and, thereby, should generate a higher production of protoporphyrin IX. In addition MAL has higher selectivity for tumour cells, inducing fewer side-effects in normal tissue. 15,16 This discrepancy between theoretical working mechanism and clearance rates needs further clinical research of the effectiveness of both treatments.

PDT is a hospital administered treatment modality during which patients have to come to the hospital one day (fractionated 5-ALA 20%) or two days one week apart (MAL in 2 sessions). Patient compliance could be higher with fractionated 5-ALA 20% than with MAL in 2 sessions because patients have to visit the hospital a second time. At some parts of the body patients experience a variable burning pain sensation during PDT which might influence completing the treatment. Kuijpers et al. found no significant differences in pain scores between ALA-PDT in 2 sessions and MAL PDT in 2 sessions.17 We expect 5-ALA 20% PDT to have more side-effects in our study as patients are treated twice on the same day.

Furthermore it is important to take into consideration the differences in patient acceptability costs (see 'economic evaluation').18 A well-designed study comparing the two topical PDT treatment modalities: fractionated 5-ALA 20% and MAL in 2 sessions will provide the answers needed to establish the position of the two modalities in the treatment of patients with sBCC. The conclusions from the proposed study can serve as a basis for updating guidelines for the treatment of sBCC to catch up with recent developments in clinical practice.