A Randomised Assessor Blinded Comparison of Low Irradiance and Conventional Irradiance Photodynamic Therapy for Superficial Basal Cell Carcinoma and Bowen's Disease

The inconvenience and pain of hospital-based photodynamic therapy (PDT) is sometimes limiting.¹ We developed very low irradiance LEDs for ambulatory PDT. Preliminary studies showed this to be convenient and relatively painless.^1-4 Here we evaluate the Ambulight® device (Ambicare Health Ltd) in a randomised controlled assessor-blinded study comparing low irradiance ambulatory PDT (APDT) with conventional PDT (CPDT) for superficial basal cell carcinoma (SBCC) and Bowen's disease (BD) (lesions ≤2cm).

A review of photodiagnostic investigations over 26 years: experience of the National Scottish Photobiology Service (1989-2015)

Background The Scottish Photobiology Service is the national referral pathway for patients with cutaneous photosensitivity diseases in Scotland. We reviewed the pattern of diagnosis of photosensitivity diseases and investigations performed between 1989 and 2015. Methods and Results Data were collected from the Photodiagnostic Database, annual reports and paper records. The total number of patients assessed each year was stable over the period studied (median 242 [range 231-266]), with most being new patients (median 69 [range 62-73]%). Monochromator phototesting was the most utilised investigation, although the use of provocation testing and photopatch testing has increased. The most common diagnosis was polymorphic light eruption, and there was a trend to increasing diagnosis of photoaggravated atopic eczema. Conclusions The pattern of diagnosis of photosensitivity diseases remains fairly stable in Scotland and we wish to emphasise the importance of this Scottish specialist service for patients with photosensitivity diseases and referrers.

Conventional and combination topical photodynamic therapy for basal cell carcinoma: systematic review and meta-analysis

BACKGROUND

Topical photodynamic therapy (PDT) is an established treatment option for low-risk basal cell carcinoma (BCC).

OBJECTIVES

To compare efficacy, cosmesis and tolerability of PDT for BCC with alternative treatments.

METHODS

MEDLINE, PubMed, Embase and CENTRAL databases were searched from inception until 1 September 2017. Included studies were randomized controlled trials (RCTs) of PDT for nodular (n) and superficial (s) BCC reporting at least one of the following outcomes: clearance at 3 months and sustained at 1 or 5 years; recurrence at ≥ 1 year; cosmesis; adverse events; tolerability.

RESULTS

From 2331 search results, 15 RCTs (2327 patients; 3509 BCCs) were included. PDT efficacy (5-year sustained clearance) was high but inferior to excisional surgery [nBCC pooled risk ratio (RR) 0·76; 95% confidence interval (CI) 0·63-0·91], and without re-treatment of partially responding lesions, was modestly inferior to imiquimod (sBCC: RR 0·81; 95% CI 0·70-0·95) and similar to fluorouracil (sBCC: RR 0·88; 95% CI 0·75-1·04). Five-year sustained clearance was inferior with conventional vs. fractionated PDT (sBCC: RR 0·76; 95% CI 0·68-0·84). PDT cosmesis was superior to surgery (sBCC: RR 1·68, 95% CI 1·32-2·14; nBCC: RR 1·82, 95% CI 1·19-2·80) and cryosurgery (BCC: RR 3·73, 95% CI 1·96-7·07), and without re-treatment of partially responding lesions was similar to imiquimod (sBCC: RR 1·01, 95% CI 0·85-1·19) and fluorouracil (sBCC: RR 1·04, 95% CI 0·88-1·24). Peak pain was higher but of shorter duration with PDT than topical treatments. Serious adverse reactions were rarer with PDT than imiquimod (sBCC: RR 0·05, 95% CI 0·00-0·84) and fluorouracil (sBCC: RR 0·11, 95% CI 0·01-2·04). Combination PDT regimens demonstrated reduced recurrence and improved cosmesis; however, results from these small studies were often nonsignificant.

CONCLUSIONS

PDT is an effective treatment for low-risk BCC, with excellent cosmesis and safety. Imiquimod has higher efficacy than single-cycle PDT but more adverse effects. Highest efficacy is with excisional surgery. Fractionated and combination PDT options warrant further study.

Monte Carlo modelling of photodynamic therapy treatments comparing clustered three dimensional tumour structures with homogeneous tissue structures

We explore the effects of three dimensional (3D) tumour structures on depth dependent fluence rates, photodynamic doses (PDD) and fluorescence images through Monte Carlo radiation transfer modelling of photodynamic therapy. The aim with this work was to compare the commonly used uniform tumour densities with non-uniform densities to determine the importance of including 3D models in theoretical investigations. It was found that fractal 3D models resulted in deeper penetration on average of therapeutic radiation and higher PDD. An increase in effective treatment depth of 1 mm was observed for one of the investigated fractal structures, when comparing to the equivalent smooth model. Wide field fluorescence images were simulated, revealing information about the relationship between tumour structure and the appearance of the fluorescence intensity. Our models indicate that the 3D tumour structure strongly affects the spatial distribution of therapeutic light, the PDD and the wide field appearance of surface fluorescence images.

Photodynamic therapy in dermatology: Dundee clinical and research experience

Topical photodynamic therapy (PDT) is increasingly accepted and used as a highly effective treatment for superficial non-melanoma skin cancer and dysplasia. We describe the developments in topical PDT for the treatment of skin diseases in our own PDT Centre in Dundee, both clinically and from a research base. Improvements in PDT could be achieved by optimisation of photosensitiser and light delivery, and these goals underpin the aims of our centre. We hope to facilitate the dissemination of use of PDT in dermatology throughout Scotland and outline some of the progress in these areas.

Review of an established UK home phototherapy service 1998-2011: improving access to a cost-effective treatment for chronic skin disease

OBJECTIVES

To review the Tayside home phototherapy service, including numbers of patients treated, diagnoses and outcomes, side-effects and safety, cost-effectiveness and absolute costs. To consider why home or outpatient phototherapy is not available to all patients who might benefit and how this could be addressed.

STUDY DESIGN

Observational and cost analysis.

METHODS

Analysis of the Tayside home phototherapy database 1998 and 2011, home phototherapy patient questionnaires, outcome data, costs and a comparison with outpatient phototherapy. Review of literature and current national guidelines for phototherapy, traditional systemic and biologic therapies for psoriasis.

RESULTS

298 courses of home narrowband UVB (NB-UVB) phototherapy were undertaken by 212 patients between 1998 and 2011, five courses in 1998 increasing to 36 in 2011. The main diagnoses treated were psoriasis (72%), atopic dermatitis (8%), and desensitization of photodermatosis (7%). For psoriasis, 74.5% achieved clearance or minimal residual activity in a median of 30 exposures (range 10-60). The estimated costs to the hospital ranged from £229 to £314 per course (£307 to £422 per effective course for psoriasis), compared with £114 for out-patient therapy (£149 per effective course for psoriasis). The total cost to society (hospital and patient costs) is around £410 per course, compared to an estimated £550 for outpatient therapy for this group of patients. Treatment was well tolerated, erythema rates were similar to outpatient therapy, there were no complaints and the vast majority would choose home over outpatient phototherapy if required in the future.

CONCLUSIONS

Hospital supervised home phototherapy appears as safe and effective as outpatient therapy and provides equality of access for patients who cannot attend for outpatient therapy. These patients may otherwise be inadequately treated or given more costly and higher risk systemic therapies, particularly for psoriasis. Commissioners and clinicians involved in dermatology services should provide accessible phototherapy for all patients who might benefit, utilizing home phototherapy where outpatient access is not possible.

Nine out of 10 sunbeds in England emit ultraviolet radiation levels that exceed current safety limits

BACKGROUND

Exposure to ultraviolet (UV) radiation from sunlight is recognized as the principal cause of skin cancer. Moreover, sunbeds have been classified as carcinogenic by the International Agency for Research on Cancer. Despite this, there is a shortage of objective data on UV exposure levels in sunbeds in England.

OBJECTIVES

We set out to measure UV emission levels in sunbeds at sites around England, and to compare these levels with both current standards and natural sunlight.

METHODS

Between October 2010 and February 2011, UV spectra were measured on site from a total of 402 artificial tanning units in England. Measurement instrumentation was calibrated, traceable to the National Physical Laboratory. Compliance with the relevant British and European standard was determined, and a skin-cancer weighting factor was used to compare the carcinogenic potential of sunbeds with that of sunlight.

RESULTS

For compliance with the European standard, erythemal-effective irradiance should not exceed 0·3 W m(-2). The values that we measured ranged between 0·10 and 1·32 W m(-2) with a mean of 0·56 ± 0·21 W m(-2) . Only 10% of sunbeds surveyed were within the recommended limit. Application of the skin-cancer weighting factor produced values that varied from 0·17 to 2·52 W m(-2) with a mean of 0·99 ± 0·41 W m(-2). The comparable value for Mediterranean noon day sun was 0·43 W m .

CONCLUSIONS

Nine out of 10 sunbeds surveyed throughout England emitted levels of UV radiation that exceed the maximum levels contained within the European standard. Moreover, the skin cancer risk for comparable times of exposure was up to six times higher than that for Mediterranean sunlight. This situation is unacceptable and stricter control measures must be put in place.

Oral 5-aminolevulinic acid induced Photodynamic Diagnostic Ureterorenoscopy--does the blood pressure require monitoring?

BACKGROUND

Photodynamic Diagnosis has been proven to improve detection of superficial bladder cancer and improve visualisation of resection margins. The use of 5-aminolevulinic acid as the photosensitising agent has been associated with side effects, specifically hypotension. We aimed to evaluate the effect of oral 5-ALA on the blood pressure in a group of patient who underwent Photodynamic Diagnostic Ureterorenoscopy.

METHODS

We carried out an observational study on all patients who underwent PDD-Ureterorenoscopy with oral 5-ALA between July 2009 and September 2011. Pre-administration, hourly post-administration and hourly post-operative blood pressures were noted. Mean arterial blood pressure and the threshold for cerebral ischaemia were calculated as well.

RESULTS

The study includes thirty-eight procedures which involved twenty-four patients with a mean age of 74 (SD±16.95). Hypotension was defined as <80% of the systolic or diastolic baseline blood pressure. Twenty patients were hypotensive pre-operatively after the ingestion of 5-ALA while 21 patients were hypotensive post-operatively. Three patients crossed their MAP threshold pre-operatively and were symptomatic. Fast infusion of intravenous fluids improved their symptoms.

CONCLUSION

Hypotension is a common occurrence after the ingestion of 5-ALA. Patients undergoing PDD Ureterorenoscopy should have their blood pressure monitored closely after the ingestion of 5-ALA.

Analysis of energy saving lamps for use by photosensitive individuals

Due to European legislation, the British government has begun the phase out of incandescent bulbs, to be replaced by energy-saving alternatives. The alternatives that are available on the market are Compact Fluorescent Lamps (CFL), Energy-Efficient Halogens (EEH) and Light Emitting Diodes (LED). Whilst previous research has shown that CFLs emit UVC, UVB and UVA, there is conflicting data available on whether double enveloped CFLs are a safer alternative to single enveloped CFLs for individuals suffering from photosensitivity. The emission spectra of 106 single enveloped CFLs and 65 double enveloped CFLs were measured. There were 17 different models of single enveloped CFLs, including lamps from 6 different manufacturers (ranging from 8-20 W) and 9 models of double enveloped CFLs from 6 different manufacturers (7-15 W). In addition, the emission spectra of 53 LEDs and 56 EEHs were also analysed. The LEDs consisted of 8 different models, from 3 manufacturers, spanning between 2.5 and 12 W. There were 11 models of EEH from 6 different manufacturers with wattages ranging from 28-70 W. In order to reduce sample bias, some bulbs were provided by the lighting industry federation and others were purchased randomly from local retailers. The results validate previous research in that considerable variation exists in the UV emitted from CFLs. This variation in UV levels is true, not only within different makes and models but also, surprisingly, within a box of 8 seemingly identical bulbs supplied by a single manufacturer. It was concluded that double enveloped CFLs do reduce the levels of UVC and UVB and therefore are a safer alternative for photosensitive individuals. However, as some double enveloped CFLs and EEHs do emit UVA at levels that provoke a reaction in the skin of UVA sensitive individuals, newly emerging LEDs that have minimal UV levels may provide a safer alternative.

Cyclobutane pyrimidine dimers are photosensitised by carprofen plus UVA in human HaCaT cells

Every year in the UK about 75,000 cases of non-melanoma skin cancer (NMSC) are registered, and about 9500 people are diagnosed with cutaneous melanoma (CM). The main risk factor for these cancers is exposure to sunlight. The effects of light on skin are wavelength dependent, with wavelengths in the UVB waveband (280-315 nm) being the most carcinogenic. UVB is directly absorbed by DNA, producing dimeric pyrimidine photoproducts including cyclobutane pyrimidine dimers (CPD) and pyrimidine (6-4) pyrimodone photoproducts (6-4PP). However UVA (315-400 nm) can also produce CPD, induce skin tumours in mice, and has been shown to be mutagenic in cell culture. Although the precise role of UVA in human skin cancer remains to be elucidated, it comprises the major portion of solar UV radiation, transmits through window glass and can be delivered in high doses from tanning lamps. Non-steroidal anti-inflammatory drugs (NSAIDs), in particular the 2-aryl propionic acid derivatives, are a well-documented group of photosensitising chemicals producing clinical phototoxic and photoallergic reactions. We have used carprofen, a model compound from this group to see if it could amplify the effects of UVA and contribute to the formation of CPD by UVA. Preliminary work has shown that carprofen combined with low doses of UVA (lambda(max): 365 nm; 5 J/cm(2)) can produce both strand breaks (SB) and CPD in human skin or blood cells. CPD were detected indirectly by both an immunofluorescence method and as T4 endonuclease V sensitive sites in the comet assay. These findings show that compounds other than fluoroquinolones and psoralen derivatives may contribute to CPD formation in skin cells in combination with UVA.

Photodynamic diagnosis (PDD) for upper urinary tract transitional cell carcinoma (UT-TCC): evolution of a new technique

INTRODUCTION

Transitional cell carcinoma of renal pelvis and ureter account was traditionally treated with nephroureterectomy. With the advent of rigid and flexible ureteroscopes endoscopic access to the ureter and renal pelvis for diagnosis and treatment has become a reality. We did fluorescence ureteroscopy using oral 5-ALA to diagnose upper tract urothelial tumours for four patients. Here we describe this technique and assess its feasibility to diagnose ureteric and renal pelvicalyceal tumours.

MATERIALS AND METHODS

A prospective pilot study was performed to assess the feasibility of PDD using oral 5-amino levulinic acid (ALA) for upper urinary tract tumours.

RESULTS

Four patients underwent PDD guided flexible ureteroscopy of the upper urinary tract. Obvious exophytic tumour seen on white light was also seen as red fluorescence on blue light. All areas with red fluorescence were biopsied (including additional areas not seen on white light) and were confirmed to be transitional cell carcinoma.

CONCLUSION

Photodynamic diagnosis using oral 5-ALA and subsequent treatment of upper tract urothelial tumours is safe and feasible with additional advantages of detecting lesions not visualised on conventional white light endoscopy.

Photodynamic therapy adjuvant to surgery in metastatic carcinoma in brain

Cerebral metastases occur in 15-40% of cancers and their incidence is increasing. We have studied the use of fluorescence image-guided surgery and repetitive photodynamic therapy in 14 metastatic brain cancers.

METHODS

Case note review of prospectively collected data on patients who were treated with PDT at the time of surgery for brain metastases. Patients were consented for the surgery and PDT. Patients were given 2 mg/kg body weight of Photofrin IV 48 h before the surgery and 20 mg/kg 5-aminolevulenic acid orally 3h before surgery. Following resection of the tumor using fluorescence, microsurgical and image guidance techniques, the post-excision cavity is filled with a balloon using 0.32% intralipid solution and up to five consecutive PDT treatments were given using 100 J/cm(2) Diode Laser 630 nm. Patients were followed up clinically and by brain imaging every 3 months till their death.

RESULTS

Seven were lung in origin and seven of variable sources. One patient with lung metastases died of unrelated cause while the remaining six had remained free from brain disease till their death. Two of the remaining seven patients died of local brain recurrence, one bowel after 4 weeks and one of unknown primary after 70 weeks.

CONCLUSION

Adjuvant repetitive PDT seems to offer an excellent local control of metastatic brain carcinomas with about 79% of patients succumb to the primary and only two out of fourteen died of brain recurrence with the best results obtained in lung cancer.

Use of mobile phones by medical staff at Queen Elizabeth Hospital, Barbados: evidence for both benefit and harm

All members of medical staff, including students, were asked to participate in a self-administered questionnaire concerning patterns of mobile phone use and care. Participants' phones were cultured for micro-organisms. Healthcare professionals working in close proximity to sensitive equipment were surveyed concerning adverse events associated with mobile phones. Telephone operators were asked to monitor time elapsed as they attempted to contact medical staff by various methods. Of 266 medical staff and students at the time of the study, 116 completed questionnaires (response rate=44%). Almost all (98%) used mobile phones: 67% used their mobile phones for hospital-related matters; 47% reported using their phone while attending patients. Only 3% reported washing their hands after use and 53% reported never cleaning their phone. In total, 101 mobile phones were cultured for micro-organisms; 45% were culture-positive and 15% grew Gram-negative pathogens. The survey of staff working in close proximity to sensitive equipment revealed only one report of minor interference with life-saving equipment. Telephone operators were able to contact medical staff within 2 min most easily by mobile phone. Mobile phones were used widely by staff and were considered by most participants as a more efficient means of communication. However, microbial contamination is a risk associated with the infrequent cleaning of phones. Hospitals should develop policies to address the hygiene of mobile phones.

Quantitative risk assessment of sunbeds: impact of new high power lamps

BACKGROUND

A survey of all sunbeds in a local authority area was carried out in 1998. Since then, there have been technological developments leading to new 'fast-tan' sunlamps which have become increasingly popular, along with unmanned sun parlours. In addition, new British and European sunbed standards have been set.

OBJECTIVES

To discover the commercial uptake of new high power sunlamps and to determine the impact on carcinogenic risk from sunbeds.

METHODS

Onsite spectral measurements, traceable to national standards, were conducted at all commercial sunbed premises within two local authorities and a quantitative risk assessment applied to the findings using a skin cancer model. Sunbed users were asked to complete a questionnaire regarding their reasons for using a sunbed and the risk associated with its use.

RESULTS

We found a 30% increase in the number of privately operated sunbeds since our 1998 survey. The median cancer-weighted exposure of all 133 sunbeds was comparable to that of Mediterranean sunlight. This was a significant increase compared to 1998. Moreover, 83% of sunbeds produced ultraviolet (UV) B radiation levels that exceeded the European standard. Fifteen per cent of respondents thought that there were no risks from use of sunbeds.

CONCLUSIONS

Sunbeds in current use carry a cancer risk comparable to Mediterranean sunlight. This is due to the use of new high power lamps. New British and European standards are being largely ignored with more than four out of five sunbeds exceeding the limit specified in the standard. There is a strong case for regulation of sunbed operators coupled to improved public education.

Photopatch testing of 1155 patients: results of the U.K. multicentre photopatch study group

BACKGROUND

Photoallergic contact dermatitis can be difficult to diagnose if not appropriately investigated. Currently, the most common U.K. photoallergens appear to be sunscreen chemicals. The investigation of choice is photopatch testing (PPT), which is probably underused. In part, this is due to differences in methodology and results interpretation.

OBJECTIVES

To conduct PPT using a group of sunscreen chemicals, defined indications and a standardized methodology including interpretation and relevance of reactions in patients attending for investigation at 17 centres across the U.K., Ireland and the Netherlands.

METHODS

Patients (n = 1155) who fulfilled the inclusion criteria were investigated with PPT using sunscreen chemicals in addition to suspected topical products. Readings were taken at 24, 48 and 72 h following standardized ultraviolet A irradiation (5 J cm(-2)). The clinical relevance of any reaction was recorded.

RESULTS

Of the 1155, 130 had allergic reactions (11.3%). Of these, 51 had photoallergy (PA) (4.4%), 64 had contact allergy (CA) (5.5%), and 15 patients had combined PA and CA (1.3%). Multiple PA was seen in some. The most common photoallergen was benzophenone-3 (27 reactions; 21%). Most reactions (60%) were clinically relevant. The most common indication for testing in patients found to have PA was a history of reacting to a sunscreen (41%). The other 59% had an exposed-site dermatitis/skin problem or a photodermatosis. Some centres (n = 8) performed readings after the standard 48-h reading, and an extra 32 PA and 22 CA reactions were detected, which were not evident at 48 h. A new photoallergen (octyl triazone) was detected in two patients.

CONCLUSIONS

Sunscreen PA and CA are probably equally uncommon. Most reactions, of both reaction types, were relevant clinically. A large proportion of patients (59%) found to have PA was unaware of reacting to a sunscreen chemical, suggesting that PA should be considered as an explanation in any exposed-site dermatitis. Although this study focused on reactions at 48 h postirradiation, readings performed up to 96 h, while inconvenient, add value by detecting additional relevant responses. A previously unknown photoallergen was found, highlighting the need for awareness of novel photoallergens in the marketplace. A standardized PPT method not only encourages more use of this investigation, but also facilitates comparison of results between centres and so will improve our understanding of PA.

Knowledge, attitudes and practice of healthcare ethics and law among doctors and nurses in Barbados

Background

The aim of the study is to assess the knowledge, attitudes and practices among healthcare professionals in Barbados in relation to healthcare ethics and law in an attempt to assist in guiding their professional conduct and aid in curriculum development.

Methods

A self-administered structured questionnaire about knowledge of healthcare ethics, law and the role of an Ethics Committee in the healthcare system was devised, tested and distributed to all levels of staff at the Queen Elizabeth Hospital in Barbados (a tertiary care teaching hospital) during April and May 2003.

Results

The paper analyses 159 responses from doctors and nurses comprising junior doctors, consultants, staff nurses and sisters-in-charge. The frequency with which the respondents encountered ethical or legal problems varied widely from 'daily' to 'yearly'. 52% of senior medical staff and 20% of senior nursing staff knew little of the law pertinent to their work. 11% of the doctors did not know the contents of the Hippocratic Oath whilst a quarter of nurses did not know the Nurses Code. Nuremberg Code and Helsinki Code were known only to a few individuals. 29% of doctors and 37% of nurses had no knowledge of an existing hospital ethics committee. Physicians had a stronger opinion than nurses regarding practice of ethics such as adherence to patients' wishes, confidentiality, paternalism, consent for procedures and treating violent/non-compliant patients (p = 0.01)

Conclusion

The study highlights the need to identify professionals in the workforce who appear to be indifferent to ethical and legal issues, to devise means to sensitize them to these issues and appropriately training them.

Ambulatory photodynamic therapy: a new concept in delivering photodynamic therapy

BACKGROUND

Photodynamic therapy (PDT) has been shown to be effective in treating Bowen's disease, superficial basal cell carcinoma and actinic keratosis.

OBJECTIVES

To investigate the feasibility of delivering PDT using a portable light-emitting diode device.

METHODS

A prototype diode array, comprising 37 AlGaInP diodes cast in epoxy with a diffuser, and driven by a battery pack, was designed and constructed. A pilot study was carried out in five patients with histologically proven Bowen's disease who were referred for PDT with 5-aminolaevulinic acid. They were all treated in the hospital-based dermatology PDT suite such that each received the same level of supervision as patients receiving PDT with nonambulatory light sources. Patients recorded pain levels. In accordance with our usual practice, patients received two treatments at a 4-week interval.

RESULTS

Four of five patients were clear at follow-up (range 6-13 months, median 9). Pain was classified as none or mild in 80% of treatments and moderate in the remainder.

CONCLUSIONS

There are many potential benefits of ambulatory PDT, including the possibility of a much higher patient throughput, and allowing effective treatment at home. This pilot study provides early promising data of the safety and efficacy of this approach.

Clinical and research applications of photodynamic therapy in dermatology: Experience of the scottish PDT centre

BACKGROUND AND OBJECTIVES

The Scottish PDT Centre has carried out 3,442 treatments on 762 patients with superficial skin lesions, especially superficial basal cell carcinoma (sBCC), Bowen's disease (BD) and actinic keratosis (AK). STUDY DESIGN MATERIALS AND METHODS: The article reviews our experience of various light sources and associated dosimetry; thereafter we discuss clinical outcome followed by some of our research studies in clinically important areas.

RESULTS

We show that improved dosimetry is required to ensure an optimal light dose is delivered to the tumour. We have shown that photosensitizers and proteins interact in such a way that their photophysical and photochemical properties are modified. We have also demonstrated the presence of DNA strand breaks with two different photosensitizers, but there is no evidence that PDT is significantly mutagenic in clinical practice.

CONCLUSIONS

In our experience, topical PDT is generally well tolerated and is an effective treatment of sBCC, BD, AK, field change and lesions at sites of poor healing.

Photogenotoxicity of hypericin in HaCaT keratinocytes: Implications for St. John's Wort supplements and high dose UVA-1 therapy

Extract of St. John's Wort (Hypericum perforatum) is commonly used as natural remedy for treatment of mild to moderate depression. However, it contains a powerful photoactive component, hypericin, which can cause a severe photodermatitis when eaten by grazing animals (hypericism). In humans, there is evidence that supplementation with St. John's Wort can reduce the minimal erythemal dose (MED) in patients undergoing high dose UVA-1 phototherapy. This is a recent development in phototherapy where the most erythemogenic parts of the UVA spectrum are filtered out, allowing delivery of higher doses of the longer wavelengths of UVA. Although current published evidence suggests that the plasma levels of hypericin are unlikely to cause clinical phototoxicity, it has been established that photoactive compounds can cause DNA damage at sub-toxic and sub-erythemal doses, the effects of which might not be apparent for many years after the event. The present study used HaCaT keratinocytes to investigate the photoclastogenic ability of hypericin on irradiation with UVA. The results show that although the combination of hypericin and UVA light increased the genotoxic burden, when all factors are taken into account, the risk of significant photogenotoxic damage incurred by the combination of Hypericum extracts and UVA phototherapy may be low in the majority of individuals.

Ultraviolet A dosimetry in photopatch test centres in Europe

OBJECTIVE

The aim of the study was to investigate the state of ultraviolet (UV) A dosimetry in photopatch testing centres in Europe.

BACKGROUND

It has been acknowledged that a widespread disparity exists in the way photopatch testing is carried out in different countries throughout Europe. This prompted the formation of a European taskforce that developed a consensus methodology. One issue that was not addressed directly was that of UVA dosimetry, which clearly impacts on the consistency of the clinical results.

STUDY DESIGN

Ten UV meters from photopatch test centres throughout Europe were set up at a reproducible position from a photopatch test light source containing UVA fluorescent lamps and the irradiances were noted from each meter. One meter served as a reference meter with calibration carried out in an optical laboratory traceable to the National Physical Laboratory.

RESULTS

The mean of all the measurements was 5.74 mW/cm(2) with a SD of 0.36 mW/cm(2). Expanded uncertainty at 95% confidence level was 12%.

CONCLUSIONS

It is desirable that meter calibration should have an accuracy of the order of +/-10%. The variation in recorded values among the 10 meters investigated was within acceptable limits. The meter must be calibrated using a similar light source to that used in the phototest equipment, in this case a UVA fluorescence lamp.