Keratoses and nonmelanoma skin tumors in long-term photochemotherapy (PUVA)

Development of Topical Nanoemulgel Using Combined Therapy for Treating Psoriasis

This study focuses on the development of topical formulation of methoxsalen using Babchi oil as formulation component that can be applied at body surfaces providing sustained delivery and enhanced penetration of methoxsalen leading to significant epidermal localization and better anti-psoriatic activity. The combination of psoralens, that is, methoxsalen (synthetic) and Babchi oil (natural) has been developed into nanoemulgel formulations. A total of four nanoemulsion formulations was developed using Babchi oil as oil phase and Tween 80 as surfactant by high-pressure homogenization method. The prepared nanoemulsions were characterized for entrapment efficiency, mean droplet size, and zeta potential. Based on characterization results, the optimized nanoemulsion formulation(s) were incorporated into the carbopol gel base to make a nanoemulgel. The prepared nanoemulgel formulations were analyzed for pH, drug content determination, spreadability, viscosity, ex vivo skin permeation, and in vivo studies. The nanoemulsions showed droplet size between 51.3 and 146.7 nm, entrapment efficiency of 92.76%-98.10%, and zeta potential of -28.1 to -54.89 mev. The nanoemulsions showed varied in vitro drug release. In ex vivo skin permeation, nanoemulgel (NG2) showed increased penetration and localized accumulation of methoxsalen across the skin compared with plain gel. Ex vivo results were substantiated by in vivo results showing significant amelioration of hyperproliferative skin symptoms. The promising results suggested that nanoemulgel system is a suitable carrier for the topical delivery of methoxsalen-Babchi oil.

Melanoma and non-melanoma skin cancer in psoriatic patients treated with high-dose phototherapy

OBJECTIVES

The carcinogenic effect of plus ultraviolet A (PUVA)-therapy in psoriatic patients has been widely demonstrated, while data on the safety of narrow band (311 nm) ultraviolet B (nb-UVB) are scarce. We investigated the occurrence of melanoma and non-melanoma skin cancer (NMSC) in psoriatic patients treated with nb-UVB or PUVA-therapy.

METHODS

This retrospective study included patients affected by psoriasis, who had been treated with nb-UVB or PUVA-therapy. Clinical data and phenotypic risk factors were collected and a total body examination was performed at a routine appointment during the study period.

RESULTS

We examined 92 patients (60 males and 32 females; mean age: 53.5 years, range: 20-83 years) treated with PUVA-therapy (42/92, 45%) or with nb-UVB (50/92, 55%) for 1-28 years (mean: 7.1 years). Among patients treated with PUVA, nine skin tumors (one melanoma, seven basal cell carcinoma (BCCs) and one squamous cell carcinoma (SCC)) were detected in 2/42 (4.7%) patients, while in the nb-UVB group, 14 skin tumors including two melanomas, four BCCs, and eight SCCs were diagnosed in 6/50 (12%) patients.

CONCLUSIONS

A noteworthy number of NMSC were diagnosed in this Mediterranean population of patients exposed to high-dose UV treatment. A thorough risk-benefit evaluation should always be done before UV treatment and patients should be carefully monitored for skin cancer during and after treatment discontinuation.

Cutaneous Carcinogenic Risk of Phototherapy: An Updated Comprehensive Review

Phototherapy is among the oldest and most highly effective treatment modalities available for moderate-to-severe psoriasis. However, concern regarding the potential carcinogenic risk associated with ultraviolet B (UVB) phototherapy and/or psoralen with ultraviolet A (PUVA) has been expressed by both providers and patients. The purpose of this review is to assess the cutaneous malignancy risks of UVB phototherapy and/or PUVA in all skin types, including Caucasian and non-Caucasian patients. We searched the MEDLINE database for original research articles regarding the skin cancer risk of phototherapy. A total of 61 articles were included. In Caucasians, an increased risk of squamous cell carcinoma with PUVA therapy was reported after >250 sessions, whereas studies among non-Caucasians did not show any increased risk. There was no convincing evidence of increased skin cancer risk associated with UVB phototherapy among all skin types. In view of the continued validation of its safety, phototherapy remains a valuable treatment option for patients with moderate-to-severe psoriasis.

Clinical manifestations of the skin photodamage as a result of a multi-course phototherapy of psoriasis patients

Goal. To study clinical manifestations and frequency of skin photodamage symptoms in psoriasis patients receiving a longterm multi-course phototherapy. Materials and methods. The study involved 106 patients suffering from psoriasis vulgaris and receiving a multi-course treatment by methods of the PUVA therapy, broadband medium-wave UV therapy and narrowband phototherapy with the wavelength of 311 nm. The average number of courses was 7 while the average number of treatment sessions was 141. Depending on the number of treatment sessions, the patients were divided into three groups: Group 1 (n = 33) - patients that received 50-100 phototherapy sessions, Group 2 (n = 58) - patients that received 101-200 treatment sessions, and Group 3 (n = 15) - patients that received over 200 treatment sessions. The control group comprised 20 psoriasis patients that did not receive any phototherapy before. Major results. The comparative analysis of the entire group of patients receiving a phototherapy revealed a statistically significant incidence of lentigo/sunspots, diffuse skin hyperpigmentation and actinic elastosis vs. the control group. The frequency of clinical manifestations characteristic of the skin photodamage grew as the number of treatment sessions increased. All of the symptoms except for guttate hypomelanosis and venous lakes demonstrated statistically significant dynamics. Conclusion. There is a dose-dependant increase in the frequency of skin photodamage symptoms in patients suffering from psoriasis vulgaris and receiving a long-term multi-course phototherapy.

Revisited the potential risks of carcinogenicity of phototherapy in patients with psoriasis

The article presents published data on the assessment of the risk of cancerogenicity of multiple courses of phototherapy methods such as PUVA therapy and UVB-311 in psoriatic patients. The authors analyzed the incidence of malignant skin neoplasms (squamous cell carcinoma, basal cell carcinoma, malignant skin melanoma) among psoriatic patients from different population groups taking into account the cumulative radiation doses and number of procedures.

Iatrogenic skin cancer: induction by psoralen/ultraviolet A and immunosuppression of organ transplant recipients

Photochemotherapy (psoralen/UVA (PUVA)) is an efficient therapeutic tool for a wide range of skin diseases. Concern, however, exists regarding the long-term carcinogenic effects of this treatment modality and, as a consequence, is being used less frequently. PUVA remains an important treatment in our therapeutic armamentarium but must be used with caution in those patients with risk factors and cumulative dose exposure must be limited. PUVA-induced cancers show features in common with skin cancers induced by immunosuppressed organ transplant recipients. Tumours in the latter group of individuals are, however, much more aggressive and difficult to manage.

PUVAthérapie et cancers cutanés

INTRODUCTION

The benefits of PUVAtherapy in many dermatological affections are well known. Its carcinogenic role in the long term has been assessed varyingly in American and European series.

OBJECTIVE

The aim of this study was to assess the role of PUVA in the onset of cancers of the skin.

METHODS

Retrospective study of patients presenting with psoriasis and followed-up in the phototherapy unit of the Michallon Hospital in Grenoble since 1976 and having received more than 150 sessions of PUVA. The parameters studied were: age, gender, phototype, age at the time of the first irradiation, type of phototherapy administered, total number of sessions, concomitant treatments, administration of retinoids and the appearance of skin cancers with the interval before their onset after the first session, their localization and their histological type.

RESULTS

One hundred six patients were retained among the 152 who replied to the inclusion criteria. Having died or been lost to follow-up, forty-six patients were excluded. Fourteen patients had presented at least one cutaneous tumor with a total number of 35. Excluding the keratoacanthomas, 13 patients had a non-melanic cutaneous cancer with a total number of 32 tumors. Ten out of the 14 were phototype III, 3 were phototype II and one was phototype IV. Nine out of 14 had received PUVAtherapy alone and 5 PUVAtherapy and broad spectrum UVB. The number of sessions of PUVA received in all the cases was more than 200 (220 to 780), corresponding to a total dose of UVA comprised between 1460 and 3882 Joules. The delay before onset of the tumors varied from 6 to 27 years after the first PUVAtherapy. The mean age at the time of the first irradiation was of 50.2 years (14-75 years). The mean duration of phototherapy was of 10 years (2.23 years).

Keratoacanthoma as a postoperative complication of skin cancer excision

BACKGROUND

Keratoacanthomas usually occur spontaneously as a single rapidly growing tumor on sun-exposed skin. Multiple keratoacanthomas are rarely seen. Keratoacanthomas may also develop after trauma, laser resurfacing, radiation therapy, and at the donor site after skin grafting.

OBJECTIVE

We report 6 cases of keratoacanthomas that developed in and around healing and healed surgical sites after treatment of skin cancer. These tumors developed 1 to 3 months after surgery and were sometimes multiple.

METHODS

We performed follow-up examinations of patients' wounds after the treatment of skin cancer. Histological examination of nodules developing in the margins of healing wound sites and in the scars of healed wound sites after Mohs micrographic surgery revealed keratoacanthomas.

RESULTS

The tumors presented as a rapidly growing nodule or nodules, with the typical morphology and pathology of keratoacanthoma. One patient developed multiple keratoacanthomas at surgical and nonsurgical sites. These nodules were treated by a combination of excision, curettage and electrodesiccation, and oral isotretinoin, 4 mg/d.

CONCLUSION

Keratoacanthoma must be considered in the differential diagnosis of a rapidly growing nodule within or around the surgical site after skin cancer surgery.

PUVA-induced lichen planus

A 28-year-old male with histologically proven psoriasis vulgaris was administered oral 8-methoxypsoralen UVA therapy (PUVA). The plaques of psoriasis gradually responded to treatment, however numerous pruritic, violaceous papules over the right forearm and left thigh developed 5 months after starting PUVA (45 sittings with a cumulative dose of 156 J/cm(2)). Histopathologic examination of these lesions was compatible with the diagnosis of lichen planus (LP). On stopping PUVA therapy, the lesions subsided in one month. This case emphasizes the hypothesis that cell injury caused by PUVA therapy could expose some sequestered antigens to autoreactive lymphocytes and induce lichen planus.

Incidence and risk factors associated with a second squamous cell carcinoma or basal cell carcinoma in psoralen + ultraviolet a light-treated psoriasis patients

Psoralen + ultraviolet A-treated psoriasis patients are at increased risk for squamous cell carcinomas and basal cell carcinomas; however, the incidence and risk factors associated with second squamous cell carcinomas and basal cell carcinomas in this population are not well qualified. Incidence and risk factors for second squamous cell carcinomas and basal cell carcinomas were studied in a cohort of 1380 psoralen + ultraviolet A-treated psoriasis patients prospectively followed for over 20 y; 264 had a squamous cell carcinoma and 258 a basal cell carcinoma after beginning psoralen + ultraviolet A therapy. After a first squamous cell carcinoma, the risk of a second squamous cell carcinoma was 26% at 1 y, 62% at 5 y, and 75% at 10 y. Risk increased with high psoralen + ultraviolet A exposure prior to the first squamous cell carcinoma (hazard ratio 3.32, 95% confidence interval 1.53, 7.18). Higher rates of post-first squamous cell carcinoma psoralen + ultraviolet A treatment also were associated with greater risk (hazard ratio 1.56 for every additional 10 treatments per year for patients with low pre-first squamous cell carcinoma psoralen + ultraviolet A exposure, 95% confidence interval 1.35, 1.81). Patients exposed to high levels of tar and/or ultraviolet B before a first squamous cell carcinoma were also at higher risk (hazard ratio 1.72, 95% confidence interval 1.14-2.60). Risk of a second basal cell carcinoma was 21% at 1 y, 49% at 5 y, and 61% at 10 y. There was some evidence that high exposure to psoralen + ultraviolet A before a first basal cell carcinoma was associated with increased risk of second basal cell carcinoma (hazard ratio 1.45, 95% confidence interval 0.97-2.17). Higher post-first tumor psoralen + ultraviolet A treatment rates also increased risk (hazard ratio 1.24 for every additional 10 treatments per year, 95% confidence interval 1.06-1.47). Psoralen + ultraviolet A-treated psoriasis patients appear to have a greatly increased incidence of second squamous cell carcinoma compared with the general population. Patients who develop a squamous cell carcinoma after starting psoralen + ultraviolet A therapy should be closely monitored for a subsequent squamous cell carcinoma.

Green tea protects against psoralen plus ultraviolet A-induced photochemical damage to skin

The use of psoralens combined with exposure to ultraviolet A radiation is a major form of treatment for psoriasis and a number of other common skin diseases. Although psoralen plus ultraviolet A treatment is highly effective, careful follow-up cohort studies have shown that it greatly increases risk for the development of cutaneous squamous cell carcinoma and melanoma. Strategies to reduce the risk of cancer development in psoralen plus ultraviolet A-treated populations are highly desirable. In prior studies, we demonstrated that green tea and constituent polyphenols protect against ultraviolet B-induced carcinogenesis and reduce the growth rate of established tumors in skin. In this study, we show that pre- and post-treatment with standardized green tea extract in psoralen plus ultraviolet A treatment populations abrogates the psoralen plus ultraviolet A-induced photochemical damage to skin. Intact mouse and human skin and reconstituted human skin were employed to assess the effect of both topical and oral administration of standardized green tea extract against psoralen plus ultraviolet A-induced photodamage. Oral administration of standardized green tea extract prior to and during multiple psoralen plus ultraviolet A treatments reduced hyperplasia and hyperkeratosis in murine skin. Standardized green tea extract treatment also inhibited accumulation of c-fos and p53 protein induction following a single exposure to psoralen plus ultraviolet A. c-fos and p53 positive cells in psoralen plus ultraviolet A-treated skin were found to be increased by 55.4 +/- 13. 6% and 62.3 +/- 10.5%, respectively, compared with saline-treated unexposed control skin. Oral administration of 0.4 or 0.8% standardized green tea extract inhibited c-fos protein accumulation by 18.5% and 46.2% (p < 0.05), respectively, and p53 protein accumulation by 26.1% and 54.3% (p < 0.05), respectively. Similarly proliferating cell nuclear antigen staining, a marker of cell proliferation was induced (73.7%) in psoralen plus ultraviolet A-treated skin. Oral administration of 0.4% or 0.8% standardized green tea extract 1 d after psoralen plus ultraviolet A treatment was effective in reducing psoralen plus ultraviolet A-induced inflammatory responses including erythema and edema formation. When standardized green tea extract was applied to EpiDerm, a reconstituted human skin equivalent, psoralen plus ultraviolet A-induced 8-methoxypsoralen-DNA adduct formation and p53 protein accumulation were inhibited. Topical application of 0.2 mg 8-methoxypsoralen per cm2 followed by exposure to ultraviolet A (2.5 J per cm2) resulted in delayed erythema formation in human subjects. Pretreatment of human skin with topical application of 0.2 mg standardized green tea extract per cm2 30 min prior to psoralen plus ultraviolet A treatment resulted in an almost complete abrogation of psoralen plus ultraviolet A-induced erythema. In summary, these data demonstrate that standardized green tea extract protects against psoralen plus ultraviolet A-induced phototoxicity by inhibiting DNA damage and diminishing the inflammatory effects of this modality.

PUVA and cancer risk: the Swedish follow-up study

There is concern about the long-term carcinogenic effects of psoralen and ultraviolet A radiation (PUVA) for treatment of skin disorders. Many authors have found an increased risk for cutaneous squamous cell carcinoma (SCC). Except in anecdotal reports, malignant melanoma had not been observed in patients treated with PUVA until recently. In the U.S.A., a 16-centre prospective study of 1380 patients showed for the first time that there might also be an increased risk for malignant melanoma in patients treated with high cumulative dosages of PUVA. We have therefore followed up the Swedish PUVA cohort until 1994. This cohort had previously been followed up until 1985. Information from 4799 Swedish patients (2343 men, 2456 women) who had received PUVA between 1974 and 1985 was linked to the compulsory Swedish Cancer Registry in order to identify individuals with cancer. The average follow-up period was 15.9 years for men and 16.2 for women. We did not find any increased risk for malignant melanoma in our total cohort of 4799 patients treated with PUVA or in a subcohort comprising 1867 patients followed for 15-21 years. For cutaneous SCC there was an increase in the risk: the relative risk was 5.6 (95% confidence interval, CI 4. 4-7.1) for men and 3.6 (95% CI 2.1-5.8) for women. Significant (P < 0.05) increases were also found in the incidence of respiratory cancer in men and women and of kidney cancer in women. In conclusion, we did not find any increased risk for malignant melanoma in our patients treated with high doses of PUVA and followed up for a long time. We confirm previous reports of an increase in the incidence of cutaneous SCC in patients treated with PUVA, and recommend that patients should be carefully selected for PUVA and rigorously followed up.

The benefits and risks of long-term PUVA photochemotherapy

In 1974 a new photobiologic principle i.e. light + drug, called photochemotherapy was discovered in Boston and immediately confirmed in Vienna. Psoralen + UVA (PUVA) photochemotherapy has now been applied to the treatment of more than 24 heterogeneous groups of diseases, especially psoriasis and mycosis fungoides. After 24 years of experience in thousands of patients with psoriasis and 23 other skin disorders, virtually the only risk is the development of squamous-cell carcinomas. This risk is low with two exceptions: previous history of treatment with ionizing radiation or inorganic trivalent arsenic, and patients with recalcitrant psoriasis who require continuous treatment for many years. In a recent report from a large USA clinical trial, melanoma developed in a few patients with psoriasis treated with PUVA. This prospective clinical trial did not have a control population, and therefore, the conclusion that PUVA can cause melanoma is tentative.

Cutaneous neoplasia following PUVA therapy for psoriasis

To determine the risk of cutaneous neoplasia following photochemotherapy (PUVA), we reviewed patients with psoriasis treated at our unit between 1979 and 1991. Two hundred and forty-five patients were assessed, with a median duration of follow-up of 9.5 years. Fifty-nine per cent were male, and 41% female. The median number of exposures was 59, and the median total dose was 133 J/cm2 for the group as a whole. Non-melanoma skin cancers (NMSC) occurred in six individuals (2.4%). Basal cell carcinoma occurred in all six and one individual also developed four squamous cell carcinomas and Bowen's disease of the penis. No cases of malignant melanoma were recorded. Patients who developed NMSC received a median number of 225 exposures and a median cumulative dose of 654 J/cm2. Compared with a control study population in West Glamorgan, Wales, there was a 1.4 (95% confidence limits (CL) 0.5 and 3.1) times increased risk of NMSC. A statistically significant increased incidence of NMSC was found for patients who had received 100 or more exposures, and 250 or more J/cm2, with risks of 3.7 (95% CL 1.0 and 9.5), and 4.0 (95% CL 1.1 and 10), respectively. A PUVA dose of < 250 J/cm2 or < 100 exposures conferred a minimal increase in risk of NMSC in our study population.

Cutaneous carcinoma and PUVA lentigines in Thai patients treated with oral PUVA

A total of 113 Thai patients who were treated with oral PUVA from 1979 to 1992 were examined for long-term cutaneous side effects of PUVA. Two psoriatic patients developed PUVA keratosis on non-sun-exposed areas. Both were skin type IV and had had phototherapy with UVB and sunlight previously. The total doses of UVA were 909 J/cm2 and 242 J/cm2 respectively. One psoriatic patient developed Bowen's disease. He had had a cumulative dose of UVA 2207 J/cm2. He also had a past history of arsenic intake and phototherapy with UVB and sunlight. PUVA lentigines were seen in 58 patients (51.4%). It was associated with older age at starting PUVA, higher cumulative UVA dose and greater number of PUVA treatment. This study suggests that previous exposure to other risk factors is important for inducing skin cancer in populations with skin phototype III, IV and V treated with oral PUVA.

PUVA, UVB, psoriasis, and nonmelanoma skin cancer

This article reviews the English-language literature on the risk of nonmelanoma skin cancer from phototherapy (UVB) or photochemotherapy (PUVA) in the treatment of psoriasis. The evolution of the debate on the carcinogenic potential of these treatment is discussed, particularly with reference to PUVA. Available data indicate that therapeutic UVB has a low risk of producing cutaneous cancers, with the possible exception of those on male genital skin. However, there is a definite cutaneous carcinogenic risk from oral PUVA. The major associated risk factors are reviewed. We provide recommendations for the assessment and treatment of patients to minimize this risk.

Squamous cell carcinoma of the skin (excluding lip and oral mucosa)

The striking impression obtained from reviewing the cancer literature is how difficult it is to analyze the data for answers to many important biologic, behavioral, prognostic, and therapeutic questions about squamous cell carcinoma of the skin. This article addresses current concepts, controversies, and management of cutaneous squamous cell carcinoma (excluding the lip and oral mucosa).

PUVA and skin cancer. A historical cohort study on 492 patients

BACKGROUND

The safety of psoralen plus ultraviolet A (PUVA) light therapy has been an issue of debate. A few multiple-center cooperative studies have reported an increase of basal cell and squamous cell carcinomas among PUVA-treated patients. In our institute, more than 1000 patients have been treated with PUVA since 1975.

OBJECTIVE

We investigated the incidence of skin cancer among patients who received high doses of PUVA to see whether such incidence increased.

METHODS

This is a historical cohort study of two comparison groups of patients. Subjects under study were 492 psoriasis patients who received PUVA treatments between 1975 and 1989. One group of 103 patients, defined as the high-dose group, received an accumulated PUVA dose of 1000 joules/cm2 or more; another group of 389 patients, as the low-dose group, received 200 joules/cm2 or less. The occurrence of skin cancer in the two comparison groups is analyzed.

RESULTS

In the high-dose group we observed an increased number of patients with squamous cell carcinoma, keratoacanthoma, and actinic keratosis. We did not see any patients with genital cancer, melanoma, or an increased number of patients with basal cell carcinoma.

CONCLUSION

The risk of squamous cell carcinoma developing in patients who received a high dose of PUVA is confirmed. We speculate a combination of factors, including PUVA, may contribute to this risk.

Plasma levels of 8-methoxypsoralen following oral or bath-water treatment

The plasma levels of 8-methoxypsoralen (8-MOP) were determined in 18 patients on PUVA treatment for their psoriasis and in two control volunteers. Seven of the patients were on oral therapy and 13 having bath treatment. The plasma levels of 8-MOP were determined up to 6 h after treatment and varied between less than 10 ng/ml and 360 ng/ml for the orally treated group, and in the bath-treatment group were all less than 10 ng/ml.

UVABA therapy for psoriasis. Efficacy with shortened treatment times with the combined use of coal tar, anthralin, and metal halide ultraviolet machines

Rapid clearing of psoriasis in a psoriasis treatment center setting has been obtained with a combination of short-contact coal tar, phototherapy from high-pressure metal halide lamps (consisting of UVA and UVB), and short-contact high-potency anthralin therapy. These intensive 1 1/2- to 2-hour treatment sessions done three or four times weekly were as efficacious as reported responses to PUVA therapy or conventional psoriasis day care therapy. The treatment schedule allows minimal time away from work, decreased hours per week in contact with crude coal tar, shortened UV treatment times, decreased cost, and a low risk of side effects. It is suggested that the use of UVA and UVB combined with anthralin (UVABA) is effective for many patients with moderate to severe psoriasis.

Psoriasis therapy and the risk of skin cancers

Photochemotherapy (PUVA) and methotrexate (MTX) are treatments frequently prescribed in patients with severe psoriasis. However, both treatments have carcinogenic potential. A group of 227 patients, who had been treated with PUVA, MTX or the combination, was investigated for the presence of cancer of the skin. As a control, the partners of these patients were investigated at the same visit. Cancers of the skin were observed in 15 out of 227 psoriatics, compared to one out of 95 control subjects. In the psoriatic patients a previous history of skin cancer, arsenic intake and X-ray treatment were observed more frequently. The increased frequency of skin cancers in psoriatics treated with PUVA, MTX and the combination of both, justifies regular surveillance on skin cancer in these patients.

'High single-dose' European PUVA regimen also causes an excess of non-melanoma skin cancer

We report the results of a long-term (12.8 years) follow-up study of the detection of malignant and benign skin tumours in patients with psoriasis, who were treated with PUVA according to the European, 'high single-dose' regimen. A total of 13 squamous cell carcinomas (SCC) and 24 basal cell carcinomas (BCC) were diagnosed in 11 of 260 patients. The incidence of both SCC and BCC was increased in comparison with the general Dutch population. The ratio of SCC to BCC in the general population was 1:8 but was 1:2.5 in our study group. A positive correlation was observed between the development of SCC and the total UVA dosage, the age of the patient at the start of the PUVA treatment and a history of arsenic use. This dose-related increase in the incidence of SCC, reported in studies from the U.S.A., has not been found in earlier European studies. The average time period between the start of PUVA therapy and the diagnosis of the first malignant skin tumour was 6.0 years for SCC and 4.7 years for BCC. Among the 49 benign skin tumours were actinic keratoses, a keratoacanthoma and 'PUVA keratoses', a newly described hyperkeratotic lesion, especially found in PUVA-treated patients.

Side-effects of psoralen photochemotherapy (PUVA)

Although psoralen photochemotherapy (PUVA) is one of the most effective forms of therapy for psoriasis, the risk of potential long-term side-effects is, as yet, not clearly determined. Chronic degenerative and pigmentary skin changes similar to those of chronic solar exposure occur after long-term PUVA treatment; PUVA also causes non-melanoma skin cancers in man, although there is, as yet, no consensus as to what cumulative phototoxic PUVA dose is carcinogenic. Long-term multicentre studies from the U.S.A. indicate a definite risk of squamous cell carcinoma for long-term PUVA-treated patients, whereas European studies reveal no overall increase in skin cancers in similar patients except for those exposed to other carcinogens. Assignment to PUVA should be based on the risk:benefit ratio for the individual patient. Careful patient selection is therefore mandatory and should be limited to those who can be monitored and controlled by informed, competent and conscientious physicians.

Overview of radiation-induced skin cancer in humans

There are about a dozen studies of the incidence of skin cancer among irradiated populations with known skin doses that are available for estimating the risk of radiation-induced skin cancer. It is of note that they provide no evidence for a dose threshold and are compatible with a linear dose-response relationship, at least for ultraviolet radiation exposed skin. The studies also provide varying amounts of evidence concerning a number of other important issues in assessing skin cancer risk: types of skin cancer induced by ionizing radiation, the appropriateness of relative risk vs absolute risk models, combined effects of ionizing and UV radiations, and variations in sensitivity to skin cancer induction among demographic and genetic subgroups. Little epidemiological information is available on several factors, such as the RBE for high-LET radiation, the effects of dose protraction or fractionation, or variations in risk by age at irradiation. A reasonable estimate of skin cancer lethality was 0.2 per cent when weighted for the relative proportions of squamous cell and basal cell skin cancers. Average risk estimates of radiation-induced skin cancer incidence were: absolute risk (AR) of 8.5 X 10(-4) person-year-Sv and excess relative risk (RR) of 52 per cent/Sv. Lifetime skin cancer risk was calculated by life-table methods for males from exposures spread out over ages 20-60 years. The estimates for excess skin cancer incidence were 2 per cent and 11 per cent per Sv under the AR and RR models, respectively, while the corresponding mortality risks were 4 X 10(-5) and 2 X 10(-4) per Sv.

Cutaneous and ocular side-effects of PUVA photochemotherapy--a 10-year follow-up study

To record the potentially serious side-effects of melanoma and non-melanoma skin cancers and ocular damage following long-term PUVA chemotherapy, we re-examined 198 of 242 patients. These comprised: 90 with psoriasis, 27 with parapsoriasis, 19 with cutaneous T-cell lymphoma, 23 with vitiligo, eight with cutaneous mastocytosis, 16 with atopic dermatitis, three with prurigo nodularis, two with polymorphous light eruption and 10 with pruritus of chronic renal failure on dialysis, treated between 1977 and 1987 in our department. During the 10-year period, 11 patients died of unrelated disease. None of the patients reviewed had previous skin cancer or had been treated with arsenic, methotrexate or ionizing irradiation before PUVA treatment. None of the patients were children under 16 years of age. The mean age was 54.5 years, the sex ratio 102:96 (M:F). The mean cumulative dose of UVA for the whole group was 169.5 J/cm2. One patient with psoriasis, psoriatic arhropathy, ankylosing spondylitis and Crohn's disease, who was on azathioprine for 6 years, developed squamous-cell carcinoma on the left lower leg. Another patient with pustular psoriasis, who received PUVA treatment to her palms and soles only, developed malignant lentigo of Hutchinson on the right lower leg. PUVA lentigines were found in about 20% of patients. All patients had a yearly ophthalmological examination. None of them developed cataracts, lens opacities or had impairment of their visual acuity.

A preliminary study on the link between PUVA and skin cancer

One hundred four psoriatic patients who had 8-methoxypsoralen-ultraviolet light A (PUVA) treatment between 1975-1987 were investigated to determine if skin cancer had ever occurred during or after the therapeutic period. Incidence data of skin cancer was applied to this group of patients to measure the expected number of patients with skin cancer. The significance of observed number versus expected of PUVA-treated patients with skin cancer was analyzed. The authors did not observe a significant increase of patients with skin cancer.

Skin cancer in patients with chronic radiation dermatitis

The cases of 76 patients with chronic radiation dermatitis resulting from low-dose ionizing radiation for benign disease were reviewed retrospectively for risk factors leading to the development of neoplasia. The patients were studied with respect to original hair color, eye color, sun reactive skin type, benign disease treated, area treated, age at treatment, and age at development of first skin cancer. Analysis of data showed 37% of patients had sun-reactive skin type I, 27% had type II, and 36% had type III. Types IV through VI were not represented. There appeared to be an overrepresentation of types I and II. Increased melanin pigmentation may therefore be either directly or indirectly protective against the development of skin cancers in patients who have received low-dose superficial ionizing radiation for benign disease. The sun-reactive skin type of patients with chronic radiation dermatitis may be used as a predictor of skin cancer risk when the total dose of ionizing radiation is not known.

8-Methoxypsoralen-DNA adducts in patients treated with 8-methoxypsoralen and ultraviolet A light

The combination of 8-methoxypsoralen (8-MOP) plus ultraviolet A light (320-400 nm), termed PUVA, is used in the treatment of psoriasis, a hyperproliferative disease of the skin. This treatment results in the formation of specific 8-MOP adducts with cellular DNA. We have previously developed monoclonal antibodies which recognize these 8-MOP photoadducts. We now report the use of these antibodies in an indirect immunofluorescence technique to study human skin biopsies. Nuclei in 3 of 5 skin biopsies from psoriasis patients undergoing PUVA therapy were positive for adducts. The presence of adducts by immunofluorescence did not correlate with plasma levels of 8-MOP. Enzyme-linked immunosorbent assays, used to determine whether 8-MOP photoadducts could be detected in DNA isolated from the lymphocytes of psoriasis patients after PUVA therapy, were negative.

Cutaneous melanomas in patients treated with psoralens plus ultraviolet A. A case report and the experience of the PUVA Follow-up Study

Psoralens plus ultraviolet A (PUVA) therapy is widely used in the treatment of psoriasis and other cutaneous conditions. We present the case of a patient who developed a superficial spreading melanoma 3 years after first being treated with PUVA. The development of melanomas in patients receiving PUVA is reviewed. During 13,224 person-years of prospective follow-up of 1380 patients enrolled in the PUVA follow-up study, three melanomas were diagnosed, which does not differ significantly from the expected rate (relative risk = 1.5 with 90% confidence interval 0.3 to 7.3). However, considering the effects of PUVA on melanocytes and that the development of melanomas may have a long latent period, continued follow-up studies are indicated.

Psoralen photochemotherapy

Psoralens and sunlight have been used by the Egyptians and Indians for hundreds of years for the treatment of vitiligo. The combination of oral psoralens and artificial ultraviolet A (PUVA) therapy was approved for the management of severe psoriasis by the Food and Drug Administration in 1982. Since then PUVA therapy has been found to be an effective modality in the treatment of many cutaneous conditions. When properly administered, the major short-term side effects are minimal. The long-term side effects may include an increased risk of squamous cell carcinoma, atypical cutaneous pigmentation, accelerated skin aging, and ophthalmologic abnormalities. By careful patient selection and limiting the cumulative UVA dosage and frequency by using combinations or alternative therapies, these side effects may be reduced. Continued reporting of carefully carried out long-term prospective studies will provide us with more knowledge of the long-term side effects of PUVA. In the meantime, for each patient on PUVA therapy the risk/benefit ratio should be carefully considered.

Cutaneous and ocular side-effects of oral photochemotherapy: results of an 8-year follow-up study

To determine the long-term cutaneous side-effects of oral photochemotherapy (PUVA), we examined 95 patients, 59 with psoriasis and 36 with mycosis fungoides (MF). These comprised 80% and 69% respectively of the patients with these disorders treated with PUVA in our department from 1977 to 1985. Two psoriatic patients had squamous carcinomas, both of whom had received high cumulative UVA doses and also methotrexate concurrently with PUVA. Six patients with MF had actinic keratoses. The mean age of these patients (69 years) was significantly greater than the mean age of the patients without actinic keratoses (54 years), but there was no significant difference in their cumulative UVA doses. No patients developed basal cell carcinomas or malignant melanoma. 'PUVA lentigines' were found in 46% of the patients. They were most frequent in patients currently being treated and in those who had received high cumulative UVA doses, but persisted for up to 7 years after discontinuing therapy. Seventy-one patients had yearly ophthalmological examinations, or a single examination at least 3 months after commencing PUVA. This examination included retinal function tests to detect any subclinical visual impairment. Five of these patients had cataract prior to PUVA therapy, and were significantly older (mean age 71 years) than those without cataract (mean age 53 years). Three patients (mean age 61 years) developed new lens opacities whilst receiving PUVA. However, none of these patients was considered to have cataract as none had impairment of visual acuity due to lens opacity. No patients without lens opacity developed evidence of subclinical visual impairment.

Psoralens and related compounds in the treatment of psoriasis

PUVA therapy has radically altered the management of severe psoriasis. It is of greatest benefit in those patients with extensive involvement, and in those unresponsive to conventional therapy. The long term side effects of PUVA currently limit its use to patients with disabling disease. The full extent of long term side effects has yet to be defined. In order to reduce the toxicity and improve the efficacy of PUVA, a better understanding of the molecular aspects of psoralen-DNA interaction, DNA repair, and mutagenesis is required. The action spectrum of PUVA in clearing psoriasis has yet to be defined. By limiting the spectrum of UVA exposure it may be possible to reduce some of the toxic effects of PUVA. The recent advances in the formulation of 8-MOP preparations has yielded a drug with more predictable pharmacokinetics and clinical response. Further research with newer psoralens may produce more effective and less toxic compounds. In the last ten years, PUVA has been both a valuable addition to dermatologists' clinical armamentarium and a useful tool in increasing our understanding of cellular biology and the interaction between ultraviolet radiation and biologic systems.

Status of ultraviolet A dosimetry in methoxsalen plus ultraviolet A therapy

The carcinogenic risk of methoxsalen plus ultraviolet A treatment (PUVA) is almost certainly related to the cumulative UVA exposure dose. A reliable estimate of UVA dose is a major component, therefore, in determining the long-term safety of this treatment modality. Thirty-one UVA meters from twenty-nine different PUVA treatment centers were compared with a calibrated UVA meter. The results inferred that 95% of UVA meters used in PUVA centers are reading between 57% and 159% of the true UVA irradiance, a factor of 2.8 in relative sensitivity. This wide variation in accuracy between the UVA meters gives cause for concern. These variations were attributed to differences in calibration procedure, optical properties of the sensors, and, most importantly, poor quality control by the manufacturers. The situation that appears to have existed since the introduction of PUVA therapy can be improved only if dermatologists agree that the present inaccurate and uncertain approach to UVA measurements is unsatisfactory. Manufacturers of UVA meters should be encouraged to provide instruments as reliable as the dosimeters used in radiotherapy, in which the prescribed dose is probably within 5% of the true value. Ideally, a standard type of UVA meter with appropriate physical properties and an agreed calibration procedure should be used by all centers engaged in PUVA treatment.

Nonmelanoma skin tumors in long-term photochemotherapy treatment of psoriasis. An 8-year follow-up study

Two hundred ninety-seven long-term photochemotherapy (PUVA)-treated patients from an original cohort of 418 subjects reported in 1980 were reevaluated in a second follow-up in order to determine the risk of tumor development under long-term PUVA. Within an observation period of up to 8 years (mean, 63.1 months) six patients with squamous cell carcinomas and three with basal cell carcinomas were observed. Eight of the nine tumor patients had been exposed to potential carcinogens such as arsenic and/or ionizing radiation prior to PUVA treatment. Five with squamous cell carcinomas were skin type I or II; in four of the six patients with squamous cell carcinomas the tumors were located on unexposed skin areas. The mean cumulative ultraviolet A (UVA) dose in three of the six squamous cell carcinoma patients was three times as high as that in the group of nontumor patients. The other three squamous cell carcinoma patients had lower mean doses than nontumor patients, as did the three patients with basal cell carcinomas. Although the cumulative UVA dose may eventually turn out to be relevant for PUVA carcinogenesis, our present data do not sufficiently substantiate a correlation between cumulative UVA dose and squamous cell carcinoma formation in PUVA-treated patients. This report confirms that previous exposure to carcinogens appears to be the most important factor for nonmelanoma skin tumor formation in long-term PUVA patients.

[Problems posed by the therapeutic use of photosensitizers in dermatology]

Three phototherapeutic regimens with photosensitization are now used in dermatology: PUVA (psoralen + UVA), TUV (crude coaltar + UV), PRT (phototherapy with hematoporphyrin derivative). The efficiency of PUVA and TUV is well known in several dermatoses. PRT is now being tested experimentally. For TUV, the lack of a standardized regimen does not allow a clear-cut evaluation of the therapy. For PUVA, late side-effects, particularly carcinogenicity have to be considered. To improve efficiency and minimize the side-effects of PUVA some procedures, such as association with retinoïds, pharmaco-kinetic studies for individual adaptation of the therapeutic regimen and the use of new less mutagenic psoralens are helpful. The persistent phototoxicity following treatments with hematoporphyrin derivative constitutes the major side-effect observed, for this phototherapy.

Aspects of psoralen phototumorigenesis with emphasis on the possible role of tumour promotion

8-Methoxypsoralen in combination with UVA radiation (PUVA) is carcinogenic in mice and probably so in man. PUVA is genotoxic and so has tumour initiation potential. Some evidence suggests that PUVA has other biological effects which may be equated with tumour promotion. Thus, the use of a two-stage model, similar to that of chemical carcinogenesis, may be a useful experimental approach for the further understanding of PUVA carcinogenesis.

PUVA therapy for psoriasis: comparison of oral and bath-water delivery of 8-methoxypsoralen

A direct clinical comparison has been made of the efficacy of oral 8-methoxypsoralen with bath-water delivery of 8-methoxypsoralen during psoralen ultraviolet A (PUVA) phototherapy for a group of forty patients with stable plaque-type psoriasis vulgaris. The 8-methoxypsoralen concentration was 3.7 mg/liter in the bath water. The efficacy of these treatments was assessed by their ability to improve or clear the psoriasis. The skin of eight of the twenty patients with oral psoralen cleared, and another eight showed good improvement. Of the twenty patients who received 8-methoxypsoralen in bath water, eight patients had clearing of the skin, whereas nine patients had good improvement during the initial 8-week treatment period. Administration of 8-methoxypsoralen in bath water required much lower ultraviolet A irradiance to achieve maximum improvement. There were no systemic side effects in the patients treated by bath-water delivery; however, some patients did develop phototoxic erythema. Minimal phototoxic doses were also studied in patients and in volunteers using both routes of psoralen delivery. The minimal phototoxic dose threshold after psoralen bath delivery gradually declined over five treatments from 5.3 +/- 0.6 joules/cm2 to 2.8 +/- 0.3 joules/cm2, suggesting an accumulation of psoralen in the skin with this method of drug delivery. Bath-water delivery of 8-methoxypsoralen was therefore found to be as effective as oral administration of 8-methoxypsoralen and yet required smaller amounts of ultraviolet A radiation and yielded fewer side effects. It would thus seem to be confirmed as a useful alternative means of 8-methoxypsoralen administration in PUVA therapy.