A Retrospective Study of Treatment of Squamous Cell Carcinoma In situ. Övermark, Meri.

Similar documents
I have a skin lump doc! What s next? 12 th August 2017 Dr. Sue-Ann Ho Ju Ee

Know who is at risk: LOOK! for ABCDs, rapidly changing lesions, do a biopsy when indicated

Photodynamic Therapy for the Treatment of Actinic Keratoses and Other Skin Lesions

Know who is at risk: LOOK! for ABCDs, rapidly changing lesions, do a biopsy when indicated

Field vs Lesional Therapies for AKs 3/2/2019, 9:00-12 AM

Clinical characteristics

Periocular skin cancer

Scottish Medicines Consortium

1) Photodynamic therapy with topical 5 aminolevulinic acid is considered medically necessary and is covered for the treatment of:

Corporate Medical Policy

Learning Objectives. Tanning. The Skin. Classic Features. Sun Reactive Skin Type Classification. Skin Cancers: Preventing, Screening and Treating

Skin disorders. Basal cell carcinoma December 2009 Anthony Ormerod, Sanjay Rajpara, and Fiona Craig ...

Photodynamic Therapy for the Treatment of Actinic Keratoses and Other Skin Lesions

Richard Turner Consultant Dermatologist

Nonmelanoma skin cancers

Skin Malignancies Non - Melanoma & Melanoma Marilyn Ng, MD Dept. of Surgery M&M Conference Downstate Medical Center July 19, 2012

Interesting Case Series. Aggressive Tumor of the Midface

Topical Diclofenac Gel, Fluorouracil Cream, Imiquimod Cream, and Ingenol Gel Prior Authorization with Quantity Limit Program Summary

Identifying Skin Cancer. Mary S. Stone MD Professor of Dermatology and Pathology University of Iowa Carver College of Medicine March, 2018

Skin lesions The Good and the Bad. Dr Virginia Hubbard Ipswich Hospital NHS Trust Barts and the London School of Medicine and Dentistry

Large majority caused by sun exposure Often sun exposure before age 20 Persons who burn easily and tan poorly are at greatest risk.

Dermatologic Applications of Photodynamic Therapy Corporate Medical Policy

Dermatologic Applications of Photodynamic Therapy

Opinion 6 March 2013

Cutaneous Malignancies: A Primer COPYRIGHT. Marissa Heller, M.D.

JAM ACAD DERMATOL VOLUME 76, NUMBER 2. Research Letters 351

Dermatopathology: The tumor is composed of keratinocytes which show atypia, increase mitoses and abnormal mitoses.

Mohs surgery for the nail unit

Medical Policy. MP Dermatologic Applications of Photodynamic Therapy

Disclosures. I have no conflicts of interest to disclose

The legally binding text is the original French version TRANSPARENCY COMMITTEE OPINION. 26 November 2008

Clinical Policy: Benign Skin Lesion Removal Reference Number: CP.MP.HN150

fluorouracil 0.5% / salicylic acid 10% cutaneous solution (Actikerall ) SMC No. (728/11) Almirall S.A.

Living Beyond Cancer Skin Cancer Detection and Prevention

Dual Wavelength Phototherapy System

General information about skin cancer

Glenn D. Goldman, MD. Fletcher Allen Health Care. University of Vermont College of Medicine

Actinic keratosis (AK): Dr Sarma s simple guide

Clinical Practice Guide. Basal cell carcinoma, squamous cell carcinoma (and related lesions) a guide to clinical management in Australia

FEP Medical Policy Manual

Photodynamic Therapy for the Treatment of Actinic Keratoses and Other Skin Lesions

Glenn D. Goldman, MD. University of Vermont Medical Center. University of Vermont College of Medicine

Disclosures. Melanoma and Non melanoma Skin Cancer: What You Need to Know. I have no conflicts of interest to disclose

Skin NCG (Anglia East & Anglia West)

A Comparison of the Efficacy of Ablative Fractional Laser-assisted Photodynamic Therapy according to the Density of Ablative Laser Channel

Dermatology for the PCP Deanna G. Brown, MD, FAAD Susong Dermatology Consulting Staff at CHI Memorial

Imiquimod to Treat Different Cancers of the Epidermis

Benign and malignant epithelial lesions: Seborrheic keratosis: A common benign pigmented epidermal tumor occur in middle-aged or older persons more

Benign versus Cancerous Lesions How to tell the difference FMF 2014 Christie Freeman MD, CCFP, DipPDerm, MSc

Modalities of Radiation

CASE REPORT Superficial Spreading Basal Cell Carcinoma of the Face: A Surgical Challenge

Dermatologic Applications of Photodynamic Therapy Corporate Medical Policy

NHS. Photodynamic therapy for non-melanoma skin tumours (including premalignant and primary non-metastatic skin lesions)

Populations Interventions Comparators Outcomes Individuals: With nonhyperkeratotic actinic keratoses on the face or scalp

Common Benign Lesions and Skin Cancers. 22nd May 2015 Dr Mark Foley

Basal cell carcinoma diagnosed on Fine-Needle Aspiration Cytology A. Pathological Case Report

SQUAMOUS CELL CARCINOMA

Extreme dermatoheliosis: How to approach the severely sun damaged patient

Patient Guide. The precise answer for tackling skin cancer. Brachytherapy: Because life is for living

MING H. JIH, MD,PHD, PAUL M. FRIEDMAN, MD,LEONARD H. GOLDBERG, MD,AND ARASH KIMYAI-ASADI, MD. Methods Phase I: Retrospective (Group 1)

Periocular Malignancies

Skin Cancer. 5 Warning Signs. American Osteopathic College of Occupational and Preventive Medicine OMED 2012, San Diego, Monday, October 8, 2012 C-1

1. Written information to patient /GP: fax ASAP to GP & offer copy of consultation letter.

Skin cancer is the most common of all cancer PROCEEDINGS CLINICAL UPDATE ON ACTINIC KERATOSIS* Murad Alam, MD ABSTRACT

Dermatologic Applications of Photodynamic Therapy

Skin Cancer of the Nose: Common and Uncommon

Photodynamic Therapy (PDT) Basics and clinical applications

Skin Cancers Emerging Trends and Treatment Approaches

Photodynamic Therapy for the Treatment of Actinic Keratoses and Other Skin Lesions

Skin Cancer 101: Diagnosis and Management of the Most Common Cancer

Photodynamic Therapy with Ablative Carbon Dioxide Fractional Laser for Treating Bowen Disease

Skin Cancer in Organ Transplant Recipients Challenges and Opportunities

If Mohs surgery is the 'gold standard for non-melanoma skin cancer treatment', why doesn't everyone have it? Antonio Ji Xu University of Oxford

Limitations of nonsurgical treatment modalities. Nonsurgical Treatments (Table V) 1/31/2018

Skin Cancer - Non-Melanoma

A dinical and histopathologic entity associated with an increased risk of nonmelanoma skin cancer

Service Line: Rapid Response Service Version: 1.0 Publication Date: September 11, 2017 Report Length: 29 Pages

Diagnosis and Management of Actinic Keratosis (AKs)

PRODUCT INFORMATION METVIX

Rhenium-SCT Questions and answers for physicians and medical personnel

Histopathology: skin pathology

AWMSG SECRETARIAT ASSESSMENT REPORT. 5-aminolaevulinic acid (Ameluz ) 78 mg/g gel. Reference number: 1074 FULL SUBMISSION

Accuracy of Clinical Skin Tumour Diagnosis in a Dermatological Setting.

Evidence for Mohs surgery

TOPICAL TREATMENT OF ACTINIC KERATOSIS

Skin Cancer. Dr Elizabeth Ogden Associate Specialist in Dermatology East and North Herts Dr Elizabeth Ogden

Premalignant skin tumours

New and Emerging Therapies: Non-Melanoma Skin Cancers. David J. Goldberg, MD, JD Skin Laser and Surgery Specialists of NY/NJ

Opinion 26 June 2013

MECHANISMS OF HUMAN DISEASE: LABORATORY SESSION PATHOLOGY OF THE SKIN LAB. Friday, February 12, :30 am 11:00 am

OCCG SERVICE SPECIFICATION (2017/18)

Case Report No-Needle Jet Intradermal Aminolevulinic Acid Photodynamic Therapy for Recurrent Nodular Basal Cell Carcinoma of the Nose: A Case Report

Description. Section: Medicine Effective Date: July 15, 2016 Subsection: Medical Policy Original Policy Date: December 7, 2011 Subject:

Developing the next generation of dermatology products to treat serious skin diseases

SKIN CANCERS AFTER SOLID ORGAN TRANSPLANTATION: Clinicopathological features. J. Kanitakis. Dept. of Dermatology Ed. Herriot Hospital Lyon, France

A Retrospective Study on the Risk of Non-Melanoma Skin Cancer in PUVA and Narrowband UVB Treated Patients

MECHANISMS OF HUMAN DISEASE: LABORATORY SESSION PATHOLOGY OF THE SKIN LAB. Friday, February 13, :30 am 11:00 am

Skin Malignancies. Presented by Dr. Douglas Paauw

LUMPS AND BUMPS: AN ORGANIZED APPROACH TO DIAGNOSIS AND MANAGEMENT

Transcription:

https://helda.helsinki.fi A Retrospective Study of Treatment of Squamous Cell Carcinoma In situ Övermark, Meri 2016 Övermark, M, Koskenmies, S & Pitkanen, S 2016, ' A Retrospective Study of Treatment of Squamous Cell Carcinoma In situ ' Acta Dermato-Venereologica, vol. 96, no. 1, pp. 64-67. DOI: 10.2340/00015555-2175 http://hdl.handle.net/10138/160249 https://doi.org/10.2340/00015555-2175 Downloaded from Helda, University of Helsinki institutional repository. This is an electronic reprint of the original article. This reprint may differ from the original in pagination and typographic detail. Please cite the original version.

Acta Derm Venereol 2016; 96: 64 67 CLINICAL REPORT A Retrospective Study of Treatment of Squamous Cell Carcinoma In situ Meri ÖVERMARK, Sari KOSKENMIES and Sari PITKÄNEN Department of Dermatology, Skin Cancer Unit, Helsinki University Central Hospital, Helsinki, Finland Squamous cell carcinoma in situ is an intra-epidermal malignancy of the skin with potential to progress to invasive carcinoma. Commonly used treatments are surgical excision, cryotherapy, photodynamic therapy, laser ablation, curettage with cautery, radiotherapy, topical 5-fluorouracil, and topical imiquimod. The efficacies of these different treatment modalities are compared in this retrospective study of 239 patients with squamous cell carcinoma in situ diagnosed and treated at our hospital during a period of 1 year. A total of 263 histologically confirmed in situ lesions were followed up for approximately 8 years. The overall recurrence rate was 6.5%. Surgical excision had the lowest recurrence rate, at 0.8%. Recurrence rates with the less-invasive treatment modalities were markedly higher; cryotherapy 4.7% and photodynamic therapy 18%. Of all recurrences, 65% were carcinoma in situ and 35% squamous cell carcinomas. Twenty-three patients had actinic keratosis in the area treated, but these were not counted as recurrences. In conclusion, excisional surgery is the gold standard treatment for squamous cell carcinoma in situ, although it has limitations. Less invasive methods may sometimes be preferred. Key words: squamous cell carcinoma in situ, Bowen s disease; cryotherapy; photodynamic therapy; imiquimod; retrospective study. Accepted Jun 11, 2015; Epub ahead of print Jun 15, 2015 Acta Derm Venereol 2016; 96: 64 67. Meri Övermark, Department of Dermatology, Skin Cancer Unit, Helsinki University Central Hospital, FIN-00029 Helsinki, Finland. E-mail: meri.overmark@hus.fi Squamous cell carcinoma in situ (carcinoma in situ, Bowen s disease), an intraepidermal malignancy of the skin, usually presents as a well-demarcated growing erythematous patch or plaque with a scaly or crusted surface. Carcinoma in situ lesions can be pigmented or verrucous, and are not constantly ulcerated. Clinically the lesions may be difficult to distinguish from actinic keratosis, superficial basocellular carcinoma (BCC), squamous cell carcinoma (SCC), psoriasis, or nummular eczema. Histological findings in carcinoma in situ are hyperkeratosis and parakeratosis with full-thickness atypia of epidermal keratinocytes; histologically, it does not invade through the basement membrane into the dermis. No differential diagnosis can be made between carcinoma in situ and invasive SCC if the biopsy from the lesion is too superficial or does not represent the tumour s invasive part. The risk of progression of any in situ lesion into an invasive SCC ranges from 3% to 5% (1). In the Caucasian population, carcinoma in situ is very common, with an incidence of 14.9 27.8 per 100,000 (2, 3). In Finland, carcinoma in situ is not included in the National Cancer Registry, and therefore the incidence in our population is unknown. Finnish people are Caucasians, the most common skin type is Fitzpatrick type III (60%), 30% are types I and II and 10% type IV. In Finland approximately 1,600 new SCCs occur annually (4). The major aetiological factors in the development of SCC and carcinoma in situ of the skin are ultraviolet (UV) radiation and accumulation of UV radiation over time. Additional risk factors are fair skin, exposure to arsenic, and immunosuppression (5). According to the literature, 30 50% of patients with carcinoma in situ have a history of non-melanoma skin cancer, and 37% have concurrent skin cancers including BCC, invasive SCC, or both (6). The treatment protocols for carcinoma in situ vary. Most commonly used are surgical excision, cryotherapy, photodynamic therapy (PDT), 5-fluorouracil, and imiquimod (7). Surgical excision offers the advantages of margin control and confirmation of diagnosis. Only a few studies have evaluated the efficacy of surgery for carcinoma in situ, and most of these do not mention the excision margins (2). In the USA a 4 6-mm margin is advised for low-risk SCC, but margins for carcinoma in situ are not specified (3). The best option in many cases is surgical excision, but less invasive treatment options are also needed, because the cutaneous lesions may be multiple or occur at sites that are less suitable for surgical removal. In elderly patients, in particular, co-morbidities may preclude an aggressive treatment modality. Few randomized clinical trials elucidate success rates of different treatments in carcinoma in situ, and most of the studies performed have concentrated on comparison of the efficacy of PDT, cryotherapy and 5-fluoro uracil, and/or imiquimod (8 10). Moreover, the follow-up periods in the studies are mostly short, up to 24 months, but, for PDT, 50 months follow-up data are also available (1, 11). 2016 The Authors. doi: 10.2340/00015555-2175 Journal Compilation 2016 Acta Dermato-Venereologica. ISSN 0001-5555

Treatment of squamous cell carcinoma in situ 65 The present study evaluated the efficacy of different treatment modalities used in SCC in situ, including surgery. The follow-up period was 8 years. This is a clinical study based on routine practice used at our hospital and not on randomization of the patients between the different treatment modalities. MATERIALS AND METHODS In Finland carcinoma in situ is treated mainly by surgical excision, cryotherapy or methyl aminolevulinate (MAL)-PDT. 5-fluorouracil is not used routinely because the drug is only available on special permission. Imiquimod is not officially approved for treatment of carcinoma in situ, although it is used in certain cases. This is a retrospective study of patients with carcinoma in situ diagnosed and treated at the Department of Dermatology, Skin Cancer Unit, Helsinki University Central Hospital, Finland over a period of one year (January to December 2006). All lesions were histologically confirmed. Patients whose diagnosis according to biopsy was carcinoma in situ, but which, after total excision, was changed into invasive skin malignancy (1 carcinoma verrucous, 9 SCC) were excluded. Three patients with 5 lesions refused treatment and were also excluded from the study. The research team gained approval for this retrospective study from the clinical research committee. The patient s characteristics that were recorded for the study were age, gender of patient, immunosuppressive therapy, anatomical site of lesion, other skin cancers before and at the time of biopsy, choice of treatment, recurrence after treatment and duration of follow-up. When surgery was carried out, histological margins were evaluated. Data were collected by reviewing patient medical and histological records and pictures. Our treatment protocols for carcinoma in situ and the followup are generally standardized. When surgery is used the recommended histological excision margins are minimum 2 mm. Cryotherapy is performed after curettage in 2 freeze-thaw cycles using liquid nitrogen with 5-mm margins and 1-min margin thawing time. In PDT we use MAL. Before cream application the lesion is carefully curettaged. After an incubation time of at least 3 h the lesion is exposed to red light (630 nm) for 8 min at a mean light dose of 75 J/cm 2. Two PDT treatments are given, 7 14 days apart. The response to treatment is controlled at least once, 6 months after treatment. Thereafter, follow-up is normally arranged by the general practitioner, who re-admits the patient to our clinic if recurrence or new lesions appear. Possible recurrence was also checked from the patients histological records which are shared by other university hospital clinics and general health care centres. RESULTS A total of 263 SCC in situ lesions in 239 patients were observed. The mean patient age was 77 years (range 35 97 years), 43% (103) were male and 57% (136) female. Many of the patients were elderly and 124 patients died during this almost 8-year follow-up period. In all cases the cause of death was unrelated to the skin cancer. Eighteen percent (44/239) had immunosuppression, 7% (17) of whom were organ transplant recipients. The other reasons for immunosuppressive therapy were rheumatoid arthritis (n = 11), systemic lupus (n = 1), dermatomyositis (n = 1), polymyositis (n = 2), polymyalgia rheumatica (n = 2), idiopathic pulmonary fibrosis (n = 1), hepatic disease due to cholangitis (n = 1), temporal arteritis (n = 1), psoriasis or psoriatic arthritis (n = 5), amyloidosis (n = 1) and haemolytic anaemia (n = 1). Four patients had a history of arsenic exposure and 1 had epidermodysplasia verruciformis. Most patients had signs of skin damage due to abundant exposure to the sun, and 57% (136) patients had previously had one or several premalignant or malignant skin cancers; 44% (106) had a history of actinic keratosis, 28% (68) carcinoma in situ, 13% (30) SCC, 36% (85) BCC, and 4% (10) malignant melanoma. At the time of biopsy 61% (146) had other skin malignancies or premalignant lesions. In the present material the head and neck were most often affected (70%). Males more often had lesions on the earlobes (14% vs. 1%) and on the scalp (15% vs. 1%), whereas females more often had lesions on the cheeks (33% vs. 15%). In both males and females the trunk (10%), upper (11%) and lower (10%) extremities were less frequently affected than the head and neck. Surgery was the treatment of choice in the majority of lesions (48%) (Fig. 1). Other treatment modalities included cryotherapy (24%) and PDT (28%). Surgery was used on the trunk (65%) more often than on other body sites. If the lesion was located on the lower extremities PDT was most often used (54%). It is also likely that larger and more indurated lesions in this area were treated with PDT due to contraindications to surgery and cryotherapy. The mean duration of follow-up was 66 months (range 2 93 months). Recurrences appeared 6 92 months (mean 64 months) after treatment. The overall recurrence rate was 6.5%. Of all recurrences 65% were carcinoma in situ and 35% SCCs (Table I). Patients with immunosuppressive treatment had only a slightly higher overall recurrence rate than immunocompetent patients (11% vs. 6.2%). Twentythree patients had actinic keratosis in treated areas, which were not counted as a recurrence. 100 80 60 40 20 0 Head and neck surgery cryo PDT Trunk Upper extremities Lower extremities Fig. 1. Treatment modalities (%) in relation to tumour localisation.

66 M. Övermark et al. Table I. Recurrences after different treatment modalities Initial treatment n/total (%) When analysing recurrence rates after different treatment modalities, surgical excision had the lowest recurrence rate (0.8%). Excision margins varied between 0 and 5 mm. In 53 cases the margins were less than the recommended 2 mm, but there were no recurrences in these cases. Only 2 actinic keratoses occurred in operated areas, 15 and 51 months after operation. When recommended margins were used, there was one recurrence of SCC lesion. Recurrence rates with the less invasive treatment modalities were higher; cryotherapy 4.7% (n = 3) and PDT 18% (n = 13). Following these less invasive methods 11 carcinomas in situ appeared (1 after cryotherapy and 10 after PDT) and 5 SCCs (2 after cryotherapy and 3 after PDT). All the recurrent carcinomas in situ and SCCs were histologically confirmed. There were also 21 actinic keratoses in the treated area (12 after cryotherapy and 9 after PDT). Of recurrent SCCs (6) 5 were excised and 1 patient died before treatment. Treatments for recurrent carcinoma in situ (11) were surgery in 5 cases, imiquimod in 3 cases, PDT in 2 cases, and cryotherapy in 1 case. DISCUSSION Carcinoma in situ Squamous cell carcinoma Excision 1/125 (0.8) 1 Cryotherapy 3/64 (4.7) 1 2 Photodynamic therapy 13 /74 (18) 10 3 Total, n/total (%) 17/263 (6.5) 11/263 (4.2) 6/263 (2.3) The lack of quality data about surgery and other treatments, together with many patient-dependent factors, affect therapeutic choice and make it difficult to perform a study on gold standard treatment. This is the first national retrospective study of SCC in situ in Finland, with 239 patients and 263 lesions. In present study surgery had the lowest recurrence rate (0.8%). There is no clear consensus about the excision margin for carcinoma in situ. In our clinic the recommended histological excision margins are 2 mm, although in the study material margins were often less. The reason why re-excision was not always carried out was mostly patient-dependent, e.g. the patients had comorbidities and were hospitalized for other reasons or died before re-treatment. However, after surgery with less than the recommended margins there were no recurrences of carcinoma in situ or SCC, only 2 actinic keratoses were documented. On the other hand, in one case in which excisional margins were much wider than recommended (4.5 mm) a SCC appeared. We still suggest 2-mm histological excision margins and, in cases in which the margins are too narrow and re-excision is not an option, other treatment modalities around the scar or careful follow-up should be carried out. Recurrence rates with cryotherapy and PDT were higher (4.7% and 18%, respectively) than after surgery (0.8%). It is possible that there was still underlying carcinoma in situ or SCC on the treated area, which appeared after superficial treatment and impaired the treatment outcome. A biopsy specimen represents only a small area of the lesion and does not always exclude invasive carcinoma. Ten patients with a diagnosis of carcinoma in situ according to biopsy, which was changed to invasive skin malignancy after total excision, were not included in the surgical group. A randomized placebo-controlled study comparing the efficacy of PDT, cryotherapy and 5-fluorouracil for treatment of carcinoma in situ found recurrence rates of 15%, 21% and 17%, respectively, 12 months after the final treatment, while spontaneous healing had occurred in 50% of the placebo group (8). In this study the diagnosis of recurrence was clinical and actinic keratoses were also regarded as recurrences. In our study the recurrence rate with actinic keratosis following cryotherapy was similar, but much higher following PDT (30% vs. 15%). This may be due to our longer follow-up time and the selection of larger lesions in the PDT group because our study was not randomized. Our study is not comparable to randomized PDT studies because it is a retrospective study and treatment regimens will modify treatment results. We could confirm previous observations that carci noma in situ lesions are typically located on sun-exposed areas. In our material 57% of patients had previously had a premalignant or malignant skin cancer, which is higher than the published proportion of 30 50% (10). At the time of biopsy 61% of patients had other malignant or premalignant lesions. We did not report actinic keratosis as recurrence of carcinoma in situ. Most of our patients had sun-damaged skin with numerous premalignant lesions and field cancerization, and it was highly probable that new actinic keratoses would appear during the 8-year follow-up. Carcinoma in situ and SCC are more likely to be true recurrences after treatment of carcinoma in situ. Retrospective studies have limitations because the choice of treatment is influenced by several factors. At present, no treatment modality is clearly superior, and the choice of treatment depends on location, size, thickness, and number of lesions; thick and small lesions are more often treated by surgery or cryotherapy and large thinner ones, especially on the face or lower limbs, by PDT. In addition, the patient s characteristics, clinician s expertise, availability of therapy, and the institutional experience are important in selection of the therapeutic approach (11). All thick and chronically ulcerative carcinomas in situ should be operated, because of the possibility of underlying SCC. Although surgery is the first-line treatment for carcinoma in situ, less invasive treatment modalities are needed for

Treatment of squamous cell carcinoma in situ 67 multiple, very large carcinomas in situ or those located at sites that heal poorly after operation. In some cases combination treat ment could be helpful, especially for large carcinomas in situ, e.g. operating first on deeper lesions and then treating the residual area with PDT. In addition, in some cases the cosmetic result after PDT is better than after surgery (8, 12). In elderly patients co-morbidities may preclude an aggressive treatment modality. Thus the advantages and disadvantages of each treatment method should be considered on an individual case basis. The authors declare no conflicts of interest. REFERENCES 1. Morton C, Birnie A, Eedy D. British Association of Dermatologist s guidelines for the management of squamous cell carcinoma in situ (Bowen s disease) 2014. Br J Dermatol 2014; 170: 245 260. 2. Shimizu I, Gruz A, Chang K, Dufresne R. Treatment of squamous cell carcinoma in situ: a review. Dermatol Surg 2011; 37: 1394 1411. 3. Westers-Attema A, van den Heijkant F, Lohman B, Nelemans P, Winnepenninckx V, Kelleners-Smeets N, et al. Bowen s disease: a six-year retrospective study of treatment with emphasis on resection margins. Acta Derm Venereol 2014; 94: 431 453. 4. Pitkänen S, Jeskanen L, Ylitalo L. [Basal cell carcinoma, squamous cell carcinoma and premalignant skin lesionshow to treat?] Duodecim 2014; 130: 643 653. (in Finnish). 5. de Berker D, McGregor J, Hughes B. Guidelines for the management of actinic keratoses. Br J Dermatol 2007; 156: 222 230. 6. Reizner G, Chuang T, Elpern D, Stone J, Farmer E. Bowen s disease (squamous cell carcinoma in situ) in Kauai, Hawaii. A population-based incidence report. J Am Acad Dermatol 1994; 31: 596 600. 7. Cox N, Eedy D, Morton C. Guidelines for management of Bowen s disease: 2006 update. Br J Dermatol 2007; 156: 11 21. 8. Morton C, Horn M, Leman J, Tack B, Bedane C, Tjioe M, et al. Comparison of topical methyl aminolevulinate photodynamic therapy with cryotherapy or fluorouracil for treatment of squamous cell carcinoma in situ: results of a multicenter randomized trial. Arch Dermatol 2006; 142: 729 735. 9. Lehmann P. Methyl aminolaevulinate-photodynamic therapy: a review of clinical trials in the treatment of actinic keratoses and nonmelanoma skin cancer. Br J Dermatol 2007; 156: 793 801. 10. Salim A, Lehman J, McColl J, Chapman R, Morton C. Randomized comparison of photodynamic therapy with topical 5-fluorouracil in Bowen s disease. Br J Dermatol 2003; 148: 539 543. 11. Cavicchini S, Serini SM, Fiorani R, Girgenti V, Ghislanzoni M, Sala F. Long-term follow-up of methyl aminolevulinate (MAL)-PDT in difficult-to-treat cutaneous Bowen s disease. Int J Dermatol 2011; 50: 1002 1005. 12. Bath-Hextall F, Matin R, Wilkinson D, Leonardi-Bee J. Interventions for cutaneous Bowen s disease. Cochrane Database Syst Rev 2013; 6: CD007281.