Botanical Agents for the Treatment of Nonmelanoma Skin Cancer
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Hindawi Publishing Corporation Dermatology Research and Practice Volume 2013, Article ID 837152, 9 pages http://dx.doi.org/10.1155/2013/837152 Review Article Botanical Agents for the Treatment of Nonmelanoma Skin Cancer Jillian W. Millsop,1 Raja K. Sivamani,2 and Nasim Fazel2 1 University of Utah, School of Medicine, 30 N 1900 E, Salt Lake City, UT 84132, USA 2 University of California, Davis, Department of Dermatology, 3301 C Street, Sacramento, CA 95816, USA Correspondence should be addressed to Nasim Fazel; [email protected] Received 6 June 2013; Accepted 9 July 2013 Academic Editor: H. Peter Soyer Copyright © 2013 Jillian W. Millsop et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Nonmelanoma skin cancers, including basal cell carcinoma and squamous cell carcinoma, are common neoplasms worldwide and are the most common cancers in the United States. Standard therapy for cutaneous neoplasms typically involves surgical removal. However, there is increasing interest in the use of topical alternatives for the prevention and treatment of nonmelanoma skin cancer, particularly superficial variants. Botanicals are compounds derived from herbs, spices, stems, roots, and other substances of plant origin and may be used in the form of dried or fresh plants, extracted plant material, or specific plant-derived chemicals. They possess multiple properties including antioxidant, anti-inflammatory, and immunomodulatory properties and are, therefore, believed to be possible chemopreventive agents or substances that may suppress or reverse the process of carcinogenesis. Here, we provide a review of botanical agents studied for the treatment and prevention of nonmelanoma skin cancers. 1. Introduction for NMSCs involves surgical removal or directed topical ther- apies in the most superficial subtypes of NMSC. However, Nonmelanoma skin cancer (NMSC) is common worldwide there is increasing interest in alternative, noninvasive treat- and includes basal cell carcinoma (BCC) and squamous ments and preventative measures in recent years, specifically cell carcinoma (SCC). Approximately two to three million in the use of naturally occurring botanicals. Botanicals are NMSCs occur globally each year [1].IntheUnitedStates a group of compounds derived from herbs, spices, stems, (U.S.), BCC is the most common form of malignancy [2, 3]. roots, and other substances of plant origin and may be used In 2012, two million new cases of NMSCs were estimated in the form of dried or fresh plants or extracted plant material to occur in the U.S., with delays in treatment leading [10]. They possess multiple properties including antioxidant, to significant morbidity [4] and deaths occurring in less anti-inflammatory, and immunomodulatory properties, and, than 1,000 [5]. Delay in treatment of NMSCs can lead to therefore, they are believed to be possible chemopreventive significant morbidity as well. Extrinsic and intrinsic risk agents or substances that may suppress or reverse the process factors contribute to skin cancer development including of carcinogenesis [7]. For example, topical ingenol mebutate, fair skin color, red and blond hair, and high susceptibility extracted from Euphorbia,wasrecentlyapprovedbythe to sunburn [6]. Chronic sun exposure is also associated U.S. Food and Drug Administration (FDA) for treatment of with skin cancer risk, especially for SCC [7]. Furthermore, actinic keratosis [11]. There is perceived safety and efficacy chronically immunocompromised organ transplant patients with botanicals despite a lack of controlled clinical trials and have a higher risk of developing SCCs [8, 9]. scientific data [10]. Furthermore, botanical extracts are often Traditional recommendations for prevention of NMSC distributed as dietary supplements in the United States with include generous use of sunscreens and avoidance of chronic little regulation [12]. Therefore, there is need for controlled or intense ultraviolet (UV) exposure. Conventional therapy studies that evaluate both of their efficacy and side effects. 2 Dermatology Research and Practice Here, we review botanical agents that have been used for noted to be 16 mm. The most common side effects included the treatment and prevention of NMSCs. Botanical agents dry skin, erythema, and patchy moist desquamation. After studiedinhumansaswellasagentsinvestigatedinpreclinical a mean of 15 months for followup, the complete clinical trials are reviewed. response rates were 57% for BCCs, 50% for SCCs, and 75% for intraepidermal carcinomas [13]. For superficial carcinomas 2. Methods that were less than 16 mm, the complete clinical response rates were 78% ( = 9) for BCCs and 100% ( = 10) for We conducted a search of the PubMed and Embase databases intraepidermal carcinomas [13]. of articles published from 1990 to 2013 to include the Furthermore, a phase IIa randomized, vehicle-controlled most recent literature. Articles containing combinations of study of 60 patients evaluated the safety (primary endpoint) MeSH terms “nonmelanoma skin cancer,” “basal cell carci- and efficacy (secondary endpoint) of ingenol mebutate gel noma,” “squamous cell carcinoma,” “complementary thera- for superficial basal cell carcinoma, with a lesion size of 4– pies,” “plant preparations,” “edible plants,” “herbal medicine,” 15 mm. In this study, Siller et al. randomized patients to Arm “antineoplastic agents,” “phytogenic,” and “botanical” were A, treatment on days 1 and 2, or Arm B, treatment on days 1 reviewed. Based on the initial review using these terms, and 8 [14]. Within each arm, patients were also randomized botanical agents and extracts identified as having possible to application of ingenol mebutate gel 0.0025%, 0.01%, or effects on NMSC treatment and prevention through studies, 0.05%, or a matching vehicle gel [14]. No severe adverse events reviews,andcasereports,werereviewed.Thesearchwas were reported. In four patients, severe local skin reactions limited to articles in English and initially resulted in 91 occurred. The most common side effects were erythema, flak- articles. The article abstracts were reviewed for relevance to ing, scaling, and dryness. The histopathological clearance rate the subject matter of treatment and prevention of UV light- was 71% (5/7) in the treatment group of Arm A that received induced NMSCs, BCCs, and SCCs, using botanical agents. 0.05%ingenolmebutategel,and86%(6/7)showedmarkedor We examined reference lists to identify any missing articles, complete clearance (50–90%) on clinical examination [14]. and a total of 74 articles were included in this review. We included only botanical agents that have been investigated in 3.2. Hypericin. Hypericum perforatum,St.John’swort,con- morethanonestudyand/orhavebeenreportedinmorethan tains the photoactive compound, hypericin, which is a potent one case. photosensitizer in photodynamic therapy. It is activated by visible (400–700 nm) or UVA (320–400 nm) light [49]. 3. Botanical Agents Studied in Humans and Hypericin has demonstrated cytotoxic and antiproliferative Animals (Tables 1 and 2) properties against cancer cells. Although an early study by Alecu et al. reported that hypericin was effective for treatment 3.1. Ingenol Mebutate. Ingenol mebutate is an extract from of BCCs and SCCs without necrosis of the surrounding tissue the Euphorbia peplus (E. peplus) plant that has been identi- when injecting hypericin solution intralesionally and then fied for its chemotherapeutic potential, and, more recently, irradiating the site with visible light [15], subsequent studies approved by the U.S. FDA for the treatment of actinic did not demonstrate efficacy of hypericin in skin cancer keratoses. Preclinical studies in murine models have shown treatment. that ingenol mebutate causes mitochondrial swelling of the A prospective pilot study by Kacerovska´ et al. investigated dysplastic keratinocytes and apoptosis by primary necrosis the use of an extract of H. perforatum in combination [48]. In a phase I/II clinical study to determine the efficacy with photodynamic therapy for BCCs, actinic keratoses, of the E. peplus sap, for which the main ingredient was and Bowens disease (carcinoma in situ) [16]. A total of 34 ingenol mebutate, on the treatment of BCCs, SCCs, and patients were enrolled, 21 of which had BCCs. The extract intraepidermal carcinomas, Ramsay et al. enrolled 36 patients was applied under occlusion to the skin lesions, followed with a total of 48 lesions who had failed past treatments, two hours later by irradiation with 75 Joules per square 2 refused surgical treatment, or were found unfit for surgical centimeter (J/cm ) of red light. Patients underwent treatment therapy due to anticoagulant use, age, site, or nature of for six weeks on average. They found complete clinical the lesion [13]. Patients were treated once daily for three response for 28% of superficial BCC patients, and only consecutive days. Complete clinical response (tumor absence partial remission was seen in nodular BCC patients [16]. after clinical examination) following treatment was 82% ( = By histology, a complete disappearance of cancer cells was 28) for BCCs, 75% ( = 4) for SCCs, and 94% ( = 16) for found in 11% of the superficial BCCs16 [ ]. All patients in the intraepidermal carcinomas at 1 month [13]. However, partial study complained of pain and burning during irradiation. responses were noted in