Medical Care
For specific guidelines and recommendations, please see “British Association of Dermatologists’ guidelines for the management of squamous cell carcinoma in situ (Bowen’s disease) 2014.” [14] These were determined by the British Association of Dermatologists in 2014.
Each treatment modality has advantages and disadvantages. Choosing the best therapeutic option involves an analysis of various factors such as lesional size, number, site, degree of functional impairment, modality availability, and cost. Because most treatments have a recurrence risk, follow-up at 6-12 months is recommended to evaluate for recurrence. Factors that dictate a shorter follow-up period include history of past recurrence, presence of multiple lesions, lesions in high-risk locations, and immunosuppression.
5-Fluorouracil is a topical antineoplastic agent that interferes with DNA synthesis via inhibition of thymidylate synthetase and subsequently cell proliferation. It is used clinically as a 5% cream once or twice daily for a variable period, ranging from 1 week to 3 months. 5-Fluorouracil has also been applied under occlusion, with dinitrochlorobenzene as a vehicle, via iontophoresis or pretreatment with an Er:YAG laser. The main advantage is easy self-application by patients. The main adverse effect is irritation with erosions and ulcerations that may last several weeks. [29, 30, 31, 32] A disadvantage is that it may not be able to penetrate deep enough to treat any deep follicular extension of the tumor cells.
Imiquimod 5% cream, [33, 34, 35, 36] a topical immune response modifier, applied 3-7 d/wk, appears to possibly be a successful treatment option for Bowen disease. It is often used for larger-diameter lesions, lower leg lesions, and erythroplasia of Queyrat. Two reports indicate sustained clearance with at least 19 months of disease-free follow-up after treatment of perianal Bowen disease with single-agent therapy using imiquimod 5% cream. Topical treatment for perianal Bowen disease may minimize the risk of scarring, poor wound healing, and functional impairment. The ideal dosing regimen is still under investigation, but the most studied regimen at this time is imiquimod 5% cream once daily for 16 weeks. Also note, however, that a cautionary report describes Bowen disease of the scalp treated with imiquimod that evolved into invasive SCC. [37]
Consider x-ray or grenz-ray radiation therapy for poor surgical candidates or patients with multiple lesions. [38, 39] It should be avoided for lower extremity lesions due to impaired healing.
Photodynamic therapy (PDT) has also been used, with variable success, for the treatment of Bowen disease. [40, 41] Photodynamic therapy involves the introduction of a photosensitizing agent into the body, which is retained preferentially by the tumor cells. Then, a light source is used to stimulate the photosensitizing agent, causing the release of toxins and leading to the destruction of the tumor. Topical 5-aminolevulinic acid (ALA) or methyl aminolevulinate (MAL) are the most commonly used photosensitizers. Various illumination sources, wavelengths of light, and dosing schedules have been used. PDT is well-suited for large lesions, multiple lesions, and poor-healing sites. [42] The adverse effects include local phototoxic effects such as burning and stinging and, rarely, erosions, ulceration, and hyperpigmentation hypopigmentation. Treatment guidelines are available from the Norwegian University of Science and Technology. [43]
Surgical Care
Simple excision with conventional margins
This surgery is the most common and preferred treatment for smaller lesions and those not in problematic areas, such as the face and digits. [44] For perianal Bowen disease, excision with wide margin is recommended. [45] Lower leg lesions are often limited by the lack of skin mobility.
Although lesions are typically well demarcated, the actual extent of the disease may be well beyond the clinical margins. For this reason, the excision should be made at least 4 mm outside the clinical margin.
Mohs micrographic surgery [46]
This is an excellent method for larger lesions, poorly demarcated lesions, recurrent lesions on the head and neck, or areas where tissue sparing is vital, such as digital or genital lesions. Mohs micrographic surgery uses the systematic surgical removal of skin cancers with very small margins of normal tissue followed by frozen section examination of nearly 100% of the tissue margin.
It offers the highest cure rate of all treatment modalities, and, because relatively thin layers are taken only in areas of proven tumor, it is a tissue-sparing procedure.
Curettage and electrodesiccation, cryotherapy, and laser ablation [47, 48, 49]
These are blind surgical methods (no pathologic confirmation of removal) that are established treatment modalities for Bowen disease.
As compared with excision and Mohs surgery, they are less likely to remove tumors that are present down adnexal structures.
Curettage and electrodesiccation is a common and safe modality. Treatment efficacy is largely determined by the skill of the clinician. It is also one of the most cost-effective treatment modalities.
Cryotherapy is another common therapeutic option, especially for single and small lesions. Suggested regimens in the literature include a single 30-second freeze-thaw cycle, 2 freeze-thaw cycles of 20 seconds with a thaw period, or up to 3 single treatments of 20 seconds at intervals of several weeks. The risk of poor wound healing (eg, hypopigmented scarring) increase with prolonged freezing times. Treatment of broad lesions is often limited because of patient discomfort.
Case reports and series have shown a benefit of using argon, carbon dioxide, and Nd:YAG lasers in the treatment of some Bowen disease lesions.
Prevention
Counsel at-risk individuals in the use of sunscreens, photoprotective clothing, and other measures to minimize further actinic damage. Frequent and routine screening should also be stressed to these patients.
Long-Term Monitoring
Patients with a history of any type of skin cancer should be evaluated with a total body skin examination every 6-12 months.
One study demonstrated the use of dermatoscopy when following Bowen disease. The visualization of vascular structures corresponded with incomplete treatment of disease or recurrence of disease. An absence of vascular structures corresponded with a complete remission. [50]
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Squamous cell carcinoma in situ, Bowen disease. Courtesy of Hon Pak, MD.
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Bowen disease right temple.
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Erythroplasia of Queyrat, squamous cell carcinoma in situ of the glans penis.
