Here, we present a protocol for local hyperthermia, a new and effective therapeutic for treating warts. We also showcase its safety and efficacy as an independent treatment.
Warts, benign epidermal proliferations, are a direct result of human papillomavirus (HPV) infection, specifically targeting the keratinocytes within the stratum corneum of the skin. The development of warts is the most common clinical manifestation of HPV, with plantar warts, condylomata acuminata, and common warts being the most frequently observed types. These growths can be unsightly and sometimes painful, affecting the quality of life for those afflicted. Although various treatments are available, ranging from topical medications to surgical procedures, the quest for a treatment that is both safe and effective while minimizing invasiveness continues. This is particularly crucial for populations with heightened risk factors, such as immuno-compromised individuals. In the clinical need for minimally invasive treatments, local hyperthermia has emerged as a promising therapeutic strategy for wart management. As demonstrated in various studies, local hyperthermia is effective as a standalone treatment, offering a valuable alternative for patients seeking less intrusive therapeutic options.
Warts, which are benign epidermal proliferations, are a direct result of human papillomavirus (HPV) infection, specifically targeting the keratinocytes within the stratum corneum of the skin1. They are most commonly manifested clinically as the formation of warts, including plantar warts, genital warts, and common warts2. Warts are typically benign in nature, and although they are occasionally subject to spontaneous resolution3, a considerable number of individuals prefer to have them excised primarily due to the discomfort they cause or social embarrassment4.
A variety of therapeutic approaches have been employed to treat warts, including laser therapy, antiviral treatments, antimitotic medications, and immunotherapies5. However, these treatments are often accompanied by adverse effects such as pain, bleeding, secondary infections, and ulceration6. Consequently, there exists an urgent demand for treatment modalities that offer enhanced safety, efficacy, and minimal invasiveness, particularly for special populations, including the elderly, children, and pregnant women, as well as for specific anatomic sites such as the perianal region and the vulva.
Addressing the demand for effective and minimally invasive treatments, local hyperthermia has emerged as a promising therapeutic strategy. Hyperthermia has been effectively utilized in the treatment of certain neoplasms7, and there are numerous studies that have demonstrated the efficacy of localized hyperthermia in the management of warts, yielding highly satisfactory outcomes8,9. The hyperthermia device used here offers a range of customizable settings, including adjustable levels and modes, designed to meet diverse therapeutic needs. The overall goal of this hyperthermia device is to provide a non-invasive, safe, and efficacious approach for wart management that is suitable for a wide range of patient populations, including those who are not candidates for more invasive procedures.
This technique of using local hyperthermia for HPV-related warts is positioned within a growing body of literature that explores the role of heat in modulating immune cell function. It builds on a previous study that established the importance of Langerhans cells in the immune response to skin infections and how their balance can be restored through controlled heat application10.
Individuals with diagnosed HPV-related warts, such as common, plantar, or genital, and who are compliant with medical guidance are considered appropriate candidates for local hyperthermia treatment. Although pregnancy is not an absolute contraindication, pregnant patients must be made aware of the associated risks and must provide informed consent to proceed11. This treatment is not recommended for those with periocular lesions, purulent infections, a propensity for severe scarring, coagulation disorders, or known photosensitivity. Additionally, patients with warts in proximity to tumors are not candidates, as this could suggest an underlying neoplastic process.
Informed consent was obtained from all participants and the treatment protocol has been approved by the Ethics Committee of the First Affiliated Hospital of Chongqing Medical University.
1. Patient selection
2. Target skin lesion selection
3. Hyperthermia treatment
4. Treatment plan
5. Precautions
Multiple hospitals have contributed to a series of investigations into the therapeutic effects of hyperthermia. This research encompasses single-arm clinical observational studies, placebo-controlled trials, and comparative analyses with cryotherapy, with the findings being published in various articles13,14,15. They found that hyperthermia was also associated with reduced pain during treatment had comparable therapeutic effects to conventional treatment, and even superior efficacy in some cases13,14. Notably, not only did the target lesions at the irradiated sites regress but there was also a significant regression of non-target lesions at non-irradiated sites. Moreover, compared to conventional treatment, there was a marked reduction in pain levels15, which may potentially enhance patient compliance and overall treatment experience.
Our study indicated that hyperthermia treatment resulted in the complete resolution of plantar warts in 13 out of 21 patients (59.1%), with partial remission observed in 8 (38.1%)14. The primary adverse event during the procedure was a mild burning sensation, with minimal observation of other side effects. Bullae formation was noted in two patients at the treatment sites. The demographics and clinical characteristics of the 21 patients who achieved resolution are detailed in Table 1. Additionally, there was no recurrence of lesions in the 13 clinically cured patients upon follow-up. These findings are juxtaposed with the average cure rates from a comprehensive review16,in the study, a variety of treatment modalities were investigated, including Imiquimod 5% cream, laser surgery, cryotherapy, surgical removal, and placebo or no treatment. Our research indicates that the efficacy of our method is comparable to that of Imiquimod 5% cream, laser surgery, surgical removal, and placebo or no treatment, but it is inferior to the efficacy of cryotherapy. Although hyperthermia's cure rates are not superior to those of conventional treatments, it is noteworthy for its minimally invasive nature, causing less pain and tissue damage.
Moreover, our study particularly emphasizes the low recurrence rate associated with hyperthermia; there was no recurrence of lesions in the 13 clinically cured patients at the last follow-up. It is particularly noteworthy that hyperthermia treatment exhibited salutary effects on both targeted and non-targeted skin lesions in individuals presenting with extensive cutaneous warts. This observation underscores the potential of hyperthermia to confer a systemic therapeutic benefit, promoting the regression of not only the lesions that were directly subjected to treatment but also those that were anatomically distinct and untreated14.
Our clinical observations demonstrate that hyperthermia treatment led to marked improvements across all types of warts, regardless of their location or the number of lesions present (Figure 4). Figure 4A depicts the appearance of plantar warts before the initiation of treatment. In contrast, Figure 4B illustrates the complete remission observed one month after the application of local hyperthermia. Figure 4C, D showcases the transformation of vulvar condylomata acuminata from the pre-treatment state to the post-treatment state, with a full resolution of the skin lesions achieved 1 month after commencing the therapy. Figure 4E,F depict penile condylomata acuminata in the pre-treatment state, and Figure 4G,H show the lesions' complete regression after 1 month. In a patient with extensive anogenital warts affecting both genital and perianal regions, with a focus on genital warts as the primary treatment area (Figure 4I), initial results after 1 month (Figure 4J) showed no significant improvement in skin lesions, accompanied by the development of erythema at the target sites. However, after 2 months of treatment (Figure 4K), there was a noticeable reduction in warts in both perianal and vulvar areas despite persistent erythema. By the end of the 3-month treatment period (Figure 4L), all warts had resolved completely, and the erythema induced by hyperthermia at the treatment sites had subsided. Notably, they reveal the intriguing phenomenon of concurrent clearance of both targeted and non-targeted lesions, including the spontaneous healing of untreated perianal lesions in a complex genital case.
Figure 1: Irradiation of lesion. Adjust the angle for the plantar warts and begin irradiation once the hyperthermia device is activated. Please click here to view a larger version of this figure.
Figure 2: Temperature settings and operational modes for thermotherapy device. (A) The machine offers nine adjustable temperature levels, each corresponding to a specific temperature setting as follows: Level 1: 40 °C; Level 2: 40.8 °C; Level 3: 41.5 °C; Level 4: 42.3 °C; Level 5: 43 °C; Level 6: 43.8 °C; Level 7: 44.5 °C; Level 8: 45.3 °C; Level 9: 46.0 °C. (B) The device has three modes for customizable temperature and exposure time adjustments. Please click here to view a larger version of this figure.
Figure 3: Local hyperthermia treatment. The treatment plan consists of three phases: the primary treatment phase, the intensified phase, and the observation phase. Please click here to view a larger version of this figure.
Figure 4: Before and after local hyperthermia treatment comparison. (A) Plantar warts before treatment. (B) One month after treatment with local hyperthermia (complete remission). (C) Vulvar condylomata acuminata before treatment. (D) The skin lesions completely resolved after 1 month of treatment. (E, F) Penile condylomata acuminata before treatment. (G, H) The skin lesions completely resolved after 1 month of treatment. (I) The patient presented with extensive condylomata acuminata affecting the genital and perianal regions, with genital warts designated as the primary target area for treatment. (J) After 1 month of treatment, there was no significant improvement in the skin lesions, and erythema developed at the target sites. (K) After 2 months of treatment, although erythema at the treatment sites persisted, warts in both the perianal and vulvar areas showed significant reduction. (L) After 3 months of treatment, the multiple warts achieved complete clearance, and the reactive erythema to the hyperthermia at the irradiated sites subsided. Please click here to view a larger version of this figure.
Variable | Response group (n=21) |
Age median (QS) | 32 years (26.5, 43.5) |
Gender (Male/%) | 11/52.4% |
Duration median (QS) | 12 (3,24) |
Number median (QS) | 5 (1,26.5) |
Diameter median (QS) | 8 mm (4,15) |
Average follow-up time | 4.6 months |
Remission (yes/%) | 8/38.1% |
Previous treatment(yes/%) | 9/42.9% |
Table 1: Demographics and clinical characteristics of patients (N=21). This table has been modified from14.
Plantar warts, condylomata acuminata, and common warts all include mucocutaneous manifestations resulting from human papillomavirus (HPV) infection; these lesions can present as solitary skin lesions or, more commonly, as multiple lesions17.
In the continuous effort to manage warts induced by Human Papillomavirus (HPV), a diverse array of therapeutic strategies has been implemented. These include destructive methods, virucidal agents, antimitotic compounds, and immunotherapeutic approaches. Despite their varying degrees of success when used in isolation or in combination, these treatments are frequently associated with adverse effects such as pain, bleeding, secondary infections, and ulceration, underscoring the need for less invasive and more effective treatment options18.
The advent of hyperthermia has introduced a promising alternative to the current therapeutic landscape. Since its initial proposal in 1992, hyperthermia has been extensively researched and repeatedly shown to be effective in the treatment of warts19. Notably, a comparative analysis performed 4 months after the commencement of treatment revealed that 54.5% of patients treated with hyperthermia achieved complete clearance of their lesions. This outcome significantly surpassed the 27.2% clearance rate observed in the cryotherapy group in a study that included 35 participants15.
Temperature emerges as a pivotal factor in the efficacy of hyperthermia treatments for HPV-induced warts, with varying temperatures potentially leading to diverse therapeutic outcomes20. A study has indicated that the application of local hyperthermia at 44 °C to a single lesion could result in the concurrent resolution of untreated plantar warts in 59.1% of the patients, underscoring the treatment's systemic effects21. However, reported cure rates for hyperthermia show considerable heterogeneity across studies.
The maximum tolerable thermal treatment temperature is 46 °C. This is based on preliminary clinical observations, which indicate that temperatures exceeding 46 °C can lead to skin injuries such as blisters and bullae.
Consequently, identifying the optimal therapeutic temperature has consistently been a focal point of research efforts. The reported efficacies in these previous studies correspond to the rates of therapeutic success observed in our clinical observations, suggesting consistency across different research settings13,14,15. A comparative analysis conducted months post-treatment revealed no significant difference in the clearance rates of targeted lesions between hyperthermia and cryotherapy, as reported by Qi et al.15. However, a significant advantage for hyperthermia was observed in the clearance of non-target lesions compared to cryotherapy15. In addition to its superior efficacy in clearing non-target lesions, hyperthermia was also associated with reduced pain during treatment. Patients who underwent cryotherapy experienced significantly higher pain scores on a visual analog scale (VAS) than those treated with hyperthermia, a difference that was statistically significant15.In a 3 month study by Wei et al., hyperthermia showed a significantly higher cure rate than placebo-controlled group13. Moreover, Chen's recent research noted no lesion recurrence in clinically cured patients upon final follow-up, suggesting hyperthermia's potential to reduce recurrence rates14.
To prevent blister occurrences, it is important to understand the conditions that may lead to blistering. In a study by Qi et al., it was observed that 2 out of 44 patients developed blisters15. Blisters were found to be more likely to form when the light was concentrated on very small warts, leading to direct exposure of the healthy skin surface or in patients with a heightened sensitivity to light. Thus, it is suggested to opt for thermal therapy on larger lesions, as smaller ones, such as filiform warts, might not be appropriate for this treatment approach13,15.
Extensive research has been dedicated to understanding the therapeutic mechanisms of hyperthermia in clearing warts. Hyperthermia's effectiveness is particularly notable due to its dual role: it induces specific immune responses against HPV-infected lesions, which are essential for both self-regression and treatment-assisted clearance of warts, and it also leads to relief in both target irradiated and non-irradiated skin lesions13,15. This targeted approach not only addresses the treated lesion but also has systemic implications; the immune reaction initiated by treating a single lesion can extend to untargeted or distant lesions. This broader effect is attributed to the systemic immune response elicited by the localized application of hyperthermia. As a result, lesions that have not been directly treated may also experience regression or achieve complete resolution, underscoring the potential of hyperthermia to offer comprehensive treatment for multiple warts13,15,18.
We observed that patients with multiple warts can also experience nearly simultaneous clearance of both targeted and non-targeted warts. This observation implies that hyperthermia potentially enhances the specific immune response against warts, highlighting its indirect but supportive role in immunotherapy. It appears to engage the skin's inherent mechanisms for the autonomous clearance of HPV infections. The principal mechanism underlying this efficacy is believed to be the modulation of Langerhans cell function within the specific immune response. This modulation enhances the ability to target and eliminate virus-infected keratinocytes13,15.
This also elucidates the rationale behind the relatively slower therapeutic onset observed with the therapy, as it may require time for the immune system to mount an effective response against the viral infection. The general application of hyperthermic therapy typically necessitates a duration of over months. Moreover, it is essential that the therapeutic phase and the intensified treatment phase are separated by a 2 week interval21,22. This protocol is based on the understanding that the homeostatic balance of Langerhans cells (LCs) within the epidermis is typically achieved within a one- to two-week timeframe. Yoshioka's research indicates that local hyperthermia at 43°C restores LC homeostasis in the epidermis within 14 days22. This timing is crucial as LCs drive the immune response against HPV-infected keratinocytes. A 2 week treatment gap ensures an ample LC presence for the next treatment cycle. With a normal skin turnover of 52-75 days, a 3 month study endpoint suffices to assess both epidermal recovery and wart clearance, which are immune response-dependent13.
Compliance is a critical factor in ensuring the efficacy of thermotherapy treatments. At the initiation of therapy, patients are informed that the therapeutic effects, while gradual, are accompanied by markedly reduced pain sensation compared to conventional laser therapy, and there is an absence of risks such as bleeding. The treatment protocol is presented to patients, detailing the benefits and drawbacks, allowing them to make an informed decision about their ability to cooperate with the treatment plan. Consequently, patients who opt for thermotherapy are typically able to adhere to the treatment regimen, as they have a realistic psychological expectation of the treatment's progression. Furthermore, for patients with multiple comorbidities who express a fear of pain, a comprehensive explanation of the treatment's merits and demerits often results in willing engagement after they have grasped the potential benefits. Therefore, pre-treatment consultation and ongoing follow-up are deemed essential components of the therapeutic process.
Despite the variety of treatments for warts, there is a clear need for safer, more effective, and minimally invasive options that also minimize pain23. This is especially important for particular groups: patients with multiple warts, those with warts in sensitive areas like the genitalia and rectum, pregnant women, children who are sensitive to pain, individuals with serious systemic diseases, and patients with extensive condylomas who have had recurrences after standard treatments. This strategy involves personalized communication with these patients prior to treatment to address their specific needs and concerns. Despite the limitations associated with treatment options during pregnancy, many women with this condition experience progressive enlargement of verrucae. Local hyperthermia, proposed as a viable therapeutic approach for pregnant women, merits consideration as a safer alternative due to its favorable safety profile in treatment24.
In conclusion, the current study's findings highlight the efficacy and safety of local hyperthermia as an innovative therapeutic strategy for treating warts, suggesting its potential as a viable alternative to traditional treatments25. Although the precise mechanisms and optimal conditions for local hyperthermia are not fully understood, this treatment has shown promising efficacy and safety in wart management. However, further analysis with larger clinical samples is needed to delineate the differences between local hyperthermia and conventional therapies more clearly. Future studies should encompass larger clinical trials to validate our findings and assess the impact of variables like wart size and the efficacy of previous treatments on wart resolution.
The authors have nothing to disclose.
The authors have no acknowledgments.
YY-WRY-V02 infrared specific wave photothermal therapeutic instrument | Liaoning Yanyang Medical Equipment Co., Ltd | No. ZL200720185403.3, China Medical University, China) |
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