Why vitiligo is associated with fewer risk of skin cancer? Providing a molecular mechanism

Incidence of skin malignancies in patients with vitiligo or psoriasis who received narrowband ultraviolet B phototherapy (308 nm/311 nm): A retrospective review of 3730 patients

BACKGROUND

Previous studies regarding the risk of skin malignancy with NBUVB have been performed in Caucasian patients, but few studies have been conducted in Asians.

AIM

The aim of the study was to determine the risk of skin cancer in Asian patients with psoriasis and vitiligo receiving NBUVB phototherapy.

METHODS

We performed a 9-year retrospective study including all patients with psoriasis and vitiligo receiving NBUVB (either 311 nm wavelength through cabin phototherapy or 308 nm through excimer lamp phototherapy) at the National Skin Centre. We matched the identification numbers of patients to the National Registry of Diseases Office database and collected data on all skin cancers diagnosed.

RESULTS

A total of 3730 patients were included. During the course of the study, 12 cases of skin cancer were diagnosed, of which 10 were basal cell carcinomas, and 2 were squamous cell carcinomas. No cases of melanoma were detected in the study. The age-standardized incidence of skin cancer in psoriasis and vitiligo patients who received phototherapy was 47.5 and 26.5, respectively, which is higher than the incidence of skin cancers in the general population. Risk of skin malignancy was positively correlated with the cumulative (p = .008) and maximum dose of phototherapy (p = .011) as well as previous systemic treatments (p = .006).

LIMITATIONS

Limitations include a relatively short follow-up period as well as the lack of quantification of solar exposure.

CONCLUSIONS

NBUVB phototherapy in Asian skin increases the risk of skin malignancy. The risk of skin malignancy is higher with psoriasis patients, greater cumulative and maximal dose of phototherapy as well as the use of systemic therapy. Despite the increased risk, the absolute number of skin malignancies remains low, especially for vitiligo patients, with no cases of melanoma diagnosed-a reassuring finding that phototherapy remains a safe alternative in the treatment of psoriasis and vitiligo.

Reduced risk of skin cancer and internal malignancies in vitiligo patients: a retrospective population-based cohort study in Taiwan

The relationship between cancer and vitiligo has been explored but with inconsistent results. To examine the long-term cancer risk in vitiligo patients, we conducted a retrospective nationwide cohort study. From the National Health Insurance Research Database of Taiwan, a total of 13,824 vitiligo patients were identified and matched with 55,296 reference subjects without vitiligo by age, gender, and propensity score estimated by major comorbidities from 1997 to 2013. Demographic characteristics and comorbidities were compared between these two groups. Incidence rate ratios and hazard ratios (HRs) were calculated to examine cancer risks. The 16-year incidence rates of overall cancers were 621.06 (566.56–675.55) and 726.99 (697.24–756.74) per 100,000 person-years in the vitiligo and reference groups. Patients with vitiligo showed a significantly decreased risk of overall cancers [adjusted HR, 0.85; 95% confidence interval (CI), 0.77 to 0.93, p < 0.001] compared with reference subjects without vitiligo after adjusting for age, sex, comorbidities, and treatments. The risks of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) were significantly reduced (adjusted HR 0.21, 95% CI 0.11–0.38, p < 0.001), as well as internal malignancies (adjusted HR 0.89, 95% CI 0.81–0.99, p = 0.026). The results were consistent across different subgroups of patients, including male gender, ages more than 40 years, and those receiving long-term systemic disease-modifying antirheumatic drugs and phototherapies. Information related to phenotype, disease duration, vitiligo lesion sites, family history of vitiligo or cancer, occupation, and personal lifestyle was not included in the database. Vitiligo is associated with reduced risks of BCC and SCC, as well as internal malignancies.

Evaluation for Skin Cancer and Precancer in Patients With Vitiligo Treated With Long-term Narrowband UV-B Phototherapy

Importance

Narrowband UV-B (NBUVB) phototherapy has been the mainstay in the treatment of vitiligo, but its long-term safety in terms of photocarcinogenesis has not been established.

Objectives

To investigate the risks of skin cancer and precancerous lesions among patients with vitiligo undergoing NBUVB phototherapy, based on the number of NBUVB phototherapy sessions.

Design, Setting, and Participants

This nationwide population-based retrospective cohort study enrolled 60 321 patients with vitiligo 20 years or older between January 1, 2007, and December 31, 2017. Patients and outcomes were identified through nationwide cohort data from the Korean national health insurance claims database, and frequency matching by age and sex was performed.

Exposures

The number of phototherapy sessions each patient received between 2008 and 2017. Patients were classified into 5 groups according to the number of phototherapy sessions (0 sessions, 20 105 patients; 1-49 sessions, 20 106 patients; 50-99 sessions, 9702 patients; 100-199 sessions, 6226 patients; and ≥200 sessions, 4182 patients). We also identifed patients who underwent at least 500 phototherapy sessions (717 patients).

Main Outcomes and Measures

Primary outcomes were the development of actinic keratosis, Bowen disease, nonmelanoma skin cancer, or melanoma after enrollment.

Results

Among the 60 321 patients with vitiligo in this study (33 617 women; mean [SD] age, 50.2 [14.9] years), the risks of Bowen disease (<50 sessions of phototherapy: hazard ratio [HR], 0.289 [95% CI, 0.060-1.392]; 50-99 sessions: HR, 0.603 [95% CI, 0.125-2.904]; 100-199 sessions: HR, 1.273 [95% CI, 0.329-4.924]; ≥200 sessions: HR, 1.021 [95% CI, 0.212-4.919]), nonmelanoma skin cancer (<50 sessions: HR, 0.914 [95% CI, 0.533-1.567]; 50-99 sessions: HR, 0.765 [95% CI, 0.372-1.576]; 100-199 sessions: HR, 0.960 [95% CI, 0.453-2.034]; ≥200 sessions: HR, 0.905 [95% CI, 0.395-2.073]), and melanoma (<50 sessions: HR, 0.660 [95% CI, 0.286-1.526]; 50-99 sessions: HR, 0.907 [95% CI, 0.348-2.362]; 100-199 sessions: HR, 0.648 [95% CI, 0.186-2.255]; ≥200 sessions: HR, 0.539 [95% CI, 0.122-2.374]) did not increase after phototherapy. The risk of actinic keratosis increased significantly for those who had undergone 200 or more NBUVB phototherapy sessions (HR, 2.269 [95% CI, 1.530-3.365]). A total of 717 patients with vitiligo underwent at least 500 sessions of NBUVB phototherapy; their risks of nonmelanoma skin cancer and melanoma were no greater than those of the patients who did not undergo NBUVB phototherapy (nonmelanoma skin cancer: HR, 0.563 [95% CI, 0.076-4.142]; melanoma: HR, not applicable).

Conclusions and Relevance

Our results suggest that long-term NBUVB phototherapy is not associated with an increased risk of skin cancer in patients with vitiligo and that NBUVB phototherapy may be considered a safe treatment.

Skin pigmentation and its control: From ultraviolet radiation to stem cells

In the light of substantial discoveries in epithelial and hair pigmentation pathophysiology, this review summarizes the current understanding of skin pigmentation mechanisms. Melanocytes are pigment-producing cells, and their key regulating transcription factor is the melanocyte-specific microphthalmia-associated transcription factor (m-MITF). Ultraviolet (UV) radiation is a unique modulator of skin pigmentation influencing tanning pathways. The delayed tanning pathway occurs as UVB produces keratinocyte DNA damage, causing p53-mediated expression of the pro-opiomelanocortin (POMC) gene that is processed to release α-melanocyte-stimulating hormone (α-MSH). α-MSH stimulates the melanocortin 1 receptor (MC1R) on melanocytes, leading to m-MITF expression and melanogenesis. POMC cleavage also releases β-endorphin, which creates a neuroendocrine pathway that promotes UV-seeking behaviours. Mutations along the tanning pathway can affect pigmentation and increase the risk of skin malignancies. MC1R variants have received considerable attention, yet the allele is highly polymorphic with varied phenotypes. Vitiligo presents with depigmented skin lesions due to autoimmune destruction of melanocytes. UVB phototherapy stimulates melanocyte stem cells in the hair bulge to undergo differentiation and upwards migration resulting in perifollicular repigmentation of vitiliginous lesions, which is under sophisticated signalling control. Melanocyte stem cells, normally quiescent, undergo cyclic activation/differentiation and downward migration with the hair cycle, providing pigment to hair follicles. Physiological hair greying results from progressive loss of melanocyte stem cells and can be accelerated by acute stress-induced, sympathetic driven hyperproliferation of the melanocyte stem cells. Ultimately, by reviewing the pathways governing epithelial and follicular pigmentation, numerous areas of future research and potential points of intervention are highlighted.

Albinism: epidemiology, genetics, cutaneous characterization, psychosocial factors

Oculocutaneous albinism is an autosomal recessive disease caused by the complete absence or decrease of melanin biosynthesis in melanocytes. Due to the reduction or absence of melanin, albinos are highly susceptible to the harmful effects of ultraviolet radiation and are at increased risk of actinic damage and skin cancer. In Brazil, as in other parts of the world, albinism remains a little known disorder, both in relation to epidemiological data and to phenotypic and genotypic variation. In several regions of the country, individuals with albinism have no access to resources or specialized medical care, and are often neglected and deprived of social inclusion. Brazil is a tropical country, with a high incidence of solar radiation during the year nationwide. Consequently, actinic damage and skin cancer occur early and have a high incidence in this population, often leading to premature death. Skin monitoring of these patients and immediate therapeutic interventions have a positive impact in reducing the morbidity and mortality associated with this condition. Health education is important to inform albinos and their families, the general population, educators, medical professionals, and public agencies about the particularities of this genetic condition. The aim of this article is to present a review of the epidemiological, clinical, genetic, and psychosocial characteristics of albinism, with a focus in skin changes caused by this rare pigmentation disorder.

The 308-nm excimer laser treatment does not increase the risk of skin cancer in patients with vitiligo: A population-based retrospective cohort study

A 308-nm excimer laser (EL) has been widely used to treat patients with localized vitiligo. However, data are rare on the influence of EL treatment on the risks of skin cancer. To evaluate the skin cancer risks after long-term EL treatment, we performed a nationwide population-based retrospective cohort study using the Korean National Health Insurance Claims Database. A total of 5,052 patients with vitiligo were classified into three groups according to the EL treatment sessions between 2009 and 2016: no, 50-99, and 100 or more EL treatments after 2-year washout period (2007 and 2008). Using multivariable Cox proportional hazard models, we found that the risks of actinic keratosis, non-melanoma skin cancers, and melanoma did not significantly differ among the groups, respectively. In conclusion, EL treatment would not increase the risks of premalignant skin lesions and skin cancers in patients with vitiligo. Based on our results, EL is likely to be a safe treatment option for patients with localized vitiligo.

Fractional CO2 Laser Pretreatment to Autologous Hair Transplantation and Phototherapy Improves Perifollicular Repigmentation in Refractory Vitiligo: A Randomized, Prospective, Half-Lesion, Comparative Study

BACKGROUND

Fractional CO2 laser and autologous hair transplantation are independently effective in the treatment of refractory and stable vitiligo.

OBJECTIVE

The authors' purpose was to evaluate the therapeutic efficacy of fractional CO2 laser pretreatment compared with autologous hair transplantation and phototherapy alone for refractory and stable vitiligo.

METHODS

A total of 20 patients with refractory and stable vitiligo were enrolled from our clinic. Resistant lesions randomly divided into 2 regions as follows: (1) Part A: fractional CO2 laser pretreatment followed by autologous transplantation and phototherapy, and (2) Part B: autologous transplantation and phototherapy alone. Five days after fractional CO2 laser application to Part A, both treatment regions received a transplant of scalp grafts. On Day 11, the entire lesion was exposed to narrow-band UVB phototherapy, twice a week for 12 weeks. The diameter of perifollicular repigmentation was measured monthly with a caliper.

RESULTS

Perifollicular repigmentation was detectable surrounding 74% of grafted hair follicles by Month 3. Furthermore, Part A demonstrated a significantly greater diameter of repigmentation with 6.6 ± 5.8 mm in Part A compared with 4.3 ± 1.8 mm in Part B (p = <.001).

CONCLUSION

In this study, our results demonstrate improved efficacy of autologous hair transplantation and narrow-band UVB with fractional CO2 laser pretreatment in refractory and stable vitiligo.

Macrophage migration inhibitory factor as an incriminating agent in dermatological disorders

Macrophage migration inhibitory factor (MIF) is a critical immunoregulatory pluripotent cytokine. It has been re-evaluated as a proinflammatory cytokine, pituitary hormone and glucocorticoid-induced immunoregulatory protein. MIF exists in human epidermis, especially in the basal layer and also is expressed constitutively by monocytes/macrophages, T cells, B cells, endocrine, and epithelial cells. In the field of dermatology, MIF is believed to be a detrimental factor in inflammatory dermatological diseases including atopic dermatitis (AD), psoriasis, vitiligo, pemphigus vulgaris, bullous pemphigoid (BP), alopecia areata (AA) as well as other conditions such as photoaging, and photocarcinigenesis. The objective of this review is to gather and summarize MIF related disorders in dermatology and present valuable information for readers and researchers.

Vitiligo: a possible model of degenerative diseases

Vitiligo is characterized by the progressive disappearance of pigment cells from skin and hair follicle. Several in vitro and in vivo studies show evidence of an altered redox status, suggesting that loss of cellular redox equilibrium might be the pathogenic mechanism in vitiligo. However, despite the numerous data supporting a pathogenic role of oxidative stress, there is still no consensus explanation underlying the oxidative stress-driven disappear of melanocytes from the epidermis. In this study, in vitro characterization of melanocytes cultures from non-lesional vitiligo skin revealed at the cellular level aberrant function of signal transduction pathways common with neurodegenerative diseases including modification of lipid metabolism, hyperactivation of mitogen-activated protein kinase (MAPK) and cAMP response element-binding protein (CREB), constitutive p53-dependent stress signal transduction cascades, and enhanced sensibility to pro-apoptotic stimuli. Notably, these long-term effects of subcytotoxic oxidative stress are also biomarkers of pre-senescent cellular phenotype. Consistent with this, vitiligo cells showed a significant increase in p16 that did not correlate with the chronological age of the donor. Moreover, vitiligo melanocytes produced many biologically active proteins among the senescence-associated secretory phenotype (SAPS), such as interleukin-6 (IL-6), matrix metallo proteinase-3 (MMP3), cyclooxygenase-2 (Cox-2), insulin-like growth factor-binding protein-3 and 7 (IGFBP3, IGFBP7). Together, these data argue for a complicated pathophysiologic puzzle underlying melanocytes degeneration resembling, from the biological point of view, neurodegenerative diseases. Our results suggest new possible targets for intervention that in combination with current therapies could correct melanocytes intrinsic defects.