Incidence of melanoma and nonmelanoma skin cancers in Indian and the global regions

Abstract

Background: 

Incidence of common types of skin cancers in India is not reported and its comparison with global load would be helpful statistics.

Aim: 

The aim of this study is to summarize and report recent skin cancer incidence in India and to compare it with the incidence globally.

Materials and Methods: 

Age-specific rates and age-adjusted rates (AARs) of the incidence of skin cancer for all ages (0–75 years) were collected from India and the world, respectively, from the National Cancer Registry Programme and GLOBOCAN 2018.

Results: 

The AAR per 100,000 of melanoma of the skin was highest in the North region of India for both males and females with 1.62 and with 1.21, respectively. The incidence of nonmelanoma of the skin or other skin cancers for males was highest in the East region with 6.2 and for females in Northeast with 3.49. Among nonmelanoma, northeast region showed the maximum incidence for both male (75.6) and female (43.6) sexes. Globally, AAR of melanoma of skin for males was highest in the Western Pacific region with 36.9 and for the females; AAR was highest in the European region with 31.7. The incidence of nonmelanoma of the skin or other skin cancers for males was highest in the Western pacific region with 225.4 and 68.6 for females.

Conclusion: 

Summary of the incidence rates of melanoma and nonmelanoma skin cancers which shows that though there are regional variations of incidence in India is lower than that of in the West.

INTRODUCTION

Skin cancers are commonly divided into two broad heads, nonmelanoma skin cancers (NMSCs) which consist of basal cell carcinomas (BCC) and squamous cell carcinomas (SCC)[¹] and melanomas. The latter is not as common as the NMSCs in India, but their severity is far more than that of nonmelanomas. NMSCs have a high incidence in European populations. Of the NMSCs, SCC is more common than BCC among dark-skinned individuals. Radiotherapy commonly induces BCC while human papillomavirus predisposes to SCC MSCs.[²] Melanomas can also be cured in its early stages but if left untreated, it is likely to spread to other parts of the body, where it can be very difficult to treat.[³]

A total of 18.1 million new cases and 9.6 million deaths from skin cancer were estimated globally in 2018.[¹] Global burden of disease study 2015 included data on melanoma incidence, mortality, and disability life years (DALY) and the assessment of global, regional, and national estimates.[⁴] The worldwide incidence of NMSC was systematically reviewed using 75 studies, it was observed that most of the studies focused on white populations in Europe, the USA, and Australia, but there were limited studies in Africa.[⁵] The review revealed that NMSC is a growing problem and stressed the need for studies on the prevention of the disease. A recent study on the epidemiology of skin cancer[⁶] stated that in Europe, the incidence would increase to 40–50/100,000 inhabitants per year in the next decade. Studies from India report clinicopathological evaluation[⁷] and also focus on the current scenarios of NMSCs,[⁸] but a systematic pan-India data analysis has not been published.

Cancer statistics are available from several cancer registries in various countries globally. A cancer registry is an organization for systematic collection, storage, analysis, interpretation, and reporting of data on subjects with cancer. These provide population-based incidence and mortality rates from population-based cancer registries (PBCRs).[⁹] Knowledge of the burden of cancer helps in etiologic studies and the effectiveness of the activities that have been undertaken to control cancer. Incidence data on skin cancers from India and its global comparison are perhaps not reported. Although the full cancer statistics is available on Globocan and in different cancer registry sites, a summary of important cancers such as melanoma and nonmelanoma might help researchers and policy-makers as a ready record to understand the magnitude of this cancer. Thus, we aimed to summarize and report incidence of melanoma of the skin and other skin cancers using data from the National Cancer Registry Programme (NCRP)[¹⁰] India and GLOBOCAN.

MATERIALS AND METHODS

Indian data on the incidence of skin cancers for the present study were obtained from the published consolidated reports of 29 PBCRs (2012–2014) NCRP) of the Indian Council of Medical Research (ICMR). This data from NCRP were available on two broad cancer categories such as melanoma of the skin and other skin cancers. As per the International Classification of Disease version 9 codes, Melanoma of the skin was C43 and other skin cancer was C44. Age-specific rates (ASRs) of incidence of skin cancer up to the age of 75 years and above and age-adjusted rates (AAR) of incidence for melanoma of the skin and other skin cancers in both the sexes in each of the 29 registries were obtained and were presented region-wise. The PBCRs in various parts across the country were divided into six regions for the present study which are as follows: North: Delhi, Patiala, South: Bangalore, Chennai, Kollam, Thiruvananthapuram, Central: Bhopal, East: Kolkata, Northeast: Cachar district, Kamrup urban, Manipur, Mizoram, Nagaland, Meghalaya, Sikkim and Tripura, West: Mumbai, Nagpur, Pune, Ahmedabad and Barshi extended. The data of Indian registries are available for public use on NCRP-ICMR website.[¹⁰] The data of cancer incidence from sites other than melanoma were termed as nonmelanoma of skin category.

Age-specific rates (ASRs) and AARs of the incidence of melanoma skin cancer and other skin sites in world for both the sexes and all ages (0–75 years) were collected from the report of the International Agency for Research on Cancer (IARC) by GLOBOCAN 2018 in 185 International Association of Cancer Registries).[¹⁹¹⁰] The world regions were divided into six regions for the present study which are as follows: African Region, American Region, South-East Asia Region, European Region, Eastern Mediterranean Region, Western Pacific Region. The global data of world regions are available for public use on GCO. IARC website.[¹⁹]

Statistical analysis

Cumulative risk (s) computed by NCRP[¹⁰] and GLOBOCAN[⁹] were based on the following formulae: Cumulative risk = 100 × (1 − exp [ −cumulative rate/100]) where, cumulative rate = (5× Σ [ASR] ×100)/100,000 and ASR is age-specific incidence rate(s). The multiplication factor five in the above formula of cumulative rate indicates the 5-year age intervals in ASRs. We computed another indicator, one in a number of persons likely to develop skin cancer in the lifetime of 0–75 years, for each skin cancer (melanoma and nonmelanoma) in each registry by using a formula 100/cumulative risk.[¹⁰] Data on indicators, namely incidence rates, AARs and one in a number of persons develop cancer were summarized for both the sexes in each of the cancer registries and presented region-wise in the form of ranges.

RESULTS

The AARs for India and the world in the age of 0–75 years are presented region-wise for melanoma and other skin cancers) [Table 1]. In India, AAR incidence of melanoma of the skin was highest in the North region with 1.62 for males and 1.21 for females. Incidence of NMS for males was highest in the East region with 6.2 and in females in the Northeast region (3.49). Percent of melanoma of the skin out of all cancers for both males and females was highest in North with 1.06 and 0.8, respectively. For males and females, NMSC is highest in the Northeast region with 5.14 and 3.98, respectively [Table 1].

Table 1: Age-adjusted rates of incidence of skin cancer among males and females in India

Globally, melanoma incidence (AAR) was 36.9 in the Western pacific region for males and for females; it was 31.7 in the European region. The incidence of NMSC was highest in the Western Pacific region both for males (225.4) and females (68.6) [Table 2]. The percent of melanoma of the skin out of all cancers for both males and females was highest in the European region with 48.3 and 53.5, respectively. Percent of nonmelanoma out of all cancers was highest in the American regions with 43.4 for males and 41.5 for females [Table 2].

Table 2: Age-adjusted rates rate of incidence of skin cancer among males and females in the world

DISCUSSION

The present study focuses on the incidence rates of melanoma and nonmelanoma skin cancers in India and worldwide. Moreover, the study also identifies the regions of India and the world with the highest cases of melanoma and nonmelanoma skin cancers. In India, among males, the incidence of both melanoma and nonmelanoma skin cancers was highest in Northeast region. Further, in the Northeast region, the incidence of melanoma was highest in Nagaland and the incidence of nonmelanoma was highest in Pasighat. Among females, the incidence of melanoma was highest in northern region (Delhi) and the incidence of other skin cancers was highest in northeast region (Pasighat). According to the AAR, the incidence of melanoma skin cancer for both males and females was highest in northern region, 1.62 and 1.21, respectively. The incidence of nonmelanoma skin cancer for males was highest in Eastern region (6.2) and for females the incidence was highest in Northeast region.[³]

Risk factors for NMSC are environmental, chemical exposures, chronic cutaneous inflammation, immunosuppression, fair phenotype, and any previous history of skin cancer. Among environmental risk factor important ones are UV radiation, indoor tanning, ionizing radiation, and psoralen UVA (PUVA) therapy. Arsenic and polycyclic aromatic hydrocarbons are the important chemical risk factors. Arsenic and UV exposures are supposed to be the most important for the Indian population.[¹¹] Risk factors for melanoma are the causes of melanoma greater than five sunburns, indoor tanning, PUVA phototherapy, fair phenotype, Parkinson's disease, immunosuppression, and any personal and/or family history of melanoma. The most likely cause in the Indian population for skin cancer are the combinations of PUVA and fair phenotype.[¹¹]

In the regions of the world, the incidence of melanoma and nonmelanoma skin cancers was highest in western pacific region. Further, in the Western Pacific region, the incidence of both skin cancers was highest in Australia and for females, the cases of melanoma were highest in New Zealand and the cases of nonmelanoma were highest in Australia. According to the AAR the incidence of melanoma skin cancers for males was highest in the Western Pacific region with 36.9 and for females, this incidence was highest in the European region with 31.7. The incidence of nonmelanoma skin cancer for both males and females was highest in Western Pacific regions.

The global burden of melanoma was reported from the burden of disease studies of 2015.[⁴] It observed that the greatest melanoma incidence was in the five world regions such as Australia, North America, Eastern Europe, Western Europe, and Central Europe. DALY and mortality were greater in males than in females, in those with age >75 years. A study reported early detection strategies for melanoma and other skin cancer. It was reported that a 5-year melanoma survival rate in the USA rose from 49% to 82% in the year 1990. In the early 1990s, the incidence of cutaneous melanomas in whites was mounting faster than any other cancer. A study from Denmark reported the increased incidence of melanoma in situ in Denmark from 1997 to 2011. During this period, melanoma in situ incidence increased from 2.6 to 8.1 and 1.4 to 4.6 in females and males, respectively.[¹²] The incidence rates of both melanoma and nonmelanoma skin cancers are increasing globally, but the mortality rates are either declining or stable.[⁶] Various authors suggested based on epidemiology from migration studies and observational, high susceptibility to melanoma initiation might be due to excessive exposure to ultraviolet (UV) radiation.[¹³] Actually, UV radiation has both harmful and beneficial effects on human skin. Ionization due to UV-C may act as strong mutagen causing cancer. Other mechanism such as free radical injury due to UV radiation might also be a cause of skin cancer. In response to UV light apoptosis of keratinocytes is responsible for skin protection against cancer. This mechanism in addition to other defense mechanism such as dissipation of UV radiation by activated melanin pigment plays a preventive role in skin cancer. There is a need to prevent harmful effects of increased harmful UV radiations.[¹⁴] Another study evaluated the effect of regular sunscreen to prevent cutaneous melanoma. The study found the reduction in invasive melanoma (hazard ratio [HR], 0.27; 91% confidence interval [CI], 0.08–0.97) compared to that of preinvasive melanoma (HR 0.73; 95% CI, 0.29–1.81) and concluded that melanoma is preventable by using sunscreen in adults.[¹⁵] National Cancer Institute's Surveillance, Epidemiology, and End Results data revealed the United States' striking disparity of 55% difference in melanoma survival between young men and women of ages of 15–39 years.[¹⁶] A study from India introduced a precise melanoma segmentation technique based on the Gradient and Feature Adaptive Contour (GRAC) model to detect melanoma skin cancer in the earliest stage and diagnosis of dermoscopic images.[¹⁷] Another study[¹⁸] applied an efficient melanoma diagnosis approach using integrated HMF multi-atlas map-based segmentation.

A model-based study on the prevalence of nonmelanoma skin cancer indicated that its prevalence is about five times higher than that of breast or prostate cancer and >31 years' prevalence of all other cancers combined and emphasized the need for population-based incidence and burden data for basal cell carcinoma and SCC.[¹⁹] A recent systematic review also reported worldwide incidence of nonmelanoma skin cancers.[⁵] The review observed that the studies were focused mostly on white population in Europe, USA, and Australia and the data for African region was limited. The basal cell carcinoma incidence rates in the UK were increasing at a greater rate than the rest of the Europe and reviews suggested the requirement of prevention studies on nonmelanoma skin cancers worldwide. Studies also reported that daily sunscreen application and beta-carotene supplementation is helpful for the prevention of basal cell and SCC of the skin. While beta-carotene supplementation did not reveal any beneficial or harmful effects on either type of skin cancers, sunscreen application was useful for the prevention of cutaneous SCC, but not for basal cell carcinoma.[²⁰]

The skin cancer incidence in India is low in proportion (0.5-–4.8 among females and 0.04–6.2 among males) to all other cancers [Tables 1 and 2] in comparison with regions of the globe (8.1–79.6 in females and 5.1–79.1 in males). A review[²¹] suspected that genetic susceptibility played an important role in arsenic susceptibility. Exposure to ultraviolet B (UVB) radiation and higher levels of arsenic in drinking water has been reported to be associated with skin cancers.[²²] No statistically correlation was found between number of lesions and arsenic content in the hairs and nails of the patients.[²³] In India, the regional variations can be explained, by certain established facts. The link of melanoma and UV light is known and this has a connection with the skin type. The Type I and II skin in the North East in conjunction with the high UV flux in that area can explain the higher incidence of NMSC and melanoma. In the East along the Ganges and parts of North India, there is a belt prone to arsenicosis which is a potential carcinogen.[²⁴] The increased melanoma in Delhi is inexplicable, but is probably a referral bias. The marked difference in the incidence with the Western data is a heartening feature and the higher incidence in the West is explained by the skin type of the Western Skin (type I) and the high ambient UV flux.[²⁵²⁶] Male preponderance for skin cancers could possibly be due to the higher UV light exposure in males due to outdoor occupational activity.

In India, at present, there are 29 PBCRs and the coverage of around 11% of the total population of India has been done. Although these registries cover various parts of our country, they do not efficiently represent various regions which are far distant from the center of location of PBCRs. In the absence of any source of data on magnitude of skin cancer, data from PBCRs are the only source which provides authentic data on the incidence and mortality of this cancer. The registries reported data on skin cancer only in two broad categories such as melanoma of skin and other skin cancers and this becomes a limitation of our study in the absence of incidence in subcategories of other skin cancers. Another limitation is that a large number of skin cancers are not registered by dermatologists in skin cancer registries.

CONCLUSION

The proportion of skin cancers is high in some particular regions of India as well as of the world. Nonmelanoma skin cancers have high incidence rate globally. Thus, effective interventions are needed to reduce the incidence of skin cancer to reduce the global burden of disease.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.