A Retrospective Chart Analysis of the Patterns and Trends of Skin Cancer

INTRODUCTION

Cutaneous malignancies affect all socio-economic groups, causing a significant global health challenge.^[1,2] Identifying demographic patterns and risk exposures is key for developing screening methods, interventions and early treatments. Over the past three decades, skin cancer demographics and risk factors have shifted, possibly due to an ageing population and ozone depletion.^[3-5] Our comprehensive Global Burden of Disease (GBD) forecasting study shows a global increase in skin neoplasm burden, including in South Asia.^[6] Limited data from South Asia increased uncertainty intervals of the estimates. Sri Lanka, with a population of 22 million,^[7] lacks data on skin cancer prevalence. We report an analysis of skin malignancy trends in Sri Lanka over 8 years from a single tertiary-care centre.

METHODOLOGY

A retrospective chart analysis was conducted. The ethics approval number is AAJ/ETH/COM/2023/DEC. This study is in accordance with the ethical standards of the Helsinki Declaration. We analysed consecutive histopathological samples received at the pathology department at the National Hospital of Sri Lanka from 2015 to 2022. Skin biopsies (punch, incision or excision) were performed by trained doctors based on lesion appearance, rapid spread, prolonged trauma or history of radiation or skin malignancy. Specimens were placed in sterile bottles with 10% formal saline and sent to the laboratory at room temperature. After formalin fixation, paraffin embedding and haematoxylin and eosin staining, they were examined under light microscopes. Lesions were categorised as benign, premalignant or malignant, including squamous cell carcinoma (SCC), basal cell carcinoma (BCC), melanoma (MM), cutaneous T-cell lymphoma (CTCL) and inconclusive samples. Continuous data were presented as mean and standard deviation, with analysis using standard descriptive methods. P < 0.05 was considered statistically significant. The data were analysed using the Statistical Package for the Social Sciences version 30.

RESULTS

A total of 639 patient samples were analysed, with a median age of 59 years [Q1 = 45, Q3 = 68], and 58.7% (n = 375) were male. Of the lesions, 30.6% (n = 196) were benign, <1% (n = 8) were premalignant and 65.8% (n = 421) were malignant. Figure 1 illustrates the distribution of the samples. Premalignant lesions included Bowen’s disease (n = 4) and Actinic Keratosis (n = 4). SCC was the most common cancer, making up 40.6% (n = 171) of cases, followed by BCC at 26.8% (n = 113). Mycosis fungoides (MF) and MM were identified in 18.2% (n = 77) and 13.7% (n = 58) of cases, respectively. Selected histopathology sections of SCC, BCC, MF and MM are shown in Figure 2. Among the BCC cases, one had a mixed nodular and superficial pattern, two were basosquamous, two were micronodular and four were infiltrative. MM subtypes included spitzoid MM, spindle cell MM and malignant epithelioid or spindle cell tumours. Of the 79 CTCL cases, 97% (n = 77) were MF, with the remainder being primary cutaneous acral CD8-positive CTCL and one sample of CD30-positive CTCL. Most SCC cases were well-differentiated (n = 92, 53.8%) at diagnosis. A significant disparity in sex was observed in SCC (male: female = 132:39, P < 0.05), but not in other cancers. The median ages for SCC, BCC, MF and MM were 59 [Q1 = 50, Q3 = 66], 65 [Q1 = 58, Q3 = 72], 38 [Q1 = 23, Q3 = 51] and 64 [Q1 = 51, Q3 = 72], respectively. The sites of involvement of SCC, BCC and MM are highlighted in Table 1. Among MF cases, 53.2% (n = 41) were found only in covered areas (e.g., thorax, thighs and abdomen) and 20% (n = 16) were located on sun-exposed areas (e.g., upper limbs, lower legs, head and neck). The annual incidence of skin cancer gradually increased, with a notable decline in 2021 [Figure 1].

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Figure 1:

Distribution of skin lesions from 2015 to 2022.

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Figure 2:

Histopathology (hematoxylin and eosin, ×10) of (a) basal cell carcinoma, (b) squamous cell carcinoma, (c) melanoma and (d) mycosis fungoides.

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DISCUSSION

Our study highlights an upward trend in skin cancer incidence, with a decline in 2021, likely due to restricted healthcare access during the COVID-19 pandemic. While BCC is the predominant skin cancer in Caucasians and East Asians,^[4] SCC is the most common skin cancer among Black and Indian populations, followed by BCC and MM.^[4,5] Similarly, SCC was the most common cancer in our cohort.

In both Caucasians and Chinese, SCC commonly occurs in sun-exposed areas (e.g., head and neck) after 60 years, while in Blacks, it is often found in sun-protected areas.^[4,5,8,9] Our study showed that SCC was frequently found on the feet, likely due to prolonged sun exposure, outdoor occupations among men, inadequate sun protection and unawareness. The use of exposed footwear or going barefoot may also contribute to occupational injuries leading to SCC.

The incidence of BCC in Caucasians remains 250/100,000 in men and 212/100,000 in women, primarily affecting those over 50 years in the head-and-neck region.^[5] While Chinese populations have similar age and site distribution, the incidence is only 6.4/100,000 in men and 5.8/100,000 in women.^[5] Similar to Black and other Asian populations,^[5] our study also found BCC to be predominantly in the head and neck, with near-equal incidence in both genders.

Global data shows the incidence of MM ranges from 8.4 to 18.9/100,000 in men and 7.6 to 12.9 in women among Caucasians, while it is just 0.2/100,000 in darker-skinned Singapore Indians.^[5,10] In Caucasian men, the trunk is the most common site, while in women, it is the legs. In Black and Asian populations, MM often occurs in less pigmented, non-sun-exposed areas, (i.e acral areas), with an age of presentation between 50 and 70 years.^[5,10] The age and site of MM in our cohort aligned with global trends, with most cases found on the feet [Table 1]. Rare subtypes of cancers highlight the importance of (epi) genetics.

This study, though conducted at the country’s premier referral centre, is limited by its single-location focus and inability to assess risk factors.

CONCLUSION

In conclusion, this study highlights a concerning rise in skin cancer among individuals with pigmented skin in this cohort. We stress the importance of investigating modifiable risk factors, developing early screening methods and reducing risk exposure in South Asian populations. Increasing awareness among all healthcare workers (e.g. podiatrists), and the public will aid in early detection and treatment.