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Dermatology
Original research
Prediction of relative survival trends in patients with cutaneous squamous cell carcinoma using a model-based period analysis: a retrospective analysis of the surveillance, epidemiology, and end results database
  1. Suzheng Zheng1,2,
  2. Hai Yu1,
  3. Jinrong Zhang1,
  4. Wai Chi Lau1,
  5. Ming Chen1,
  6. Hongtao Cheng3,
  7. Hua Xian4,
  8. Wai-kit Ming5,
  9. Leong Nga Cheng1,6,
  10. Yong He1,
  11. Shuli Huang7,
  12. Wenhui Chen8,
  13. Jun Lyu9,10,
  14. Liehua Deng1,2
  1. 1 Department of Dermatology, The First Affiliated Hospital of Jinan University and Jinan University Institute of Dermatology, Guangzhou, China
  2. 2 Department of Dermatology, The Fifth Affiliated Hospital of Jinan University, Heyuan, China
  3. 3 School of Nursing, Jinan University, Guangzhou, China
  4. 4 Department of plastic surgery, The Dermetolgy Hospital of Southern Medical University, Guangzhou, China
  5. 5 Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China
  6. 6 Department of Dermatology, Kiang wu hospital, Macau, China
  7. 7 Department of Dermatology & STD, The Affiliated Hospital of Southwest Medical University, Luzhou, China
  8. 8 Shanghai Aige Medical Beauty Clinic Co., Ltd. (Agge), Shanghai, China
  9. 9 Department of Clinical Research, The First Affiliated Hospital of Jinan University, Guangzhou, China
  10. 10 Guangdong Provincial Key Laboratory of Traditional Chinese Medicine Informatization, Guangzhou, China
  1. Correspondence to Liehua Deng; LiehuaDeng{at}126.com; Jun Lyu; lyujun2020{at}jnu.edu.cn; Wenhui Chen; 3126832945{at}qq.com

Abstract

Objectives Cutaneous squamous cell carcinoma (CSCC) represents a malignancy characterised by the aberrant proliferation of skin epithelial cells, and certain instances of squamous cell carcinoma (SCC) exhibit features indicative of a heightened proclivity for recurrence, metastasis, and mortality. Tracking the latest survival rates for CSCC is crucial for patient care and public health strategies.

Design This was a retrospective study.

Setting The Surveillance, Epidemiology, and End Results (SEER) Programme database was established by the National Cancer Institute in 1973. It is one of the commonly used cancer databases in the United States, covering a variety of tumour types including lung cancer, breast cancer, gastric cancer, colorectal cancer, prostate cancer, etc. It collects cancer diagnosis, treatment and survival data for approximately 50% of the US population, providing systematic evidence support and valuable first-hand information for clinicians' evidence-based practice and clinical medical research. The data used in this study covers 20 years of information on patients with cutaneous squamous cell carcinoma from 2000 to 2019.

Participants In this study, we identified a cohort of 2 04 055 patients, comprising 95 287 women and 1 08 768 men, who were diagnosed with CSCC between 2000 and 2019 in the SEER database. The inclusion criteria for this research encompassed individuals aged 15 years and older, availability of data spanning from 2000 to 2019, confirmation through microscopic examination, and the presence of a primary tumour classified as CSCC. Exclusion criteria involved cases solely validated through autopsy or a death certificate, those alive or with indeterminable survival times, and instances with incomplete data.

Outcome measures The SEER database’s patient trends and relative survival rate for patients with CSCC were evaluated using period analysis method from 2000 to 2019. The anticipated 5 year relative survival rate among CSCC patients for the years 2020 to 2024 was projected using a generalised linear model.

Results A total of 204,055 CSCC patients were identified, 95 287 women and 1 08 768 men. Most patients were male, white, lived in urban areas, presenting with localised metastases, aged 55–64 years, and had untyped CSCC. During the observation period, the 5 year relative survival rate of CSCC patients showed a slight improvement overall, while the 5 year relative survival rate of some subtypes showed obvious fluctuations. Particularly noteworthy was the substantial amelioration observed in the small cell nonkeratinizing SCC subtype, escalating from 60.4% in 2000 to 72.8% in 2019. The 5 year overall relative survival rates for CSCC patients during the intervals 2000–2004, 2005–2009, 2010–2014, and 2015–2019 documented rates of 62.4%, 63.4%, 64.3%, and 66.3%, respectively. Males had slightly lower survival rates than females, older patients had lower rates than younger patients, and white patients had better outcomes than non-white patients. Urban patients had higher survival rates than rural patients. Patients with distant metastases had significantly lower survival rates.

Conclusion The temporal span from 2000 to 2019 witnessed a gradual yet delimited increase in survival rates among CSCC patients. This incremental trajectory persists, with a prognosticated survival rate of 67.1 anticipated between 2020 and 2024.

  • Dermatological epidemiology
  • Dermatological tumours
  • EPIDEMIOLOGY

Data availability statement

Data may be obtained from a third party and are not publicly available. Publicly available datasets were analyzed in this study. This data can be found at: https://seer.cancer.gov.

http://creativecommons.org/licenses/by-nc/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

https://doi-org.ezproxy.u-pec.fr/10.1136/bmjopen-2024-086488

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    STRENGTHS AND LIMITATIONS OF THIS STUDY

    • This study stratified the data in detail by age, race, sex, subtype, and urban and rural residence to reveal the association of these variables with survival.

    • This study used a relative survival rate calculation method based on the period analysis method to combine the actual survival rate with the expected survival rate to provide a more comprehensive prognostic assessment.

    • The study’s retrospective design has inherent limitations.

    • The relatively low proportion of selected pathologic subtypes in the database and the small sample size necessitate caution when analysing rare subtypes.

    • The findings, based on an analysis of US data, should undergo further validation to ascertain their applicability to other countries.

    Introduction

    Cutaneous squamous cell carcinoma (CSCC) denotes a malignancy arising from the keratin-forming cells within the epidermis. Positioned as the second most prevalent form of skin cancer, CSCC is distinguished by an aberrant and expedited proliferation of squamous cells.1–3 Frequently mutated genes in individuals with CSCC include TP53, CDKN2A, RAS, and NOTCH1. Risk factors contributing to CSCC development encompass fair skin types (Fitzpatrick types I-III), older age, male sex, UV radiation exposure (from sunlight or artificial sources), environmental carcinogens, chronic scarring conditions, immunosuppression, familial cancer syndromes, and infection with human papillomavirus.2 4 5 Chronic exposure to UV light, particularly from sunlight, is widely recognised as the primary etiological factor for this type of cancer. While squamous cell carcinoma (SCC) most frequently arises on sun-exposed areas — such as the head, neck, arms, and face — it can also develop on other parts of the body. Clinically, SCC typically presents as a firm, indurated, and scaly lesion, often accompanied by ulceration or bleeding. Although generally slow-growing, some cases may follow an unexpectedly aggressive progression. Surgery is the cornerstone of CSCC treatment, along with other treatments such as radiation therapy, immunotherapy, and targeted therapy.6–8 In addition to treatment, preventive strategies are equally critical, highlighting the importance of regular skin examinations to detect any abnormal lesions early.

    In clinical practice, the 5 year survival rate is a crucial benchmark for evaluating cancer treatment efficacy and tracking patients’ prognostic trajectories.9 This measure provides a robust indicator, offering valuable insights into overall survival trends and long-term outcomes within specific geographic regions. Relative survival, which elucidates the ratio between the observed survival of individuals with cancer and the expected survival within the general population, stands as a crucial indicator frequently employed in cancer statistics to evaluate patient prognosis.10 11 Analysing relative survival rates using period analysis method can unveil cyclic patterns in the data, enhance predictive accuracy, and offer profound insights for medical decision-making.12 This approach enables healthcare professionals to extract nuanced insights from time-series data, supporting the refinement of therapeutic strategies and informed medical decision-making. Leveraging current data, it allows for precise estimation of survival rates, examination of emerging trends, and model-based period analysis, thereby enabling the projection of future survival outcomes. Although previous studies have explored the survival rate of CSCC, most studies have focused on specific regions or time periods and have not been updated for many years.13 14 This study employed period analysis to examine data from the Surveillance, Epidemiology, and End Results (SEER) database spanning 2000 to 2019, offering a comprehensive, long-term perspective on survival trends. It also elucidated the combined impact of various subtypes, gender, age, race, and geographic location on the survival outcomes of CSCC patients.

    Following the stratification of data by race, metastatic stage, residence, sex, histology, and age, this study leveraged period analysis to scrutinise patterns of survival within the cohort of patients diagnosed with CSCC registered in the SEER database covering the period from 2000 to 2019. Additionally, we employed a model-based period analysis to extrapolate and project survival rates for the timeframe of 2020–2024. The investigation delved into unravelling potential factors contributing to variations in survival rates during this specified period.

    Methods

    Data source

    The study utilised data from the SEER database, an extensive, population-based repository that includes information on approximately 50% of all cancer cases in the United States. The SEER programme serves as an essential resource, providing detailed data on cancer incidence, prevalence, and survival. This wealth of information is derived from the amalgamation and dissemination of data from population-based cancer registries.15 As a globally esteemed centre for cancer surveillance data, the SEER database stands as a cornerstone for researchers worldwide, providing reliable, population-based cancer analysis outcomes. Its extensive, longitudinal, and up-to-date data make it an invaluable resource for conducting thorough and reliable investigations in the field of cancer research.16 For this study, CSCC patient data spanning from 2000 to 2019 was retrieved utilising the SEER*Stat software (version 8.4.2). Furthermore, patient follow-up data until December 2020 was obtained.

    The inclusion criteria for this study encompassed individuals aged 15 years and older, with available data from 2000 to 2019, confirmed through microscopic examination, and a primary tumour diagnosed as CSCC. Exclusion criteria involved cases solely validated through autopsy or a death certificate, those alive or with indeterminable survival times, and instances with incomplete data. Ultimately, a total of 2 04 055 cases that satisfied the predetermined criteria were included in the study.

    Variable selection and classification

    The selection of CSCC subtypes was based on a classification system utilising ICD-O-3 codes, which encompass tumour histology, malignant behaviour, and tumor site. Certain rare subtypes were excluded due to their limited case numbers, ensuring the statistical robustness of the analysis. The final inclusion comprised nine pathological subtypes of CSCC. Other demographic indicators were categorised as follows: race (black, Asian or Pacific Islander, American Indian/Alaska Native, and white), age groups (15–44, 45–54, 55–64, 65–74, and ≥75 years), sex (male and female), metastatic stage (distant, localised, and regional), and residence location (urban and rural).

    Statistical analysis

    Descriptive statistics were employed to compile and display the sociodemographic and clinical details of every observation period. Patient prognoses were determined through the analysis of relative survival rates. The relative survival rate, which is the ratio of the actual and projected survival rates, is calculated as

    Embedded Image

    In the formula, the actual and expected survival rates are denoted by Embedded Image and Embedded Image , respectively. In order to distinguish between various time periods, such as years or certain timeframes, for the purpose of computing relative survival rates, the variable i usually represents discrete time intervals or observation periods. It is equivalent to calculating the 5 year relative survival rate when k is set to 5. The SES/geography/race Annual Life Tables provided the expected survival rates, which were then computed using the Ederer II method using US mortality data from SEER.

    In this study, the 5 year relative survival rates of individuals diagnosed with CSCC between 2000 and 2019 were assessed using the period analysis method. Point estimates of relative survival rates and their standard errors were produced using the Greenwood method. Cases diagnosed in four distinct periods (2000–2004, 2005–2009, 2010–2014, and 2015–2019) were included, and linear models were applied to estimate the slope and intercept. The 5 year relative survival rate for patients diagnosed with CSCC between 2020 and 2024 was then predicted using a generalised linear model based on period analysis. The linear model is represented as Y = β1X + β0 + ε, where ε denotes the error term, Y represents the relative survival rate, and X represents the year. The software used throughout the entire analytic procedure was the Joinpoint Regression Programme (version 4.9.1.0) for fitting the linear model, and the SEER*Stat software (version 8.4.2) for computing relative survival rates.

    Patient and public involvement

    There was no patient or public involvement in this research as we used SEER database as source material.

    Results

    In this study, we identified a cohort of 2 04 055 patients, comprising 95 287 women and 1 08 768 men, who were diagnosed with CSCC between 2000 and 2019 in the SEER database. Table 1 delineates the distribution of CSCC cases identified and recorded for each observation period in the SEER database. Notably, the majority of patients were male, of white ethnicity, residing in urban areas, with localised metastases, aged 55–64 years, and diagnosed with untyped CSCC. The untyped CSCC accounted for nearly three-fourths of all CSCC cases, with white patients constituting 81.6% of the total and urban residents representing 85.2%. The distribution of cases across observation periods remained relatively consistent with regard to age, gender, race, residence, and stage.

    View this table:
    Table 1

    CSCC incidence (basic situation) 2000–2019

    Table 2 presents the 5 year relative survival rates for various CSCC subtypes, stratified by gender. Based on the results of the period analysis, the survival rates in the five subtypes of untyped SCC, large cell nonkeratinizing squamous cell carcinoma (LCNSCC), keratinizing SCC, basaloid squamous cell carcinoma (BSCC), and small cell nonkeratinizing squamous cell carcinoma (SCNSCC) increased during 2015–2019 compared with 2000–2004, while the other subtypes showed varying degrees of change and fluctuation. In all three subtypes of untyped SCC, micro-invasive squamous cell carcinoma (MISCC), and BSCC, the relative survival rates of females were relatively higher than those of males, and this trend was reflected in SCC. Furthermore, significant differences were observed between subtypes in terms of variations in relative survival rates. The 5 year relative survival rate of SCC increased gradually during the observation period. The subtype with the most improvement in survival was the SCNSCC, which went from 60.4% in 2000 to 72.8% in 2019. From 2015 to 2019, the tumours with the highest 5 year relative survival rates were MISCC (90.4%), LCNSCC (74.3%), and papillary SCC (73.1%). As per the generalised linear model, the 5 year relative survival rates of SCC and the five subtypes exhibiting an ascending trend in relative survival are anticipated to persistently increase between 2020 and 2024. In contrast, the other subtypes are anticipated to experience declines or fluctuations to varying degrees. Figures 1 and 2 visually illustrate the trends in relative survival across different pathological subtypes and between genders.

    View this table:
    Table 2

    Five year relative survival rates for patients with CSCC and its subtypes by sex from 2000 to 2019 and predicted relative survival rates for patients with CSCC and its subtypes from 2020 to 2024

    Figure 1
    Figure 1

    Trends in the 5 year relative survival rates of patients with each subtype of CSCC.

    Figure 2
    Figure 2

    Trends in the 5 year relative survival rates of patients with each subtype of CSCC and between different sexes.

    Table 3 presents the 5 year relative survival rates for CSCC by age group. Notably, survival rates improved across all age groups from 2000 to 2019. Throughout the study period, the 5 year relative survival rates for younger age groups consistently exceeded those of the older age groups. While the 5 year relative survival rates for all age groups increased gradually, the 15–44 age group exhibited relative stability during the observation period. In the period between 2015 and 2019, the 5 year relative survival rates for CSCC were as follows for different age groups: 75.5% for 15–44, 70.2% for 45–54, 67.2% for 55–64, 65.4% for 65–74, and 55.5% for those aged ≥75. According to the generalised linear model, patients ≥75 years old will have the lowest 5 year relative survival rate (56.5%) between 2020 and 2024, while CSCC patients aged 15–44 will have the highest 5 year relative survival rate (75.2%). Figure 3 illustrates the trend in relative survival for CSCC patients across different age groups.

    View this table:
    Table 3

    Five year relative survival rates of CSCC patients by age group from 2000 to 2019 and forecast of CSCC patients‘ relative survival rates from 2020 to 2024

    Figure 3
    Figure 3

    Trends in 5 year relative survival rates of CSCC patients in different age, race, residential area, and metastatic stage groups.

    Table 4 displays the 5 year relative survival rates for patients with CSCC based on race, residence, and stage of metastasis. From 2015 to 2019, white patients exhibited the highest survival rates, with a mean of 67.3±0.3%. Notably, all racial groups showed an upward trend in 5 year survival rates from 2000 to 2019. The generalised linear models predict that for the period of 2020–2024, the 5 year relative survival rates will be 68.2%, 66.5%, 62.3%, and 56.2% for white, Asian or Pacific Islander patients, American Indian/Alaska Native, and black patients, respectively. Furthermore, survival rates for CSCC were observed to be higher in urban areas compared with rural areas. Notably, in both urban and rural settings, the relative survival rate for CSCC displayed an upward trajectory over time. The generalised linear model predicts that this positive trend will persist in the coming years. Across all three metastatic stages, relative survival rates exhibited a consistent increase over time. The generalised linear model forecasts further improvements between 2020 and 2024. However, it is important to highlight that the relative survival rates for distant and regional metastases continue to significantly differ from those for localised metastases, with relative survival rates for distant metastases remaining below 40%. Trends in the relative survival of CSCC patients by race, place of residence, and stage of metastasis are shown in figure 3.

    View this table:
    Table 4

    Five year relative survival rates of CSCC patients by race, area and metastatic stage from 2000 to 2019 and forecast of CSCC patients’ relative survival rates from 2020 to 2024

    Discussion

    In this study, a period analysis method was applied for the first time to comprehensively analyse data from 2000 to 2019 using the SEER database. The goal was to evaluate trends in the long-term survival of CSCC patients and to project relative survival rates for the period from 2020 to 2024. Over the observed period, relative survival rates for CSCC demonstrated varying degrees of improvement from 2000 to 2019. In recent years, there has been sustained exploration of innovative therapeutic approaches, particularly in the fields of immunotherapy and targeted therapy. This includes the investigation of PD-1 inhibitors, CTLA-4 inhibitors, epidermal growth factor receptor (EGFR) inhibitors, and BRAF inhibitors as promising treatment options for CSCC.7 17 Public health policies also play a key role in improving skin cancer prevention and early detection. The expansion of skin cancer screening programmes has enabled more people at high risk to undergo regular skin examinations, increasing the chances of early detection and treatment.18 19 In light of ongoing advancements in the treatment and management of CSCC, we anticipate that the positive trends observed will persist from 2020 to 2024.

    The diverse characteristics of CSCC subtypes contribute to variations in malignancy and treatment response, thereby impacting patient survival. Given the differences in the degree of differentiation among CSCC subtypes, a classification system can be established, categorising them into low, intermediate, and high-risk histologic variants.3 Notably, high-risk histologic variants are often associated with a lower degree of differentiation. In practice, accurately classifying pathological subtypes of most CSCCs proves challenging in the majority of cases.20 This challenge arises either due to the inability of pathologists to precisely determine the tumour type or insufficient information provided by clinicians for classification. In previous studies LCNSCC, SCNSCC, Spindle cell SCC, BSCC and adenoid SCC resulted in lower relative survival rates due to low differentiation.21–23 In this study, we observed that LCNSCC and SCNSCC, two types of non-keratinised squamous cell carcinomas, exhibited a significant upward trend in relative survival during the observation period. This improvement may be closely linked to recent advancements in targeted therapies and immunotherapies.4 7 24 In particular, EGFR inhibitors and PD-1 inhibitors have shown strong promise in a number of studies, in advanced and metastatic CSCC, associated with improved overall survival.4 25 26 Currently, numerous studies have concluded that complete surgical resection of the tumour is the treatment of choice for CSCC. Ensuring the complete removal of the primary tumour plays a crucial role in preventing the impact of metastasis and recurrence on patient survival.7 Significantly, despite the heterogeneity observed among CSCC subtypes, the overall relative survival of CSCC demonstrated a gradual increase from 2000 to 2019. This positive trend may be attributed to advances in medical technology and a more comprehensive understanding of CSCC.

    Gender is an important factor influencing the prognosis of CSCC, and existing studies have found that male patients with CSCC have higher morbidity and mortality rates than their female counterparts, a trend that was also found in the present study.2 5 27 28 This difference was explored in a study by Budden et al., which also noted that female immunity in CSCC provides better protection than male immunity protection, but it is unclear whether this gender difference is due to differences in behaviour and exposure to carcinogens or to gender-related susceptibility.29 30 Although the role of non-ultraviolet factors, such as sex hormones, in skin cancer is becoming increasingly recognised, robust population-based and molecular evidence is still needed to fully elucidate their impact. The molecular pathways involving sex hormones in keratinocytes remain underexplored, and the mechanisms underlying persistent oestrogen receptor expression and subsequent mutagenesis remain unclear.31 In the present study, differences in survival trends between subtypes and sexes were observed. Revealing the mechanisms behind these differences requires further exploration involving factors such as behavioural differences, hormonal regulation and immune function.

    Age has been identified as a key determinant in the prognosis of CSCC, with older patients demonstrating lower survival rates.32–34 The morbidity and mortality of CSCC increases dramatically with age.2 27 People are more likely to experience years of UV exposure which increases the risk of the disease, an ageing immune system which weakens resistance, and comorbid chronic diseases which affect treatment complexity and response rates.35 36 In this study, we observed a clear gradual increase in survival in patients older than 45, a trend that correlates strongly with advances in immunotherapy.25 Immunotherapy may have played a significant role in this age group, enhancing treatment efficacy, as evidenced by the marked increase in survival rates. The complex interplay of biological factors, therapeutic response, and the ageing process highlights the importance of personalised treatment strategies based on age-specific considerations.

    There are significant racial differences in CSCC. The most prevalent type of skin cancer among Asian and black individuals is CSCC, which commonly manifests in areas such as the groin and anogenital region — sites that are either partially or fully shielded from sun exposure.37 38 This may lead to delayed diagnosis, more advanced disease and thus affect patient survival.39 In this study, black and American Indian/Alaska Native individuals exhibited significantly lower survival rates compared with other racial groups, with black patients showing a particularly concerning survival rate of only around 50%. Notably, squamous carcinomas in non-sun-exposed areas and squamous carcinomas with previous scar formation are more likely to be aggressive than those that develop in sun-exposed areas.37 40 Furthermore, a study by Nadhan et al., found that high-risk HPV subtypes 16, 18, 31, and 33 were associated with up to 67% of SCC lesions in the anal region of non-white patients.41 The discrepancies in survival rates could result from a variety of socioeconomic and medical conditions, including inadequate insurance coverage, a lack of access to healthcare, HPV infection, and skin cancer prevention knowledge.28 40

    The higher survival rates for CSCC observed in urban dwellers compared with rural residents can be attributed to several factors. This is attributed to the fact that cities have more abundant medical resources, high levels of health education, health-conscious lifestyles, and better socioeconomic conditions, which contribute to the availability of more timely and effective treatments and improved survival rates.42–44 Collectively, these factors help explain the disparities in CSCC survival rates between urban and rural areas. In this study, survival rates varied significantly by metastatic stage, with later stages of metastasis correlating with lower survival rates. At each metastatic stage, patients experienced a significant decline in survival rates. The reduced survival associated with distant metastasis of CSCC may be attributed to several factors, including increased treatment challenges, compromised function of vital organs, suppressed immune response, and heightened difficulty in administering integrated therapies.45–47 Available studies have concluded that factors such as immunosuppression, degree of differentiation, and squamous carcinoma thickness greater than 2.0 mm are associated with the risk of CSCC metastasis, whereas mortality is primarily associated with the degree of lymph node involvement.17 48 49 Thus, distant metastasis makes the treatment of CSCC more difficult, leading to decreased survival.

    The present investigation utilised data from the SEER database. However, changes in medical practices and diagnostic criteria throughout the study period may have introduced time-dependent biases in the survival estimates. Although we took measures to minimise bias introduced by changes in reporting standards, diagnostic criteria, and data integrity through meticulously designed inclusion and exclusion criteria, we acknowledge that other potential confounders, such as medical insurance policies, comorbidities, and treatment methods, could significantly influence survival outcomes. Due to the limitations of the SEER database’s data collection scope, these factors were not fully addressed in the current analysis. Additionally, the introduction of new diagnostic technologies, treatment options, and preventive measures may have had a significant impact on patient survival. While this study primarily focuses on the overall survival trends, we acknowledge that these dynamic advancements could have influenced the observed survival patterns. Finally, the validity of generalised linear models depends on several key assumptions, including the distribution of the error term and the linear relationship between the response variable and the predictor variables. It is important to acknowledge that real-world data may not always adhere to these assumptions, potentially affecting the accuracy of the model’s predictions. Future studies could further investigate the specific impact of evolving treatment methods on survival outcomes and utilise more comprehensive databases to enhance the representativeness and generalisability of the findings. This would offer a deeper understanding of the data and contribute to the refinement of CSCC management and treatment strategies.

    This study underscores the elevation in survival rates of CSCC propelled by the advancements in immunotherapy and targeted therapies. For CSCC, in addition to treatment, preventive measures are equally important. In the past few years, machine learning and deep learning technologies have made significant progress in skin cancer detection.50 51 These technologies can not only improve the accuracy of diagnosis at an early stage, but also provide clinicians with more powerful tools to detect and manage SCC patients earlier, which may significantly improve patient prognosis.52 These advancements highlight the significant potential of artificial intelligence in enhancing the detection and management of CSCC. Future research should delve into the mechanisms underlying the improved survival rates of CSCC patients, with particular focus on early detection programmes and health promotion initiatives. By advancing personalised treatment strategies, these efforts will play a crucial role in improving the prognosis for future SCC patients.

    Conclusion

    In this study, the relative survival rates of CSCC patients demonstrated an overall upward trend over time, although variations were observed across different CSCC subtypes. This positive trajectory is anticipated to persist through the period 2020–2024. The favourable change can be attributed to advancements in early detection techniques, therapeutic treatments, increased health education, and the dissemination of sun protection measures, among other factors. However, the prognosis of CSCC patients remains influenced by various factors, including racial differences, gender, age, and tumour metastasis. Future advancements should focus on strengthening oncology education, improving early diagnosis, and refining treatment strategies to further enhance patient survival outcomes. Analysing the survival rates of CSCC over the past two decades provides crucial insights into future trends, guiding the development of more effective treatment strategies and the formulation of comprehensive health policies aimed at improving the prognosis of CSCC.

    Data availability statement

    Data may be obtained from a third party and are not publicly available. Publicly available datasets were analyzed in this study. This data can be found at: https://seer.cancer.gov.

    Ethics statements

    Patient consent for publication

    Ethics approval

    This study was based on publicly available data and did not require ethical approval according to relevant ethical guidelines and regulations. The study adhered to the data use agreement of the SEER database to ensure compliance with ethical and regulatory standards.

    Acknowledgments

    We heartily thank all of the employees and scientists at each of the SEER registry locations.

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    Footnotes

    • SZ, HY and JZ are joint first authors.

    • Contributors SZ, HY and JZ: Formal analysis, visualisation, writing original draft, writing review and editing. WCL, MC: Data curation, writing original draft, writing review and editing. HC and HX: Data curation, formal analysis, writing review and editing. WM and LNC: Data curation, formal analysis, writing review and editing. YH: Writing original draft, writing review and editing. SH: Writing original draft, writing review and editing. WC, JL and LD: Visualisation, writing original draft, writing review and editing. All authors contributed to the article and approved the submitted version. LD is the guarantor.

    • Funding The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The study was supported by Key Scientific Problems and Medical Technical Problems Research Project of China Medical Education Association (2022KTZ009) and Guangdong Provincial Key Laboratory of Traditional Chinese Medicine Informatization (2021B1212040007).

    • Competing interests None declared.

    • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

    • Provenance and peer review Not commissioned; externally peer reviewed.