Melanoma of the Skin and Exposure to Solar Ultraviolet Radiation at Work in Modena Territory: a Case-control Study to Promote an Active Search and Prevention of Occupational Diseases Based on Recent INAIL Criteria

This is a monocentric, observational, case-control study conducted at the Dermatology Clinic of the University Hospital of Modena (Azienda Ospedaliero-Universitaria di Modena), Italy.

Background and Rationale:

Skin melanoma is a significant public health concern. While its link to solar ultraviolet radiation (UVR) is established, the specific role of occupational (long-term, cumulative) exposure, as opposed to recreational (intermittent, intense) exposure, is still a subject of detailed investigation. In the period 2008-2014, skin melanoma was included in List 2 (limited probability of occupational origin) of diseases to be mandatorily reported as "occupational" by physicians (Italian law DPR 1124/1965) for the exposure agent "solar radiation". After 2014, it was removed from that list, partly due to evolving scientific evidence suggesting that UV-related malignant melanoma was more strongly related to a pattern of solar ultraviolet radiation exposure typically associated with leisure time activities rather than occupational outdoor activities, especially during childhood and adolescence. Recent classifications by the World Health Organization (WHO) now distinguish melanoma subtypes based on their association with cumulative solar damage (CSD). This is a crucial development, as occupational outdoor activity is a primary factor associated with cumulative sun damage. A joint WHO/International Labour Organization (ILO) meta-analysis found a significantly increased risk for one specific CSD-related subtype, Lentigo Maligna Melanoma, in outdoor workers. In line with this, the Italian National Institute for Insurance against Accidents at Work (Istituto Nazionale per l'Assicurazione contro gli Infortuni sul Lavoro, INAIL) has recently proposed new criteria for recognizing specific CSD-related melanomas as occupational diseases in this worker population.

This study aims to apply these novel criteria in a clinical setting to investigate the association between occupational UVR exposure and CSD-related melanoma subtypes.

Study Objectives:

• The primary objective is to evaluate the association between occupational solar UVR exposure and the risk of developing melanoma, with a specific focus on subtypes related to cumulative solar damage (CSD).

Secondary objectives include:

• Comparing occupational and recreational UVR exposure patterns between melanoma cases and controls.
• Correlating melanoma subtypes (CSD-related vs. non-CSD-related) and their body location with specific UVR exposure histories.
• Applying the recent INAIL criteria to identify cases of melanoma that qualify for reporting as occupational diseases.
• Quantitatively estimating individual occupational UVR exposure levels by applying a validated European job-exposure matrix (JEM) developed by Würtz et al. in 2025.
• Calculating and comparing an individualised melanoma risk score for each participant, based on established non-occupational risk factors, according to the model developed and externally validated by Fortes et al. in 2010.
• Analysing the relationship between quantitative occupational UVR exposure and the individualised melanoma risk score.

Study Population and Recruitment:

The study population will consist of patients referred to the Dermatology Clinic for examination of suspicious skin lesions. All enrolled participants will provide written informed consent.

Cases: Approximately 120 adult patients (≥18 years) with a new, histopathologically confirmed diagnosis of cutaneous melanoma.

Controls: Approximately 180 adult patients (≥18 years) who undergo a dermatological screening for a suspicious lesion, but for whom the result of the screening is negative for melanoma. These controls will be matched to cases based on similar age and gender to minimize confounding.

Methods:

Data Collection: After enrolment, all participants (cases and controls) will undergo a single, structured interview conducted by trained healthcare personnel (e.g., resident physicians). The interview will use a detailed questionnaire designed specifically for this study based on a comprehensive literature review.

Questionnaire Content: The questionnaire will collect data on:

• Socio-demographics and general information: Age, gender, country of birth, smoking habits, physical characteristics linked to determine phototype, ease of sunburn, residential history.
• Dermatological anamnesis: Skin melanoma diagnosis, type of melanoma, location, past diagnosis of skin melanoma(ta) and location, past diagnosis of non-melanoma(ta) skin cancers, family history of melanoma and other skin cancers, presence and number of lentigines in sun-exposed and non-sun-exposed areas, presence and number of nevi on the arms and on the rest of the body; history of prolonged treatments with immunosuppressors; use of tanning beds.
• Occupational History: A detailed, chronological work history. For every job (classified according to the international ISCO-88 classification), the specific job duties, the general company activities, and the country and region (for latitude-based UV index assessment) will be required. If possible, specific dates of job start and job end will be collected, as well as the frequency of use of UVR protective measures (clothing, hat, or sun creams).
• Extra-work solar exposure: The study will investigate the habits of staying outside, frequency of sunburn, going to the sea or to high mountains, and the use of sun protection creams, hats, or UV protective clothing. Data will be separated for holiday time versus free/leisure time, and further divided for the age periods 0-20 and ≥21 years.

Data Management and Analysis:

• Data Handling: All collected data will be anonymized and stored in a secure electronic database (RedCap).
• Exposure Assessment: An expert assessment, guided by a Job Exposure Matrix developed from the EU-funded EPHOR project, will be used to categorize participants' cumulative occupational UVR exposure.
• Statistical Analysis: Standard descriptive statistics will characterize the study population. The association between UVR exposure (both occupational and recreational) and other risk factors for melanoma will be assessed by calculating Odds Ratios (OR) with 95% confidence intervals using multivariate regression analysis. Subgroup analyses will be performed based on melanoma subtype and tumour location. Statistical software such as STATA or SPSS will be used.

Quality Assurance:

The study protocol, including the questionnaire and data management plan, will be standardized. Interviewers will receive specific training to ensure consistent data collection. Data entry will include range and consistency checks to ensure quality.

Ethical Considerations:

The study will be conducted after approval from the relevant Ethical Committee of the University Hospital of Modena. Participation is voluntary, and participants may withdraw at any time without affecting their medical care. For outdoor workers diagnosed with a CSD-related melanoma located on sun-exposed skin, the study procedure includes assistance in reporting the disease to INAIL as a potential occupational illness, as per current Italian recommendations.