38. Occupational neoplasms - etiology, pathogenesis, clinical manifestations, diagnosis, differential diagnosis, criteria for occupational diagnosis, treatment, medical expertise.

Introduction

This topic covers occupational neoplasms: malignant tumours caused or promoted by agents encountered at work. It explains which carcinogens are responsible, how they damage cells, how the tumours present, how they are diagnosed and separated from non-occupational cancers, how treatment is organised, and how the link to work is established for medical expertise.

Definition and general concepts

An occupational neoplasm is a malignant tumour in which exposure to a workplace carcinogen is the main or a significant cause. Cancer makes up a large share of occupational disease in many countries, and the tumours are usually indistinguishable under the microscope from those with other causes. The occupational origin is therefore inferred from the exposure history, the tumour's site and type, and the epidemiological pattern.

Etiology: occupational carcinogens

The best-established occupational carcinogens are classified as Group 1 (carcinogenic to humans) by the International Agency for Research on Cancer. The main groups and their typical tumours are shown below.

Several conditions are regarded as precancerous in the occupational setting and should be recognised early:

• Chronic posttraumatic or postcombustion scars, which may undergo malignant change (Marjolin ulcer is the classic example).
• Comedones, folliculitis and oil acne caused by oil mist in machinists, which may progress to skin cancer on exposed areas.
• Actinic keratoses and chronic radiodermatitis from UV or X-ray exposure.