Basal cell carcinoma is primarily associated with which type of UV light exposure?

• A. UV-A
• B. UV-C
• C. UV-B
• D. UV-D

Answer: (C)

Basal cell carcinoma arises from DNA damage in epidermal cells caused by UV light, and the most causative component is UV-B. UV-B has shorter wavelengths and higher energy, which directly creates DNA lesions such as thymine dimers. If these lesions are misrepaired, mutations accumulate in growth-control genes (like p53 and hedgehog pathway genes such as PTCH1) that drive basal cell development. UV-C is largely blocked by the atmosphere and is not a major factor for skin cancer, while UV-A penetrates deeper and contributes more to photoaging and other skin changes; it’s UV-B that is most strongly linked to BCC. UV-D isn’t a standard category in this context.