Are all skin cancers, except malignant melanoma, caused by Ultraviolet A (UVA) exposure, while malignant melanoma is more related to Ultraviolet B (UVB) exposure?

The Statement is Incorrect: Both UVA and UVB Cause All Major Skin Cancers

The premise of this question is fundamentally wrong—both UVA and UVB radiation are linked to the development of all three major forms of skin cancer, including melanoma, basal cell carcinoma, and squamous cell carcinoma. 1

UV Radiation Affects All Skin Cancers

The CDC guidelines explicitly state that "the two most important types of UV radiation, UV-A and UV-B radiation, have both been linked to the development of skin cancer" and that "persons with high levels of exposure to UV radiation are at an increased risk for all three major forms of skin cancer." 1

Key Facts About UV Radiation Types:

UVA Radiation: 1

• Not absorbed by the ozone layer
• Penetrates deeply into the skin
• Causes premature aging and immune system suppression
• Contributes to all skin cancer types

UVB Radiation: 1

• Partially absorbed by the ozone layer
• Causes tanning and burning
• Linked to cataracts and skin cancer development
• Contributes to all skin cancer types

Melanoma and UV Exposure

Approximately 65-90% of melanomas are caused by UV exposure, with both UVA and UVB playing roles. 1, 2, 3 The pattern of exposure matters more than the specific wavelength:

• Intermittent intense exposures (severe, blistering sunburns) carry higher melanoma risk 1
• Childhood and adolescent sunburns double melanoma risk 2
• The relationship involves both UVA and UVB damage to DNA 1, 4

Non-Melanoma Skin Cancers

Basal Cell Carcinoma (BCC): 1

• Associated with both UVA and UVB radiation
• Risk increased by intermittent intense exposures (similar to melanoma)
• Develops primarily on sun-exposed sites

Squamous Cell Carcinoma (SCC): 1

• Strongly associated with chronic cumulative UV exposure (not intermittent)
• This is the key distinction—SCC follows a different exposure pattern than melanoma and BCC
• Both UVA and UVB contribute to its development

Clinical Bottom Line

The critical distinction is not which UV wavelength causes which cancer, but rather the pattern of exposure:

• Intermittent intense exposure → Higher risk for melanoma and BCC 1
• Chronic cumulative exposure → Higher risk for SCC 1

All recommended skin cancer prevention measures protect against both UVA and UVB radiation because both wavelengths contribute to all major skin cancer types. 1