Plantar melanoma: a case-control study in Paraguay

Area of Science:

• Dermatology
• Epidemiology
• Oncology

Background:

• Plantar melanoma, a rare but aggressive skin cancer, most commonly affects the sole of the foot.
• In Paraguay, like other global populations, the plantar surface is a primary site for malignant melanoma.
• Previous research on risk factors for plantar melanoma is limited, particularly in South American populations.

Purpose of the Study:

• To investigate risk factors associated with plantar melanoma in Paraguay.
• To conduct the first case-control study on plantar melanoma in this region.
• To identify potential environmental, lifestyle, and constitutional factors influencing plantar melanoma development.

Main Methods:

• A case-control study involving 60 incident plantar melanoma cases and 256 hospital controls was conducted in Paraguay (1988-1993).
• Data collected included demographics, lifestyle, foot exposures (footwear, activities, injuries), and constitutional factors (skin type, nevi).
• Statistical analysis adjusted for potential confounders to determine odds ratios (OR) and confidence intervals (CI).

Main Results:

• Reported foot injuries showed a strong association with plantar melanoma risk (OR = 40.9, CI = 14.8-112.7).
• The presence of nevi (moles) on the soles was also significantly linked to increased risk (OR = 5.9, CI = 2.5-14.3).
• An outdoor workplace was associated with increased melanoma occurrence (OR = 2.3, CI = 1.1-4.8), whereas barefoot walking did not appear to be a risk factor.

Conclusions:

• Foot injuries and the presence of nevi on the soles are significant risk factors for plantar melanoma in Paraguay.
• Occupational exposure to outdoor environments may contribute to plantar melanoma risk.
• Future research should address recall bias in injury reporting and implement blinding for sole pigmentation assessment.