Melanoma from an orange?
Yes, it is one of the factors.

Analyzed data from over 100,000 healthcare workers followed for 24–26 years, and assessed the association between citrus consumption and risk of cutaneous melanoma.

What they found
• People who ate/drank citrus less than 2 times per week were taken as the "norm" (risk = 1.00).
• At a frequency of ≥1.6 times per day, the risk of melanoma was 36% higher (HR 1.36; 95% CI 1.14–1.63; p<0.001) after adjusting for other factors (age, skin type, sunburns, UV exposure, smoking, etc.).
• Among individual products, the most pronounced association was with grapefruit: consumption ≥3 times per week was associated with a 41% higher risk of melanoma compared to non-consumers (HR 1.41; 95% CI 1.10–1.82).
Interestingly, the association was stronger for melanomas on sites with continuous sun exposure (head, neck, arms, and legs).

Why might this be?
Citrus fruits are rich in psoralens and furocoumarins — photosensitizing substances that, under UV radiation, can damage DNA and increase the risk of skin cancer (mechanism known from PUVA therapy and old "tanning" lotions with psoralen).
Citrus fruits (as well as celery, parsley, carrots) also lead to an increased likelihood of burns after laser procedures through a similar mechanism.

Important to understand
• Melanoma is a multifactorial disease with no single cause; it results from many factors.
• Blonde or red hair color increases risk by 2 times.
• Having more than 11 moles on one right arm (shoulder and forearm) increases risk by 5 times.
• Carriers of a pathogenic variant of the BRCA2 gene have a 2.5-fold increased risk.

Practical takeaway
If you eat a lot of citrus (especially grapefruit) and are often in the sun:
• enhance photoprotection (clothing is better than cosmetics, avoid direct sun from 12 to 4 PM, monitor UV index, apply SPF if simple methods are not enough);
• monitor your skin (new "moles" of irregular shape or atypical color) and regularly see a dermatologist;
• do not give up fruits: citrus has many proven benefits.

@drakarasev