The rapper Salmo showed a scar on his temple on social media. He said he had a basal cell carcinoma removed and linked the diagnosis to sunscreen: «I, like many others, used sunscreen and the result is skin cancer». The tumour and its recurrence remain information he himself reported: there are no public medical records or clinical data that would allow anyone to reconstruct the cause.
A diagnosis can say which tumour was found. It cannot automatically establish which exposure caused it. For skin cancers what matters is the ultraviolet radiation accumulated over the years, skin type, sunburns, age, tanning beds, genetic predisposition and immune system conditions. UV radiation is a recognised cause of melanoma, squamous cell carcinoma and basal cell carcinoma: it damages DNA and can promote tumour development partly by weakening the skin's immune defences.
The controversy, however, rests on a real piece of data. A 2023 study on the UK Biobank analysed 472,672 people and found more skin cancer diagnoses among those who reported using sun protection more often. But here there is already a first distortion: the questionnaire did not ask only about cream. It asked whether the person used protection — for example «sun lotion, a hat» — when spending time outdoors in summer.
More importantly, the study was not an experiment on sunscreens. It analysed the interaction between genetic variants, individual characteristics and behaviours. People who protect themselves more are not chosen at random: they more often have fair skin, burn easily, spend a lot of time outdoors, have already had lesions or are aware of their own risk. They protect themselves more precisely because they are more likely to get sick.
It is the same mistake one would make by observing that people who take painkillers feel more pain and concluding that painkillers cause it. What's more, we don't always know what happened first: someone may have started using more protection after a sunburn, a dermatology appointment or a diagnosis. The authors themselves point to greater UV exposure, insufficient application and protection started after diagnosis as possible explanations for the result.
To get closer to a causal answer you need to compare similar groups. In the Australian Nambour trial, 1,621 adults were randomly assigned either to daily use of a broad-spectrum SPF 15+ cream on the head, neck, hands and forearms, or to use according to their own habits. After four and a half years, daily use had reduced squamous cell carcinomas. For basal cell carcinoma, neither a benefit nor a statistically significant harm emerged.
In the follow-up through 2006, 11 melanomas were diagnosed in the daily-cream group and 22 in the other. Invasive melanomas were 3 against 11. This is a signal in favour of protection, but it should be read with caution: cases were few and the reduction in all melanomas stopped just beyond the conventional threshold of statistical significance. The best available randomised evidence does not, in any case, show an increase in tumours caused by sunscreen.
The safety of individual filters is another matter. In 2020 an FDA study showed that six active ingredients could be measured in the blood after very heavy application on 75 per cent of the body. This means they are absorbed and that adequate data are needed to assess them. It does not mean they cause cancer: the authors themselves specified that the results did not indicate people should stop using protection. In Europe, filters are assessed one by one, with concentration limits.
The question in the headline can therefore be answered like this: in some studies, people who use more protection have more tumours because they are often fairer-skinned, more exposed or already more aware of their own risk. The data describes the people who turn to protection; it does not show that protection is what makes them sick.
Sunscreen is not a shield. It does not cancel out the UV received over the years, does not protect where it isn't applied and should not be used as a reason to stay in the sun longer. Prevention starts with shade, clothing and reducing exposure. Sunscreen protects the skin that remains uncovered.
