Brown spots observed on the skin are generally totally benign and perfectly safe. However, you should remain vigilant and report any suspicious marks to your doctor, because some brown spots can be a sign of cancer.
Summary
There are two main types of skin cancer: carcinoma and melanoma. Melanomas are the most serious skin cancers because they have a strong tendency to migrate to other organs as metastases.
Regardless of the type of skin cancer, it usually starts with a pigmented mark of varying intensity, hence the confusion between brown spots and cancer.
Given the risk of skin cancer, it is essential that you consult a health professional who will tell you what to do in case of brown spots and refer you to a dermatologist if necessary.
Most age spots do not degenerate into cancer. However, some sun spots can become thicker over time and lead to the formation of actinic keratoses, which are precancerous lesions that can develop into skin carcinoma. Skin carcinoma is a cancer that develops from keratinocytes in the epidermis. They account for about 90% of skin cancers(1). Although these cancers have a near-zero metastatic potential, they can have local, locoregional, aesthetic and psychological consequences that are sometimes significant, with a risk of recurrence in some cases.
A brown spot may be a sign of melanoma when it meets at least two of the following criteria:
It is essential that you report the presence of such a lesion, which may also be combined with other symptoms such as fatigue, weight loss or pain.
The sun is the main risk factor for both brown spots and skin cancer. To avoid skin cancer, you must therefore use effective sun protection from an early age.
(1)National Cancer Institute: https://www.e-cancer.fr/Professionnels-de-sante/Depistage-et-detection-precoce/Detection-precoce-des-cancers-de-la-peau/Epidemiologie
