When melanoma affects a loved one, worry for yourself and your children is legitimate. The reality deserves nuance: the vast majority of melanomas aren't hereditary. But a family history changes the level of vigilance, and that's precisely what your check-up seeks to know when it asks about a melanoma in your parents, siblings or children, or about a skin cancer you may already have had.
1. Heredity or shared habits?
Having a first-degree relative (parent, brother, sister, child) who has had a melanoma multiplies the risk by about two. But this figure hides an important subtlety: within a family, you share not only genes, but also a phototype and sun-exposure habits. Part of this excess risk is therefore linked to the environment, and remains, as such, modifiable. In other words, genes may predispose, but the sun remains the main factor you can act on.
2. When do we talk about familial melanoma?
We speak of a familial form when several cases of melanoma occur in the same family. This represents about 10% of all melanomas. Several predisposition genes have been identified, the best known being CDKN2A; others (CDK4, BAP1, MITF, MC1R) play a more modest role. One particular situation is worth knowing: FAMMM syndrome (familial atypical multiple mole melanoma), which combines very many atypical moles with a family history, often with earlier melanoma (around 30-40) and an increased risk of pancreatic cancer.
3. The signals that should suggest a predisposition
Not all family histories are equal. Certain elements raise the likelihood of a genuine hereditary predisposition:
| Family situation | What it suggests |
|---|---|
| A 1st-degree relative (parent, sibling, child) who has had a melanoma | Risk about doubled: regular dermatological monitoring and reinforced sun protection. |
| Several relatives affected, or a melanoma before 40 | Suggests a possible predisposition: a specialist opinion is advised. |
| Several melanomas in the same person | A strong marker: genetic counselling deserves discussion. |
| Melanoma + pancreatic cancer in the family | Points to a hereditary syndrome (CDKN2A gene): genetic counselling recommended. |
4. Genetic counselling: for whom, why?
In France, an expert consensus frames the search for a predisposition. A genetic analysis may be offered, for example, when at least two proven invasive cutaneous melanomas have been diagnosed before 75 in two relatives (first or second degree) or in the same person, or in case of association with pancreatic, eye, kidney or other specific cancers. This process is always done with a geneticist. One essential point: a test doesn't change the treatment, but it guides the monitoring of the person and their family. And a negative result doesn't cancel the sun-related risk, which remains to be taken into account.
5. What a family history changes day to day
Good news: a well-identified family risk is managed very well. Concretely, this means:
- ●Earlier, closer dermatological monitoring, sometimes with photographic mapping of moles.
- ●Strict sun protection from childhood, all the more important since genetic risk and habits are passed on together.
- ●Regular self-examination, ideally monthly, to spot any new or changing lesion.
- ●Informing relatives, since prevention benefits the whole family.
Far from being a fate, a family history is above all an invitation to vigilance. Your health check-up is the occasion to discuss it, assess your situation and, if necessary, organise suitable follow-up.
Further reading
Related articles on the Iris Prévention blog:
- ●Counting your moles: why your forearm says a lot about your risk
- ●Skin self-examination: the complete method in 10 minutes
- ●Skin cancer: understanding, spotting and preventing the most common cancer
- ●The sun capital: this invisible counter that never recharges
💡 Key tips
- Having a parent, sibling or child who has had a melanoma roughly doubles your risk. But this figure also reflects the phototype and sun habits shared within the family: part of the risk therefore remains modifiable.
- Only about 10% of melanomas are "familial." The vast majority are sporadic and linked mainly to the sun. A family history is a signal for vigilance, not a fate.
- Certain elements point to a hereditary predisposition: several relatives affected, a melanoma before 40, several melanomas in the same person, or the melanoma + pancreatic cancer association in the family.
- FAMMM syndrome combines very many atypical moles (often more than 50) and a family history. Its best-known gene, CDKN2A, strongly raises melanoma risk, and pancreatic-cancer risk too.
- A genetic test is only prescribed in specific situations, with a geneticist. It doesn't change treatment but guides monitoring, and a negative result doesn't erase the sun-related risk, which still needs protecting.
Sources and references
- ●French Society of Dermatology, Recommendations for diagnosing genetic predisposition to cutaneous melanoma and managing at-risk people
- ●French National Cancer Institute (INCa), Skin melanoma: risk factors and familial forms
- ●Scientific reviews, Genetic Landscape of Familial Melanoma (CDKN2A, CDK4, BAP1, MC1R)
- ●StatPearls, Familial Atypical Multiple Mole and Melanoma Syndrome (FAMMM)
