Skin carcinomas are the most frequent types of skin cancer, and are easily curable. Skin melanoma, on the other hand, is rarer and much more aggressive.
What are skin cancers?
The term ‘skin cancer’ covers two distinct types of skin tumor:
- Basal or spindle-cell carcinomas (also called epithelial cancer), which affects the epithelial cells that produce keratin. Basal cell forms of cancer are by far the most frequent, representing some 70% of cases for nearly 100,000 diagnosed cases each year in France. These tumors have a favorable prognosis. Treatment generally consists of surgical ablation. If the tumor is not fully removed, there is a risk of local recurrence. However, these tumors do not metastasize.
- Melanoma, which affects the cells that produce melanin. In 2015, estimates show that more than 14,000 cases of skin melanoma were diagnosed in France (source: INCa).
Skin cancers affect both men and women and have become increasingly common since 1980. This increase is undoubtedly due to the sun-exposure fad: exposure to UV radiation is a proven risk factor in the occurrence of skin cancer.
While carcinomas appear to result mainly from prolonged sun exposure, heavy doses of sun (as in sunburn), especially in childhood, promote the development of melanomas.
The incidence seems to have decreased slightly in recent years, certainly thanks to large-scale efforts to encourage prevention and more and more frequent use of sun protection, both physical (hats, t-shirts, etc.) and chemical (sunscreen).
Early detection is one of the most important factors in treating skin melanoma. Each year, the French dermatologists’ union organizes an awareness day. The earlier treatment begins, the better the chance of a cure.
There are signs to watch for, and everyone can monitor their own skin. Melanoma generally takes the form of a flat, pigmented (black or brown) spot. In 15% to 20% of cases, it appears in an existing mole whose appearance changes. Consult a dermatologist about any mole or black spot on the skin that changes. Only after this initial consultation, if a risk does exist, the physician may direct you to Institut Curie.
Treatment of skin cancers at Institut Curie
At Institut Curie, most treatment is provided to patients with skin melanoma, in close collaboration with the Dermatology and Venereology department of Groupe Hospitalier Cochin (AP-HP, Pavilion Tarnier).
Depending on the type of melanoma and how far it has spread, care may include surgery, drug treatments (chemotherapy, targeted therapies, immunotherapy), or radiotherapy, singly orbi in comnation. Decisions about treatment are made during cross-disciplinary meetings.
If the cancer has not spread, surgery is the standard treatment for skin melanomas: surgical exeresis remains the most effective treatment for skin melanoma.
Along with tumor ablation, one or more lymph nodes are often removed as well. Analyzing these can assess whether there has been any invasion by the tumor or to check the spread if it has occurred.
As a forerunner in the sentinel lymph-node technique for breast cancer, Institut Curie has been using it for years to determine the risk of tissue invasion and metastasis among patients with a skin melanoma thicker than 1 mm. The technique consists of identifying the first link in the regional lymph node chain and searching it for the presence of any tumor cells. The procedure can identify a characteristic lymph node in the chain with limited and acceptable post-operative discomfort.
When the sentinel lymph node is unharmed, the prognosis is favorable, and regular clinical monitoring with no other treatment is implemented.
If, on the other hand, the analysis of the sentinel lymph node shows the presence of cancer cells, the entire lymph node chain is removed. Adjuvant treatment may then be recommended. In recent years, drug treatments for melanomas have greatly evolved, with developments including targeted therapies and, even more recently, immunotherapy. The aim of these treatments is to check the tumor’s progression.
In recent years, treatment for advanced forms of skin melanoma has greatly benefitted from the development of immunotherapies. The existence of the Cancer Immunotherapy center will accelerate the availability of immunotherapy to patients even further.
Translational and basic research on skin cancers
Multiple research teams are working to better understand skin melanoma. Stephan Vargner’s work focuses on the mechanisms behind resistance to targeted therapies. Half of patients with melanoma present a mutation in a protein called BRAF. Drugs that target this mutated protein, vemurafenib (Zelboraf®) and dabrafenib (Tafinlar), can significantly slow the evolution of this type of skin cancer. Unfortunately, these anti-BRAF drugs lose their effectiveness over time. Vargner’s team is studying ways to overcome this resistance.
Lionel Larue’s team is studying melanocytes, the cells responsible for skin pigmentation from which melanoma develops.
Temporary, uncontrolled melanocyte growth results in the formation of moles, within which the melanocytes rest and remain harmless. The Normal and Pathological Development of Melanocytes team has identified the gene that makes benign forms of melanoma more likely to become malignant. It is also studying the potential for a characteristic molecular signature for often highly invasive forms of skin cancer.
THE basic and translational research conducted within the Cancer Immunotherapy center will also benefit treatments for skin melanoma, one of the developmental models for the latest immunotherapies.