Skin Cancer

Carcinomas, which are the most common types of skin cancer, generally have a good prognosis. 

Squamous cell carcinoma: It develops from the keratinocytes of the epidermis. It can occur spontaneously, but is often preceded by a precancerous skin or mucosal lesion that progresses in several stages (actinic keratosis, squamous cell carcinoma in situ, also known as Bowen’s disease). It can present in various forms and affect the oral or genital mucous membranes.

Squamous cell carcinoma has a good prognosis, but its management must be rigorous because it can recur locally or lead to metastases. Metastases occur when cancer cells have spread along lymphatic pathways (to the lymph nodes) or through the bloodstream to other organs. For forms with a poor prognosis and recurrences, treatment requires discussion and a decision made during a multidisciplinary team meeting (MDT).

Basal cell carcinoma (BCC): It develops from keratinocytes in the deep layer of the epidermis. It occurs without a preexisting lesion. There are several clinical forms: nodular BCC, superficial BCC, and sclerodermoid BCC. BCC does not metastasize, but it must be treated rigorously because it can cause significant local damage. Its progression is slow, and treatment can be approached without haste.

Merkel cell neuroendocrine carcinoma (CCM): This is a rare and aggressive cutaneous carcinoma with a high risk of recurrence, and metastatic spread can occur anywhere. Most relapses occur within two years of the primary tumor’s discovery. In 2008, scientists discovered the Merkel cell polyomavirus, a human virus present in approximately 80% of MCC cases. Most people have already been exposed to polyomaviruses (members of a family of double-stranded DNA viruses) by the age of 20. When the Merkel cell polyomavirus infects a cell, it produces proteins that can lead to uncontrolled cell growth, resulting in cancer.

These cancers are rarer but more aggressive because they can spread rapidly throughout the body. They develop from melanocytes. These melanocytes produce melanin and are responsible for our skin color. Melanoma most commonly affects patients around age 50, but it can be diagnosed in younger individuals. However, it is extremely rare before puberty. It primarily appears on the skin, but it can also affect the mucous membranes or the eye (choroid or conjunctiva). 

Histological analysis confirms the diagnosis, determines the thickness of the melanoma (Breslow index), and assesses the degree of skin invasion, thereby helping to determine the appropriate follow-up treatment. Its thickness is directly correlated with the prognosis: the thicker the melanoma, the greater the risk of metastasis.

Acute exposure: Repeated sunburns, especially during childhood, are a major risk factor.

Chronic exposure: Prolonged and cumulative exposure to the sun throughout one’s lifetime also increases the risk.

Artificial UV radiation: Using tanning beds is associated with an increased risk, particularly before age 35. 

Light phototype (I and II): People with fair skin, red or blond hair, and light-colored eyes are at significantly higher risk.

Atypical nevus syndrome: The presence of a large number of irregular-looking "moles" is a factor requiring close monitoring.

Congenital nevi: Present at birth, their risk of becoming malignant increases with size.

Family history: About 10% of melanomas occur in a family context (at least two cases in the family), particularly in connection with mutations in the CDKN2A/p16, CDK4, or MITF genes.

Xeroderma pigmentosum: a rare genetic disorder that impairs the skin’s ability to repair UV-induced damage, resulting in a very high risk.

Immunosuppression: A weakened immune system (organ transplant, HIV, immunosuppressive treatments) reduces the body’s ability to eliminate abnormal cells.

Surgery 

The primary treatment for melanoma is surgery. First, the surgeon removes the tumor along with a safety margin around it. The lesion is then analyzed in a laboratory, in particular to measure its thickness—a key piece of information for determining the next steps in treatment. A second procedure is then performed to ensure that all edges of the excised area are clear of cancer.

In the case of distant metastases 

If there is a single, operable metastasis, surgery may be considered. In this case, it will be followed by additional (adjuvant) treatment with immunotherapy.

In cases of inoperable metastases or multiple metastases, drug therapy must be initiated. First, testing for a genetic mutation in the BRAF gene must be performed. 

If a BRAF mutation is detected, targeted therapy combining two drugs (anti-BRAF and anti-MEK) may be recommended. Immunotherapy may also be recommended. Radiation therapy is primarily recommended for brain and bone metastases. Stereotactic radiation therapy yields good results for certain brain metastases.

The first-line treatment is surgery. The squamous cell carcinoma must be completely removed, along with margins of healthy tissue surrounding the tumor. Reconstruction may therefore be necessary afterward.

Surgery is always the treatment of choice for invasive basal cell carcinomas.

When surgery is not an option, a targeted therapy called vismodegib (an oral medication) has shown good results. Radiation therapy may also be recommended.

Surgical treatment of the primary tumor is always the preferred option, followed by radiation therapy to the surgical site. In advanced or metastatic cases, immunotherapy with an anti-PD-L1 agent (Avelumab) may be recommended. An alternative to this treatment may be chemotherapy with carboplatin and etoposide.

In cases where standard treatment has proven ineffective, and if the patient wishes, they can often be offered the opportunity to participate in a clinical trial if they are eligible. This allows them to receive innovative treatments that are not yet available on the market.