Metastatic melanoma is an advanced stage of skin cancer where tumor cells spread from their original location to other parts of the body. This occurs when melanoma, which primarily affects melanin-producing cells (melanocytes) in the skin, mucous membranes, and eyes, progresses. This spread categorizes the cancer as stage 4 or metastatic melanoma.
How Melanoma Spreads
Melanoma cells can detach from the primary tumor and travel through the body’s circulatory systems, typically entering either the lymphatic system or the bloodstream. The lymphatic system, with its tiny vessels, often leads melanoma cells to nearby lymph nodes. Once there, cells may gain protection from oxidative stress, allowing survival and spread.
From lymph nodes, or directly from the primary tumor, cells can enter the bloodstream. The bloodstream then provides a pathway to distant organs and tissues, forming new tumors. Common sites for these metastases include distant skin, lymph nodes, lungs, liver, bones, and the brain.
Signs of Advanced Melanoma
When melanoma spreads beyond the skin, it can cause a range of symptoms depending on the affected body system. General signs might include persistent fatigue, unexplained weight loss, or a feeling of being unwell. The appearance of new, firm lumps or nodules under the skin, sometimes far from the original melanoma, can also indicate spread.
If melanoma has spread to the lymph nodes, these may become hard, swollen, or painful, particularly in areas like the neck, armpit, or groin. Lung metastasis can manifest as a persistent cough, shortness of breath, or chronic chest pain, sometimes accompanied by bloody sputum. Liver involvement might lead to discomfort or pain in the upper right abdomen, nausea, poor appetite, a swollen abdomen (ascites), or jaundice, which is a yellowing of the skin and eyes.
Spread to the brain can result in headaches, seizures, memory problems, or changes in mood, personality, and even weakness or numbness in an arm or leg. Bone metastasis often causes continuous, gnawing bone pain, particularly backache that worsens with rest. This can also lead to weaker bones that are more prone to fractures, or elevated blood calcium levels causing confusion, sickness, and abdominal pain.
Confirming the Diagnosis
Confirming metastatic melanoma involves diagnostic procedures to identify cancer spread. Initially, a biopsy of the suspected cancerous skin lesion is performed; a small tissue sample is removed for microscopic examination. This helps determine if melanoma is present and its thickness, indicating spread risk.
Various imaging tests assess for metastasis. CT scans use X-rays for detailed images of internal organs and soft tissues, revealing enlarged lymph nodes or suspicious spots. MRI uses magnets and radio waves for detailed pictures, especially for brain tumors. PET scans involve injecting a radioactive substance absorbed by rapidly growing cancer cells, making them “light up.” Ultrasound may also visualize lymph nodes and guide biopsies.
Blood tests provide supplementary information, though not for initial diagnosis. Doctors may check levels of lactate dehydrogenase (LDH), an enzyme whose elevated levels can indicate more advanced melanoma and a less favorable prognosis. Molecular testing of biopsy or blood samples can identify specific gene mutations, like in the BRAF gene, influencing treatment choices.
Treatment Options
Treating metastatic melanoma often involves a combination of systemic therapies, the primary approach for widespread disease, alongside local treatments for specific tumor sites. Immunotherapy works by stimulating the body’s own immune system to recognize and attack cancer cells. This includes checkpoint inhibitors (e.g., pembrolizumab, nivolumab, ipilimumab) that block proteins preventing immune cells from attacking cancer.
Targeted therapy focuses on specific molecules within cancer cells that drive their growth and survival. About half of melanomas have a BRAF gene mutation. BRAF inhibitors (e.g., dabrafenib, vemurafenib) and MEK inhibitors (e.g., trametinib, cobimetinib) are often used in combination to block signaling pathways driving cancer cell proliferation. These therapies are specific and offer different mechanisms of action than immunotherapy.
Chemotherapy uses drugs to kill or slow cancer cell growth, though less common now due to newer immunotherapies and targeted therapies. It may still be considered when other treatments are ineffective or for localized regional treatments like isolated limb infusion or perfusion.
Local treatments manage specific tumors or symptoms. Surgery may remove isolated metastases, especially if small or confined to a single area like the brain or lung. Radiation therapy uses high-energy rays to destroy cancer cells, often for symptom control (e.g., brain metastases, painful bone lesions). Treatment selection is individualized, considering mutation status, metastasis extent and location, and prior therapies.
Outlook and Living with Metastatic Melanoma
The outlook for metastatic melanoma has improved with treatment advancements, though it still varies widely. Prognosis factors include cancer spread extent, specific organ involvement, and treatment response. While historical survival rates were low, modern therapies have improved outcomes for many patients.
Ongoing management and follow-up care are important for living with the disease. This involves regular monitoring via imaging and blood work to track disease and assess treatment effectiveness. Supportive care manages symptoms and improves quality of life. This includes pain management, nutritional support, and psychological support for emotional and mental health challenges.