Skin cancer kills by spreading from the skin to vital organs, where growing tumors disrupt normal function until organs fail. Melanoma is responsible for the vast majority of skin cancer deaths, even though it accounts for only a small fraction of skin cancer diagnoses. The 5-year survival rate for melanoma that has spread to distant organs is 35%, based on data from people diagnosed between 2015 and 2021. Understanding how this progression happens, and what it actually looks like, can help make sense of a diagnosis that starts on the surface of the body but becomes a systemic threat.
How Melanoma Spreads From the Skin
Melanoma begins in the pigment-producing cells of the skin. In its earliest stages, it’s highly treatable because the cancer cells are confined to a thin layer of tissue that can be surgically removed. The danger comes when those cells break through deeper layers and enter the body’s drainage and circulation systems.
Research from UT Southwestern has revealed that melanoma cells typically travel first through the lymphatic system, the network of vessels and nodes that filters fluid throughout your body. This stopover turns out to be critical. Melanoma cells that pass through lymph nodes absorb high levels of a fatty acid called oleic acid, which gets built into their outer membranes. This makes them far more resistant to a type of cell death that would normally kill them once they enter the bloodstream. In the words of the lead researcher, the cells “load up on oleic acid in the lymph, and then once they go into the blood, they’re bulletproof.” Cells that enter the bloodstream directly are more vulnerable to oxidative stress, which damages their membranes and destroys them. But cells that first pass through lymph nodes survive the journey and are more likely to establish new tumors in distant organs.
Which Organs Fail and Why
Once melanoma cells reach the bloodstream, they can seed tumors almost anywhere. The most common and dangerous destinations are the brain, lungs, and liver. Each organ fails in a different way, and patients often have cancer in multiple organs at once.
Brain
Melanoma has a strong tendency to spread to the brain. Tumors growing inside the skull create pressure on surrounding brain tissue because the rigid bone leaves no room for expansion. This pressure causes headaches, confusion, personality changes, seizures, vision problems, weakness, and trouble with balance or speech. In some cases, cancer cells spread along the thin membranes and fluid surrounding the brain and spinal cord rather than forming a single mass. This pattern affects multiple areas of the nervous system simultaneously and is particularly difficult to treat. Brain metastases are one of the most common direct causes of death in advanced melanoma.
Lungs
Tumors in the lungs progressively replace healthy tissue and block airways, making it harder and harder to get enough oxygen. Fluid can build up around the lungs as well, compressing them further. Shortness of breath worsens over weeks or months, and persistent coughing adds to discomfort and exhaustion.
Liver
The liver filters blood and produces essential proteins. When tumors overtake enough liver tissue, the organ can no longer clear toxins or maintain the blood’s chemical balance. This leads to a buildup of waste products, jaundice, fluid accumulation in the abdomen, and eventually organ shutdown.
Non-Melanoma Skin Cancers Rarely Kill
Basal cell carcinoma and squamous cell carcinoma are far more common than melanoma, but they account for less than 0.1% of all cancer deaths. Basal cell carcinoma almost never spreads beyond the skin. Squamous cell carcinoma is more biologically aggressive and can metastasize or invade deep local structures if neglected for a long time, but this outcome is uncommon. When squamous cell carcinoma does cause death, it typically happens through local extension into critical structures in the head and neck, or, more rarely, through distant spread similar to melanoma’s pattern.
Indirect Causes of Death
Not every skin cancer death results from a tumor directly destroying an organ. Cancer can kill through several indirect pathways.
Advanced cancer suppresses the immune system, leaving patients vulnerable to infections that a healthy body would fight off. Viral infections that were dormant, like the virus that causes shingles, can reactivate. Bacterial infections can progress to sepsis, a life-threatening whole-body inflammatory response.
Some cancers release hormones or hormone-like substances that throw off the body’s chemistry. One of the more common examples is a protein that raises calcium levels in the blood, which causes dehydration, muscle weakness, confusion, and heart rhythm problems. Cancer can also trigger the release of inflammatory molecules that drive fever, severe weight loss, and muscle wasting, a combination called cachexia that progressively weakens the body’s ability to function.
What the Final Days Look Like
In the last days and weeks of life, a constellation of symptoms reflects the body’s systems shutting down. Fatigue deepens day by day, and most people spend increasing amounts of time sleeping or in a state of reduced consciousness. Shortness of breath is common and often worsens. Pain may require medications given by injection when swallowing becomes difficult. Delirium, where a person becomes confused, withdrawn, or occasionally agitated and experiences hallucinations, is one of the most common end-of-life symptoms.
Physical signs of the body’s decline include irregular breathing with periods of very shallow breaths or brief pauses, a drop in blood pressure, cold or bluish hands and feet, and reduced urine output. A rattling sound with each breath, caused by fluid collecting in the throat and airways when a person is too weak to clear them, is often a sign that death will come within hours or days. Sudden muscle twitches or jerks that a person cannot control may occur. Heavy bleeding is rare but can happen in the final hours.
How Treatments Have Changed Survival
The outlook for advanced melanoma shifted dramatically starting around 2011, when two new classes of drugs became available. One targets a specific genetic mutation found in about half of melanomas, blocking the signals that tell cancer cells to grow. The other, immunotherapy, removes molecular “brakes” that cancer puts on the immune system, allowing the body’s own defenses to attack tumors. Between 2013 and 2016, the death rate from melanoma dropped by about 18% overall, a decline largely attributed to these treatments.
These therapies are not without serious risks. In one study of melanoma patients treated with immunotherapy, about 5% of deaths were caused not by the cancer itself but by immune-related side effects of the treatment. The most common fatal complications were damage to the heart and lungs, followed by liver damage and multi-organ failure. Most of these deaths occurred after just the first dose of treatment. Heart-related toxicity carried the highest risk of death. Still, for the majority of patients with advanced melanoma, the survival benefit of these treatments far outweighs the risks.