Skin cancer affects the body in stages, starting with local tissue damage at the tumor site and potentially progressing to widespread organ disruption if the cancer spreads. The extent depends heavily on the type: basal cell carcinoma rarely travels beyond the skin, squamous cell carcinoma occasionally spreads, and melanoma is the most likely to metastasize to distant organs like the lungs, liver, bones, and brain. When caught early, localized melanoma has a five-year survival rate above 99%. Once it reaches distant organs, that drops to 35%.
Local Tissue Destruction
All three major types of skin cancer begin by damaging the tissue immediately around the tumor. Basal cell carcinoma, the most common form, invades the deeper layers of skin but seldom travels to other parts of the body. That doesn’t make it harmless. Left untreated, it can grow into surrounding structures, destroying cartilage, bone, and soft tissue, particularly on the face and head. Neglected tumors can cause significant disfigurement, eating into the nose, ears, or eye sockets over months or years.
Squamous cell carcinoma behaves similarly at first, growing outward and downward through the skin. As these tumors enlarge, they often ulcerate, creating open sores that bleed, crust over, and become vulnerable to bacterial infection. Chronic ulceration is one of the most common complications of untreated skin cancer, and in severe cases, secondary infections can become serious health threats on their own.
Nerve Invasion and Neurological Symptoms
One of the less well-known effects of skin cancer is its ability to invade nerves. This happens in roughly 2.5% to 14% of squamous cell carcinomas and up to 10% of basal cell carcinomas, most often on the head and face. When a tumor grows into the space surrounding a nerve, it can travel along that nerve pathway away from the original tumor site.
The first symptom is usually an abnormal skin sensation: tingling, numbness, or a strange crawling feeling, sometimes described as ants moving across the skin. This typically follows the path of a facial nerve branch. Over months, the sensation can spread as the cancer reaches deeper nerve structures. If motor nerves are involved, the result can be progressive facial paralysis, starting with weakness in one area of the face before eventually affecting the entire side. Pain and numbness around a skin cancer lesion can be an early warning sign that the cancer is spreading into surrounding nerves.
How Melanoma Spreads to Other Organs
Melanoma is the type of skin cancer most capable of affecting the entire body. It spreads through two main routes: the lymphatic system and the bloodstream. Melanoma cells typically reach nearby lymph nodes first, which is why swollen or painful lymph nodes in the armpit or groin are often the first sign of advancing disease. From there, cells can enter the bloodstream and travel to distant organs.
Research from the National Cancer Institute has revealed why the lymph node stopover matters. Melanoma cells traveling through the blood are normally vulnerable to oxidative stress, which damages their outer membranes and kills them. But cells that pass through lymph nodes first absorb high levels of oleic acid, a fatty acid found in lymph fluid. This oleic acid gets incorporated into their cell membranes, essentially shielding them from the oxidative damage that would otherwise destroy them. As one researcher described it, the melanoma cells “load up on oleic acid in the lymph, and then once they go into the blood, they’re bulletproof.” This helps explain why melanoma that has reached the lymph nodes is so much more dangerous than melanoma that hasn’t.
The most common sites where melanoma eventually settles are the lungs, liver, bones, brain, and skin in other parts of the body.
Effects on the Lungs and Liver
When melanoma spreads to the lungs, it can cause persistent cough, shortness of breath, and chest pain. These symptoms often develop gradually and may initially be mistaken for respiratory infections or other lung conditions. Liver metastases can cause abdominal pain, nausea, jaundice (yellowing of the skin and eyes), and a general feeling of being unwell. Both organs can lose function as tumors grow and displace healthy tissue.
Effects on Bones
Cancer that reaches the bones weakens them structurally, causing pain that often worsens at night or with activity. Affected bones can fracture from minor impacts or even normal movement. Beyond the mechanical damage, bone metastasis disrupts calcium regulation. As cancer cells break down bone tissue, excess calcium floods the bloodstream, a condition called hypercalcemia. This triggers nausea, vomiting, constipation, confusion, and severe dehydration.
Bone metastasis also interferes with the production of blood cells, which are made inside bone marrow. Cancer cells can crowd out the marrow, leading to anemia (low red blood cells causing fatigue and weakness), increased susceptibility to infections (from low white blood cells), and unusual bruising or bleeding (from low platelets). When bone metastasis occurs in the spine, it can compress the spinal cord, causing back or neck stiffness, weakness in the arms and legs, and loss of bladder or bowel control.
Effects on the Brain
Melanoma has a particular tendency to spread to the brain. Brain metastases can cause headaches, seizures, vision changes, confusion, and personality shifts. These symptoms depend on where in the brain the tumors develop and how quickly they grow. Brain involvement represents one of the most serious complications and significantly affects quality of life and prognosis.
Whole-Body Effects of Advanced Disease
Even beyond the specific organs involved, advanced skin cancer takes a toll on the entire body. Unexplained weight loss is common, driven partly by the cancer consuming the body’s energy resources and partly by changes in metabolism that cancer triggers. Persistent, deep fatigue that doesn’t improve with rest is one of the most frequently reported symptoms. This fatigue stems from the immune system’s constant effort to fight the cancer, the metabolic demands of tumor growth, and often from anemia caused by bone marrow involvement or internal bleeding.
Hard or swollen lymph nodes and new lumps under the skin can appear as the cancer establishes itself in new locations. Unexplained pain, sometimes difficult to pinpoint, is another hallmark of advanced disease. These systemic symptoms often overlap, compounding each other. Hypercalcemia from bone metastasis, for instance, causes its own fatigue and confusion on top of the exhaustion already caused by the cancer itself.
Why Stage at Diagnosis Changes Everything
The impact skin cancer has on the body is dramatically different depending on when it’s found. Localized melanoma, still confined to the skin where it started, has a five-year survival rate above 99%. Regional melanoma, meaning it has reached nearby lymph nodes or tissues, drops to 76%. Distant melanoma, which has spread to far-off organs, falls to 35%. These numbers, based on patients diagnosed between 2015 and 2021, reflect a period of significant advances in treatment, particularly immunotherapy, which has improved outcomes for advanced melanoma considerably compared to a decade earlier.
Basal cell carcinoma and smaller squamous cell carcinomas rarely reach the distant stage. Their primary threat is local destruction, which can still be severe, particularly on the face. Larger squamous cell carcinomas carry a higher risk of lymph node involvement and, less commonly, distant spread. Melanoma grows quickly and is the form most likely to metastasize, making it responsible for the vast majority of skin cancer deaths despite being less common than basal or squamous cell carcinoma.