Skin cancer spread is detected through a combination of physical signs you can spot yourself, blood markers your doctor tracks, and imaging scans that reveal what’s happening inside the body. The specific warning signs and testing approach depend heavily on which type of skin cancer you have, since melanoma, squamous cell carcinoma, and basal cell carcinoma each behave very differently when it comes to metastasis.
Physical Signs That Skin Cancer May Have Spread
The earliest visible clue is often a change in your nearby lymph nodes. Regional lymph nodes are the most common first destination for spreading skin cancer. You might feel firm, swollen, or painless lumps in areas like your groin, armpit, or neck, depending on where the original cancer is located. These lumps don’t go away on their own and tend to grow gradually over weeks.
Small nodules under the skin near the original cancer site are another red flag. These subcutaneous nodules can be the first sign of blood-borne spread in melanoma. They sometimes appear as small, firm bumps you can feel but not always see. “Satellite” lesions, which are tiny clusters of cancer cells that pop up in the skin between the primary tumor and the nearest lymph nodes, also signal that cancer is moving beyond its original location.
When skin cancer has spread to distant organs, the symptoms shift to match whichever organ is affected. Spread to the lungs can cause a persistent cough or shortness of breath. Spread to the brain may trigger headaches, seizures, or changes in vision. Spread to the liver can cause abdominal pain or jaundice. Unexplained weight loss and deep fatigue that doesn’t improve with rest are general warning signs that cancer may be active elsewhere in the body.
How Spread Risk Differs by Skin Cancer Type
Melanoma is the most aggressive type. It can spread to lymph nodes, lungs, liver, brain, and bone, and it does so more readily than the other types, especially when the original tumor is thick or ulcerated.
Squamous cell carcinoma spreads at a much lower rate, with an overall metastasis rate of roughly 1.2% to 5%. That range shifts based on the tumor’s location on the body, its size, and how abnormal the cells look under a microscope. Tumors on the lips, ears, or in areas of chronic scarring carry higher risk.
Basal cell carcinoma is the least likely to spread. Despite being the most common skin cancer (accounting for about 80% of all nonmelanoma skin tumors), its metastasis rate is extremely rare, ranging from 0.0028% to 0.55%. When it does spread, it most often goes to regional lymph nodes, followed by the lungs and bones. Basal cell carcinomas that have been neglected for years or have recurred multiple times after treatment are the ones most likely to metastasize.
Tests Used to Detect Spread
Sentinel Lymph Node Biopsy
This is the most important test for determining whether melanoma has reached the lymph nodes. A surgeon identifies the first lymph node that drains the area around the tumor, removes it, and sends it to a pathologist. If cancer cells are found there, the cancer has begun to spread regionally.
Not every melanoma patient needs this biopsy. Guidelines from the National Comprehensive Cancer Network base the recommendation on tumor thickness. If your melanoma is thinner than 0.8 mm and not ulcerated, the chance of lymph node involvement is under 5%, so biopsy typically isn’t recommended. For tumors between 0.8 and 1.0 mm thick, or thinner tumors with ulceration, the risk climbs to 5% to 10%, and biopsy should be discussed. For any melanoma thicker than 1.0 mm, the risk exceeds 10%, and biopsy is strongly recommended.
Certain features can push thinner melanomas into the “should be biopsied” category: if the cells are dividing rapidly, if cancer cells are found in blood or lymph vessels within the sample, if the patient is under 40, or if the initial biopsy didn’t capture the full depth of the tumor.
Imaging Scans
When there’s concern about distant spread, PET-CT is the most accurate imaging tool available. A meta-analysis published in the Journal of the National Cancer Institute found that PET-CT had an 80% sensitivity for staging distant metastases and 86% sensitivity for surveillance of distant metastases, outperforming CT, PET, and ultrasound used alone. It works by combining metabolic information (cancer cells burn more sugar than normal cells, which lights up on the scan) with detailed anatomical images.
CT scans of the chest, abdomen, and pelvis are also commonly used, and brain MRIs are recommended for high-risk patients (stage IIIC or higher) to catch brain metastases that PET-CT can sometimes miss. Ultrasound plays a role too, particularly for monitoring lymph nodes near the original cancer site during follow-up visits.
Blood Tests
A blood enzyme called LDH (lactate dehydrogenase) serves as a marker for advanced melanoma. LDH levels rise when cells are being damaged or destroyed in large numbers, which happens when melanoma is spreading aggressively. Elevated LDH is actually built into the staging system: stage IV melanoma is further subdivided based on whether LDH is normal or elevated, with elevated levels signaling a worse outlook. For every increase of 100 IU/L in baseline LDH, the risk of death rises by about 44%. However, LDH isn’t specific to cancer. It can be elevated from exercise, liver disease, or other conditions, so it’s used alongside imaging rather than on its own.
What the Stages Mean for Spread
Melanoma staging directly reflects how far the cancer has traveled. Stages 0 through II mean the cancer is still confined to the skin, with higher numbers indicating a thicker or ulcerated tumor. Stage III means cancer has reached nearby lymph nodes or has developed satellite lesions between the primary tumor and the nearest nodes, but hasn’t traveled to distant organs. Stage IV means distant metastasis: cancer has been found in faraway skin, soft tissue, lungs, other organs, or the brain.
The survival difference between these stages is significant. Based on data from people diagnosed between 2015 and 2021, the five-year relative survival rate for regional melanoma (stage III) is 76%. For distant melanoma (stage IV), it drops to 35%. These numbers have improved considerably over the past decade thanks to newer treatments, and they represent averages across all patients, including those diagnosed before the most effective current therapies were widely available.
Follow-Up Schedules After Treatment
Melanoma patients require lifelong monitoring because of the risk of both recurrence and developing an entirely new melanoma. The intensity of that monitoring depends on your stage at diagnosis.
For early-stage melanoma (stage IA through IIA) with no evidence of remaining disease, you’ll have clinical exams every 6 to 12 months for five years, then annually. These visits focus on examining your skin and checking regional lymph nodes. Routine imaging isn’t recommended at these stages because the chance of finding hidden metastasis is low enough that the false alarms from scans cause more harm than benefit.
For higher-risk melanoma (stage IIB through IV with no evidence of disease after treatment), visits are more frequent: every 3 to 6 months for the first two years, every 3 to 12 months for the next three years, and annually after that. Imaging with CT or PET-CT every 3 to 12 months may be added to screen for metastasis you can’t feel yet. Patients with stage IIIC or higher should also have periodic brain MRIs for up to three years, since melanoma has a particular tendency to spread to the brain.
The first five years after diagnosis carry the highest risk of recurrence or distant spread. After five years without recurrence, the risk drops substantially, and most guidelines scale back the intensity of surveillance accordingly. European guidelines stop routine imaging after year 10 for most stages, though clinical skin exams continue indefinitely.