Squamous cell carcinoma (SCC) is the second most common skin cancer after basal cell carcinoma. It originates from squamous cells in the epidermis. The time it takes for SCC to spread is not a fixed number, as various factors influence its progression. While early spread is uncommon, early detection plays an important role in successful treatment.
Understanding Squamous Cell Carcinoma Growth
Squamous cell carcinoma typically grows slowly, often starting as a localized skin lesion. They usually appear in sun-exposed areas like the face, ears, neck, lips, and hands. If left untreated, SCC can grow into deeper skin layers. Despite this potential for invasion, most SCCs are cured with early intervention and generally do not spread beyond the initial local area.
A typical SCC might take months to years to reach one centimeter. Most cases are diagnosed and treated before they become problematic. However, growth rates can vary, influenced by factors like the tumor’s location, an individual’s immune response, and specific tumor characteristics. While most SCCs are slow-growing, rarer, more aggressive forms can progress rapidly.
Factors Affecting Its Spread
While many SCCs are slow-growing and localized, certain factors influence their spread (metastasis). Tumor characteristics, such as size and depth, play a role. Larger lesions and those that have grown deeper into the skin carry a higher risk of spread. For instance, tumors with a depth greater than 3.2 mm have been associated with increased metastatic risk. The tumor’s location also matters, with SCCs on the lips, ears, genitals, old scars, or areas of chronic inflammation at higher risk for spread.
Histological features (microscopic appearance of cancer cells) are another determinant. Aggressive microscopic patterns, such as perineural invasion (where cancer cells spread along nerves), are associated with a poorer outlook. Poorly differentiated cells (meaning they appear less like normal cells under a microscope) also indicate a more aggressive SCC with higher potential for rapid growth and metastasis. The patient’s immune status significantly affects risk; individuals with weakened immune systems (such as organ transplant recipients) have a higher risk of developing more aggressive SCCs prone to spreading.
Previous treatment history can also influence behavior. Tumors that recur after initial treatment may exhibit more aggressive characteristics. Certain rare types of SCC, like Marjolin’s ulcer (which develops in areas of previously traumatized or chronically inflamed skin), are inherently more aggressive. These ulcers can arise many years after the initial injury (often 10 to 25 years later) and have a higher rate of metastasis compared to typical SCCs.
Recognizing Signs of Metastasis and What to Do
If SCC spreads, it commonly travels through the lymphatic system, often reaching regional lymph nodes first. For example, an SCC on the cheek might spread to lymph nodes in the neck. Distant metastasis occurs when cancer cells travel through the bloodstream to other organs. The most common sites for distant spread are the lungs and bones.
Signs of regional spread often include enlarged, firm lymph nodes near the original tumor site. Symptoms of distant metastasis can be general, including unexplained weight loss, persistent fatigue, or bone pain if the cancer has spread there. Respiratory issues might indicate lung involvement. If any suspicious signs appear, prompt medical evaluation is important.
A doctor will perform a physical examination and may recommend a biopsy of the suspicious area to confirm cancer. Imaging tests, such as CT or PET scans, help determine the extent of spread. Treatment for metastatic SCC often involves a combination of approaches, including surgery to remove the primary tumor and affected lymph nodes, radiation therapy to destroy cancer cells, and systemic therapies like chemotherapy or immunotherapy. Immunotherapy drugs are approved for advanced forms of SCC not curable by surgery or radiation.