Squamous cell carcinoma (SCC) is a prevalent form of cancer, originating in the flat, scale-like cells found in various body tissues. While most commonly recognized as cutaneous SCC (cSCC), it can also develop in other organs. For the vast majority of people diagnosed with cSCC, the outlook is highly favorable, and the chance of a fatal outcome is extremely low. However, the risk of dying depends heavily on the tumor’s location and how advanced it is at diagnosis.
Overall Survival Rates for Cutaneous SCC
The prognosis for cSCC, the second most common form of skin cancer, is generally excellent because it is usually caught and treated early. For tumors localized to the skin, the five-year survival rate is exceptionally high, often reported to be around 95% to 99%. This high rate reflects the non-aggressive nature of most cSCCs and the effectiveness of standard treatments like surgical excision. The chance of cSCC spreading beyond the original site is rare, with the cumulative incidence of metastasis estimated at around 1.9% over a 10-year period. If the cancer spreads regionally to nearby lymph nodes, the five-year survival rate decreases significantly. If cSCC progresses to distant metastasis, the outlook becomes much more guarded. The five-year survival rate for metastatic cSCC is reported to be less than 50%, and for stage 4 skin SCC, the four-year survival rate can drop to as low as 6%.
Key Factors That Increase Mortality Risk
A small subset of cSCC cases is classified as high-risk, meaning they have a greater potential to spread and cause death. Certain tumor characteristics are strong predictors of a poor outcome. For example, tumors exceeding 2 centimeters in diameter or those that have invaded deeply into the skin tissue carry a higher risk.
Tumor depth, often measured as Breslow thickness, is particularly informative; a thickness greater than 2 millimeters is associated with a significantly increased risk of recurrence and metastasis. Histological features, which describe the appearance of cancer cells under a microscope, also play a role. Poorly differentiated tumors, and those showing perineural invasion (cancer cells tracking along a nerve), indicate more aggressive disease.
The tumor’s location is another important variable, as certain anatomical sites are known to be higher risk. Tumors on the lip, ear, scalp, face, fingers, and toes have a greater likelihood of spreading or recurring. This is partly due to the complex underlying structures, which allow for deeper invasion and easier access to lymphatics.
A patient’s immune status is the most powerful predictor of aggressive cSCC behavior. People who are chronically immunosuppressed, such as organ transplant recipients, face a substantially increased risk of their cSCC becoming aggressive and metastasizing. The risk of metastatic cSCC in organ transplant recipients can be five times higher compared to the general population. Immunosuppression is a significant factor in death from both locoregional and distant metastases.
Prognosis of SCC in Other Body Locations
Squamous Cell Carcinoma is a general term for cancer that can arise from squamous cells anywhere in the body, not just the skin. When SCC originates in internal organs, the chances of dying are fundamentally different and generally much higher than for cSCC. This difference is largely due to the late stage at which internal cancers are often detected.
SCC of the lung, a common type of non-small cell lung cancer, has a significantly more serious prognosis than cSCC. The five-year relative survival rate for lung SCC localized to the lung is approximately 65%. This rate drops sharply if the cancer has spread regionally to nearby structures and lymph nodes, falling to about 37%. Once lung SCC has spread to distant sites, such as the liver or brain, the five-year relative survival rate is only about 8%. Similarly, SCC of the head and neck, which includes cancers of the mouth, throat, and larynx, also carries a much higher risk of mortality. For oral SCC, the five-year survival rate is approximately 70%, substantially lower than the survival rate for localized cSCC.
The Role of Early Detection and Surveillance
For cutaneous SCC, the most important factor in maintaining the excellent survival rate is early detection. Finding and treating the tumor when it is small and confined to the surface of the skin is the greatest determinant of a positive outcome. Regular self-examination of the skin is a simple and powerful tool that allows for prompt reporting of any suspicious, non-healing lesions to a physician. Adhering to a strict surveillance schedule is particularly important for people who have already been diagnosed with cSCC or who fall into a high-risk category. Post-treatment follow-ups include clinical examinations of the treated area and the surrounding lymph nodes to detect any recurrence or new lesions quickly. Early intervention prevents the cancer from developing the aggressive features, such as depth or spread, that elevate the risk of death.