Bowen's disease is a type of skin cancer, find out more about getting diagnosed and what treatment you might expect. Bowen's disease is a very early form of squamous cell skin cancer. It's also called squamous cell carcinoma in situ. Doctors call Bowen's disease pre invasive. That means that there are cancer cells there but they are only in the outermost layer of skin, the epidermis. Sometimes it can spread along the skin surface. If left untreated, there is a small chance that Bowen's disease can spread into the deeper layers of the skin. This means it has become an invasive cancer and it can then spread into the lymphatic system. It takes a long time for Bowen's disease to develop into an invasive cancer. But the risk of developing into a cancer remains until Bowen's is treated.