Cancer survivors who received chemotherapy or a transplant or who underwent radiation therapy are at risk of developing a second cancer later in life. Second cancers are more common in patients treated for leukemias and lymphomas. Multiple myeloma patients who received stem-cell transplant using their own stem cells sometimes develop an oral plasmacytoma. Oral squamous cell cancer is the most common second cancer occurring in transplant patients. The lips and tongue are the sites most often affected.