Second malignancies in patients who have head and neck cancer: incidence, effect on survival and implications based on the RTOG experience.

The development of second malignant tumors (SMTs), in patients who have had their first tumor treated successfully, represents a serious limitation of current therapeutic strategies for head and neck cancers. To improve our understanding of the current magnitude of the problem and the various factors that might influence its importance, we reviewed the Radiation Therapy Oncology Group's (RTOG) prospectively collected registry of all head and neck patients seen in participating member institutions between February 1977 and April 1980. A total of 928 patients were identified who had squamous cell carcinomas of the head and neck region, no prior or coincident history of another malignant tumor, and whose planned treatment consisted of radiation therapy only. A total of 110 second, independent, malignant tumors occurred in these patients. Overall, the estimated risk of developing a second tumor within 3 years of radiotherapy was 10%, within 5 years 15%, and within 8 years 23%. Minor differences in frequency were observed for different primary sites. These SMTs unquestionably influenced subsequent survival adversely. Analysis of the database also revealed that the extent of the primary tumor influenced the risk of a second; most occurred in patients who presented with the smallest primary tumors because of their better survival. Our data indicate that preventive medicine should have its greatest impact in those patients who are treated for an early stage primary tumor.