Steady decrease of the time interval between the occurrence of the primary and subsequent primary early (stage I-II) head and neck cancers

Introduction: For patients with early‐stage (stage I‐II) cancers in the head and neck, a serious cause of death is second primary cancers. To improve the survival of these patients, early detection of subsequent new primary cancers is essential. The purpose of this study was to investigate the time‐ intervals about multiple cancers in the head and neck of early‐stage. Study design: A retrospective study was performed using a database of our institution. Material and methods: A total of 2,144 patients with early‐stage squamous cell carcinoma of the head and neck were reviewed. We calculated the time intervals between the detection of each new primary cancer and the date of diagnosis of the index primary cancer. Results: 249 subsequent primary cancers were documented in 172 patients. The median time‐interval between the first cancer and the detection of the second primary cancer was 4.2 years, with steady shortening of the interval: between the second and third primary cancers was 1.7 years, and between the third and fourth primary cancers was 0.9 years. Regardless of the number of subsequent cancers, the second cancers developed in about 4 years after initial treatment. Conclusions: We demonstrate that the time intervals of the occurrence of subsequent primary cancers steadily shorten along with the increase of the number of new primary early‐stage head and neck cancers. This indicates the need for increasing both the frequency and duration of follow‐up, so as to ensure early detection of subsequent new primary cancers.