Purpose: The objective was to assess the influence of treatment-related and patient-related factors on the risk of developing a second primary tumor (SPT) of the upper aerodigestive tract (UADT) in patients with locoregionally advanced nonmetastatic carcinomas of the head-and-neck region.
Methods and materials: The data of 521 patients with a minimum follow-up of 1 year were pooled: 224 patients from the Swiss Group for Clinical Cancer Research (SAKK) 10/94 trial, treated with 1.2 Gy b.i.d. to 74.4 Gy, and randomized to receive or not to receive simultaneous chemotherapy with cisplatin (excluding nasopharyngeal and maxillary sinus carcinomas); and 297 patients from Geneva, all treated with accelerated radiotherapy with concomitant boost to 69.9 Gy and predominantly cisplatin-based concomitant chemotherapy in 33% of patients (including 21 patients with nasopharyngeal carcinomas). An exploratory analysis using competing risk methodology was performed.
Results: A total of 65 SPT of the UADT were observed after a median observation time of 4.7 years. The overall risk of experiencing an SPT of the UADT at 10 years in the presence of all other possible events was estimated to be 33%. There were no SPTs after treatment for nasopharyngeal carcinoma. In a multivariate logistic regression analysis, there was no difference in occurrence of SPT at 3 years with respect to the administration of chemotherapy (p = 0.31), age (p = 0.62), performance status (p = 0.61), gender (p = 0.27), presence of nodal disease (p = 0.51), or T stage (p = 0.72). However, patients treated with concomitant boost had fewer SPTs (p = 0.0093).
Conclusions: Our data do not suggest that addition of chemotherapy to radiotherapy influences the incidence of second cancers in patients with head-and-neck cancer. The difference in the incidence of SPT between the two radiotherapy schedule groups merits further exploration.