Renyuan Huang, Jiahao Lou, Chenghao Li, Zhen Xu, Qingqing Xu, Yuntong Zhou, Weijie Cai, Ling Ye, Lulu Zhang, Mian Xi, Lei Chen
In this cross-era institutional study, the IMRT cohort showed a numerically higher observed crude incidence and shorter latency of radiation-related SMNs than the historical 2D-RT cohort. Male sex, younger age, and smoking history were independent risk factors for SMN development. Among patients who developed SMNs, observed overall survival estimates were higher in the IMRT cohort.
BACKGROUND AND PURPOSE: To clarify the long-term risk and prognostic implications of second malignant neoplasms (SMNs) among nasopharyngeal carcinoma survivors in intensity-modulated radiotherapy (IMRT) and historical two-dimensional radiotherapy (2D-RT) cohorts.
MATERIALS AND METHODS: We extracted data from 8,032 and 39,118 initially diagnosed, non-metastatic NPC patients treated with IMRT ± chemotherapy and 2D-RT ± chemotherapy, respectively. Risk factors for SMN development in the IMRT cohort were evaluated using univariate and multivariable Cox proportional hazards models. Survival outcomes were assessed using the Kaplan-Meier method.
RESULTS: Radiation-related SMNs occurred in 212 patients in the IMRT cohort and 247 patients in the historical 2D-RT cohort, corresponding to observed crude proportions of 3.49% and 0.63%, respectively. In the IMRT cohort, the 5-, 10-, and 15-year competing-risk cumulative incidences were 1.15%, 3.09%, and 6.66%, respectively. Median latency to SMN diagnosis was 7.3 years in the IMRT cohort and 9.5 years in the historical 2D-RT cohort. The oral cavity and sinonasal region were common SMN sites, and squamous cell carcinoma was the predominant histology. In multivariable Cox analysis within the IMRT cohort, male sex, age ≤ 50 years, and smoking history were independently associated with SMN development. Among patients with SMNs, 5-year overall survival was 38.6% in the IMRT cohort and 29.3% in the historical 2D-RT cohort.
CONCLUSIONS: In this cross-era institutional study, the IMRT cohort showed a numerically higher observed crude incidence and shorter latency of radiation-related SMNs than the historical 2D-RT cohort. Male sex, younger age, and smoking history were independent risk factors for SMN development. Among patients who developed SMNs, observed overall survival estimates were higher in the IMRT cohort.