Background To develop a common follow‐up strategy for appropriate imaging examination at an appropriate time for nasopharyngeal carcinoma (NPC). Methods Independent prognostic factors were identified by Cox regression analysis, and a nomogram model was developed. Random survival forest (RSF) model was constructed to depict probability of disease failure during a 5‐year follow‐up and establish a reasonable risk‐based follow‐up strategy. Results The nomogram model finally categorized the patients into three risk groups. RSF model demonstrated distribution trends for local and regional recurrences, bone metastasis, liver metastasis, and lung metastasis of NPC. Adequate imaging at follow‐up should be considered between 10 and 21 months for patients at moderate‐risk of recurrence or metastasis and 7–36 months for those at high‐risk. Conclusions The temporal distribution of incidence rates of recurrence or metastasis varied among different risk groups. We recommend implementing a focused and targeted imaging surveillance intervention at appropriate times to improve its efficiency and reduce costs.

Background To identify patients at low risk of synchronous bone metastasis who should not receive bone scans when initially diagnosed with nasopharyngeal carcinoma (NPC). Methods In total, 6652 patients were enrolled in the training cohort and 1919 patients in the multicenter external validation cohort. Logistic regression analyses were performed to assess independent predictors of synchronous bone metastasis for the nomogram model. Results After risk stratification, 46.3% (3081/6652) patients were separated into the low‐risk group with an incidence of 0.71% for synchronous bone metastasis. The odds ratio of the intermediate and high‐risk groups was 5.61 and 23.82 times that of the low‐risk group, respectively. For patients with high EBV DNA, we recommend routine screening for N2‐3 female patients, but that all male subgroups are screened. Conclusions Bone scans should not be routine. Patients in the low‐risk group should not be screened, which would avoid excessive radiation and economize iatrical resource.

Objective To identify the main risk factors for metachronous metastatic nasopharyngeal carcinoma (NPC) in different periods after radiotherapy and estimate the weight of various factors in the early or late metachronous metastasis (EMM/LMM) groups. Methods This retrospective registry consists of 4434 patients with newly diagnosed NPC. Cox regression analysis was used to assess the independent significance of various risk factors. The Interactive Risk Attributable Program (IRAP) was used to calculate the attributable risks (ARs) for metastatic patients during different periods. Results Among 514 metastatic patients, 346 (67.32%) patients diagnosed with metastasis within 2 years after treatment were classified into the EMM group, while other 168 patients were classified into the LMM group. The ARs of T-stage, N-stage, pre-Epstein-Barr virus (EBV) DNA, post-EBV DNA, age, sex, pre-neutrophil-to-lymphocyte ratio, pre-platelet-to-lymphocyte ratio, pre-hemoglobin (HB), and post-HB were 20.19, 67.25, 2.81, 14.28, 18.50, - 11.17%, 14.54, 9.60, 3.74% and - 9.79%, respectively, in the EMM group. In the LMM group, the corresponding ARs were 3.68, 49.11, - 18.04%, 2.19, 6.11, 0.36, 4.62, 19.77, 9.57 and 7.76%, respectively. After multivariable adjustment, the total AR for tumor-related factors was 78.19%, and that for patient-related factors was 26.07% in the EMM group. In the LMM group, the total AR of tumor-related factors was 43.85%, while the weights of patient-related factors was 39.97%. In addition, except for these identified tumor- and patient-related factors, other unevaluated factors played a more important role in patients with late metastasis, with the weight increasing by 15.77%, from 17.76% in the EMM group to 33.53% in the LMM group. Conclusion Most metachronous metastatic NPC cases occurred in the first 2 years after treatment. Early metastasis was mainly affected by tumor-related factors, which accounted for a declining percentage in the LMM group.