Determination of prognostic factors of cervical cancer patients: application of a competing risk model

Objective: To explore the prognostic factors of cervical cancer patients under the condition of competing risks.Methods: The data of Chinese cervical cancer patients (1988-2008) were collected from Surveillance, Epidemiology and End Results (SEER) database. It was marked as interesting event that the patients died of cervical cancer, and the competing event was defined as death from other reasons (such as myocardial infarction, other cancers, etc.). In considering the competing risks, the cumulative risk model was used to estimate cumulative incidence of interesting event according to age at diagnosis, stage by International Federation of Gynecology and Obstetrics (FIGO) criteria, degree of lymph node metastasis, and radiotherapy or not. The differences between the two groups were compared by Gray test, and the multivariate regression analysis was performed by Fine-Gray model.Results: A total of 585 cases of cervical cancer were included in this analysis, in which 50 cases occurred interesting event (dead of cervical cancer), and 43 cases occurred competing events (dead from other diseases). The results of Gray test showed that cumulative incidence rates of interesting events were statistically different among different ages at diagnosis, FIGO stages and lymph node metastasis degrees, as well as radiotherapy or not (all P < 0.001). The multivariate regression analysis showed that FIGO stage and lymph node metastasis degree were independent risks of the prognosis of cervical cancer in Fine-Gray model (both P < 0.05). In the presence of competing risks, the relative risk of death of cervical cancer in patients at stage 0 (carcinoma in situ), stage Ⅱ and stage Ⅲ were 0.022, 2.34 and 3.57 times of stageⅠ; while the risks of death of cervical cancer in the patients with regional metastatic lymph nodes (proximal) (relative risk = 2.497) and distant metastatic lymph nodes (relative risk = 3.518) were higher than that in the patients without lymph node metastasis.Conclusion: In consideration of competing risks, the patients of higher FIGO stage and higher degree of lymph node metastasis have poorer prognosis. In the presence of competing risks, more reasonable analysis method and model should be used to analyze the data. DOI:10.3781/j.issn.1000-7431.2015.33.302