Abstract
The association between long‐term variation of postdiagnosis platelets and survival of pancreatic cancer (PC) has never been discussed by using dynamic survival analysis method. In this retrospective study, we analyzed 311 histologically confirmed PC patients identified from a mega population‐based electronic inpatients database from 2012 to 2013 in China. Counting process approach was applied to restructure the original survival data, the association between post‐diagnosis platelet count and overall survival (OS) of PC was evaluated by multiple failure‐time Cox proportional hazards model. After counting process adjustment, multiple failure‐time Cox proportional hazards model revealed that, regardless of the treatment modalities PC patients received, postdiagnosis thrombocytopenia was prominently associated with OS, compared with PC patients with normally ranged platelet count, the HRs ranged from 2.04 (95% CI: 1.14–3.67) to 10.82 (95% CI: 2.63–44.54), and this inverse association was robust based on further sensitivity analysis. On the contrary, the association between thrombocytosis and OS of PC tended to be inconclusive. Our findings suggested that postdiagnosis thrombocytopenia was associated with significantly compromised survival among PC patients from this large retrospective cohort. Underlying mechanisms behind this association should be further investigated.
Highlights
The prognostic value of circulating platelets in malignant tumors attracts lasting study interest [1,2,3,4]
We aimed to evaluate the association between time-varying platelet count measured after cancer diagnosis and overall survival (OS) of pancreatic cancer (PC) through the application of counting process approach and the subsequent multiple failure-time Cox proportional hazards model, besides, we compared results of multiple failure-time Cox model with common Cox model which analyzed the association between platelet count measured at diagnosis and OS of PC
Under the assumption of constant effect, after adjusted for age at diagnosis and sex, we found that: postdiagnosis thrombocytopenia was prominently associated with compromised survival in all four subgroups, compared with PC patients with normally ranged platelet count, the hazard of death (HR) ranged from 2.04 to 10.82, whereas an increased postdiagnosis platelet count only showed significant influence in survival in PC patients who received palliative chemotherapy (HR: 2.00; 95% CI: 1.10–3.63) (Table 3)
Summary
The prognostic value of circulating platelets in malignant tumors attracts lasting study interest [1,2,3,4]. Most currently available studies on the association between platelet count and PC survival analyzed platelet count measured at baseline, mostly defined as at diagnosis or prior to cancer treatment. In this case, compared with measurements from certain transient moments, the long-term variation in platelet count after PC diagnosis and its influence on survival undoubtedly bear more significance in clinical practice. On the basis of widely used Cox proportional hazards model, several extensions have been proposed to evaluate the effect of time-varying or time-dependent variables [10]. The most intuitive way is to construct a function over time for time-varying independent, and integrate this time function into Cox model with other constant covariates. The logic behind this method is simple, to correctly define this “time function” will be extremely
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