Parametric survival analysis of gastric cancer patients

A total of 1026 patients with gastric cancer was followed up for five years after surgery and classified into different groups according to surgeons' assessment of nodal involvement, serosal invasion, peritoneal spread, and hepatic metastasis. The survival of each group was studied by parametric analysis, using the log normal model and three parameters estimated: proportion of patients cured (c), mean (m), and SD of log survival times of patients not cured. With these parameters, compared with the conventional five-year survival or the median time, the survival pattern of each group was delineated in detail, and prognostic inferences beyond the follow-up period were made feasible. Groups with more localized lesions were characterized by higher values of c and m. This implied that although patients in these groups have a better chance of cure, they are exposed to a relatively higher risk of late death due to recurrence. This method proved also useful to compare the prognostic values of different classification and to develop better staging systems.