The improved cure fraction for esophageal cancer in Linzhou city

Abstract

BackgroundSurvival of esophageal cancer in Linzhou was seen to increase over the past few decades and is higher than the average level of China due to the implementation of comprehensive prevention and control measures. In population-based studies, relative survival is a common index to approximate disease-specific survival. However, the cure fraction maybe great interest to patients and physicians. This study aimed to investigate the cure fraction of esophageal cancer in Linzou city during 2003–2012 with a cure model.MethodsWe carried out a population-based study of 8067 esophageal cancer patients in the Linzhou city during 2003–2012. Flexible parametric cure models were used to estimate cure proportions and median survival times of uncured by year of diagnosed and age. In each model, an interaction between calendar year and age were included. All variables in the model were included both as constant and time-varying effects.ResultsThe 5-year relative survival rate was increased in every age group from 2003 to 2012. The huge increase in the cure proportion was observed in each age group. At the year of 2011–2012, 79.8%, 58.0%, 123.4% and 162.7% improvements of cure proportion were seen in age group 19–49, 50–59, 60–69 and 70–99 years compared with year of 2003–2004. Meanwhile, survival of ‘uncured’ patients changed little in all age group.ConclusionsThe improvement of survival in Linzhou city during 2003–2012 was mainly due to an increasing cure proportion. Huge improvement of cure fraction within short period is likely due to the organized screening of esophageal cancer in Linzhou city.

The relative survival and cure fraction of gastric cancer estimated through flexible parametric models using data from population‐based cancer registration during 2003‐2012 in Linzhou, China

“…Higher cure proportion and longer survival time of the “uncured” were interpreted as a general improvement in treatment, and higher cure proportion with shorter time of “uncured” was interpreted as a selective improvement in treatment, which enables uncured patients with a longer survival time to be cured. However, higher cure proportion with unchanged survival time of the uncured might occur following the introduction of some diagnostic procedure, such as screening, which included more patients who have no excess risk . Besides the high cure proportion in Linzhou, the survival time of “uncured” patients hardly changed along with calendar periods.…”

“…21 And instead of using a specific parametric distribution, the shape of the survival distribution was modeled with restricted cubic spline with 4 internal knots at 20th, 40th, 60th, and 80th centiles on the distribution of uncensored log event times. 13,22 The age of subjects was reclassified into four age groups (19-49, 50-59, 60-69, and 70-99), and calendar years were reclassified to five calendar periods (2003-2004, 2005-2006, 2007-2008, 2009-2010, and 2011-2012) for further analysis. Calendar years were modeled continuously using splines when generating figures.…”

“…However, healthcare providers, physicians, and patients still believe that the proportion of cured patients by varied interventions and advanced treatment needs further research. This value could be determined by introducing the concept of “statistical cure,” which happens when the curve of cumulative relative survival shows a plateau; the cure fraction then can be defined as the proportion of cured patients in the plateau out of all patients …”

“…In recent studies, cure fraction and survival function were estimated using cure models, in which the cancer patients were divided into uncured patients and cured patients. In this study, cured patients are defined as having the same mortality rate with people of the same age and sex in the general population; thus, cured patients will not experience excess mortality due to the cancer . Flexible parametric models were seen to fit better than the traditional mixture or nonmixture cure models; therefore, relative survival and cure fraction of gastric cancer were estimated using population‐based cancer registration data through the flexible parametric cure models.…”

“…This value could be determined by introducing the concept of "statistical cure," which happens when the curve of cumulative relative survival shows a plateau; the cure fraction then can be defined as the proportion of cured patients in the plateau out of all patients. [10][11][12][13] In recent studies, cure fraction and survival function were estimated using cure models, in which the cancer patients were divided into uncured patients and cured patients. In this study, cured patients are defined as having the same mortality rate with people of the same age and sex in the general population; thus, cured patients will not experience excess mortality due to the cancer.…”