Proportion cured models applied to 23 cancer sites in Norway

Abstract

Statistical cure is reached when a group of patients has the same mortality as cancer-free individuals. Cure models predict the cured proportion and the median survival of fatal cases. Cure models have seldom been applied and tested systematically across all major cancer sites. Incidence and follow-up data on 23 cancer sites recorded at the Cancer Registry of Norway 1963-2007 were obtained. Mixture cure models were fitted to obtain trends and up-to-date estimates (based on period approach) assuming cured and uncured groups exist. The model converged for cancers of the mouth and pharynx, oesophagus, stomach, colon, rectum, liver, gallbladder, pancreas, lung and trachea, ovary, kidney, bladder, CNS, non-Hodgkin lymphoma (only for males) and leukemia. The proportion of cured patients increased 1963-2002 for both sexes, with the largest changes (in percent) seen for leukemia (46.4 and 46.7) and CNS (35.9, 42.0), males given first. Median survival time for the uncured cases increased for colon and rectal cancer, and there was a three-fold increase in median survival time for patients with fatal ovarian cancers. Cancers of bladder and CNS had the highest up-to-date proportion cured (in percent), 67.4 and 64.0, respectively, pancreas and liver were amongst the lowest (5.7 and 9.9, respectively). Cure models are useful when monitoring progress in cancer care, but must be applied and interpreted with caution. The absolute estimates of the cure proportion are speculative and should not be calculated where cure is not medically anticipated.Increasingly, cancer patients as a group-at least those diagnosed with treatable cancers in higher-resource settings-survive their initial diagnosis and remain tumor-free for longer periods than has been observed in previous decades 1 This favorable trend in cancer care has warranted the development of novel statistical tools to monitor the effectiveness of early detection strategies and the quality of clinical care and cancer management, including procedures to estimate the proportion of cured patients alongside the median survival of fatal cases using so-called cure models.2,3 From the offset, the inherent differences between the concepts of clinical versus statistical cure need to be understood. Statistical cure is applicable to observations examined at the group level and is distinct from medical cure of the individual, as commonly determined in a clinical setting on the basis of lack of specific symptoms of the patients, achieved, for example, when all cancerous cells in the body have been persistently eradicated. 4 The models, when applied to population-based cancer survival data, serve to provide estimates of the proportion of statistically cured individuals, that is, a group of cancer patients whom, after a certain time period, are observed to have little or no excess mortality relative to the general population.Such models have been applied to aid clinical interpretation of survival trends for specific cancer sites in one or more populations. A recent EUROCARE study presented es...

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

“…It was much higher than results in our study, which may be due to earlier stage at diagnosis and improvement in treatment caused by the gastric cancer management . The cure proportions reported in Europe countries were approximately 20%‐30%, which were lower than those in Japan and recent period in our study . The difference in cure proportion usually related to the gastric cancer treatment and stage at diagnosis .…”

Can hepatic resection provide a long‐term cure for patients with intrahepatic cholangiocarcinoma?

“…In a recent study by Cvancarova et al, cure models were applied to major cancer sites recorded in the Cancer Registry of Norway between 1963 and 2007, including a wide array of cancers including those of the esophagus, stomach, pancreas, liver, colon, bladder, and central nervous system, among others . In this study, although cancers of bladder and central nervous system had the highest percentage of cured patients (67.4% and 64.0%, respectively), those of the pancreas and liver had among the lowest rates (5.7% and 9.9%, respectively) . A separate study conducted among 818,902 Italian patients with cancer confirmed a low cure rate for patients with liver and pancreatic cancers (<10%) .…”

“…In doing this, the nonmixture cure model can provide a clinically useful measure of the probability of cure among patients with cancer after treatment . In a recent study by Cvancarova et al, cure models were applied to major cancer sites recorded in the Cancer Registry of Norway between 1963 and 2007, including a wide array of cancers including those of the esophagus, stomach, pancreas, liver, colon, bladder, and central nervous system, among others . In this study, although cancers of bladder and central nervous system had the highest percentage of cured patients (67.4% and 64.0%, respectively), those of the pancreas and liver had among the lowest rates (5.7% and 9.9%, respectively) .…”

“…As previously described, we applied the nonmixture cure fraction model, chosen for its applicability in tumor recurrence modeling . The nonmixture cure model is a parametric cure model that estimates an asymptote for the survival function at the cure proportion.…”

Defining the Chance of Statistical Cure Among Patients with Extrahepatic Biliary Tract Cancer

“…Cure models have been introduced in the statistical literature and more recently have been applied in the clinical literature. One recent study investigated the probability to be cured and the time to cure among patients following surgery for a wide variety of tumors, including mouth and pharynx, esophagus, lung and trachea, ovary, bladder, non-Hodgkin lymphoma and leukemia [20]. In a separate study, investigators evaluated the cure fraction of patients with liver and pancreatic cancers [21].…”