On the use of flexible excess hazard regression models for describing long-term breast cancer survival: a case-study using population-based cancer registry data.

BACKGROUND: Breast cancer prognosis has dramatically improved over 40 years. There is, however, no proof of population 'cure'. This research aimed to examine the pattern of long-term excess mortality due to breast cancer and evaluate its determinants in the context of cancer registry data. METHODS: We used data from the Geneva Cancer Registry to identify women younger than 75 years diagnosed with invasive, localised and operated breast cancer between 1995 and 2002. Flexible modelling of excess mortality hazard, including time-dependent (TD) regression parameters, was used to estimate mortality related to breast cancer. We derived a single "final" model using a backward selection procedure and evaluated its stability through sensitivity analyses using a bootstrap technique. RESULTS: We analysed data from 1574 breast cancer women including 351 deaths (22.3%). The model building strategy retained age at diagnosis (TD), tumour size and grade (TD), chemotherapy and hormonal treatment (TD) as prognostic factors, while the sensitivity analysis on bootstrap samples identified nodes involvement and hormone receptors (TD) as additional long-term prognostic factors but did not identify chemotherapy and hormonal treatment as important prognostic factors. CONCLUSIONS: Two main issues were observed when describing the determinants of long-term survival. First, the modelling strategy presented a lack of robustness, probably due to the limited number of events observed in our study. The second was the misspecification of the model, probably due to confounding by indication. Our results highlight the need for more detailed data and the use of causal inference methods.

Trends in incidence and predictions of cutaneous melanoma across Europe up to 2015.

BACKGROUND: Melanoma is a significant health problem in Caucasian populations. The most recently available data from cancer registries often have a delay of several months up to a few years and they are generally not easily accessible. OBJECTIVES: To assess recent age- and sex-specific trends in melanoma incidence and make predictions for 2010 and 2015. METHODS: A retrospective registry-based analysis was performed with data from 29 European cancer registries. Most of them had data available from 1990 up to 2006/7. World-standardized incidence rates (WSR) and the estimated annual percentage change (EAPC) were computed. Predictions were based on linear projection models. RESULTS: Overall the incidence of melanoma is rapidly rising and will continue to do so. The incidence among women in Europe was generally higher than in men. The highest incidence rates were seen for Northern and north-western countries like the UK, Ireland and the Netherlands. The lowest incidence rates were observed in Portugal and Spain. The incidence overall remained stable in Norway, where, amongst young (25-49 years) Norwegian males rates significantly decreased (EAPC -2.8, 95% CI -3.6; -2.0). Despite a low melanoma incidence among persons above the age of 70, this age group experienced the greatest increase in risk during the study period. CONCLUSIONS: Incidence rates of melanoma are expected to continue rising. These trends are worrying in terms of disease burden, particularly in eastern European countries.