Camille Maringe

Cancer survival in Australia, Canada, Denmark, Norway, Sweden, and the UK, 1995–2007 (the International Cancer Benchmarking Partnership): an analysis of population-based cancer registry data

Summary Background Cancer survival is a key measure of the effectiveness of health-care systems. Persistent regional and international differences in survival represent many avoidable deaths. Differences in survival have prompted or guided cancer control strategies. This is the first study in a programme to investigate international survival disparities, with the aim of informing health policy to raise standards and reduce inequalities in survival. Methods Data from population-based cancer registries in 12 jurisdictions in six countries were provided for 2·4 million adults diagnosed with primary colorectal, lung, breast (women), or ovarian cancer during 1995–2007, with follow-up to Dec 31, 2007. Data quality control and analyses were done centrally with a common protocol, overseen by external experts. We estimated 1-year and 5-year relative survival, constructing 252 complete life tables to control for background mortality by age, sex, and calendar year. We report age-specific and age-standardised relative survival at 1 and 5 years, and 5-year survival conditional on survival to the first anniversary of diagnosis. We also examined incidence and mortality trends during 1985–2005. Findings Relative survival improved during 1995–2007 for all four cancers in all jurisdictions. Survival was persistently higher in Australia, Canada, and Sweden, intermediate in Norway, and lower in Denmark, England, Northern Ireland, and Wales, particularly in the first year after diagnosis and for patients aged 65 years and older. International differences narrowed at all ages for breast cancer, from about 9% to 5% at 1 year and from about 14% to 8% at 5 years, but less or not at all for the other cancers. For colorectal cancer, the international range narrowed only for patients aged 65 years and older, by 2–6% at 1 year and by 2–3% at 5 years. Interpretation Up-to-date survival trends show increases but persistent differences between countries. Trends in cancer incidence and mortality are broadly consistent with these trends in survival. Data quality and changes in classification are not likely explanations. The patterns are consistent with later diagnosis or differences in treatment, particularly in Denmark and the UK, and in patients aged 65 years and older. Funding Department of Health, England; and Cancer Research UK.

Population-based cancer survival trends in England and Wales up to 2007: an assessment of the NHS cancer plan for England

BACKGROUND The National Health Service (NHS) cancer plan for England was published in 2000, with the aim of improving the survival of patients with cancer. By contrast, a formal cancer strategy was not implemented in Wales until late 2006. National data on cancer patient survival in England and Wales up to 2007 thus offer the opportunity for a first formal assessment of the cancer plan in England, by comparing survival trends in England with those in Wales before, during, and after the implementation of the plan. METHODS We analysed population-based survival in 2.2 million adults diagnosed with one of 21 common cancers in England and Wales during 1996-2006 and followed up to Dec 31, 2007. We defined three calendar periods: 1996-2000 (before the cancer plan), 2001-03 (initialisation), and 2004-06 (implementation). We estimated year-on-year trends in 1-year relative survival for patients diagnosed during each period, and changes in those trends between successive periods in England and separately in Wales. Changes between successive periods in mean survival up to 5 years after diagnosis were analysed by country and by government office region of England. Life tables for single year of age, sex, calendar year, deprivation category, and government office region were used to control for background mortality in all analyses. FINDINGS 1-year survival in England and Wales improved for most cancers in men and women diagnosed during 1996-2006 and followed until 2007, although not all trends were significant. Annual trends were generally higher in Wales than in England during 1996-2000 and 2001-03, but higher in England than in Wales during 2004-06. 1-year survival for patients diagnosed in 2006 was over 60% for 12 of 17 cancers in men and 13 of 18 cancers in women. Differences in 3-year survival trends between England and Wales were less marked than the differences in 1-year survival. North-South differences in survival trends for the four most common cancers were not striking, but the North West region and Wales showed the smallest improvements during 2001-03 and 2004-06. INTERPRETATION The findings indicate slightly faster improvement in 1-year survival in England than in Wales during 2004-06, whereas the opposite was true during 2001-03. This reversal of survival trends in 2001-03 and 2004-06 between England and Wales is much less obvious for 3-year survival. These different patterns of survival suggest some beneficial effect of the NHS cancer plan for England, although the data do not so far provide a definitive assessment of the effectiveness of the plan.

Lung cancer survival and stage at diagnosis in Australia, Canada, Denmark, Norway, Sweden and the UK: a population-based study, 2004–2007

Background The authors consider whether differences in stage at diagnosis could explain the variation in lung cancer survival between six developed countries in 2004–2007. Methods Routinely collected population-based data were obtained on all adults (15–99 years) diagnosed with lung cancer in 2004–2007 and registered in regional and national cancer registries in Australia, Canada, Denmark, Norway, Sweden and the UK. Stage data for 57 352 patients were consolidated from various classification systems. Flexible parametric hazard models on the log cumulative scale were used to estimate net survival at 1 year and the excess hazard up to 18 months after diagnosis. Results Age-standardised 1-year net survival from non-small cell lung cancer ranged from 30% (UK) to 46% (Sweden). Patients in the UK and Denmark had lower survival than elsewhere, partly because of a more adverse stage distribution. However, there were also wide international differences in stage-specific survival. Net survival from TNM stage I non-small cell lung cancer was 16% lower in the UK than in Sweden, and for TNM stage IV disease survival was 10% lower. Similar patterns were found for small cell lung cancer. Conclusions There are comparability issues when using population-based data but, even given these constraints, this study shows that, while differences in stage at diagnosis explain some of the international variation in overall lung cancer survival, wide disparities in stage-specific survival exist, suggesting that other factors are also important such as differences in treatment. Stage should be included in international cancer survival studies and the comparability of population-based data should be improved.

Breast cancer survival and stage at diagnosis in Australia, Canada, Denmark, Norway, Sweden and the UK, 2000-2007: A population-based study

Background:We investigate whether differences in breast cancer survival in six high-income countries can be explained by differences in stage at diagnosis using routine data from population-based cancer registries.Methods:We analysed the data on 257 362 women diagnosed with breast cancer during 2000–7 and registered in 13 population-based cancer registries in Australia, Canada, Denmark, Norway, Sweden and the UK. Flexible parametric hazard models were used to estimate net survival and the excess hazard of dying from breast cancer up to 3 years after diagnosis.Results:Age-standardised 3-year net survival was 87–89% in the UK and Denmark, and 91–94% in the other four countries. Stage at diagnosis was relatively advanced in Denmark: only 30% of women had Tumour, Nodes, Metastasis (TNM) stage I disease, compared with 42–45% elsewhere. Women in the UK had low survival for TNM stage III–IV disease compared with other countries.Conclusion:International differences in breast cancer survival are partly explained by differences in stage at diagnosis, and partly by differences in stage-specific survival. Low overall survival arises if the stage distribution is adverse (e.g. Denmark) but stage-specific survival is normal; or if the stage distribution is typical but stage-specific survival is low (e.g. UK). International differences in staging diagnostics and stage-specific cancer therapies should be investigated.

Socioeconomic inequalities in cancer survival in England after the NHS cancer plan

Background:Socioeconomic inequalities in survival were observed for many cancers in England during 1981–1999. The NHS Cancer Plan (2000) aimed to improve survival and reduce these inequalities. This study examines trends in the deprivation gap in cancer survival after implementation of the Plan.Materials and method:We examined relative survival among adults diagnosed with 1 of 21 common cancers in England during 1996–2006, followed up to 31 December 2007. Three periods were defined: 1996–2000 (before the Cancer Plan), 2001–2003 (initialisation) and 2004–2006 (implementation). We estimated the difference in survival between the most deprived and most affluent groups (deprivation gap) at 1 and 3 years after diagnosis, and the change in the deprivation gap both within and between these periods.Results:Survival improved for most cancers, but inequalities in survival were still wide for many cancers in 2006. Only the deprivation gap in 1-year survival narrowed slightly over time. A majority of the socioeconomic disparities in survival occurred soon after a cancer diagnosis, regardless of the cancer prognosis.Conclusion:The recently observed reduction in the deprivation gap was minor and limited to 1-year survival, suggesting that, so far, the Cancer Plan has little effect on those inequalities. Our findings highlight that earlier diagnosis and rapid access to optimal treatment should be ensured for all socioeconomic groups.

Stage at diagnosis and colorectal cancer survival in six high-income countries: A population-based study of patients diagnosed during 2000–2007

Abstract Background. Large international differences in colorectal cancer survival exist, even between countries with similar healthcare. We investigate the extent to which stage at diagnosis explains these differences. Methods. Data from population-based cancer registries in Australia, Canada, Denmark, Norway, Sweden and the UK were analysed for 313 852 patients diagnosed with colon or rectal cancer during 2000–2007. We compared the distributions of stage at diagnosis. We estimated both stage-specific net survival and the excess hazard of death up to three years after diagnosis, using flexible parametric models on the log-cumulative excess hazard scale. Results. International differences in colon and rectal cancer stage distributions were wide: Denmark showed a distribution skewed towards later-stage disease, while Australia, Norway and the UK showed high proportions of ‘regional’ disease. One-year colon cancer survival was 67% in the UK and ranged between 71% (Denmark) and 80% (Australia and Sweden) elsewhere. For rectal cancer, one-year survival was also low in the UK (75%), compared to 79% in Denmark and 82–84% elsewhere. International survival differences were also evident for each stage of disease, with the UK showing consistently lowest survival at one and three years. Conclusion. Differences in stage at diagnosis partly explain international differences in colorectal cancer survival, with a more adverse stage distribution contributing to comparatively low survival in Denmark. Differences in stage distribution could arise because of differences in diagnostic delay and awareness of symptoms, or in the thoroughness of staging procedures. Nevertheless, survival differences also exist for each stage of disease, suggesting unequal access to optimal treatment, particularly in the UK.

Stage at diagnosis and ovarian cancer survival: evidence from the International Cancer Benchmarking Partnership.

OBJECTIVE We investigate what role stage at diagnosis bears in international differences in ovarian cancer survival. METHODS Data from population-based cancer registries in Australia, Canada, Denmark, Norway, and the UK were analysed for 20,073 women diagnosed with ovarian cancer during 2004-07. We compare the stage distribution between countries and estimate stage-specific one-year net survival and the excess hazard up to 18 months after diagnosis, using flexible parametric models on the log cumulative excess hazard scale. RESULTS One-year survival was 69% in the UK, 72% in Denmark and 74-75% elsewhere. In Denmark, 74% of patients were diagnosed with FIGO stages III-IV disease, compared to 60-70% elsewhere. International differences in survival were evident at each stage of disease; women in the UK had lower survival than in the other four countries for patients with FIGO stages III-IV disease (61.4% vs. 65.8-74.4%). International differences were widest for older women and for those with advanced stage or with no stage data. CONCLUSION Differences in stage at diagnosis partly explain international variation in ovarian cancer survival, and a more adverse stage distribution contributes to comparatively low survival in Denmark. This could arise because of differences in tumour biology, staging procedures or diagnostic delay. Differences in survival also exist within each stage, as illustrated by lower survival for advanced disease in the UK, suggesting unequal access to optimal treatment. Population-based data on cancer survival by stage are vital for cancer surveillance, and global consensus is needed to make stage data in cancer registries more consistent.

Cancer mortality in ethnic South Asian migrants in England and Wales (1993–2003): patterns in the overall population and in first and subsequent generations

Background:Cancer mortality has been examined among ethnic South Asian migrants in England and Wales, but not by generation of migration.Methods:Using South Asian mortality records, identified by a name-recognition algorithm, and census information, age-standardised rates among South Asians, and South Asian vs non-South Asian rate ratios, were calculated.Results and conclusions:All-cancer rates in ethnic South Asians were half of those in non-South Asians in first-generation (all-cancer-standardised mortality ratio (SMR) in males 0.51 and in females 0.56) and subsequent-generation South Asians (SMR in males 0.43 and in females 0.36). The higher mortality in first-generation South Asians for liver (both sexes), oral cavity and gallbladder cancer (females), particularly marked among Bangladeshis, was reduced in subsequent generations.

Cancer incidence in South Asian migrants to England, 1986–2004: Unraveling ethnic from socioeconomic differentials

Studies on cancer in migrants are informative about the relative influence of environmental and genetic factors on cancer risk. This study investigates trends in incidence from colorectal, lung, breast and prostate cancer in England among South Asians and examines the influence of deprivation, a key environmental exposure. South Asian ethnicity was assigned to patients recorded in the population‐based National Cancer Registry of England during 1986–2004, using the computerized algorithm SANGRA: South Asian Names and Groups Recognition Algorithm. Population denominators were derived from population censuses. Multivariable flexible (splines) Poisson models were used to estimate trends and socioeconomic differentials in incidence in South Asians compared to non‐South Asians. Overall, age‐adjusted cancer incidence in South Asians was half that in non‐South Asians but rose over time. Cancer‐specific incidence trends and patterns by age and deprivation differed widely between the two ethnic groups. In contrast to non‐South Asians, lung cancer incidence in South Asians did not fall. Colorectal and breast cancer incidence rose in both groups, more steeply in South Asians though remaining less common than in non‐South Asians. The deprivation gaps in cancer‐specific incidence were much less marked among South Asians, explaining some of the ethnic differences in overall incidence. Although still lower than in non‐South Asians, cancer incidence is rising in South Asians, supporting the concept of transition in cancer incidence among South Asians living in England. Although these trends vary by cancer, they have important implications for both prevention and anticipating health‐care demand.

Deriving stage at diagnosis from multiple population-based sources: colorectal and lung cancer in England

Background:Stage at diagnosis is a strong predictor of cancer survival. Differences in stage distributions and stage-specific management help explain geographic differences in cancer outcomes. Stage information is thus essential to improve policies for cancer control. Despite recent progress, stage information is often incomplete. Data collection methods and definition of stage categories are rarely reported. These inconsistencies may result in assigning conflicting stage for single tumours and confound the interpretation of international comparisons and temporal trends of stage-specific cancer outcomes. We propose an algorithm that uses multiple routine, population-based data sources to obtain the most complete and reliable stage information possible.Methods:Our hierarchical approach derives a single stage category per tumour prioritising information deemed of best quality from multiple data sets and various individual components of tumour stage. It incorporates rules from the Union for International Cancer Control TNM classification of malignant tumours. The algorithm is illustrated for colorectal and lung cancer in England. We linked the cancer-specific Clinical Audit data (collected from clinical multi-disciplinary teams) to national cancer registry data. We prioritise stage variables from the Clinical Audit and added information from the registry when needed. We compared stage distribution and stage-specific net survival using two sets of definitions of summary stage with contrasting levels of assumptions for dealing with missing individual TNM components. This exercise extends a previous algorithm we developed for international comparisons of stage-specific survival.Results:Between 2008 and 2012, 163 915 primary colorectal cancer cases and 168 158 primary lung cancer cases were diagnosed in adults in England. Using the most restrictive definition of summary stage (valid information on all individual TNM components), colorectal cancer stage completeness was 56.6% (from 33.8% in 2008 to 85.2% in 2012). Lung cancer stage completeness was 76.6% (from 57.3% in 2008 to 91.4% in 2012). Stage distribution differed between strategies to define summary stage. Stage-specific survival was consistent with published reports.Conclusions:We offer a robust strategy to harmonise the derivation of stage that can be adapted for other cancers and data sources in different countries. The general approach of prioritising good-quality information, reporting sources of individual TNM variables, and reporting of assumptions for dealing with missing data is applicable to any population-based cancer research using stage. Moreover, our research highlights the need for further transparency in the way stage categories are defined and reported, acknowledging the limitations, and potential discrepancies of using readily available stage variables.