The study was conducted by the International Cancer Benchmarking Partnership. The analyses – funded by the Department of Health and led by the Cancer Research UK Cancer Survival Group at the London School of Hygiene & Tropical Medicine – included 257,362 women diagnosed with breast cancer during 2000-7 and recorded in cancer registries in six countries*.
Three-year survival was 87-89 per cent in the UK and Denmark, and 91-94 per cent in the other four countries. One-year survival varied less, from 94.3 per cent in the UK to 98.4 per cent in Sweden.
The study investigated whether international differences in survival up to three years after diagnosis were explained by differences in the stage of disease at diagnosis.
In the UK, similar proportions of women were diagnosed in the early stages as in most of the other countries, but survival was lower than in the other countries for women with late-stage breast cancer (TNM** Stages III and IV). This suggests that lower overall breast cancer survival in the UK is not because women are being diagnosed at a later stage than in other countries.
The UK also had the highest proportion of women with missing information about their stage at diagnosis.
In Denmark, only 30 per cent of women had early-stage disease (TNM Stage I), compared to 42-45 per cent elsewhere. This suggests that low overall breast cancer survival in Denmark – the only country that had not fully implemented a national breast screening programme before 2007 – was due to women being diagnosed at a later stage of disease.
Generally, women eligible for screening (typically 50-69 years) are diagnosed at an earlier stage than younger and older women.
One year after diagnosis, survival for women with early-stage disease (TNM Stage I) was close to 100 per cent in all countries. For women with later-stage disease, international differences were wide. For women with the most advanced cancers (TNM Stage IV), one-year survival ranged from 53 per cent in the UK to 67 per cent in Sweden, and three-year survival varied from 28 per cent in the UK to 42 per cent in Sweden, a range of 14 per cent in both cases.
International differences in survival were also wider for older women.
Three-year survival was four per cent higher in Sweden (96 per cent) than in the UK (92 per cent) for women aged 50-69 years, but for women aged 70 years or more, the difference was 12 per cent (Sweden 91 per cent vs. UK 79 per cent).
These findings suggest that older women with breast cancer and women with more advanced disease may be treated less aggressively in the UK than in the other five countries.
Dr Sarah Walters, lead author from the Cancer Research UK Cancer Survival Group at the London School of Hygiene and Tropical Medicine, said: “What is special about this study is that routinely-collected data from cancer registries enabled us to monitor international trends and differences in breast cancer survival for all women with breast cancer, not just the small and selected groups of women usually included in clinical trials.
“The reasons for low overall survival in the UK and Denmark are different. In Denmark, women are diagnosed with more advanced disease, but survival at each stage is similar to that in other countries. In the UK, women are diagnosed at a similar stage as elsewhere, but survival is lower than women with the same stage of disease in other countries. The roll-out of national mammography screening will be expected to improve overall survival in Denmark. In the UK, we should now investigate whether the treatment of women with later-stage breast cancer meets international standards. There is particular concern that this is not the case, especially for older women”.
Sara Hiom, Cancer Research UK’s director of early diagnosis, said: “International comparisons like this are vital in helping us better understand what is influencing cancer survival. We’re beginning to see some important clues now, but while we’re closing the survival gap for breast cancer UK women continue to fare worse than in these other countries. We know that UK women diagnosed with breast cancer are not routinely given CT scans to check if the disease has spread, which could mean we aren’t always accurately staging more advanced disease. But we also need to investigate the possibility that fewer women with later stage breast cancer in the UK receive the best treatment for their circumstances.
“It’s vital for women to understand that their breast cancer risk continues to increase the older they get. Diagnosing and treating the disease earlier is key to improving outcomes for women and we must ensure this is a reality for all.”
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Breast cancer survival and stage at diagnosis in Australia, Canada, Denmark, Norway, Sweden and the UK, 2000-2007: a population-based study. British Journal of Cancer, 2013.
Notes to editors
* National data were analysed for Norway and Denmark, and regional data from the other countries: Australia (New South Wales); Canada (British Columbia and Manitoba); Sweden (Uppsala-Örebro and Stockholm-Gotland health regions); United Kingdom (Northern Ireland; Wales; England: West Midlands Cancer Intelligence Unit, Northern and Yorkshire Cancer Registry and Information Service, Oxford Cancer Intelligence Unit, and Eastern Cancer Registration and Information Centre).
** The stage of a cancer indicates how big it is and how far it has spread. The most widely used international system to classify cancer stage is called TNM. This indicates the size and position of the tumour (T), whether cancer cells have spread into the lymph nodes (N) and whether the tumour has spread anywhere else in the body – secondary cancer or metastases (M).
About the International Cancer Benchmarking Partnership (ICBP):
The International Cancer Benchmarking Partnership (ICBP) is a unique and innovative global partnership of clinicians, academics and policymakers. It is the first of its kind, seeking to understand how and why cancer survival varies between countries. The ICBP is chaired by Sir Mike Richards, National cancer Director for England, and programme management is provided by Cancer Research UK. www.icbp.org.uk