Module 1 - Epidemiology
Module 1 Epidemiology
Initial results from Module 1 were published in the Lancet in January 2011 (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) and were based cancer registry data on over 2.4 million cancer patients diagnosed during the period 1995 to 2007. Whilst survival in all countries improved for all four cancers studied and higher in Northern Ireland than elsewhere in the UK it was lower than that of the Australian and Canadian jurisdictions and two Swedish regions. Whilst the actual survival was still low, the rate of improvement was greatest in the UK. The differences in survival between jurisdictions suggested that later diagnosis or differences in treatment, particularly in Denmark and the UK, and in patients diagnosed aged 65 years and older were contributory factors. Further more detailed analysis has been carried out in each of the four cancer sites with particular emphasis on the role of stage at diagnosis in explaining differences in cancer survival. A preliminary paper was prepared on the comparability of stage data between countries ‘Comparability of stage data in cancer registries in six countries: lessons from the International Cancer Benchmarking Partnership’ in June 2012.
Key Findings
- Problems with the comparability of stage data internationally were highlighted in all four papers; the consistency and intensity of recording stage information varies widely between countries in the partnership across all cancer types studied.
- The UK was the worst at recording stage at diagnosis – across all four cancer types.
- The UK has the lowest overall cancer survival across four cancer types when compared to the other countries. Sweden was one of the best performing countries; people in Sweden were the most likely to survive at least one year after their diagnosis for breast, bowel and lung (Sweden did not submit data relating to ovarian cancer).
- In comparison to the other ICBP countries, Denmark generally had the fewest number of women diagnosed at earlier stages.
- Factors such as differences in treatment or access to treatment, differences in how doctors stage cancers and late diagnosis may partially explain the international cancer survival differences.
- Some of these factors are currently being investigated by other areas of the partnership.
Module 1 investigated at what role treatment plays in international survival differences. Results from this analysis are expected in late 2013.
Module 4 is looking at the time it takes between a patient noticing something was wrong to contacting a doctor, to then being diagnosed and starting treatment for the cancer. Researchers think that shorter times to diagnosis and treatment are likely a key element in improving survival for patients. First results of the study are expected in late 2014.
Ovarian cancer (Stage at diagnosis and ovarian cancer survival: Evidence from the International Cancer Benchmarking Partnership)
This study found that differences in stage at diagnosis may only partially explain the variation between countries in the proportion of women who survive ovarian cancer. The study found that the UK and Denmark had the lowest one-year ovarian cancer survival of the five countries. Denmark also had the fewest women diagnosed at earlier stages which could partly explain why their ovarian cancer survival is lower than in some other countries. Overall, the UK had similar proportions of women diagnosed at each stage of the disease as in the other participating countries. But women who were diagnosed at later stages of the disease were less likely to survive ovarian cancer in the UK. This suggests that treatment or access to treatment is poorer in the UK for women diagnosed at later stages, than in the other countries in the study.
This study also found that there was a large difference in records that were missing information on stage at diagnosis for ovarian cancer. The UK was the worst at recording stage at diagnosis. Three out of ten ovarian cancer tumours reported in the UK had no information on stage at diagnosis. This is compared to less than one out of ten ovarian cancers in Norway. It isn’t clear if this is because fewer women have the stage of their cancer recorded by doctors in the UK or whether this is because the transfer process of stage data to the cancer registries is less complete in the UK than in the other countries. Survival in the UK was also lower among those whose stage at diagnosis had not been recorded. The paper highlights the need for routine recording and transferral of stage data to cancer registries in all countries.
Researchers found that differences in stage at diagnosis may only partially explain the differences between countries in the number of people who survive lung cancer. One-year small cell and non-small cell lung cancer net survival varied widely between these six countries in 2004-7. One-year survival from non-small cell lung cancer ranged from 30% in the UK to 46% in Sweden. Survival from this type of lung cancer was relatively low in Denmark, intermediate in Norway and higher in Australia and Canada. The UK also had the lowest one-year small cell lung cancer survival, Sweden and Australia had the highest.
The proportion of patients diagnosed at an early stage for non-small cell lung cancers was slightly lower in the UK and Denmark in comparison to other countries. Differences in the proportions of people diagnosed at different stages of the disease, ‘stage distribution’, could be due to delays in diagnosis or differences in staging. Denmark had low survival for patients with early stage disease, but average survival for those with more advanced disease. The UK survival figures were among the lowest at all stages compared to the other countries. In Canada patients had high survival at early stages of lung cancer but relatively poor survival at advanced stages of lung cancer.
There are many possible reasons for the international differences in survival including differences in treatment or access to treatment, late diagnosis or differences in how doctor's 'stage' lung cancers. Inaccurate or incomplete recording of stage information could lead to inappropriate treatment and poorer lung cancer survival. This could also affect the pattern of stage distribution in a country. This study found large differences in the number of records missing information on stage at diagnosis for lung cancer. Again the UK was the worst at recording stage. Three out of ten non-small cell lung cancers and four out of ten small cell lung cancers reported in the UK had no information on stage at diagnosis recorded. It isn’t clear if this is because fewer people are staged by doctors in the UK or because the transfer process of stage data to the cancer registries is less complete in the UK than in the other countries.
The number of UK breast cancer patients diagnosed in the early stages of the disease was similar to the number in Canada, Norway and Sweden (countries with higher cancer survival than the UK). Denmark had the lowest proportion of patients diagnosed at the earliest stage, three out of ten women, compared to four out of ten women in Canada (a country with higher survival). This could partly explain why Denmark’s breast cancer survival is lower than in some other countries, as finding breast cancers at an early stage improves the chances of survival. More than 99% of women when diagnosed at the earliest stage of the disease (stages 1 and 2) survived their disease for at least 3 years in all the countries included in the study. This finding suggests that all of the countries in the study are good at treating early stage breast cancer. However survival rates for all stages combined for women diagnosed in the UK were lower when compared to other countries in the study.
UK survival figures for women diagnosed with late stage breast cancer were significantly lower than for other countries in the study. For women diagnosed at a late stage, five out of ten women in the UK survived their disease for at least one year after diagnosis compared to seven out of ten women in Sweden (the country with the highest survival). Three out of ten women in the UK survived their disease for at least three years after diagnosis compared to four out of ten women in Sweden. This suggests that treatment or access to treatment is poorer in the UK for women diagnosed at later stages, than in other countries. Treatment and late diagnosis may partially explain the differences between countries in the number of women who survive breast cancer. Survival differences could also be impacted by inaccurate or incomplete recording of stage information which may lead to the patient receiving inappropriate treatment. This study found that there were large differences in the number of records missing information on stage at diagnosis for breast cancer. The UK was the worst at recording stage. One out of four breast cancers reported in the UK had no information on stage at diagnosis recorded. It isn’t clear if this is because fewer women are have their stage recorded by doctors in the UK or because the transfer process of stage data to the cancer registries is less complete in the UK than in the other countries.
Colorectal cancer
Wide differences in international stage distributions and survival exist between the countries in this study. Survival and stage distribution for colon (large bowel) and rectal (back passage) cancer were investigated separately in this study. Colon cancer is more commonly diagnosed early (stage A) in Canada, at intermediate stages (stage B and C) in Sweden and the UK, and at an advanced stage (stage D) in Denmark. The stage distribution for rectal cancer was similar in Canada, Norway and Sweden – with 45-52% of cancers diagnosed at stage A and B, around 25-30% at an intermediate stage and 21-23% diagnosed at the latest stage. Denmark had the highest proportion of patients diagnosed at the latest stage, D. Colon and rectal cancer patients in the UK were less likely than in other countries to be diagnosed at the latest stage (19% stage D in the UK compared to 31% in Denmark). The UK had the highest proportion of colon and rectal cancers diagnosed at stage C, an intermediate stage, compared to the other countries. The study found that the UK and Denmark had the lowest one-year colon and rectal cancer survival of the six countries. Survival was intermediate in Norway and Canada for colon cancer and highest in Sweden and Australia. Survival was intermediate in Norway for rectal cancer and highest in Sweden, Canada and Australia
Treatment and late diagnosis may partially explain the differences between countries in the proportion of people who survive colon and rectal cancer.
Survival differences could also be impacted by inaccurate or incomplete recording of stage information which may lead to the patient receiving inappropriate treatment. Late diagnosis appears to be contributing to poor survival in colon and rectal cancers in the Denmark.
There was a large difference in how many records were missing information on stage at diagnosis for colon and rectal cancer. The UK was the worst at recording stage at diagnosis; three out of ten colon and rectal tumours had stage at diagnosis data missing. The abstract of the paper published investigating stage at diagnosis and colorectal cancer survival in the ICBP countries can be found here.
For more information on Module 1 please contact Conan Donnelly
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