1. International Trends in Female Breast Cancer Incidence and Mortality Rates
NAACCR/IACR 2019
MaryBeth Culp, MPH
Presented by Lindsey Torre, MSPH

2. CONTENTS 01 02 03 04 05 Introduction & Risk Factors
Global variation in estimated incidence and mortality rates (GLOBOCAN 2018) 03
Temporal trends in incidence and mortality rates for select countries 04
Discussion and Limitations 05
Conclusions
Today I will briefly discuss known risk factors for breast cancer and show results from previous studies on global incidence and mortality rates. Next I will present maps from the online GLOBOCAN database with incidence and mortality rates by country. Then I will show the results from this study of updated short- and long-term trends in incidence and mortality rates for select countries and finish with a discussion and statement of the limitations of the data sources used.

3. Introduction
Previous research reported global breast cancer incidence and mortality rates and trends through 2012
This project provides updated short- and long-term trends worldwide
Previous publications have reported global breast cancer incidence and mortality rates and trends through 2012.
The focus of this project is to provide the most updated short- and long-term trends worldwide.

4. Breast Cancer Risk Factors
Among other factors, this table from “Breast Cancer Facts and Figures ” lists some of the top known factors that increase the relative risk for breast cancer in women.
Some of the factors circled in red that I will also discuss later in the presentation include alcohol consumption, reproductive factors, obesity, and adult weight gain.
Breast Cancer Facts and Figures

5. Age-Standardized Incidence and Mortality Rates in High/Very- High Human Development Index Regions vs. Low/Medium HDI
When examining breast cancer incidence and mortality by human development index regions, you can see that incidence is much higher among countries with high or very high human development while mortality is higher among countries with low or medium human development.
Bray et al CA Cancer J Clin 2018

6. Breast cancer incidence rates are highest in Australia/New Zealand, parts of Europe and Northern America, while the lowest rates are found in sub-Saharan Africa and parts of Asia.
cancer.org

7. In contrast, breast cancer mortality is the highest among middle African countries and Melanesia (Fiji with the highest mortality rate of any country).
cancer.org

8. Methods
cancer.org

9. Data sources:
Cancer Incidence in Five Continents Time Trends: CI5plus
International Agency for Research on Cancer/World Health Organization cancer mortality database
NORDCAN database: incidence and mortality for Nordic countries
US Surveillance, Epidemiology and End Results (SEER)
JoinPoint modeling used to examine short- and long-term trends in breast cancer incidence and mortality rates
Average Annual Percent Change
For this project, cancer incidence data come from the Cancer Incidence in Five Continents Time Trends CI5 plus database, which contains annual incidence rates for 124 selected populations from 108 cancer registries published in CI5, for the longest period available (up to 2012).
The mortality data come from the international agency for research on cancer world health organization cancer mortality database.
In order to provide the most recent incidence and mortality data available through 2016, we also used the NORDCAN database, which provides data for the Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden) and the most recent US SEER database.
JoinPoint regression modeling was used to examine short- and long-term trends in breast cancer incidence rates. This modeling involves fitting a series of joined straight lines on a logarithmic scale to the trends in the annual rates. The direction and magnitude of the resulting trends are described by the average annual percent change (AAPC), which is the linear slope across each line segment between two join points.
In describing the change in trends, I will use increase or decrease when the AAPC was statistically significant (p<0.05), otherwise I will use the term stable.

10. Results
cancer.org

11. Incidence Trends in Countries by Region
These two graphs show trends in incidence rates over time among countries in North America and Europe.
Incidence rates in the United States were among the highest of any country over time.
In general, among North American and European countries, breast cancer incidence rates increased over time since 1985 and stabilized more recently, although rates continue to increase in some countries.
Sources: CI5plus, NORDCAN, SEER

12. Incidence Trends in Countries by Region
These graphs show selected countries from Asia and Latin America where incidence trends are generally increasing over time as well.
Breast cancer incidence rates were increasing over time as well as in the most recent years examined specifically in Thailand (in red), India (in black), China (in dark green) and Ecuador (in light blue) whereas rates in the Philippines (in magenta) were stable over time until the most recent 5 years when they were decreasing.
Source: CI5plus

13. Incidence Trends in Countries by Region
These graphs present trends from Oceania and Africa.
Trends for each of the three countries displayed here were increasing initially followed by stabilizing trends in more recent years.
Source: CI5plus

14. Changes in Incidence Rates During the Five Most Recent Years (Average Annual Percent Change - AAPC)
↑ in 9 countries
→ in 36 countries
↓ in 1 countries
In describing the change in incidence rates, the terms increase or decrease are used when the annual percent change was statistically significant (p<0.05), otherwise the term stable is used.
This graph shows that the majority of the countries saw stable rate trends in the most recent five years of data.
Countries with increasing trends include: Ecuador, China, India, Slovakia, Thailand, and Spain
As mentioned on the previous slide, the only country with decreasing trends is the Philippines
Source: CI5plus

15. Mortality Trends in Countries by Region
In general, the mortality trends among North American and European countries are decreasing over time, with the most dramatic decreases seen in the United States, Canada and the United Kingdom.
Sources: IARC/WHO cancer mortality database, NORDCAN, SEER

16. Mortality Trends in Countries by Region
Breast Cancer mortality rates in Israel were initially trending upwards, with a sharp decline starting in the early 1990s.
The three countries with increasing mortality trends in recent years are Thailand (in red), the Philippines (magenta), and Panama (purple).
Source: IARC/WHO cancer mortality database

17. Mortality Trends in Countries by Region
Breast cancer mortality trends in New Zealand and Australia were generally decreasing over the study period while trends in Mauritius were increasing over time.
Source: IARC/WHO cancer mortality database

18. Changes in Mortality Rates During the Five Most Recent Years (AAPC)
↑ in 3 countries
→ in 61 countries
↓ in 11 countries
In describing the change in incidence rates, the terms increase or decrease are used when the annual percent change was statistically significant (p<0.05), otherwise the term stable is used.
This graph shows that the majority of the countries saw stable mortality rate trends in the most recent years of data.
Those countries with declining trends were mainly higher human development index countries.
Although the Philippines had decreasing trends in incidence rates in recent years, mortality rates were trending upwards.
Sources: IARC/WHO cancer mortality database, NORDCAN, SEER

19. Discussion – Incidence Trends
Since 1985, breast cancer incidence rates have been generally increasing worldwide
In the most recent years of data, most countries have stabilizing trends with a few increasing
Since 1985, breast cancer incidence rates have generally been increasing worldwide although in the most recent years of data the trends have stabilized with a few increasing trends.
Reasons for increasing incidence in HICs are thought to include increases in prevalence of risk factors (such as reproductive factors and excess body weight) as well as increased detection through mammography.
Increasing incidence in LMICs is also thought to be caused by increases in such risk factors, and increased breast cancer awareness may also contribute to rising rates.
In HICs, stable or declining breast cancer incidence has also been attributed to declines in the use of postmenopausal hormone therapy around the early 2000s and possibly plateaus in participation in mammography screening.

20. Global Trends in Modifiable Risk Factors
These graphs illustrate changes in risk factors for breast cancer worldwide as well as for select countries mentioned in this presentation.
As seen here, generally the fertility rate has been falling among most countries while the prevalence of obesity is rising, both risk factors that might contribute to higher incidence rates of breast cancer.
Source: World Bank Open Data
Source: NCD Risk Factor Collaboration

21. Global Trends in Modifiable Risk Factors
As we see here, in many countries of the world today, more than 10% of postmenopausal breast cancer cases are attributable to excess body weight.

22. Global Trends in Modifiable Risk Factors – Alcohol Consumption
Globally, alcohol consumption has been increasing since the 1990s and is projected to continue to increase over the next decade.
Meanwhile, the prevalence of current drinkers is increasing while the prevalence of non-drinking decreases.
It will be important to monitor trends in alcohol consumption and how it may relate to breast cancer incidence trends going forward.
Source: Manthey et al The Lancet

23. Global Distribution of Breastfeeding at 12 Months
Data are from 153 countries between 1995 and 2013.
The patterns of breastfeeding a child at 12 months varies globally, with the majority of low and middle development regions having a higher percentage of breastfed babies at 12 months compared to countries with higher human development regions.
Never breastfeeding is estimated to almost double a woman’s risk of breast cancer.
Source: Victora et al The Lancet

24. Discussion - Mortality
In the most recent years of data, many countries have decreasing trends in breast cancer mortality rates especially among high human development countries.
Decreasing trends may reflect better access to care, awareness of breast cancer, or breast cancer screening programs.
In the most recent years of data, many countries have decreasing trends in breast cancer mortality rates, especially among high human development countries.
These decreasing trends may reflect better access to care and breast cancer awareness and/or screening, although the relative contributions of treatment and screening are unclear and vary by each country’s individual circumstances.
Increasing mortality reflects increases in incidence and, in some cases, limited access to treatment.

25. Percentage of Clinical Stage 1 Breast Cancer Cases by Human Development Index
In general, breast cancer screening programs lead to a higher percentage of early-stage disease identification.
This chart illustrates that the percentage of breast cancers diagnosed at early stages varies widely around the world and is generally related to a country’s human development index level with higher human development index countries having a higher percentage of cases diagnosed at an early stage.
Source: da Costa Vieira et al Clinics (Sao Paulo, Brazil)

26. Limitations
Lack of high quality incidence and mortality data in low and medium human development countries
A word of caution, however. Interpretation of global variation of incidence and mortality data is limited by lack of high quality data in low and medium human development index countries. High quality cancer registries cover less than 2% of the population in Africa and 4-6% of the population in Asia and South America.
In this study, only one country in Africa had long-term breast cancer incidence data and three had long-term mortality data.
Furthermore, some of the GLOBOCAN estimates that are used to make the maps presented early in the presentation are based on case series or information from neighboring countries so we should use caution in interpreting these maps.

27. Conclusion
Overall, breast cancer incidence rates appear to be increasing globally while mortality rates are declining mainly among higher human development index countries.
Future research should examine:
Ways to address modifiable risk factors in order to decrease incidence of breast cancer AND
Interventions that might address higher mortality rates in lower development regions
Overall, breast cancer incidence rates appear to be increasing globally among many countries while mortality rates are declining mainly among higher human development index countries.
Future research should examine ways to address modifiable risk factors in order to decrease incidence of breast cancer and find interventions that might address higher mortality rates in lower development regions

28. QUESTIONS?

29. Please end the presentation with this slide.