World Burden of Cancer

1. World Burden of Cancer Epi 242 Cancer Epidemiology Binh Goldstein, Ph.D. October 7, 2009

2. Measures of Cancer Frequency: Incidence • number of new cases occurring • can be expressed as an absolute number of cases per year or as a rate per 100,000 persons per year. • incidence rate provides approximation to average risk of developing a cancer and is necessary to compare risk of disease between populations • reduction in incidence is the appropriate statistics to use when considering impact of primary prevention strategies

3. Measures of Cancer Frequency: Mortality • number of deaths occurring • mortality rate is the number of deaths per 100,000 persons per year • mortality rates measure average risk of dying from a specific cancer • number of deaths is one measure of outcome or impact of cancer • Fatality, (1-survival), is probability that an individual with cancer will die from it and is generally assumed to be most severe sequelae of disease

4. Measures of Cancer Frequency: Prevalence • NO agreed definition of “prevalence” of cancer • number of persons in a defined population alive at a given time who have had cancer diagnosed at some time in past • partial prevalence limits number of patients to those diagnosed during fixed time in past and is more useful prevalence measure of cancer burden • prevalence for cases diagnosed within 1, 3, 5 years are likely to be of relevance to different stages of cancer therapy: initial treatment (1 year), clinical follow-up (3 years) and cure (5 years) • patients still alive 5 years after diagnosis are considered “cured” since their death rates are similar to general population (some exceptions, like breast cancer)

5. Other Measurements: Survival • survival time defined as time that elapsed between diagnosis and death • most basic measure of patients’ survival is the observed survival • 5-year observed survival is percentage of patients alive after 5 years of follow-up from date of diagnosis

6. Other Measurements: Relative Survival • deaths from other competing causes will lower the observed survival rates and preclude comparison between groups where probability of death in the general population vary • relative survival rate can be calculated to avoid this problem • relative survival rate is observed survival rate in a patient group divided by expected survival of a comparable group in the general population with respect to age, sex, and calendar period of investigation

7. Measures of Cancer Frequency • How are the different measures related? • M = I x F, where F is fatality • M ≈ I(1-S), where S is 5-year survival • P = I x D, where D is duration • F = (1-S)

8. Other Measurements of Burden • PYLLs (Potential Years of Life Lost) • QALYs (Quality Adjusted Life Years) • DALYs (Disability Adjusted Life Years)

9. Global Cancer Statistics

12. Incidence by sex and cancer site, World 2002 Source: Table 1: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108

13. Mortality by sex and cancer site, World 2002 Source: Table 1: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108

14. Estimated Age-adjusted Survival (%) Source: Table 2: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108

15. Incidence and prevalent cases, World 2002 Source: Figure 3: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108

16. The Major Cancers • Lung (ICD-10 C33 and C34) • Breast (female, C50) • Colon/rectum (C18-C20) • Stomach (C16) • Prostate (C61) • Liver (C22) • Cervix uteri (C53) • Esophagus (C15)

17. Age Standardized Incidence Rates

18. World Age Standardized Incidence and Mortality Rates

19. Lung cancer • 1.35 million new cases and 1.18 million deaths worldwide estimated in 2002 • 50% new cases occurred in more developed countries (previously 69%) • more common in males (2.9 male:female ratio) • patterns of lung cancer occurrence determined largely by past exposure to tobacco smoking

20. Age-standardized incidence rates for lung cancer Source: Figure 5: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108

22. Lung cancer incidence trends • in countries where smoking was first established (UK, US, Australia, etc.), rates declining among men • in most other countries, rates rising • rates in women generally increasing since tobacco habit is fairly recent, except in countries where their smoking prevalence is declining

23. Lung cancer mortality trends • similar to incidence trends

24. Breast cancer • 1.15 million new cases and 410,000 deaths worldwide estimated in 2002 • most common cancer in women • Over half of new cases occurred in more developed countries • stage of disease at diagnosis is most important prognostic factor • most prevalent cancer in world because of its good prognoses • risk increases with age but slows at about 50 years because of menopause and lower estrogen levels

25. Age-standardized incidence and mortality rates for breast cancer Source: Figure 6: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108

28. Breast cancer incidence trends • generally increasing at all ages

29. Breast cancer mortality trends • may be declining in recent years (like in US, Canada, and some European countries) due to screening and detection of early stage cancers and more effective treatment

30. Colorectal cancer • About 1 million new cases and 529,000 deaths worldwide estimated in 2002 • 3rd most common cause of cancer in world but 2nd most common in developed countries. • good prognoses (40-50% 5-year survival) makes it the 2nd most prevalent cancer • males and females have similar rates

31. Age-standardized incidence rates for colorectal cancer Source: Figure 7: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108

33. Colorectal cancer incidence trends • increasing trend in low-risk areas • stabilized or decreasing trends in high-risk areas • greatest increases observed in Asia (especially Japan) and Eastern Europe (possibly from “westernization” of lifestyle/diet)

34. Colorectal cancer mortality trends • decreasing trend in developed countries may be due to decreasing in incidence, improved treatment, and improvements in early detection (from screening)

35. Stomach cancer • 934,000 new cases and 700,000 deaths worldwide estimated in 2002 • ranked 4th in number of new cancers but 2nd in most common cause of deaths from cancer • almost two-thirds of cases occur in developing countries • more common in males (1.75 male:female ratio) • however, in younger age groups (<40 years) rates in women are greater than men

36. Age-standardized incidence rates for stomach cancer Source: Figure 8: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108

38. Stomach cancer incidence trends • general decline in rates among both developed and developing countries because of improved food preservation practices (refrigerators) and better nutrition (higher vegetable and fruit intake)

39. Stomach cancer mortality trends • generally declining in both less and more developed regions

40. Prostate cancer • 679,000 new cases and 221,000 deaths worldwide estimated in 2002 • 2nd most common new cancer and most prevalent form of cancer among males • 75% of cases occur in men aged 65+ • prostate-specific antigen assay introduced in mid to late ‘80s

41. Age-standardized incidence rates for prostate cancer Source: Figure 5: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108

43. Prostate cancer incidence trends • in many developed countries incidence increased greatly, especially among younger men (<65 yrs) • most dramatic increases are in high-risk areas partly due to detection of prevalent latent cancers using PSA • less developed countries also increasing

44. Prostate cancer mortality trends • generally increasing but not as dramatically as incidence • since 1990s, decline in several developed countries attributed to earlier detection and improved treatment

45. Liver cancer • 626,000 new cases and 598,000 deaths worldwide estimated in 2002 • 6th most common cancer and 3rd most common cause of deaths from cancer • 82% of cases occur in developing countries (55% in China) • male:female ratio is about 2.4

46. Age-standardized incidence rates for liver cancer Source: Figure 10: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108

48. Liver cancer incidence trends • difficult to interpret because of ICD revisions • 7th revision includes gall bladder cancer • 9th revision includes category of “unspecified 10 or 20” • ↓ among Chinese because of ↓ in prevalence of HBV • ↑ in Japan because of ↑ alcohol consumption and HCV prevalence • ↑ in developed countries possibly from ↑ HCV infection (from transfusions and drug use)

49. Liver cancer mortality trends • similar to incidence trends • increase in mortality among developed countries not necessarily from alcohol (since mortality from liver cirrhosis is decreasing)