Chapter 4: Cancer incidence in Canada: trends and projections (1983-2032) – Pancreas cancer - HPCDP: Volume 35, Supplement 1, Spring 2015

Chapter 4: Projections by Cancer Site

6. Pancreas cancer

Cancer of the pancreas is the second most common digestive system cancer after colorectal cancer. One in 71 males and 1 in 69 females can expect to be diagnosed with pancreas cancer in their lifetime, and 1 in 72 males and 1 in 71 females can expect to die from it.^{Endnote 1} The average annual number of new cases in 2003–2007 was 1810 in males and 1900 in females (Tables 4.6.1 and 4.6.2), approximately 2.2% and 2.6% of all male and female cancer cases, respectively. Pancreas cancer is the fourth leading cause of cancer death in Canada and has the lowest 5-year relative survival rate, at just 8% in 2006–2008.^{Endnote 1} This poor prognosis results from 80% of the cancers being diagnosed at a late stage.^{Endnote 111}

Between 2003 and 2007, the incidence rates of pancreas cancer increased steadily with age, to 97.1 per 100 000 in males aged 85 or older and 97.8 per 100 000 in females of the same age (Tables 4.6.3 and 4.6.4).

Overall, males were 21% more likely to be diagnosed than were females (ASIR of 10.3 and 8.5, respectively). The disease was rarely seen before age 45, with only 3% and 2% of all male and female pancreas cancer cases diagnosed in that age group, respectively (Tables 4.6.1 and 4.6.2). Approximately 64% of the new pancreas cancers in males occurred in those aged 65 or older; the corresponding percentage for females was 75%. Figure 4.6.2 shows the ASIRs decreasing and then stabilizing over time for both sexes. The male-to-female ratio of ASIRs decreased over time also, becoming stable or uniform in the last observation period (2003–2007) in each age group.

Figure 4.6.1 shows that the downward trend in overall male ASIRs had levelled off in the last 2 observation periods, while the rates in females had changed little throughout the entire observation period. During 1998–2007, ASIRs remained relatively constant, although they decreased non-significantly in males by 0.3% per year and increased non-significantly by 0.4% per year in females (Figures 3.1 and 3.2).

The projections of male pancreas cancer incidence show stability in the predicted rates for Canada and its regions except in Quebec and the Atlantic region (Figure 4.6.1). The male rates in Quebec are expected to decrease by 10%, from 12.2 per 100 000 in 2003–2007 to 10.9 per 100 000 in 2028–2032, whereas incidence rates in the Atlantic region will rise by 16%, from 10.9 to 12.7 per 100 000 over the same period. For females, the analysis shows predicted stability in the Canadian and regional rates. The Atlantic region, which used to have relatively low incidence, is predicted to experience the highest rates, while Ontario will continue to have the lowest incidence in males. For females, Quebec and Ontario will remain in their respective highest and lowest ranking in the rates.

The overall age-specific incidence rates in Canada are expected to stabilize in each age group (Figure 4.6.2). The difference in ASIRs between sexes appears to narrow with advancing age, starting from age 45.

From 2003–2007 to 2028–2032, the pancreas cancer ASIRs in Canada are projected to remain stable in males, at 10.3 to 10.5 per 100 000, and to increase by 7% in females, from 8.5 to 9.1 per 100 000 (Tables 4.6.3 and 4.6.4). The annual number of male cases is projected to increase by 101%, from 1810 to 3635, and the number of female cases, by 96%, from 1900 to 3730 (Tables 4.6.1 and 4.6.2).

Comments

Lower incidence rates for cancer of the pancreas occurred in Newfoundland and Labrador, especially in females. These low rates are likely artefactual, given that death certificate information for Newfoundland and Labrador was not available for the data used in this study (see details in Chapter 5).

The International Agency for Research on Cancer (IARC) stated that tobacco smoking is the most important modifiable risk factor for pancreas cancer.^{Endnote 47, Endnote 86} Smoking doubles the risk of developing pancreas cancer compared with not smoking,^{Endnote 86} and about 27% to 33% of pancreas cancers are caused by tobacco smoking.^{Endnote 52, Endnote 112} The latency time between starting smoking and developing pancreas cancer is approximately 20 years.^{Endnote 113, Endnote 114} The evidence also suggests that between 5% and 10% of all cases of pancreas cancer have a hereditary component,^{Endnote 115} and having a family history of pancreas cancer significantly increases the risk (odds ratio = 3.2, 95% CI: 1.8 – 5.6).^{Endnote 115} Certain hereditary conditions such as hereditary pancreatitis also increase the risk.^{Endnote 53, Endnote 111, Endnote 116}

The role of dietary factors in the etiology of pancreas cancer is inconclusive. The 2012 World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) report stated that there is limited and inconclusive evidence that foods containing folate protect against pancreas cancer, but suggests that diets high in fruits decrease risk and diets high in red meats increase risk.^{Endnote 117} A recent large pooled analysis of 14 prospective cohort studies published during 1994–2010 concluded that dietary folate intake is not associated with the risk.^{Endnote 118} Moderate consumption of coffee and alcohol do not appear to increase risk, but heavy alcohol drinking and alcohol bingeing may increase risk.^{Endnote 86}

The 2012 summary of 23 prospective studies indicates an increase in pancreas cancer risk with increasing BMI.^{Endnote 119} The 2 systematic reviews report that occupational physical activity is protective, while recreational activity exposures are not significantly associated with the risk for pancreas cancer.^{Endnote 120, Endnote 121} Recent meta- and pooled analyses show that diabetes is associated with 40% to 94% increased risk of pancreas cancer.^{Endnote 122, Endnote 123} However it remains unclear whether diabetes is an early manifestation or an etiological factor of pancreas cancer.^{Endnote 122}

Similar trends in pancreas cancer incidence rates are observed in Great Britain.^{Endnote 124} The observed changes in the ASIRs of pancreas cancer for males and females partly reflects the change patterns of smoking in Canadian population,^{Endnote 42, Endnote 43} given the latency period.