Detectable Symptomatology and Risk of Pancreatic Cancer
Detectable Symptomatology and Risk of Pancreatic Cancer
Distributions of the various factors among cases and controls are given in Table 1. Cases were on average 1–2 years older than controls and included slightly larger percentages of other races than of whites. Body mass indices (weight in kilograms divided by the square of height in meters) were similar for cases and controls, although slightly more cases were obese (body mass index >30) than controls, especially among men. History of pancreatic cancer among first-degree relatives, non-O blood group, Jewish ancestry, and H. pylori seropositivity were more prevalent among cases. Cases also smoked more and longer than controls, were more likely to be current smokers, and had quit for less time. History of diabetes mellitus, pancreatitis, and regular use of proton-pump inhibitors were all more frequent among cases than among controls and occurred at older ages. Ever regular use or current use of histamine receptor-antagonist medications and of antacids did not show substantial case-control differences.
Table 2 shows parameter estimates and odds ratios for the factors used in predicting absolute 5-year risks, including the 4 time variables in the exponential time-decay model β1 I exp(−β2 t), as described above. In our data, not all of the time parameters had statistically significant parameter values at a 2-sided P value of 0.05; however, they have been retained in the model because of evidence from the literature that the magnitudes of risk decline over time. Figure 1 gives graphical presentations of the decline in the odds ratio of pancreatic cancer by how many years in the past diabetes was diagnosed, cigarette smoking ceased, proton-pump inhibitor use started, and pancreatitis occurred. In each of the figure panels, we also show the odds ratio and its 95% confidence limits according to strata of 0–2 years in the past and additional past intervals when the factor occurred. The continuous odds ratio in each panel is seen to lie within the category 95% confidence limits in all cases and generally does a good job of representing the category odds ratios over past time.
(Enlarge Image)
Figure 1.
Estimated odds ratio for pancreatic cancer in a case-control study, Connecticut, 2005–2009. The odds ratio is calculated as a continuous value according to the model formula exp{β1 I exp(−β2 t)}, where I denotes personal history of the particular factor (0 or 1) and t its time-in-the-past variable (in years). Shown in the figure is the continuous odds ratio, along with the odds ratio of the factor grouped according to categories of years before interview when the factor occurred. A) Diagnosis of diabetes mellitus; B) current cigarette smoking or smoking cessation; C) start of proton pump-inhibitor use; and D) diagnosis of pancreatitis. The thick continuous dashed lines indicate the estimated model odds ratios; dotted continuous lines, 95% confidence limits for the model odds ratios; thick black horizontal step lines, estimated odds ratios for the categories of years before interview; and shaded boxes, 95% confidence limits for the category odds ratios. Category widths were chosen in order to obtain approximately equal numbers of control subjects in each group.
Table 3 gives estimated absolute risks of developing pancreatic cancer over 5 years by categories of age and sex according to various combinations of the risk factors listed in Table 2. These risks are estimated directly as SEER/D, as outlined above. At all ages, lifelong nonsmokers of non-Jewish ancestry and with O blood type who had never been diagnosed with diabetes or pancreatitis or regularly used proton-pump inhibitors had 5-year risks of less than 0.15%. Such unexposed individuals are infrequent, comprising 3.3% of cases and 13% of controls. Various combinations of the risk factors led to estimated risks that reached 5%–10% in the older age groups. These combined-factor risk scenarios were found among our study subjects and are not extrapolations. For example, smokers who had had pancreatitis comprised 1.3% of controls and 4.4% of cases, and proton-pump inhibitor users with diabetes comprised 2.6% of controls and 8.8% of cases. In total, 0.87% of controls had estimated 5-year absolute risks of 5% or higher.
Results
Distributions of the various factors among cases and controls are given in Table 1. Cases were on average 1–2 years older than controls and included slightly larger percentages of other races than of whites. Body mass indices (weight in kilograms divided by the square of height in meters) were similar for cases and controls, although slightly more cases were obese (body mass index >30) than controls, especially among men. History of pancreatic cancer among first-degree relatives, non-O blood group, Jewish ancestry, and H. pylori seropositivity were more prevalent among cases. Cases also smoked more and longer than controls, were more likely to be current smokers, and had quit for less time. History of diabetes mellitus, pancreatitis, and regular use of proton-pump inhibitors were all more frequent among cases than among controls and occurred at older ages. Ever regular use or current use of histamine receptor-antagonist medications and of antacids did not show substantial case-control differences.
Table 2 shows parameter estimates and odds ratios for the factors used in predicting absolute 5-year risks, including the 4 time variables in the exponential time-decay model β1 I exp(−β2 t), as described above. In our data, not all of the time parameters had statistically significant parameter values at a 2-sided P value of 0.05; however, they have been retained in the model because of evidence from the literature that the magnitudes of risk decline over time. Figure 1 gives graphical presentations of the decline in the odds ratio of pancreatic cancer by how many years in the past diabetes was diagnosed, cigarette smoking ceased, proton-pump inhibitor use started, and pancreatitis occurred. In each of the figure panels, we also show the odds ratio and its 95% confidence limits according to strata of 0–2 years in the past and additional past intervals when the factor occurred. The continuous odds ratio in each panel is seen to lie within the category 95% confidence limits in all cases and generally does a good job of representing the category odds ratios over past time.
(Enlarge Image)
Figure 1.
Estimated odds ratio for pancreatic cancer in a case-control study, Connecticut, 2005–2009. The odds ratio is calculated as a continuous value according to the model formula exp{β1 I exp(−β2 t)}, where I denotes personal history of the particular factor (0 or 1) and t its time-in-the-past variable (in years). Shown in the figure is the continuous odds ratio, along with the odds ratio of the factor grouped according to categories of years before interview when the factor occurred. A) Diagnosis of diabetes mellitus; B) current cigarette smoking or smoking cessation; C) start of proton pump-inhibitor use; and D) diagnosis of pancreatitis. The thick continuous dashed lines indicate the estimated model odds ratios; dotted continuous lines, 95% confidence limits for the model odds ratios; thick black horizontal step lines, estimated odds ratios for the categories of years before interview; and shaded boxes, 95% confidence limits for the category odds ratios. Category widths were chosen in order to obtain approximately equal numbers of control subjects in each group.
Table 3 gives estimated absolute risks of developing pancreatic cancer over 5 years by categories of age and sex according to various combinations of the risk factors listed in Table 2. These risks are estimated directly as SEER/D, as outlined above. At all ages, lifelong nonsmokers of non-Jewish ancestry and with O blood type who had never been diagnosed with diabetes or pancreatitis or regularly used proton-pump inhibitors had 5-year risks of less than 0.15%. Such unexposed individuals are infrequent, comprising 3.3% of cases and 13% of controls. Various combinations of the risk factors led to estimated risks that reached 5%–10% in the older age groups. These combined-factor risk scenarios were found among our study subjects and are not extrapolations. For example, smokers who had had pancreatitis comprised 1.3% of controls and 4.4% of cases, and proton-pump inhibitor users with diabetes comprised 2.6% of controls and 8.8% of cases. In total, 0.87% of controls had estimated 5-year absolute risks of 5% or higher.
