Pathopoiesis Mechanism of Smoking and Shared Genes in Pancreatic Cancer
To raise new questions, new possibilities, to regard old problems from a new angle requires creative imagination and marks the real advance in science (Einstein & Infeld, 1938, p. 92).
Pancreatic cancer (PC) at the start of the 21st century continues to be a vital unresolved health problem, remaining as one of the deadliest human cancers. By the year 2030, it is projected that PC will be the second leading cause of cancer death after lung cancer among the major types of cancer (Rahib et al. 2014). The outcome of this study would provide valuable insights into the etiopathogenesis of PC and cancer types with a shared-gene association (CTSG-A), as well as the possible recognition of the probable unique pattern of PC malignancy among defined age groups, between men and women, in correlation to the modification effect of smoking to cancer predisposition genes (CPG), or its combined impact. Additional understanding of the pathopoiesis dynamics of smoking status, gender, and age in individuals with CPG in the induction and promotion of PC could help promote pre- and post behavioral diagnosis change. This study may assist in developing a novel patient management approach to accurately assess the disease burden under the lens of public health and modern epidemiology. Although genetic changes can be either somatic or hereditary, described as de novo (new), PC does not arise de novo (Maitra & Hruban, 2008), but rather initiated by a probable gene mutation such as p16/CDKN2A that results to debilitating metabolic effects of uncontrolled growth. Given the assumption that a disease is caused by a factor that can be controlled, exploring the relationship between modifiable health behaviors such as smoking and family cancer history (FCH), CPG or shared genes was a legitimate endeavor. In this study, genetic syndromes associated with PC were interchangeably referred to as FCH, CPG, or shared genes. Pancreatic cancer and other cancers found to have a shared-gene association (S-GA) were the dependent variables, and smoking status, age, and gender were the independent variables; this study addressed the following research questions (RQs) and hypotheses:
RQ1: Is cigarette smoking associated with the etiopathogenesis of pancreatic cancer and cancer types with shared gene association (CTSG-A)?
H01: Smoking level has no correlation with prevalence of PC and CTSG-A.
H1: Smoking can increase the risk of PC and CTSG-A.
RQ2: Is there a relationship between the combined role of age and gender in the etiopathogenesis of PC and CTSG-A?
H02: Age and gender have no correlation with prevalence of PC and CTSG-A.
H2: Age and gender are correlated with the prevalence of PC and CTSG-A.
The unique contribution of this dissertation to the current body of knowledge involved examining the links between tobacco use, gender, age, PC, and shared genes. This dissertation could promote population health, and lessons learned could reshape the current understanding of cancer epidemiology by providing the scientific justification for the implementation of screening, surveillance, and education programs. The outcome of this dissertation would fit into the practical intervention approach of adopting a healthy lifestyle such as smoking cessation as part of positive, meaningful social change to improve prognosis and quality of life during PC progression.
Pandol et al. (2012) noted the economic burden of PC with an expected yearly cost of $4.9 billion and underscored the significance of determining the mechanisms underlying the effect of smoking compounds that may provide additional insights into the pathogenesis of the disease. The investigation gave valuable insights into the etiopathogenesis of pancreatic growth from its induction and promotion. Moreover, findings of Hart, Kennedy, and Harvey (2008); and Schenk et al. (2001) support the unique probable contribution of this dissertation to the existing body of knowledge, generating a snapshot of a possible correlation of smoking, gender, and age to the development of PC and CTSG-A, enhancing the knowledge on the pathopoiesis mechanism of these predictors in disease induction and promotion. The plethora of findings of the past and present studies highlighted the causal significance of modifiable risk factors and genetics in the pathosis of PC. The goal of these studies falls largely within the confines of understanding the insights of genetic alterations and specific modifiable risk factors. Much of the recent research concentrates in this line of inquiry; therefore, recognizing the modifying effect of smoking to individuals with family aggregation justifies the merit of this dissertation and future endeavors.
Blackford et al. (2009) noted that previous researchers overlooked the distinction between the passenger and driver mutations that explains the often unconvincing associations between smoking and driver mutations. Recognizing this gap, and while there are continued studies on different aspects of the PC genomic landscape, this dissertation intends to provide a descriptive analysis of the prevalence pattern of PC and CTSG-A known to have increased risk of extrapancreatic malignancies versus nonsmokers. The mechanisms through which smoking, gender, age, and CPG affect PC remain unknown, making it critical to explore the role of these three predictors in the disease clustering to develop a more efficient management and clinical approach. With an exhaustive understanding of the patterns of somatic alteration in pancreatic carcinogenesis comes the opportunity to understand the influence of these factors on metastatic progression (Yachida & Iacobuzio-Donahue, 2013). The burden of chronic diseases such as PC is often neglected on the public agendas. The increasing annual economic burden of PC is beyond genetics and social inequalities, making it necessary to embrace the shift in the level of analysis from traditional to modern epidemiologic and New Public Health approach. The significance of the successful delivery of the New Public Health both at the level of society and individual behavior (Halpin et al., 2010) justifies the intent of this dissertation on the need for further exploration of the pathopoiesis mechanism of tobacco use and FCH, the etiopathogenic role of gender and age. The unveiling of the “Precision Medicine Initiative” during the State of the Union Address of President Barack Obama on January 20, 2015, springboard the new effort of revolutionizing a new model of patient-powered research that could accelerate biomedical discoveries and provide clinicians with new tools, knowledge, and therapies. New research directions are warranted to reverse the lethal outcome of this disease.
Study Design and Approach
The causality of tobacco-related mutagenic risk factors and the correlation between gender and age and CPG will not only raise awareness of the significance of cancer risk screening and counseling but will also increase the understanding of environmental, genetic, and biodemographic interaction (EGBI) contributing to the development and progression of PC. The results of this study may be used to promote lifestyle change in reducing cancer risk. Improving the perceived corollary of individuals with inherited genes and quality of life during the expression or final stage of the disease is dependent on the favorable adjustment of behavioral risk factors. This study intended to explore the association between smoking, gender, and age in individuals with CPG. I used a cross-sectional design to determine the prevalence of pancreatic cancer and CTSG-A among smokers and non-smokers. The potential association of smoking, gender, and age as predictors of the outcome variable (PC/CTSG-A) were explored using a cross-sectional design. Secondary data were recoded and randomized using IBM Statistical Package for the Social Sciences (SPSS, Version 23, 64-bit edition). Although logistic regression makes no assumptions about the distributions of the predictor variables (smoking, gender, age), ordinal modeling was the fundamental property of the design of this study to test whether smoking level and age are effect modifiers to inherited genes or combined causative predictors in the induction and promotion of PC and CTSG-A.
The population for the study was defined as participants of the Behavioral Risk Factor Surveillance System (BRFSS) survey. Subject selection criteria were set narrowly, by selecting specifically those who smoke and do not smoke with PC/CTSG-A (survivorship module), versus non-smokers with PC/CTSG-A. Association between smoking, age, gender, PC, and PC/CTSG-A are explored using hypothetical conceptual cohort. A hypothetical conceptual cohort is defined as participants from the 2014 BRFSS survey who qualified as high-risk based on the level of smoking. The dependent variable under Level 1 or Category 1 in this dissertation comprised cancer types with P16(CDKN2A) and PRSS1 mutations. The cancer types that were included as part of this category were pancreatic, melanoma, esophageal, leukemia, lung, bladder, renal, brain, osteosarcoma (bone), and cancer of the head and neck. Level two or category two includes cancer types with BRCA1, STK11, and LKB1 mutations. While p16 is related to breast cancer, BRCA1 is two times to have a relative risk of PC, with higher risk by age 70. The cancer types that are considered to be part of this category are breast, ovarian, and prostate cancer. Level three or category three are composed of cancer types with bMLH1, and bMSH2 mutations. The cancer types in this category are endometrial, colorectal, and stomach cancer. Regression methods were used to assess and adjust for confounding, and determine whether there is effect modification, as well as simultaneously evaluate the relationships of risk factors (smoking, age, gender). Given that this study involves PC/CTSG-A, and more than one independent variables, ordinal logistic regression analysis was performed to assess confounding and effect modification. The impact of multiple risk factors (smoking, gender, age) is examined as opposed to focusing on a single risk factor. Two separate logistic regression analyses were conducted to assess differences in induction and promotion of pancreatic cancer/CTSG-A by gender and three age groups (<51, 52-69, 70>).
The effect of tobacco use, age, and sex in the etiopathogenesis of PC and CTSG-A was assessed using cumulative odds ordinal logistic regression with proportional odds. While the results of this study supported the null hypotheses that smoking does not correlate with the prevalence of PC and CTSG-A as confirmed by the GENLIN parameter estimates, both gender and age are statistically significant predictors with <.05 p-values. The odds of male respondents developing PC and CTSG-A versus the female respondents is .418 (95% Cl, .344 to .509) with a statistically significant effect, X2 (1) = 75.507. The odds ratio of 1.374 (95% CI, 1.184 to 1.595), Wald χ2(1) = 17.538 is suggestive to the increased probability of developing the disease as the persons reach the age between 62 and 69 years of age. Separate binomial logistic regression analysis shows age was associated with an increased likelihood of developing the disease. Analogous to the results of the ordinal logistic regression analysis, the odds of the male participants of the 2014 BRFSS survey is 2.472 times greater to develop the disease as opposed to female respondents. The findings of this study could support the importance of behavioral risk factor and their roles in reducing the prevalence of PC and CTSG-A, enhancing the late-stage quality of life.
Ab-initio studies have established that family history of PC can manifest due to genetic factors and shared environmental factors. The scientific perspective of this dissertation, current, and past studies are parallel to Albert Einstein’s concept of “natura naturans”—everything is connected. In this dissertation, the assumption that P16(CDKN2A), PRSS1, BRCA1, STK11, LKB1, bMLH1, and bMSH2 are correlated with the development of the disease is mathematically or statistically correct and deserves further investigation.
Presenting a New Metatheory
The Unified Paradigm of Cancer Causation (UPCC), a metatheory introduced in this dissertation could provide arguments on the positive association (synergism) between tobacco use and FCH, giving more clarity to Rothman’s notion of epidemiologic interaction or the paradigm of sufficient cause. UPCC is a composite construct of the germ theory and the somatic mutation theory of carcinogenesis (SMT) in combination with the traditional or Darwinian evolutionary system (Greaves & Maley, 2012), Knudson’s two-hit theory (Hermanowicz, 2015), genome theory, Darwinian theory of social change (Richerson & Boyd, 2000), and the multi-level biologic, social integrative construct (MBASIC). The theoretical cocktail of UPCC could interlock new insights on tumor initiation, metastases diagnostic, and treatment strategies. The dynamic interplay of gene-culture transmission recognized in UPCC could initiate the evolution of culture that embraces the value of evidence-based screening, surveillance, management, and personal genomics. Central to human adaptations is the use of socially learned information (Richerson, Boyd & Henrich, 2010), from literacy program of a health system, emphasizing the significance of 21st-century approach. The combined causal association of a variety of levels as recognized by Lynch and Rebbeck (2013) that are linked to cancer incidence and mortality justify the supposition of UPCC. It is critical to underscore the magnitude of intercalating the mandatory early screening, and management of the health system. The complex, integrative approach of UPCC supports the views of Loomis, and Wing (1990), Pearce (1996), and McEwen and Getz (2013) in embracing the new epidemiologic paradigm congruent to the advances in cancer genome sequencing. Theorizing the pathopoiesis mechanism of smoking, inherited genes, and association of gender and age in the etiopathogenesis of PC/CTSG-A warrants exploration of its causal footprints, conjoining both biomedical and lifestyle (Krieger, 2011).
New Public Health at the Level of Society and Individual Behavior
Darwinism is a collection of concepts, empirical methods and mathematical tools designed to understand the dynamics of genetics and cultural evolution (Richerson & Boyd, 2000). Therefore, this dissertation supports the rationale of cultural value transmission of smoking cessation that could lower the risk to individuals with CPG. Smoking cessation as a cultural item is a clear implication for positive social change. While smoking cessation is the probable social implication of this dissertation, it is important to stress the epidemiologic value of a study on the apparent correlation between gender and age, modification effect of tobacco use among individuals with PC and CTSG-A. The outcome of a risk factor epidemiologic study in individual terms could uplift precision medicine to meet the challenges in tailoring medical interventions based on patient’s biological profile, genetic and epigenetic traits, giving a better understanding of EGBIs. The results of this dissertation have several implications for social change, such as recognizing cultural values in developing effective communication structured from the statistically significant etiopathogenic role of gender and age in the development of PC and CTSG-A. This will give a clear understanding of what to ask, and what actions to take, allowing the family to openly explore treatment alternatives during the terminal phase of the illness (Ballard-Reisch & Letner, 2003). Primary prevention must be prioritized as an integral part of global cancer control. No regulatory standards nor advanced innovations could change the hearts and minds of the general population unless evidence-based studies support it. Social change will be dependent upon the continued dissemination of current cancer research built on integrative social molecular pathological epidemiology (MPE). Pearce (1996) argue that epidemiology must reintegrate itself into public health and must rediscover the population perspective. However, while the new paradigm of downstream (individual) approach could produce a lifestyle approach to social policy, the cumulative outcome of research in cancer epidemiology could equate positive implications to population health.
Improving the future of individuals diagnosed with PC through the concerted efforts of policymakers, public health professionals, clinicians and scientists, the Recalcitrant Cancer Research Act of 2012 lays the foundation for a heightened focused on further development and use of prevention, screening and therapeutic strategy (Rahib et al., 2014). The genuine progress against PC as recalcitrant cancer warrants strategic direction and guidance on the continued understanding, development of efficient early detection strategy and identifying therapeutic targets that could stem the tide of its growing economic burden.
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