Journal of Preventive Medicine

Introduction
Pancreatic cancer is the 12th most common cancer in men and the 11th most common cancer in women. More than 495,000 new cases of this cancer were reported in 2020. The most common type of pancreatic cancer is adenocarcinoma, which accounts for more than 90% of all pancreatic cancers. Only about 6% of people with this disease survive for 5 years after diagnosis; the one-year survival rate after diagnosis is 24%. Recent studies in Iran have shown that the prevalence of pancreatic cancer is increasing. This increase has been reported more in men and in people over 60 years of age. Although many epidemiological studies have been conducted to determine the risk factors of this disease, the underlying causes are still not fully understood. Almost like all cancers, genetic and environmental factors play an important role in the development of pancreatic cancer. A family history of cancer indicates the presence of one or more inherited faulty genes causing cancer in the family. Environmental factors such as smoking and drug abuse also have a role in the occurrence of this disease. Evaluation of general characteristics (e.g., age, gender, history of cancer, family history of cancer) and manifestations of adenocarcinoma in people suffering from this disease is particularly important in identifying possible risk factors of adenocarcinoma. This study aims to investigate the general characteristics and manifestations of adenocarcinoma.
Methods
The study population included all patients with adenocarcinoma referred to Firouzgar Hospital in Tehran, Iran in 2020 (600 patients including 352 males and 248 females). After evaluating the entry and exit criteria, demographic information and possible risk factors were extracted from the medical files of participants. Inclusion criteria were having adenocarcinoma and complete medical records. The exit criteria were the existence of a disease other than adenocarcinoma and incompleteness of the medical records. Data were collected using a two-part checklist surveying demographic information (age, gender, blood group, history of diabetes, history of pancreatitis, use of cigarettes, opium, methamphetamine, alcohol, hookah and other drugs, history of high blood pressure, history of viral hepatitis, history of other cancers, history of inflammatory bowel disease, history of primary sclerosing cholangitis, history of gallstones, and history of gallbladder polyps) and disease-related information (tumor location and disease manifestations). Data analysis was done in SPSS v. 16 software. Mean and standard deviation were used to describe quantitative data, and frequency and percentage were used to describe qualitative data.
Results
In this study, 600 patients participated. Their mean age was 62.02±13.31 years; 58.7% were male and 41.3% were female;194 were housekeeper (32.3%) and only 10 were retired (1.7%).
In the examination of endoscopic ultrasound, the most involved area in the pancreas was the head of the pancreas. The most common complaint and manifestation of the disease was stomachache. The main symptoms and manifestations of the disease included abdominal pain, jaundice, weight loss and itching. Moreover, 100 patients (16.7%) had a history of diabetes, 78 patients (13%) had a history of diabetes in their first-degree relatives, and 91 patients (15.2%) had a history of diabetes in themselves and in their first-degree relatives. Furthermore, 96 patients (16%) had a history of high blood pressure, 93 patients (15.5%) had a history of high blood pressure in their first-degree relatives, and 77 patients (12.8%) had a history of high blood pressure in themselves and in their first-degree relatives. Among the 600 patients with adenocarcinoma, 34.8% (n=209) had a history of cigarette smoking. Risk factors with lowest frequency included heroin use, history of extrahepatic gallstones, history of viral hepatitis, use of methadone, hookah, alcohol, and history of pancreatitis. None of the patients with adenocarcinoma had a personal history of inflammatory bowel disease and gallbladder polyps.
Discussion
In overall, the results of the present study revealed cigarette smoking, family history of other cancers, opium use, history of type 2 diabetes and history of high blood pressure as the most common risk factors of pancreatic adenocarcinoma. These risk factors have the capacity to be investigated in observational studies, including case-control and cohort studies. One of the most important limitations of the present study was the lack of a control group. Moreover, investigating possible risk factors only in patients cannot prove to be a risk factor in the study population. It is recommended that observational studies in this field be conducted. In the present study, it was not possible to measure genetic polymorphisms. Therefore, it is recommended to measure these factors in future studies.

Ethical Considerations
Compliance with ethical guidelines
This study was a retrospective study after obtaining the code of ethics from the Ethics Committee of Iran University of Medical Sciences (code of ethics IUMS.FMD.REC.1399.237) was done.

Funding
This article is financially supported by the research vice-chancellor of the Iran University of Medical Sciences, Tehran, Iran (Grant No.: 17033-4-1-99).

Authors' contributions
Collecting samples, analyzing data, drafting the article and conducting experiments: Abolfazl Ghaffari; Guidance, analysis of the results and writing of the article: Amirhossein Faraji; Collaboration in initial data analysis and checklist preparation: Mehdi Nikkhah; Consulting and writing: Hossein Azderkash; Statistical consulting and data analysis: Mahmoudreza Khoonsari; Collaboration in sample preparation, data analysis and consultation: Elham Sobh Rakhshankhah.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
The researchers of this study acknowledged the Research Vice-Chancellor of the Iran University of Medical Sciences and the medical staff of Firouzgar Hospital for their cooperation in the various stages of this research project.


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