Abstract
The use of opium has been classified by the International Agency for Research on Cancer (IARC) as a carcinogenic to humans (Group 1 carcinogen), but there is still a lot that needs to be clarified regarding the association between opium use and cancer. To study this association further, I used the data collected by the Iranian Opium and Cancer (IROPICAN) study in ten provinces of Iran. This study focuses on examining the association between opium use and cancers of the head and neck, bladder, colon, and rectum. The overall aim of this project is to evaluate the association between the consumption of opium and cancers of the head and neck, colorectum, and bladder.
This dissertation utilized 633 histologically confirmed cancer cases of head and neck squamous cell carcinoma (HNSCC), 717 cases of bladder cancer (BC), 848 cases of colorectal cancer (CRC), and 3,477 common controls selected from hospital visitors who did not have cancer and were not relatives or friends of the cancer cases. The extensive questionnaire used in the study covered a variety of topics, including opium use (e.g., information on age at initiation, duration, frequency, typical amount, and route), as well as potential confounding factors such as tobacco use (e.g., cigarettes, nass, and waterpipe), and dietary factors. The response rate was 99% for the cancer cases and 89% for the controls.
In the validation and pilot phases of the study, the reported opium use showed a reasonably good level of accuracy, with a sensitivity of 70% for cancer cases and 69% for controls. The study showed excellent reliability with intra-class correlation coefficients of 0.96 for ever opium use and 0.88 for regular opium use.
Multivariable unconditional logistic regression models were used to estimate the odds ratios (OR) and 95% confidence intervals (CI). The ORs were adjusted for potential confounders for each cancer type. Regular opium use was associated with a highly increased risk of HNSCC (OR: 3.8, 95% CI: 3.0, 4.8). There was a strong dose–response relationship between opium use and HNSCC risk, with increasing risk seen with higher frequency and amount of use, and with longer duration. Regular opium use was found to significantly increase the risk of cancers of the pharynx OR 2.9, 95% CI: 1.4, 6.0), larynx (OR 6.6, 95% CI: 4.7, 9.1), and other sites within the head and neck region (OR: 6.0, 95% CI: 2.4, 14.7). There was a significant interaction between opium use and cigarette smoking affecting HNSCC risk, with an OR of 8.2 (95% CI: 6.2, 10.7) among those who used opium and smoked cigarettes at the same time compared to those who had never used anything, but the association with opium remained significant among individuals who had never used tobacco.
Regular opium consumption was also associated with an increased risk of BC, with an OR of 3.5 (95% CI: 2.8, 4.3) compared to those who had never used opium. The risk of BC decreased to one-third among individuals who had stopped using opium more than ten years before the date of the interview, compared to those who still used opium. The risk of developing BC was found to be 4.8 (95% CI: 3.7, 6.3) among current opium users. However, for those who had stopped using opium more than 10 years prior to the interview, the risk of BC decreased to 1.5 (95% CI: 1.0, 2.4). The OR for individuals who used both crude opium (teriak) and opium juice was 7.4 (95% CI: 4.1, 13.3). There was a joint effect of opium and tobacco, with an OR of 7.7 (95% CI: 6.0, 9.7) for individuals who used both opium and tobacco.
No association was found between regular opium consumption and the risk of CRC (OR 0.9, 95% CI: 0.7, 1.2) compared to individuals who never used opium. Still, the study suggests that opium use two or more times per day may be associated with an increased risk of CRC with an OR of 2.0 (95% CI: 1.1, 3.8) compared to non-users of opium.
Regular opium use was found to be strongly associated with an increased risk of developing BC and HNSCC, but the link between regular opium use and CRC was weak. The studies included in my thesis will add to the understanding of the impact of opium use on the risk of developing cancer in the head and neck, bladder, colon, and rectum, and serve as a crucial background for future investigations in this field.
This dissertation utilized 633 histologically confirmed cancer cases of head and neck squamous cell carcinoma (HNSCC), 717 cases of bladder cancer (BC), 848 cases of colorectal cancer (CRC), and 3,477 common controls selected from hospital visitors who did not have cancer and were not relatives or friends of the cancer cases. The extensive questionnaire used in the study covered a variety of topics, including opium use (e.g., information on age at initiation, duration, frequency, typical amount, and route), as well as potential confounding factors such as tobacco use (e.g., cigarettes, nass, and waterpipe), and dietary factors. The response rate was 99% for the cancer cases and 89% for the controls.
In the validation and pilot phases of the study, the reported opium use showed a reasonably good level of accuracy, with a sensitivity of 70% for cancer cases and 69% for controls. The study showed excellent reliability with intra-class correlation coefficients of 0.96 for ever opium use and 0.88 for regular opium use.
Multivariable unconditional logistic regression models were used to estimate the odds ratios (OR) and 95% confidence intervals (CI). The ORs were adjusted for potential confounders for each cancer type. Regular opium use was associated with a highly increased risk of HNSCC (OR: 3.8, 95% CI: 3.0, 4.8). There was a strong dose–response relationship between opium use and HNSCC risk, with increasing risk seen with higher frequency and amount of use, and with longer duration. Regular opium use was found to significantly increase the risk of cancers of the pharynx OR 2.9, 95% CI: 1.4, 6.0), larynx (OR 6.6, 95% CI: 4.7, 9.1), and other sites within the head and neck region (OR: 6.0, 95% CI: 2.4, 14.7). There was a significant interaction between opium use and cigarette smoking affecting HNSCC risk, with an OR of 8.2 (95% CI: 6.2, 10.7) among those who used opium and smoked cigarettes at the same time compared to those who had never used anything, but the association with opium remained significant among individuals who had never used tobacco.
Regular opium consumption was also associated with an increased risk of BC, with an OR of 3.5 (95% CI: 2.8, 4.3) compared to those who had never used opium. The risk of BC decreased to one-third among individuals who had stopped using opium more than ten years before the date of the interview, compared to those who still used opium. The risk of developing BC was found to be 4.8 (95% CI: 3.7, 6.3) among current opium users. However, for those who had stopped using opium more than 10 years prior to the interview, the risk of BC decreased to 1.5 (95% CI: 1.0, 2.4). The OR for individuals who used both crude opium (teriak) and opium juice was 7.4 (95% CI: 4.1, 13.3). There was a joint effect of opium and tobacco, with an OR of 7.7 (95% CI: 6.0, 9.7) for individuals who used both opium and tobacco.
No association was found between regular opium consumption and the risk of CRC (OR 0.9, 95% CI: 0.7, 1.2) compared to individuals who never used opium. Still, the study suggests that opium use two or more times per day may be associated with an increased risk of CRC with an OR of 2.0 (95% CI: 1.1, 3.8) compared to non-users of opium.
Regular opium use was found to be strongly associated with an increased risk of developing BC and HNSCC, but the link between regular opium use and CRC was weak. The studies included in my thesis will add to the understanding of the impact of opium use on the risk of developing cancer in the head and neck, bladder, colon, and rectum, and serve as a crucial background for future investigations in this field.
| Original language | English |
|---|---|
| Place of Publication | Tampere |
| Publisher | Tampere University |
| ISBN (Electronic) | 978-952-03-3373-7 |
| ISBN (Print) | 978-952-03-3372-0 |
| Publication status | Published - 2024 |
| Publication type | G5 Doctoral dissertation (articles) |
Publication series
| Name | Tampere University Dissertations - Tampereen yliopiston väitöskirjat |
|---|---|
| Volume | 993 |
| ISSN (Print) | 2489-9860 |
| ISSN (Electronic) | 2490-0028 |