Differences in risk factors for head and neck cancer among men and women in Nepal: A case-control study.

BACKGROUND: Head and neck cancer (HNC) is a major cause of cancer morbidity and mortality in Nepal. The study aims to investigate differences in risk factors for head and neck cancer by sex in Nepal. METHODS: A hospital-based case-control study was conducted at the B.P. Koirala Memorial Cancer Hospital in Nepal from 2016 to 2018. A semi-structured questionnaire consisting of socio-demographic characteristics, dietary habits, reproductive factors, household air pollution, tobacco use (smoking and chewing), alcohol consumption, and second-hand smoking was used to collect the data. Odds ratios (OR) and 95 % confidence intervals (CI) were estimated using unconditional logistic regression adjusting for potential confounders. RESULTS: A total of 549 HNC cases (438 men and 111 women) and 601 age-matched healthy controls (479 men and 122 women) were recruited in this study. An increased risk of HNC for low education level and family income were observed among men (adjusted odds ratio (AOR) for 3rd grade and less= 1.58, 95 % CI= 1.14-2.18; AOR for family monthly income < 5000 Rupees = 1.64, 95 % CI 1.20-2.24). The AORs among women were higher than the men for known risk factors (AOR for smoking 1.34 (95 % CI 0.96-1.86) for men, 2.94 (95 % CI 1.31-6.69) for women; AOR for tobacco chewing 1.76 (95 % CI 1.27-2.46) for men, 10.22 (95 % CI 4.53-23.03) for women). CONCLUSION: Our results point to an effect modification by sex for HNC risk factors with high AORs observed among women.

Trends and clinicopathological characteristics of oral squamous cell carcinomas reported at a tertiary cancer hospital in Nepal during 1999 to 2009.

OBJECTIVE: Reliable data describing the trends and clinicopathological characteristics of oral squamous cell carcinoma (OSCC) in the Nepalese population are very limited. The current study aimed to examine the demographics, trend, and clinicopathological characteristics of OSCC reported to the main referral/tertiary cancer hospital, the B.P. Koirala Memorial Cancer Hospital (BPKMCH) in Nepal for a period of 11 years (1999-2009). MATERIAL AND METHODS: This is a cross-sectional study. Data were retrieved retrospectively from hospital register maintained in the Department of Ear, Nose, Throat at BPKMCH, categorized into demographic and clinicopathological variables and SPSS (V25) was used for the analysis. RESULTS: In a period of 11 years, 3,452 cases of head and neck cancer were registered at the Department of Ear, Nose, Throat, BPKMCH. Out of 1,111 oral cancer cases, 1,081 (97.3%) were OSCC. A trend for increasing number of OSCCs presenting to BPKMCH was observed during that period. OSCC was found to be more common among males (73.0%), Brahmin/Chhetri ethnic groups (33.0%), in age group of 51-60 years (31.9%), and in Terai region (62.0%). Tongue (42.8%) was the most common site, followed by buccal mucosa (27.2%). Nevertheless, when stratified with respect to the geographical location and ethnicity, buccal mucosa was the most common site for OSCC in Terai region (63.9%, p = .002) and in Madhesi ethnic group (34.2%, p < .001). Majority of OSCC cases were diagnosed at advanced stage (49.7%, Stage IV) and received a combination therapy (42.0%). CONCLUSIONS: Hospital-based records can provide valuable information on disease characteristics in countries like Nepal. This study revealed that the clinicopathological characteristics of OSCC in Nepal follow the global trend. Nevertheless, relationship between specific intraoral sites for OSCC with geographic location and ethnic groups is an interesting observation and requires further population-based studies to clarify these findings.

Helicobacter pylori was not detected in oral squamous cell carcinomas from cohorts of Norwegian and Nepalese patients.

Helicobacter pylori (HP) infection is an established causative agent for gastric cancer. Although the oral cavity is a part of the gastrointestinal system, the presence and possible causative role of HP in oral squamous cell carcinoma (OSCC) is a subject of controversy. Therefore, the current study aimed to investigate HP infection in two cohorts of OSCC patients with different demographic characteristics, lifestyles and habitual risk factors. A total of 242 formalin-fixed paraffin-embedded OSCC specimens from two different patient cohorts (Norway, n = 171 and Nepal, n = 71) were used to examine HP using immunohistochemistry (IHC) and quantitative polymerase chain reaction (qPCR). Two different HP specific genes (23S rRNA and ureA) were used for TaqMan-based qPCR, and for subsequent verification using HP specific RIDAGENE HP kit and SYBR Green based qPCR. All of the OSCC specimens from both cohorts were found to be negative for HP infection with IHC and qPCR, although the positive control specimens tested positive. Our findings suggest that HP is absent in the examined OSCC cohorts, irrespective of race, lifestyle and habitual risk factors. This indicates that, in contrast to gastric cancer, HP is an unlikely contributing factor for OSCC pathogenesis.

Evolutionary selected Tibetan variants of HIF pathway and risk of lung cancer.

Tibetans existed in high altitude for ~25 thousand years and have evolutionary selected unique haplotypes assumed to be beneficial to hypoxic adaptation. EGLN1/PHD2 and EPAS1/HIF-2α, both crucial components of hypoxia sensing, are the two best-established loci contributing to high altitude adaptation. The co-adapted Tibetan-specific haplotype encoding for PHD2:p.[D4E/C127S] promotes increased HIF degradation under hypoxic conditions. The Tibetan-specific 200 kb EPAS1 haplotype introgressed from an archaic human population related to Denisovans which underwent evolutionary decay; however, the functional variant(s) responsible for high-altitude adaptation at EPAS1/HIF-2α have not yet been identified. Since HIF modulates the behavior of cancer cells, we hypothesized that these Tibetan selected genomic variants may modify cancer risk predisposition. Here, we ascertained the frequencies of EGLN1D4E/C127S and EGLN1C127S variants and ten EPAS1/HIF-2α variants in lung cancer patients and controls in Nepal, whose population consists of people with Indo-Aryan origin and Tibetan-related Mongoloid origin. We observed a significant association between the selected Tibetan EGLN1/PHD2 haplotype and lung cancer (p=0.0012 for D4E, p=0.0002 for C127S), corresponding to a two-fold increase in lung cancer risk. We also observed a two-fold or greater increased risk for two of the ten EPAS1/HIF-2α variants, although the association was not significant after correcting for multiple comparisons (p=0.12). Although these data cannot address the role of these genetic variants on lung cancer initiation or progression, we conclude that some selected Tibetan variants are strongly associated with a modified risk of lung cancer.

Household air pollution and lung cancer risk among never-smokers in Nepal.

More than half of the global population relies on biomass fuels (wood, charcoal, crop residue, dung) for cooking and/or heating purposes. Household air pollution (HAP) resulting from the use of these solid fuels is of particular concern, given the overall prevalence as well as the intensity of exposure and the range of potential adverse health outcomes. Long term exposure to HAP is a major public health concern, particularly among women and children in low and middle income countries. In this study, we investigated the association between exposure to HAP resulting from combustion of biomass and lung cancer risk among Nepalese population. Using a hospital-based case-control study (2009-2012), we recruited 606 lung cancer cases and 606 healthy controls matched on age (±5 years), gender, and geographical residence. We used unconditional logistic regression to compute odds ratios (ORs) and 95% Confidence Intervals (95% CI) for lung cancer risk associated with HAP exposures, adjusting for potential confounders (tobacco use, TB status, SES, age, gender, ethnicity, and exposure to second hand smoke. In our overall analysis, we observed increased risk of lung cancer among those who were exposed to HAPs (OR: 1.77, 95% CI: 1.00-3.14). A more detailed analysis stratified by smoking status showed considerably higher risk of lung cancer associated with increasing duration of exposure to HAP from biomass combustion, with evidence of a borderline exposure-response relationship (Ptrend=0.05) that was more pronounced among never-smokers (Ptrend=0.01). Our results suggest that chronic exposure to HAP resulting from biomass combustion is associated with increased lung cancer risk, particularly among never-smokers in Nepal.

Ethnic Variation in Consumption of Traditional Tobacco Products and Lung Cancer Risk in Nepal.

Lung cancer is the leading contributor to cancer deaths in the developing world. Within countries, significant variability exists in the prevalence of lung cancer risk, yet limited information is available whether some of the observed variability is associated with differences in the consumption pattern of local tobacco products with differing potency. We recruited 606 lung cancer cases and 606 controls from the B.P. Koirala Memorial Cancer Hospital in Nepal from 2009-2012. We estimated odds ratios (ORs) and 95% confidence intervals (CI) for lung cancer risk associated with different tobacco products, using unconditional logistic regression. Unfiltered cigarettes tended to be the most frequently used products across ethnic subgroup with about 53.7% of Brahmins, 60.1% of Chettris, and 52.3% of Rai/Limbu/Magar/others. In contrast, about 39.9% of Madishe/Tharu smokers reported using bidi compared with only 27.7% who smoked unfiltered cigarettes. Among those who only smoked one type of product, choor/kankat smokers had the highest lung cancer risk (OR 10.2; 95% CI 6.2-16.6), followed by bidi smokers (OR 5.6; 95% CI 3.6-8.7), unfiltered cigarettes (OR 4.9; 95% CI 3.4-7.2), and filtered cigarettes (OR 3.4; 95% CI 2.2-5.3). A clear dose-response relationship was observed between increased frequency of smoking and lung cancer risk across all ethnic subgroups. These results highlight the important role of traditional tobacco products on lung cancer risk in the low income countries.

Malignant Neoplasm Burden in Nepal - Data from the Seven Major Cancer Service Hospitals for 2012.

In Nepal, while no population based cancer registry program exists to assess the incidence, prevalence, morbidity and mortality of cancer, at the national level a number of hospital based cancer registries are cooperating to provide relevant data. Seven major cancer diagnosis and treatment hospitals are involved, including the BP Koirala Memorial Cancer hospital, supported by WHO-Nepal since 2003. The present retrospective analysis of cancer patients of all age groups was conducted to assess the frequencies of different types of cancer presenting from January 1st to December 31st 2012. A total of 7,212 cancer cases were registered, the mean age of the patients being 51.9 years. The most prevalent age group in males was 60-64 yrs (13.6%), while in females it was 50-54 yrs (12.8%). The commonest forms of cancer in males were bronchus and lung (17.6%) followed by stomach (7.3%), larynx (5.2%) and non Hodgkins lymphoma (4.5%). In females, cervix uteri (19.1%) and breast (16.3%), were the top ranking cancer sites followed by bronchus and lung (10.2%), ovary (6.1%) and stomach (3.8%). The present data provide an update of the cancer burden in Nepal and highlight the relatively young age of breast and cervical cancer patients.

Socioeconomic status and lung cancer risk in Nepal.

BACKGROUND: Lung cancer is the most common cancer among men and the third most common cancer among women in Nepal. Socioeconomic disparities in lung cancer have not been studied in the Nepalese population. METHODS: We conducted a lung cancer case-control study, including 209 cases and 313 controls at the main cancer hospital in Nepal, the B.P. Koirala Memorial Cancer Hospital (BPKMCH). RESULTS: We observed differences in lung cancer risk by ethnicity; the Rai, Limbu and Magar groups had a higher risk of lung cancer than Brahmin (OR=3.11, 95%CI=1.55-6.23). An inverse association was observed between education and lung cancer risk (p for trend=0.0008). We also observed greater lung cancer risk among unmarried individuals (OR=2.25, 95%CI=1.12-4.53), and lower risk in individuals who lived in the Central region compared to the West (OR=0.47, 95%CI=0.26-0.85). There were greater proportions of late stage cancers among women compared to men, in the Rai/Limbu/Magar ethnic groups, in individuals with lower education and in older age groups. CONCLUSIONS: Disparities in lung cancer risk were observed by race/ethnicity, education, marital status, and by region of residence. Further research on socioeconomic influence on lung cancer in Nepal is warranted to develop better prevention efforts against the disease.