Influencing factors of lung cancer in nonsmoking women: systematic review and meta-analysis

Global, regional, and national burden of trachea, bronchus, and lung cancer among women of reproductive age, 1990-2019

BACKGROUND

Trachea, bronchus, and lung (TBL) cancer has demonstrated a discernible feminization and a tendency towards younger onset in recent decades. Therefore, our objective is to examine the most recent patterns in the worldwide prevalence of TBL among women of reproductive age on a global, regional, and national scale.

METHODS

To assess the prevalence trends of TBL in women of reproductive age, we calculated the estimated annual percentage change (EAPC), age-standardized incidence rate (ASIR), age-standardized death rate (ASDR), and disability-adjusted life years (DALYs) for 204 countries and territories from 1990 to 2019. These calculations were based on the Global Burden of Disease (GBD) 2019 database.

RESULTS

From 1990 to 2019, there was a global increase in the absolute number of incidence cases, deaths, and DALYs of TBL in women of reproductive age. However, the ASIR, ASDR, and age-standardized DALY rates were decreasing over this period, with EAPC of -0.77 (95 % confidence interval [CI]: -1.03 to -0.51), -1.08 (95 % CI: -1.34 to -0.82), and -1.10 (95 % CI: -1.36 to -0.84), respectively. This trend was observed even in regions with higher Socio-Demographic Index (SDI). East Asia consistently had the highest ASIR, ASDR, and age-standardized DALY rate, but there was a decreasing trend. Conversely, Eastern Sub-Saharan Africa displayed an increasing burden pattern. When examining countries individually, Monaco, Greenland, and Palau had the highest ASIR. Moreover, in most countries, the ASIR for TBL increased with age, particularly among women aged 35-49 years.

CONCLUSIONS

Despite a global decline in ASIR, ASDR, and age-standardized DALY rates for TBL in women of reproductive age over the past three decades, there is still a troubling increase observed in low- and low-middle SDI regions. It is crucial to implement effective preventive and curative measures in these regions in order to address this concerning trend.

Lung cancer risk associated with occupations in women: a pooling study

BACKGROUND

Occupation is an important risk factor for lung cancer. This knowledge is mainly based on studies conducted on men, with the results being generalized to women.

AIMS

We aimed to identify the relationship between different occupations and lung cancer in women.

METHODS

Pooling study in which data were pooled from six case-control studies conducted at 13 Spanish hospitals and 1 hospital in Portugal. Each woman's longest held job was coded as per the ISCO-08. Results were adjusted for age, smoking, and exposure to residential radon.

RESULTS

The study population comprised 1262 women: 618 cases and 644 controls. The reference group were white-collar workers. The adjusted multivariate analysis showed a higher risk of developing lung cancer among teaching professionals (odds ratio [OR]: 4.36; 95% confidence interval [CI] 1.73-11.02), cooks (OR: 3.59; 95% CI 1.52-8.48), domestic cleaners and helpers (OR: 2.98; 95% CI 1.54-5.78), homemakers (OR: 2.30; 95% CI 1.26-4.21) and crop farmers, livestock farmers and gardeners (OR: 2.06, 95% CI: 1.11-3.81). For adenocarcinoma, the highest risk was observed in teaching professionals, and for small-cell carcinoma, the highest risk was observed in cooks. Higher risks were observed for small-cell carcinoma compared to other histological types.

CONCLUSIONS

Some occupations may be associated with an increased risk of lung cancer in women and this risk could vary by histologic subtype; however, further research is needed to confirm these associations. In any case, protection measures must be implemented in the workplace aimed at reducing the risk of lung cancer among women workers, and more studies exclusively focused on women are warranted.

Reproductive factors and risk of lung cancer among 300,000 Chinese female never-smokers: evidence from the China Kadoorie Biobank study

BACKGROUND

Lung cancer is the leading cause of cancer mortality among Chinese females despite the low smoking prevalence among this population. This study assessed the roles of reproductive factors in lung cancer development among Chinese female never-smokers.

METHODS

The prospective China Kadoorie Biobank (CKB) recruited over 0.5 million Chinese adults (0.3 million females) from 10 geographical areas in China in 2004-2008 when information on socio-demographic/lifestyle/environmental factors, physical measurements, medical history, and reproductive history collected through interviewer-administered questionnaires. Cox proportional hazard regression was used to estimate adjusted hazard ratios (HRs) of lung cancer by reproductive factors. Subgroup analyses by menopausal status, birth year, and geographical region were performed.

RESULTS

During a median follow-up of 11 years, 2,284 incident lung cancers occurred among 282,558 female never-smokers. Ever oral contraceptive use was associated with a higher risk of lung cancer (HR = 1.16, 95% CI: 1.02-1.33) with a significant increasing trend associated with longer duration of use (p-trend = 0.03). Longer average breastfeeding duration per child was associated with a decreased risk (0.86, 0.78-0.95) for > 12 months compared with those who breastfed for 7-12 months. No statistically significant association was detected between other reproductive factors and lung cancer risk.

CONCLUSION

Oral contraceptive use was associated with an increased risk of lung cancer in Chinese female never-smokers. Further studies are needed to assess lung cancer risk related to different types of oral contraceptives in similar populations.

Health effects associated with exposure to secondhand smoke: a Burden of Proof study

Despite a gradual decline in smoking rates over time, exposure to secondhand smoke (SHS) continues to cause harm to nonsmokers, who are disproportionately children and women living in low- and middle-income countries. We comprehensively reviewed the literature published by July 2022 concerning the adverse impacts of SHS exposure on nine health outcomes. Following, we quantified each exposure-response association accounting for various sources of uncertainty and evaluated the strength of the evidence supporting our analyses using the Burden of Proof Risk Function methodology. We found all nine health outcomes to be associated with SHS exposure. We conservatively estimated that SHS increases the risk of ischemic heart disease, stroke, type 2 diabetes and lung cancer by at least around 8%, 5%, 1% and 1%, respectively, with the evidence supporting these harmful associations rated as weak (two stars). The evidence supporting the harmful associations between SHS and otitis media, asthma, lower respiratory infections, breast cancer and chronic obstructive pulmonary disease was weaker (one star). Despite the weak underlying evidence for these associations, our results reinforce the harmful effects of SHS on health and the need to prioritize advancing efforts to reduce active and passive smoking through a combination of public health policies and education initiatives.

Lung Cancer in Women: The Past, Present, and Future

Lung cancer is the leading cause of cancer death for women in multiple countries including the United States. Women are exposed to unique risk factors that remain largely understudied such as indoor pollution, second-hand tobacco exposure, biological differences, gender differences in tolerability and response to therapy in lung cancer, and societal gender roles, that create distinct survivorship needs. Women continue to lack representation in lung cancer clinical trials and are typically treated with data generated from majority male patient study populations, which may be inappropriate to extrapolate and generalize to females. Current lung cancer treatment and screening guidelines do not incorporate sex-specific differences and physicians also often do not account for gender differences when choosing treatments or discussing survivorship needs. To best provide targeted treatment approaches, greater representation of women in lung cancer clinical trials and further research is necessary. Clinicians should understand the unique factors and consequences associated with lung cancer in women; thus, a holistic approach that acknowledges environmental and societal factors is necessary.

Review of mendelian randomization studies on age at natural menopause

Menopause marks the end of the reproductive phase of life. Based on epidemiological studies, abnormal age at natural menopause (ANM) is thought to contribute to a number of adverse outcomes, such as osteoporosis, cardiovascular disease, and cancer. However, the causality of these associations remains unclear. A powerful epidemiological method known as Mendelian randomization (MR) can be used to clarify the causality between ANM and other diseases or traits. The present review describes MR studies that included ANM as an exposure, outcome and mediator. The findings of MR analyses on ANM have revealed that higher body mass index, poor educational level, early age at menarche, early age at first live birth, early age at first sexual intercourse, and autoimmune thyroid disease appear to be involved in early ANM etiology. The etiology of late ANM appears to be influenced by higher free thyroxine 4 and methylene tetrahydrofolate reductase gene mutations. Furthermore, early ANM has been found to be causally associated with an increased risk of osteoporosis, fracture, type 2 diabetes mellitus, glycosylated hemoglobin, and the homeostasis model of insulin resistance level. In addition, late ANM has been found to be causally associated with an increased systolic blood pressure, higher risk of breast cancer, endometrial cancer, endometrioid ovarian carcinoma, lung cancer, longevity, airflow obstruction, and lower risk of Parkinson's disease. ANM is also a mediator for breast cancer caused by birth weight and childhood body size. However, due to the different instrumental variables used, some results of studies are inconsistent. Future studies with more valid genetic variants are needed for traits with discrepancies between MRs or between MR and other types of epidemiological studies.

Where there are fumes, there may be lung cancer: a systematic review on the association between exposure to cooking fumes and the risk of lung cancer in never-smokers

PURPOSE

Lung cancer in never-smokers (LCINS) is the seventh leading cause of cancer, and exposure to cooking fumes has recently emerged as a potential risk factor. This systematic review is the first to summarize and evaluate the relationship between exposure to cooking fumes and the risk of LCINS.

METHODS

This study conducted an online literature search of PubMed, CINAHL, and PsychInfo databases. Inclusion criteria were original research articles published in English, that assessed the relationship between exposure to cooking fumes and the risk of lung cancer between 1 January 2012 and 6 December 2022, and that included never-smokers.

RESULTS

Thirteen case-control studies and three prospective cohort studies, focusing mostly on women with LCINS, met the inclusion criteria. Seven case-control studies reported an association between exposure to cooking oil fumes and an increased risk of LCINS. Two case-control studies found that using a fume extractor was associated with a decreased risk of LCINS. In other case-control studies, coal use was linked to an increased risk of LCINS, and participants who did not use a ventilator in their kitchens had a higher risk for LCINS. Poor ventilation [Adjusted Hazard Ratio (AHR) = 1.49; 95% CI: 1.15, 1.95] and poor ventilation in combination with coal use (AHR = 2.03; 95% CI: 1.35, 3.05) were associated with an increased risk for LCINS in one prospective cohort study.

CONCLUSION

The evidence reviewed underscores the need to develop culturally-tailored interventions that improve access to affordable and clean fuel through engaging relevant stakeholders.