Parental lung cancer as predictor of cancer risks in offspring: clues about multiple routes of harmful influence?

Association between family history of lung cancer and lung cancer risk: a systematic review and meta-analysis

BACKGROUND

Familial risk of lung cancer has been widely studied but the effects of sociodemographic factors and geographical regions are largely unknown.

METHODS

PubMed and Embase were systematically searched until 1^st October 2019. A total of 84 articles were identified and (19 cohort and 66 case control studies) included in this systematic review and meta-analysis. Pooled summary estimates and 95% confidence intervals were estimated, and the analysis was stratified by sociodemographic factors and geographical regions.

RESULTS

Geographical regions, sex, age of proband, smoking status, type of first-degree relatives, number of affected relatives, and early onset of lung cancer in affected relatives were significant determinants of familial risk of lung cancer. Higher risk of familial lung cancer was found among Asians as compared to non-Asians, younger individuals (age≤50) as compared with older individuals (age>50), individuals with ≥2 affected relatives as compared with individuals with one affected relative, ever-smokers as compared with never-smokers, Asian females as compared with Western females, and never-smokers in Asia as compared with never-smokers in the West.

CONCLUSIONS

Familial risk of lung cancer is influenced by both genetic and environmental factors. Future studies should control for environmental factors such as air pollution and environmental tobacco smoke which are prevalent in Asia.

Environment-induced epigenetic reprogramming in genomic regulatory elements in smoking mothers and their children

Epigenetic mechanisms have emerged as links between prenatal environmental exposure and disease risk later in life. Here, we studied epigenetic changes associated with maternal smoking at base pair resolution by mapping DNA methylation, histone modifications, and transcription in expectant mothers and their newborn children. We found extensive global differential methylation and carefully evaluated these changes to separate environment associated from genotype-related DNA methylation changes. Differential methylation is enriched in enhancer elements and targets in particular "commuting" enhancers having multiple, regulatory interactions with distal genes. Longitudinal whole-genome bisulfite sequencing revealed that DNA methylation changes associated with maternal smoking persist over years of life. Particularly in children prenatal environmental exposure leads to chromatin transitions into a hyperactive state. Combined DNA methylation, histone modification, and gene expression analyses indicate that differential methylation in enhancer regions is more often functionally translated than methylation changes in promoters or non-regulatory elements. Finally, we show that epigenetic deregulation of a commuting enhancer targeting c-Jun N-terminal kinase 2 (JNK2) is linked to impaired lung function in early childhood.

Adverse health effects related to tobacco smoke exposure in a cohort of three-year olds

AIM

To analyse the importance of mothers' smoking during pregnancy and/or environmental tobacco smoke (ETS) exposure in early childhood for children's health and well-being at the age of 3 years.

METHODS

Four groups from a population based cohort (n=8850) were compared: children with nonsmoking mother during pregnancy and nonsmoking parents at the age of 3 years (n=7091); children with only foetal exposure (n=149); children exposed only postnatally (n=895) and children exposed both pre- and postnatally (n=595). Odds ratios and 95% confidence intervals were calculated.

RESULTS

Children exposed both pre- and postnatally had more wheezing (1.14; 1.07-1.21) and rhinitis (1.16; 1.06-1.26), used more cough-mixture (1.07; 1.01-1.14) and broncodilatating drugs (1.08; 1.02-1.15) and suffered more from excessive crying (1.31; 1.13-1.51) and irritability (1.27; 1.09-1.48) compared to children with nonsmoking parents. Children exposed only postnatally had more rhinitis (1.24; 1.12-1.37), used more cough-mixture (1.14; 1.05-1.29) and suffered more from poor sleep (1.26; 1.07-1.47) than children of nonsmoking parents. Children with prenatal exposure only used more broncodilatating drugs (1.45; 1.03-2.04) and suffered more from poor sleep (2.06; 1.09-3.87).

CONCLUSION

Health differences, small but significant, indicate that prenatal and/or postnatal ETS exposure alone, or in combination, seems to interfere with child health, supporting the importance of zero tolerance. However, as most smoking parents in Sweden try to protect their children from ETS exposure, the results also might indicate that protective measures are worthwhile.

Risk of bladder cancer associated with family history of cancer: do low-penetrance polymorphisms account for the increase in risk?

The relationship between family history of cancer in first-degree relatives and risk of bladder cancer was examined in the Spanish Bladder Cancer Study. Information on family history of cancer was obtained for 1,158 newly diagnosed bladder cancer cases and 1,244 controls included in 18 hospitals between 1998 and 2001. A total of 464 (40.1%) cases and 436 (35.1%) controls reported a family history of cancer in >/=1 relative [odds ratio (OR), 1.32; 95% confidence interval (95% CI), 1.11-1.59]; the OR was 1.23 (95% CI, 1.01-1.50) among those with only one relative affected and 1.67 (95% CI, 1.23-2.29) among those with >/=2 affected relatives (P(trend) = 0.0004). A greater risk of bladder cancer was observed among those diagnosed at age </=45 years (OR, 2.67; 95% CI, 1.10-6.50) compared with those diagnosed over age 45 years (OR, 1.27; 95% CI, 1.06-1.52). The OR of bladder cancer among subjects reporting a family history of cancer of the bladder was 2.34 (95% CI, 0.95-5.77). Statistically significant associations emerged between bladder cancer risk and family history of cancer of the esophagus, lung, prostate, and brain. The OR of bladder cancer for those reporting family history of bladder cancer was 4.76 (95% CI, 1.25-18.09) among NAT2-slow acetylators and 1.17 (95% CI, 0.17-7.86) among NAT2-rapid/intermediate acetylators (P(interaction) = 0.609). Among individuals with GSTM1 null and present genotypes, the corresponding ORs were 2.91 (95% CI, 0.44-19.09) and 4.21 (95% CI, 1.26-14.14), respectively (P(interaction) = 0.712). Limitations of our study are small sample size in subgroup analyses, reliability of family history data, and possible residual confounding by shared environmental exposures. Overall, our findings support the hypothesis that genetic factors play a role in bladder cancer etiology. Whether these correspond to low-penetrance cancer-predisposing polymorphisms acting together and/or interacting with environmental factors warrants further research.