Maternal smoking during pregnancy and childhood lymphoma: A meta‐analysis

Abstract

Results from epidemiological studies exploring the association between childhood lymphoma and maternal smoking during pregnancy have been contradictory. This meta-analysis included all published cohort (n 5 2) and case-control (n 5 10) articles; among the latter, the data of the Greek Nationwide Registry for Childhood Hematological Malignancies study were updated to include all recently available cases (-2008). Odds ratios (ORs), relative risks and hazard ratios were appropriately pooled in three separate analyses concerning non-Hodgkin lymphoma (NHL, n 5 1,072 cases), Hodgkin lymphoma (HL, n 5 538 cases) and any lymphoma (n 5 1,591 cases), according to data availability in the included studies. An additional metaregression analysis was conducted to explore dose-response relationships. A statistically significant association between maternal smoking (any vs. no) during pregnancy and risk for childhood NHL was observed (OR 5 1.22, 95% confidence interval, CI: 1.03-1.45, fixed effects model), whereas the risk for childhood HL was not statistically significant (OR 5 0.90, 95% CI: 0.66-1.21, fixed effects model). The analysis on any lymphoma did not reach statistical significance (OR 5 1.10, 95% CI 5 0.96-1.27, fixed effects model), possibly because of the case-mix of NHL to HL. No dose-response association was revealed in the metaregression analysis. In conclusion, this meta-analysis points to a modest increase in the risk for childhood NHL, but not HL, among children born by mothers smoking during pregnancy. Further investigation of doseresponse phenomena in the NHL association, however, warrants accumulation of additional data.Childhood lymphomas are the third most frequent type of malignancy in childhood following leukemia and central nervous system tumors. 1 Little is known about the etiology of both categories of childhood lymphomas (Hodgkin lymphoma, HL and non-Hodgkin lymphoma, NHL). EpsteinBarr virus infection, 2 socioeconomic status, 3 change of residence, 4 genetic susceptibility 5 and environmental factors 6,7 have been studied as potential risk factors for childhood HL.Even less is known about the epidemiology of childhood NHL, which has been linked to Epstein-Barr virus infection, 8 hormonal factors, 9 environmental factors 10 and congenital or acquired immunodeficiency disorders. 11 Although maternal smoking during pregnancy is relatively frequent, its role in the etiology of childhood lymphomas remains unclear. There is a causal association between maternal smoking and fetal growth restriction, and most probably also with (elective and spontaneous) preterm birth, stillbirth and placental abruption. Smoking is also associated with other outcomes such as some congenital malformations (notably cleft palate). 12,13 Very few studies investigating the association between maternal smoking and long-term outcomes have controlled for familial factors. Those who have done so find no long-term effects of smoking. So far, this has been investigated for such different outcomes as obesity, 14 criminality, 15 academ...

Maternal Smoking and the Risk of Cancer in Early Life – A Meta-Analysis

“…This can partly be explained by the fact that we excluded several original studies included in their work, since the study populations overlapped with bigger, epidemiological studies, which were published after Boffetta’s meta-analysis was reported. A meta-analysis focusing on childhood lymphoma reported increased risk for non-Hodgkin lymphoma, but it did not suggest any association with Hodgkin lymphoma or all lymphoma types combined [98]. In our analysis, non-Hodgkin’s lymphoma and any other type of lymphoma were associated with maternal smoking.…”

A Meta-Analysis of Parental Smoking and the Risk of Childhood Brain Tumors

“…Consistent with a previous meta-analysis published in 2002 [43], our meta-analysis also found no association between maternal smoking during pregnancy and the risk of CBT. Previous studies have reported that maternal smoking during pregnancy is a possible risk factor for stillbirth [44], child overweight [45] and childhood NHL [46] but not for childhood HL [46], leukemia [47] or testicular cancer [48]. Therefore, maternal smoking may have different effects on offspring through multiple mechanisms, specific and non-specific.…”

Birth characteristics and risk of lymphoma in young children

“…There is a growing body of evidence that exposures during the prenatal period, which is a highly vulnerable period of development (3, 4), may contribute to development of pediatric lymphoma. (5, 6)…”