Marijuana use in early pregnancy increases child’s risk of cancer
Roger Dobson
Mothers who use marijuana in the first trimester may increase the risk of their child developing neuroblastoma, the second most common solid tumour found in children, a US study has found.
The results of the case control study to investigate the role of illicit drugs in the development of the tumour show that mothers’ use of any illicit or recreational drug during pregnancy was associated with an increased risk of neuroblastoma in the offspring (odds ratio 1.82 (95% confidence interval 1.1 to 3.0) (Cancer Causes and Control 2006;7:663-9).
“This is the first study to investigate the association between specific recreational drugs and neuroblastoma within distinct time segments around pregnancy. Our findings indicate that the strongest effect of maternal marijuana use is seen with exposure in the first trimester and among children diagnosed before age one,” write the authors of the study, from the National Cancer Institute and other centres in the United States.
Neuroblastoma is the second commonest solid tumour in childhood (after brain cancer), and its causes are poorly understood, say the authors. The mean age at diagnosis is 17.3 months, which has led to speculation that environmental exposures around the time of conception and during pregnancy may be implicated.
The study identified 538 cases at 139 North American hospitals and compared these children with 504 controls.
Overall, 88 mothers (9%) reported use of any drug during the 10 month period from one month before pregnancy to childbirth. Of these women, 75 used marijuana and 61 used only marijuana and no other drugs.
The time period with the strongest association with neuroblastoma was the first trimester (adjusted odds ratio 4.8 (1.6 to 16.5). In contrast, use of illicit drugs in the month before conception was not associated with a higher risk of neuroblastoma (adjusted odds ratio 0.9 (0.4 to 1.9)), and nor was use after birth (adjusted odds ratio 0.7 (0.4 to 1.4).
The authors, who say that most studies of marijuana and childhood cancer were not designed to identify a specific time of greatest risk, point out that weeks 3 to 8 after conception, during the first trimester of pregnancy, are a critical period for organ development and vulnerability to teratogens.
They also say that parental marijuana use has been associated with several other childhood malignancies, including leukaemia, brain tumours, and rhabdomyosarcoma. “Our findings further expand previous investigations of parental marijuana use in the prenatal period as a potential risk factor for other childhood cancers,” they write.
ncbi.nlm.nih.gov |
