Abstract
Acute lymphoblastic leukemia (ALL) and childhood brain tumors (CBT) are 2 of the most common forms of childhood cancer, but little is known of their etiology. In 2 nationwide case-control studies we investigated whether breastfeeding, age of food introduction, or early diet are associated with the risk of these cancers. Cases aged 0–14 years were identified from Australian pediatric oncology units between 2003 and 2007 (ALL) and 2005 and 2010 (CBT) and population-based controls through nationwide random-digit dialing. Mothers completed questionnaires giving details of infant feeding up to the age of 2 yr. Data from 322 ALL cases, 679 ALL controls, 299 CBT cases, and 733 CBT controls were analysed using unconditional logistic regression. Breastfeeding was associated with a reduced risk of ALL [odds ratio (OR) = 0.52, 95% confidence interval (CI): 0.32, 0.84), regardless of duration. Introduction of artificial formula within 14 days of birth was positively associated with ALL (OR = 1.57, 95% CI: 1.03, 2.37), as was exclusive formula feeding to 6 mo (OR = 1.81, 95% CI: 1.07, 3.05). No associations were seen between breastfeeding or formula use and risk of CBT. Our results suggest that breastfeeding and delayed introduction of artificial formula may reduce the risk of ALL but not CBT.
ACKNOWLEDGMENTS
The Aus-ALL and Aus-CBT consortia conducted the study and the Telethon Kids Institute (formally the Telethon Institute for Child Health Research; TICHR), University of Western Australia, was the coordinating center. Bruce Armstrong (Sydney School of Public Health), Elizabeth Milne (TICHR), Frank van Bockxmeer (University of Western Australia), Rodney Scott (University of Newcastle), Lin Fritschi (WA Institute for Medical Research), Lesley Ashton (Children's Cancer Institute Australia (CCIA)), Nicholas de Klerk (TICHR), Caroline Bower (TICHR), Margaret Miller (Edith Cowan University), John Attia (University of Newcastle), Michelle Haber (CCIA), Murray Norris (CCIA), Judith Thompson (WA Cancer Registry), and Peter Dallas and Ursula Kees (TICHR) were the research investigators.
The authors acknowledge the contribution made by our clinical co-investigators who recruited and cared for study patients at each participating hospital: Catherine Cole and Nicholas Gottardo (Princess Margaret Hospital, TICHR); John Heath and Elizabeth Smibert (Royal Children's Hospital, Melbourne); Peter Downie (Monash Medical Centre, Melbourne); Liane Lockwood, Tim Hassall, and Ross Pinkerton (Royal Children's Hospital Brisbane); Maria Kirby (Women's and Children's Hospital, Adelaide); Stewart Kellie and Luciano dalla Pozza (Children's Hospital at Westmead); Frank Alvaro (John Hunter Hospital, Newcastle); Glenn Marshall and Richard Cohn (Sydney Children's Hospital) and John Daubenton (Royal Hobart Hospital). The authors also acknowledge the Clinical Research Associates at each hospital, and the study coordinators: Jackie Mansour, Somer Dawson, Tamika Heiden, and Helen Bailey, and Peter Cosgrove for programming the dietary folate calculations.
FUNDING
The National Health and Medical Research Council (NHMRC) funded Aus-ALL (Grant number: 254539) and Aus-CBT (Grant number: 404089). Elizabeth Milne was supported by an NHMRC Fellowship. Support for Rodney Scott was in part from NBN Children's Cancer Research Fund.
SUPPLEMENTAL MATERIAL
Supplementary data for this article can be accessed on the publisher's website.