Acute Leukemias - Republican Scientific Medical Library

88 Chapter 5 · Acute Lymphoblastic Leukemia: Epidemiology and Etiology
HAPs (RR = 1.21; 95% confidence interval, 1.03, 1.42) and
in tracts ranked highest for point source HAP exposure
(RR = 1.32; 95% confidence interval, 1.11, 1.57). The
authors suggest that more comprehensive exposure assessments
and individual level data are needed to better
understand the observed relationships.
5.3.3.4 Tobacco Smoke
The association of tobacco smoke and lymphohematopoietic
cancers has been assessed in several studies. In
general, the most consistent findings are for non-Hodgkin
lymphoma, and those for leukemia are not statistically
significant [2, 141]. However, several studies, including
more than a dozen case control studies and
two large cohort studies, have looked at the association
between passive smoke exposure and childhood leukemia,
and have reported inconsistent results [13]. Limitations
of these studies include imprecise exposure estimates
and limited adjustment for potentially confounding
variables. A meta-analysis reported no statistically
significant association between maternal smoking during
pregnancy and all leukemias or ALL [9]. More recently,
the large United Kingdom Childhood Cancer
Study examined this issue and also did not find any statistically
significant associations of parental tobacco
smoking and either leukemia or ALL [102].
5.3.3.5 Diet
There have been only a limited number of studies investigating
the role of diet in the occurrence of leukemia
among adults. In one study, Kwiatkowski reported a decreased
risk of ALL with increased consumption of vegetables,
and an increased risk with consumption of
milk, poultry, and soft water [66]. In another study, as
part of the Iowa Women’s Health Study, Ross and colleagues
reported that a diet rich in vegetables had a protective
effect against adult leukemia, although only 3 of the
138 leukemia cases were ALL [121]. A Canadian population-based
case-control study, reported by Fritschi and
colleagues, found that greater fish consumption was associated
with a lower risk of leukemia [27]. Unfortunately,
cancer subtypes were not presented.
It has been suggested that both maternal and childhood
diets may affect the risk of childhood leukemia. A
Chinese case-control study found a reduced risk of
childhood leukemia associated with a child’s consump-
tion of cod liver oil, which contains high levels of vitamin
A and D [134].
Parental diets may also affect childhood leukemia
risks. Some concern was raised by two case control
studies, in the early 1990s, investigating the possible association
of processed meat consumption by child and/
or parents with risk of childhood leukemia [104] and
ALL [128], suggesting that N-nitroso precursors used
as preservatives might be converted into N-nitroso carcinogens.
The only statistically significant results found
had to do with hot dog consumption, which may have
been due to confounding by socioeconomic status [13].
As part of the Northern California Childhood Leukemia
Study, Jensen and colleagues report that maternal
consumption of vegetables, protein sources, and fruits
were associated with a lower risk of ALL, as did maternal
consumption of provitamin A carotenoids and the
antioxidant glutathione [52]. In the same study, Kwan
and colleagues reported a protective effect from child
consumption of bananas, oranges, and orange juice
[65]. In a nationwide study in Greece, Petridou and colleagues
found that a diet rich in fruits and vegetables
during pregnancy decreases the child’s risk of leukemia,
while one with sugar, syrups, meats, and meat products
increases the risk [105].
Following a specific mechanistic hypothesis regarding
diet, Ross and colleagues have examined the role of
dietary inhibitors of DNA topoisomerase II, an enzyme
necessary for gene transcription, DNA recombination
and replication, and acute childhood leukemia [119,
122, 140]. They report that maternal consumption of
foods containing DNA topoisomerase II inhibitors may
increase the risk of AML but does not appear to affect
the risk of ALL. Maternal consumption of fruits and
vegetables, on the other hand, decreases the risk of ALL.
5.3.3.6 Maternal Pharmaceutical Use
There are limited data on the possible association between
maternal use of pharmaceuticals and the risk of
ALL. A study by Wen and colleagues found that maternal
use of vitamins and iron during pregnancy was associated
with a decreased the risk of childhood ALL,
while parental use of amphetamines or diet pills and
mind-altering drugs before and during the index pregnancy
was associated with an increased the risk of
childhood ALL, especially if both parents used the
drugs [155]. They also reported that maternal use of