
Cancer Epidemiology Biomarkers & Prevention Vol. 9, 193-197, February 2000
© 2000 American Association for Cancer Research
Blood Levels of Organochlorines before and after Chemotherapy among Non-Hodgkins Lymphoma Patients
Dalsu Baris1,
Larry W. Kwak,
Nathaniel Rothman,
Wyndham Wilson,
Angela Manns,
Robert E. Tarone and
Patricia Hartge
Divisions of Cancer Epidemiology and Genetics [D. B., N. R., A. M., R. E. T., P. H.] and Clinical Sciences [L. K., W. W.], National Cancer Institute, Bethesda, Maryland 20892-7240
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Abstract
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Several small studies suggest a link between environmental exposure to
organochlorine compounds and risk of non Hodgkins lymphoma (NHL).
Because NHL is uncommon, studies of the topic often use a
population-based case-control design, in which cases generally are
enrolled after treatment has begun. If chemotherapy affects blood
levels of organochlorines, exposure will be misclassified and findings
distorted. To determine whether chemotherapy alters serum levels of
organochlorines in NHL cases, we compared serum samples before and
after treatment in 22 cases diagnosed with NHL between March 1994 and
August 1995 and enrolled in a clinical trial at the United States
National Cancer Institutes Clinical Center. The time difference
between pretreatment and posttreatment samples ranged from 15 to 27
months with an average of 20 months. Laboratory analyses were conducted
in blinded pretreatment and posttreatment pairs of the subjects.
Pretreatment and posttreatment organochlorine serum levels were
compared using Pearson correlation coefficient (r) and
paired t test. The pretreatment and posttreatment serum
levels were highly correlated for
1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and
polychlorinated biphenyls (PCBs) PCB-138, PCB-153, PCB-156, and total
PCBs (ranging from 0.78 to 0.93). Serum levels of all of these
organochlorines significantly decreased between initiation and
completion of chemotherapy, 25% for total PCB (P =
0.0044), 28% for DDE (P = 0.0014), 25% for
PCB-138 (P = 0.0053), 27% for PCB-153
(P = 0.0031), and 29% for PCB-156
(P = 0.045). Neither weight change nor lipid change
was correlated with changes in chemical levels. There was no
association between the length of time between blood draws and changes
in chemical levels. Our data raise the possibility that lymphoma
treatment depresses serum organochlorine levels.
 |
Introduction
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The incidence of
NHL2
has risen steadily in both developed and developing countries, long
predating the epidemic of NHL related to AIDS (1)
. The
causes of this increase are unknown (2)
. Some
environmental and occupational chemical exposures have been
investigated. For example, an association between agricultural exposure
to DDT and risk of NHL has been observed in several questionnaire-based
case-control studies (3, 4, 5)
. More recently, this
hypothesis has been tested, using biological measures of DDE (the major
metabolite of DDT) and other organochlorines. In a hospital-based
case-control study of 28 NHL cases and 17 controls, Hardell et
al., (6)
found that PCBs (but not DDE) measured in
adipose tissue were associated with increased risk of NHL. In a nested
case-control study of 74 NHL cases and 147 controls carried out in a
general population-based cohort enrolled in 1974 and followed through
1994, Rothman et al., (7)
also found that PCBs,
but not DDE, were associated with increased risk of NHL.
To assess the contribution of organochlorine exposure in the general
population to risk of NHL, large studies are needed. Because DDT and
PCB exposure in the general population cannot be assessed by
questionnaire alone, biological measurement of these compounds is
essential. Although case-control studies nested within prospective
cohorts are ideal to assess this question, many cohort studies will not
have a large enough number of NHL cases to be able to address this
issue. Furthermore, if organochlorines contribute to the etiology of
NHL, they may function as promoters via their suggested
immune-modulating properties (8)
. If so, assessing
exposure levels close to the time of NHL diagnosis becomes important,
another limitation of cohort studies where most cases are diagnosed
years after enrollment. Finally, disentangling the effects of PCBs,
DDE, dioxins, and other organochlorines requires relatively large serum
volumes that are generally unavailable in prospective cohort studies.
For all of these reasons, large population-based case-control studies
of NHL will be a likely choice to study the organochlorine-NHL
hypothesis. In many case-control studies, cases are enrolled after
treatment has begun; therefore, it is critical to determine whether
disease onset or treatment alters organochlorine levels. Disease
effects can be assessed indirectly by studying organochlorine levels in
a range of cases that vary by stage/grade and the presence or absence
of clinical symptoms. Treatment effects can be assessed by studying
patients before and after the initiation of chemotherapy.
We used a preexisting collection of paired serum samples from 22 cases
to assess the effects of treatment on organochlorine levels.
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Materials and Methods
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Patient Population.
Eligible cases included 42 previously untreated men and women who were
diagnosed with follicular, low-grade NHL between March 1994 and August
1995 and enrolled in a modified ProMACE chemotherapy (cyclophosphamide,
doxorubicin, etoposide, and prednisone) clinical trial at the NCI
Clinical Center. A total of 22 patients (6 women and 16 men) had
available cryopreserved pretreatment and posttreatment serum samples of
sufficient quantity for the analysis. All patients had signed the
informed consent before entering the trial and Institutional Review
Board approval was obtained from the NCI Clinical Center.
Assay Methods for DDE and PCBs.
Randomly numbered serum samples were stored below -70°C.
Laboratory analyses were conducted in blinded pretreatment and
posttreatment pairs of the subjects assayed in the same batch. One ml
of thawed serum was transferred by pipette to a centrifuge tube, and
the volume of the serum was recorded to ±0.01 ml. Ten ng of a
surrogate PCB (PCB-198) was added to the serum. One ml of methanol was
added to denature albumin. The mixture was extracted three times with 5
ml of 50% ethyl ether:n-hexane, and the extracts were
combined and concentrated to 10.0 ml. Two ml of this extract were
removed for lipid determination. The remaining 8 ml were concentrated
to 1 ml and transferred to 1 g of Florisil SPE column, and the
pesticides and PCBs were eluted with 10 ml of n-hexane
(fraction 1), followed by 10 ml of 1% ethyl ether in
n-hexane (fraction 2). The fractions were concentrated to
1.0 ml, spiked with 10 ng of internal standard (PCB-119), and analyzed
by gas chromatography with electron capture detection. Gas
chromatography with electron capture detection was calibrated by
repetitive analysis of standard mixtures of selected individual PCB
congeners at six levels for the quantification of individual congener
and total PCB levels. The analysis method for individual PCB congeners
was a modified version of established methods (9, 10, 11, 12, 13)
. The
total PCB level in each sample was also determined by summing the
individual PCB congener levels. The procedure for determining the total
PCB levels was validated by comparing to the Webb-McCall method
(14)
.
We limited our analysis to PCB-138, PCB-153, and PCB-156 because
these congeners were among those showing higher serum concentrations
and a lower percentage of samples below the detection limit. The limit
of detection was 0.2 ng/ml for DDE and 0.05 ng/ml for individual PCBs
congeners and total PCBs. There were two subjects with DDE levels below
the detection limit and six subjects with PCB-156 levels below the
detection limit. For purposes of computation, we replaced the
undetectable values by half of the values of the detection limits. The
coefficients of variation for the DDE and PCB assays ranged from 35 to
49%.
Lipid Determination.
One-g aluminum pans were embossed with labels and dried in an oven at
105°C for 1 h, allowed to cool in a desiccator, and then weighed
to ±0.00001 g. Two ml of serum extract were transferred to each pan
with n-hexane rinses. The pans were allowed to air dry,
protected from dust, and then heated to 105°C and held at that
temperature for 15 min. The pans were allowed to cool in a desiccator
and then reweighed. Several empty (blank) pans were run simultaneously
to check for method bias. The method for the total lipid analysis was
adopted from the methods used by Sheldon (15
, 16)
.
We calculated lipid-corrected values by dividing serum levels of
chemicals by the total lipid value. To calculate the total
lipid-corrected PCB levels, we divided each congener by the total lipid
value and summed them.
Statistical Analysis.
Pretreatment and posttreatment organochlorine serum levels were
compared using Pearson correlation coefficient (r), paired
t tests, and sign tests (17)
. Two sided
Ps are reported for all comparisons.
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Results
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On an average, 20 months elapsed between the pretreatment and
posttreatment blood draws (Table 1)
. There was a significant weight gain of
5% (P =
0.012) and a nonsignificant increase in total lipid levels of
6.5%
(P = 0.17).
The pretreatment and posttreatment levels were highly correlated for
DDE, PCB-138, PCB-153, PCB-156, and total PCBs and correlation
coefficients varied from 0.78 to 0.93. Figs. 1
and 2
show the correlation between the lipid-adjusted levels of pretreatment
and posttreatment total PCBs and DDE, respectively. Lipid adjustments
decreased the variability (i.e., SD of PCB and DDE
measurements were reduced) but did not appreciably alter the
correlation coefficients. All subsequent analyses are shown with lipid
adjustments.

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Fig. 1. Correlation between the lipid-adjusted serum levels of total PCBs among
NHL patients (r = 0.84).
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As shown in Table 2
, total PCBs fell from 0.73 µg/g lipid before treatment to 0.55 µg/g
lipid after treatment overall. This change in total PCBs was
significant (P = 0.0044 for paired t test
and P = 0.0009 for sign test), with an average decrease
(0.18 µg/g lipid) of 25%. Levels of significance were the same for
paired t test with log transformation and sign test. The
decline in DDE was also significant (P = 0.0014 by
paired t test and P = 0.0026 by sign test),
with an average decrease of 0.18 µg/g lipid (about a 28% decrease).
The decline in PCB-138 was significant (P = 0.0053 by
paired t test and P = 0.0009 by sign test),
with an average decline of 0.027 µg/g lipid (about a 25% decrease).
The decline in PCB-153 was significant (P = 0.0031 by
paired t test and P = 0.0043 by sign test),
with an average decline of 0.038 µg/g lipid (about a 27% decrease).
The decline in PCB-156 was marginally significant (P =
0.045 by paired t test and P = 0.021 by sign
test), with an average decrease of 0.006 µg/g lipid (about a 29%
decrease).
We examined the effects of various possible cofactors on change
in total PCB levels. The results were unaffected by adjustment for
weight, age, sex, histological type, weight change, or change in lipid
concentrations (Figs. 3
and 4
). The decrease in total PCBs levels was largest for the stage 4
patients (n = 16; pretreatment, 0.82 µg/g lipid;
posttreatment, 0.60 µg/g lipid; 26.8% decline) compared with the
patients with stage 3 and below (n = 6; pretreatment,
0.48 µg/g lipid; posttreatment, 0.42 µg/g lipid; 12.5% decline);
however, the difference was not significant (P = 0.20).
The decrease in DDE levels was similar for the stage 4 patients
(pretreatment, 0.76 µg/g lipid; posttreatment, 0.55 µg/g lipid;
27.6% decline) compared with the patients with stage 3 and below
(pretreatment, 0.35 µg/g lipid; posttreatment, 0.25 µg/g lipid;
28.5% decline; P = 0.23).

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Fig. 3. Correlation between weight change and change in levels of
lipid-adjusted total PCBs (r = -0.01).
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Changes in levels of separate chemicals were highly correlated with
each other (Table 3)
. The lower correlation coefficients for PCB-156 partly reflect the
larger number of values below the level of detection (pre- and
posttreatment values were both less than the detectable level for 6 of
the 22 patients). Lipid change was uncorrelated with the changes in
chemical levels. We found no evidence of an association between weight
and the change in organochlorine levels (P = 0.91 for
total PCBs and P = 0.77 for DDE). There was no
association between the length of time between blood draws and the
change in chemical levels.
 |
Discussion
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Pretreatment and posttreatment levels for DDE, PCB-138, PCB-153,
PCB-156, and total PCBs were highly correlated among 22 patients.
Posttreatment levels were significantly lower for each chemical, and
the decline varied between 25 and 29%; the results were unaffected by
adjustment for weight, age, sex, histological type, weight change, or
change in lipid concentrations. Our observation of high correlation
between pre- and posttreatment levels of PCBs and DDE agrees with the
findings from a breast cancer study (18)
, but the 25%
decrease we observed does not. In the breast cancer study, increases of
serum levels of PCBs (29.4%) and DDE (15.8%) were observed among the
chemotherapy group compared with the surgery group. The interval of
observation was shorter (13 months) in the breast cancer study.
It is unlikely that secular trends could explain the decline
observed during the interval between pretreatment and posttreatment
blood sample collections, given that half-lives of these compounds are
thought to be 530 years (19
, 20)
. Moreover, we found no
association between the length of time between blood draws and the
change in chemical levels. Furthermore, a study of healthy women found
little variation in serum samples collected over a 3-month interval
(21)
, although this was shorter than the interval in our
study.
In addition to the true biological elimination of the chemical,
temporal changes in body weight may influence serum levels of PCBs and
DDT because organochlorines are stored in adipose tissue. Our data show
no association between weight change and decline in chemical levels.
The consistency of the decrease across all chemicals and the large
magnitude of the decline suggest that chemotherapy may account for the
change. With these data, it is not possible to determine whether values
had already fallen, had risen, or stayed the same after diagnosis.
We were not able to look at intervening periods that precisely mimic
the sample collection window of a population-based case-control study
with rapid ascertainment (i.e., <1 month after diagnosis).
It would be instructive to follow cases over the entire treatment
course with samples collected frequently to clarify when the decline
occurs. We are currently following a series of cases from pretreatment
over the course of chemotherapy with the second and third blood draws
occurring within a few months, thereby determining whether we
see a change in organochlorine levels during the time frame that is
relevant for a population-based case-control study with rapid
ascertainment. Although we did not have a control group in our study,
we felt that it was important to publish this initial evaluation from a
sample of convenience because of its unexpected results and to raise a
cautionary note for people attempting to study the organochlorine-NHL
relationship in a case-control study.
One could speculate that lymphoma itself increases serum organochlorine
levels, which then revert to predisease levels among patients who
respond to treatment. If the disease causes weight loss, this could
release stored organochlorines into the blood stream and organochlorine
levels would therefore be elevated. We cannot exclude this scenario
because many of our cases had low-grade lymphomas and either partial or
complete response to treatment. Our data did not allow us to examine
directly a possible disease effect. To indirectly assess such an
effect, one could evaluate levels in a range of untreated cases with
different stages/grades.
Our study has several strengths. We took advantage of previously
collected serum samples from a well-documented NCI clinical trial with
a patient population that was fairly homogeneous in stage/grade level
and treatment regimen. Furthermore we were able to examine the effect
of weight change.
Overall, if there is no evidence of a disease effect and decline does
not occur during the first few months of treatment (or is so
highly consistent across cases that it can be adjusted for in the
analysis), case-control studies may have a role in studying the
organochlorine-NHL hypothesis. If these issues cannot be clearly
resolved, then the resolution of this hypothesis will require large
cohort studies.
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Acknowledgments
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We thank Dr. Edo Pellizzari, Analytical and Chemical Sciences of
Research Triangle Institute, North Carolina, for assistance and
guidance in analysis of serum samples using nationally recognized
protocols.
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Footnotes
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The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 To whom requests for reprints should be
addressed, at Division of Cancer Epidemiology and Genetics, National
Cancer Institute, Executive Plaza South, Room 8122, Bethesda, MD
20892-7240. Phone: (301) 435-4707; Fax: (301) 402-1819; E-mail: barisd{at}epndce.nci.nih.gov 
2 The abbreviations used are: NHL, non-Hodgkins
lymphoma; DDT,
2,2-bis-(p-chlorophenyl)-1,1,1-trichloroethane; DDE,
1,1-dichloro-2,2-bis(p-chloro-phenyl)ethylene; PCB,
polychlorinated biphenyl; NCI, National Cancer Institute. 
Received 5/21/99;
revised 11/15/99;
accepted 11/24/99.
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References
|
|---|
-
Devesa S. S., Fears T. Non-Hodgkins lymphoma time trends: United States and international data. Cancer Res., 52: 5432s-5440s, 1992.
-
Hartge P., Devesa S. S. Quantification of the impact of known risk factors on time trends in non-Hodgkins lymphoma incidence. Cancer Res., 52: 5566s-5569s, 1992.[Medline]
-
Woods J. S., Pollisar L., Severson R. K., Heuser L. S., Kilander B. G. Soft tissue sarcoma and non-Hodgkins lymphoma in relation to phenoxyherbicides and chlorinated phenol exposure in western Washington. J. Natl. Cancer Inst., 78: 899-910, 1987.
-
Persson B., Dahlander A. M., Fredrikson M., Brage H. N., Ohlason C. G., Axelson O. Malignant lymphomas and occupational exposures. Br. J. Ind. Med., 46: 516-520, 1989.[Medline]
-
Cantor K. P., Blair A., Everett G., Gibson R., Burmeister L. F., Brown L. M., Schiman L., Dick F. R. Pesticides and other agricultural risk factors for non-Hodgkins lymphoma among men in Iowa and Minnesota. Cancer Res., 52: 2447-2455, 1992.[Abstract/Free Full Text]
-
Hardell L., Van Bavel B., Lindstrom G., Fredrikson M., Hagberg H., Liljegren G., Nordström M., Johansson B. Higher concentrations of specific polychlorinated biphenyl congeners in adipose tissue from non-Hodgkins lymphoma patients compared with controls without a malignant disease. Int. J. Oncol., 9: 603-608, 1996.
-
Rothman N., Cantor K. P., Blair A., Bush D., Brock J., Helzlsouer K., Zahm S. H., Nordham L. L., Pearson G. R., Hoover R. N., Comstock G. W., Strickland P. T. A nested case-control study of non-Hodgkins lymphoma and serum organochlorine residues. Lancet, 350: 240-244, 1997.[Medline]
-
IARC . IARC Monographs on the Evaluation of Carcinogenic Chemicals to Humans, Vol. 53: Lyon, France 1993.
-
Wolff M. S., Thornton J., Fischbein A., Lilis R., Selikoff I. J. Disposition of polychlorinated biphenyl congeners in occupationally exposed persons. Toxicol. Appl. Pharmacol., 62: 294-306, 1982.[Medline]
-
Cooper S. D., Mosely M. A., Pellizzari E. D. . Development and standardization of methods for analysis of biological tissues for PCBs, Las Vegas, Nevada United States EPA Contract No. 68-03-3099. 1984.
-
Mullin M. D., Pochini C. M., McCrindle S., Romkes M., Safe S. H., Safe L. M. High-resolution PCB analysis: synthesis and chromatographic properties of all 209 PCB congeners. Environ. Sci. Technol., 18: 468-476, 1984.
-
Burse V. W., Head S. L., Korver M. P., McClure P. C., Donahue J. F., Needham L. L. Determination of selected organochlorine pesticides and polychlorinated biphenyls in human serum. J. Anal. Toxicol., 14: 137-142, 1990.[Medline]
-
Burse V. W., Groce D. F., Korver M. P., McClure P. C., Head S. L., Needham L. L., Lapeza C. R., Jr., Smrek A. L. Use of reference pools to compare the qualitative and quantitative determination of polychlorinated biphenyls by packed and capillary gas chromatography with electron capture detection. Part 1. Serum Analyst, 115: 243-251, 1990.
-
Webb R. G., McCall A. C. Quantitative PCB standards for electron capture gas chromatography. J. Chromatogr. Sci., 11: 366-373, 1973.[Medline]
-
Sheldon L. S. . Polychlobiphenyl in human blood serum, Bethesda, MD Report #F50, NIH Contract No. NOI-ES-45061 1989.
-
Sheldon L. S. . Pesticides and breast cancer in North Carolina, Bethesda, MD RTI Subcontract 50817. NCI No. R01-ES-07128 1995.
-
Snedecor G. W., Cochran W. G. . Statistical Methods, Ed. 7 83-89, Iowa University Press Ames, Iowa 138140, and 175188. 1980.
-
Gammon M. D., Wolff M. S., Neugut A. I. Treatment for breast cancer and blood levels of chlorinated hydrocarbons. Cancer Epidemiol. Biomark. Prev., 5: 467-471, 1996.[Abstract]
-
Hunter D. J., Hankinson S. E., Laden F., Colditz G. A., Manson J. E., Willet W. C., Speizer F. E., Wolff M. S. Plasma organochlorine levels and the risk of breast cancer [see comments]. N. Engl. J. Med., 337: 1253-1258, 1997.[Abstract/Free Full Text]
-
Wolff M. S., Fischbein A., Slikoff I. J. Changes in PCB serum concentrations among capacitor manufacturing workers. Environ. Res., 59: 202-216, 1992.[Medline]
-
Gammon M. D., Wolff M. S., Neught A. I., Terry M. B., Papadopulaos K., Levin B., Wang Q., Santella R. M. Temporal variation in chlorinated hydrocarbons in healthy women. Cancer Epidemiol. Biomark. Prev., 6: 327-332, 1997.[Abstract]
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