BRANCH:Fecal Microbiota Among Participants in a Pre-paid Health Plan
Background/Significance: Commensal microbes (the microbiota), particularly in the gut, are
required for human health and are postulated to affect cancer risk through several
mechanisms. This proposed study builds upon a pilot within the NCI Division of Cancer
Epidemiology and Genetics (DCEG) that identified highly acceptable methods for collecting
fecal specimens and significant correlation between fecal microbial beta-glucuronidase
activity and a marker of breast cancer risk, urine levels of estrogens. The proposed study
will determine the correlation between levels of fecal enzyme activities and systemic
estrogens in a random sample of postmenopausal women at Kaiser Permanente Colorado (KPCO).
Demonstration of an association between the fecal microbiota and systemic estrogens would
help to motivate future studies of how microbes affect cancer risk.
Objectives: The main objective is to characterize the fecal microbiota and its association
with levels of systemic estrogens among randomly sampled postmenopausal female members of a
health maintenance organization (HMO). A secondary objective will determine the proportions
of women who consent and then provide questionnaire data, a fecal specimen to characterize
the microbiota, and a urine specimen to quantify systemic estrogens; and differences between
participants (N=60) and non-participants. A third objective will determine whether
consecutive, newly diagnosed postmenopausal breast cancer cases have similar participation
rates, fecal microbiota characteristics and urine estrogen levels compared to the randomly
Methods: We will randomly sample from the KPCO population of approximately 50,000 women ages
55-69 who have recently had a negative screening mammogram. An invitation packet (letter,
information pamphlet, consent form, eligibility questionnaire, and opt-out postcard) will be
sent in batches of 100, up to a maximum of 500 women. The consenting women will receive a
second packet with a cancer risk-factor questionnaire, a link to the on-line Block brief
food frequency questionnaire, and a specimen collection kit (with illustrated instructions)
for collecting a fecal and urine specimen. Participants (minimum 60, maximum 80) will ship
the specimens to the DCEG repository. As amended, consecutive newly diagnosed breast cancer
cases (target N=60) will be enrolled in the oncology clinic prior to definitive surgery,
with the same eligibility criteria as for the random sample. Urine estrogens will be
quantified by DCEG at NCI Frederick. Fecal microbial classification and enzymatic expression
and activity will be performed at the University of Maryland Medical School (UMMS).
Analyses: Data will be analyzed and summarized for publication with representatives from
KPCO, DCEG and UMMS. Simple proportions will be used to estimate participation rates.
Extant electronic records at KPCO will be used to compare participants to non-participants,
overall and by pre-specified subgroups (5-year age groups, race/ethnicity, length of KPCO
enrollment), with descriptive statistics and logistic regression. For the primary
objective, fecal microbial 16S rRNA pyrosequences will be classified by phylogenetic and
principal components analyses, while estrogen levels and Beta-glucuronidase RNA expression
and enzymatic activity levels will be categorized using log standard deviations. The study
will have 80% power to detect a 17% increase in estrogen level per 2.4-fold increase in
glucuronidase activity and 80% power to detect a 3-fold case-control difference in
above-median microbiome alpha diversity.
Levels of estrogen in urine of postmenopausal women will be compared to categories and functions of all microbes in feces, which will test hypothesis by enterohepatic circulation.
James J Goedert, M.D.
National Cancer Institute (NCI)
United States: Federal Government
|Kaiser Permanente Colorado||Denver, Colorado 80205|