Colorectal Adenomatous Polyps Clinical Trial
Official title:
Calcium/Vitamin D, Biomarkers & Colon Polyp Prevention
The study team has developed a set of biomarkers of risk for colon cancer; this study tests 1) whether or not calcium and/or vitamin D supplementation can favorably affect these biomarkers in persons who are at higher than average risk for colon cancer (ie, have already undergone the removal of colon growths, called adenomatous polyps, which are known to be precursors to developing colon cancer), and 2) whether effects on the biomarkers predict who will get new colon polyps or not.
This study is an add-on study ('adjunct study') to a clinical trial that is already being
conducted (the 'parent study'). Study participants will be composed of persons who are
already participating in the parent study, "Vitamin D/Calcium Polyp Prevention Study". In
the parent study, a total of 1,964 people nationally are being randomly assigned to four
different treatment groups: 1) calcium supplements, 600 mg twice a day; 2) vitamin D
supplements, 500 IU twice a day; 3) both the calcium and vitamin D supplements twice a day;
and 4) placebo tablets twice a day. The treatment period lasts three to five years at the
end of which study participants undergo a follow-up colonoscopy to look for new polyps. The
parent study began about a year prior to the start of this adjunct study, thus, there are
already some patients in the trial who are receiving their study 'treatments' (i.e., have
been 'randomized'), but more patients will be recruited into the parent study.
Depending on whether someone has already been randomized, participants of the parent study
will be invited to take part in the adjunct study in one of two ways: 'Aim 1' only, or 'All
Aims'. First, patients who have already been randomized will be asked to allow biopsies to
be made of their rectal tissue during their 3- or 5-year follow-up colonoscopy (Aim 1).
Biopsies, which will be used for our biomarker measurements, are very tiny pieces of tissue
that can be examined under the microscope. Second, patients who have not yet been randomized
will be invited to participate more fully (All Aims) in the adjunct study. This involves
having outpatient rectal biopsies taken immediately after their first phone call, their
1-year follow-up visit, and 7 - 21 days before their 3- or 5-year follow-up colonoscopy.
Finally, during their 3- or 5-year colonoscopy, biopsies will be taken from three areas of
the colon: the rectum (same area as the outpatient biopsies), the sigmoid colon, and the
ascending colon. From all of the biopsies taken from all of the visits and colon sites,
biomarker measurements will be of normal proteins that occur in the surface cells lining the
colon. Study researchers will then analyze whether calcium and/or vitamin D affect these
biomarkers and whether the effects predict who gets new polyps.
;
Observational Model: Case-Only, Time Perspective: Prospective
| Status | Clinical Trial | Phase | |
|---|---|---|---|
| Completed |
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|
Phase 2 | |
| Completed |
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N/A |