Antioxidant Supplement and Reduction of Metachronous Adenomas of the Large Bowel: a Double Blind Randomized Trial

Evaluation of the Efficacy of a Combination of Micronutrients (Vitamin A, C, E, Selenium and Zinc) in Reducing the Incidence of Colorectal Metachronous Adenomas. A Double Blind, Phase III, Randomized, Placebo-controlled Trial

Status

Terminated

Phases

Phase 3

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT01437826

Enrollment

411

Registered

2011-09-21

Start date

1988-03-31

Completion date

1996-06-30

Last updated

2011-09-21

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Colorectal Adenomas

Keywords

chemoprevention, colorectal cancer, metachronous adenoma, randomized trial

Brief summary

The trial was aimed at evaluating the efficacy of a multiagent antioxidant compound (vitamin A, C, E, selenium and zinc) in reducing the incidence of metachronous adenomas of the large bowel after endoscopic polypectomy. This is a randomized study: a 50% reduction in the incidence of metachronous adenomas was expected in patients allocated to the active compound (intervention) arm as compared to those assigned to a placebo.

Detailed description

Adenomatous polyps (or adenoma) are benign lesions of the large bowel that are frequent in people aged 60 or more: about one in four of them has at least one adenoma. In time, adenoma could progress to cancer. Even though only a small rate of adenomas will develop into cancer almost 70-80% of colorectal cancer origin from an adenoma and colorectal cancer is one of the most frequent malignant tumors in the western world. Several epidemiological studies showed that subjects who had low intake and/or low blood levels of selenium were at increased risk of developing colorectal cancer.

Interventions

DRUGantioxidants

tablets composed of 200 mcg selenium \[as l-selenomethionine\], 30 mg zinc, 2 mg vitamin A \[retinol\], 180 mg vitamin C \[ascorbic acid\] and 30 mg vitamin E \[D-α-tocopherol acetate\]

DRUGplacebo

placebo had an identical appearance as intervention

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

PREVENTION

Masking

DOUBLE (Subject, Investigator)

Eligibility

Sex/Gender

ALL

Age

25 Years to 75 Years

Healthy volunteers

Inclusion criteria

* age 25-75 years * at least one histologically confirmed adenoma endoscopically removed from the large bowel resulting in a polyp-free colon-rectum (clean colon).

Exclusion criteria

* polypectomy performed more than 6 months before enrolment in the trial * history of Familial Adenomatous Polyposis * inflammatory bowel disease * adenoma with invasive carcinoma * ten or more adenomas * large sessile adenoma (3 cm or more * colorectal resection * invasive cancer at any site * life-threatening and/or chronic heart, liver or kidney diseases * current use of vitamin or calcium supplements * mental disability

Design outcomes

Primary

Measure	Time frame
occurrence of metachronous adenomas or cancer detected during endoscopic follow up examinations	five years

Countries

Italy

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026