Table 1.
Case series of FOBT results with diet manipulation
| STUDY | N | POPULATION | FOBT TEST | INTERVENTION | REHYDRATION STATUS | DELAY TO DEVELOPMENT | RESULTS | COMMENTS |
|---|---|---|---|---|---|---|---|---|
| Broderick and Harris,14 1982 | NC | NC | Hemoccult | Challenge diet: 2 raw turnips daily for 9 d | NC | NC | 0 positive results | No reaction to boiled turnip directly applied to FOBT strip |
| Macrae et al,15 1982 | 156 | Healthy volunteers, mean age 22.1 y | Hemoccult II | 250 g rare beef daily for 6 d, 6 servings high-peroxidase fruit and vegetables daily for 6 d, both combined, exclusion diet | Nonrehydrated and rehydrated | Within 5 d | 1.9% of nonrehydrated samples produced positive results with full challenge (NS) | 16.7% of rehydrated samples produced positive results with full challenge diet |
| Rose et al,16 1989 | 49 | Healthy volunteers, 16–30 y | Hemoccult II, Hemoccult SENSA | 6 d each of exclusion diet, 250 g rare beef daily, and 3 cups high-peroxidase fruit and vegetables daily | Nonrehydrated | Within 72 h | Hemoccult II: 4% positive with meat challenge (NS); Hemoccult SENSA: 8% positive with meat challenge (NS) | 1 positive result on exclusion diet for both tests; 0 positive for vegetable challenge |
| Thomas et al,17 1989 | 18925 | Participants in the Nottingham trial, 50–74 y | Hemoccult | Unrestricted diet followed by low-peroxidase* dietary restriction if participant had a positive test result | Nonrehydrated | NC | 3.4% positive results for unrestricted diet, of which 77.0% were false positive for CRC and adenoma | Only 463/18 925 subjects (2.4%) were shown to have false-positive results on an unrestricted diet |
| Feinberg et al,18 1990 | 46 | Healthy medical students | Hemoccult II, Hemoccult SENSA | Challenge diet: 350–450 g cooked red meat daily for 3 d, then abstain from red meat for 7 d during testing | Nonrehydrated | NC | Hemoccult II positive results: 15.4% (day 1), 5.5% (day 3), 0% (day 4–7); Hemoccult SENSA positive results: 46.2% (day 1), 8.3% (day 3), 0% (day 4–7) | Percentages represent tests rather than subjects, which were not reported |
| Robinson et al,19 1993 | 2 series (347 and 574) | Consecutive participants in the Nottingham trial, 50–74 y, with ≥ 1 positive test result | Hemoccult | Low-peroxidase* dietary restriction over 6-d testing period | Nonrehydrated | NC | If results of ≥ 5 of 6 tests were positive, 88.1% (series 1) remained positive with dietary restriction | In the second series, all subjects with ≥ 5 positive results proceeded directly to colonoscopy |
| Robinson et al,20 1995 | 35260 | Participants in the Nottingham trial, 50–74 y | Hemoccult | Unrestricted diet followed by low-peroxidase* dietary restriction if participant had a positive test result | Nonrehydrated | NC | 3.4% positive results for unrestricted diet, of which 88.4% were false positive for CRC | Only 1061/35 260 subjects (3.0%) were shown to have false-positive results on an unrestricted diet |
| Rozen et al,21 1995 | 527 | CRC screening and follow-up service attendees, 95% asymptomatic (27% were following up adenomas or cured CRC), mean age 59 (SD 12) y | Hemoccult SENSA | Low-peroxidase* dietary restriction for 2 d, increased to 3 d for the last 100 subjects | Nonrehydrated | Within 1 d of final application, increased to 72 h after final application for last 100 subjects | Positive results in 17% in first group; 7% in last 100 subjects (P = .02) | Most patients evaluated with sigmoidoscopy or colonoscopy to determine false-positive rate of 15%, but results combined for all 527 subjects |
| Sinatra et al,22 1999 | 61 | Healthy volunteers, 18–30 y | Hemoccult, Hemoccult SENSA | Challenge diet: 750 g high-peroxidase fruit and vegetables daily for 3 d | Nonrehydrated | 24 hours, 48 hours, 72 hours | Hemoccult: 1.6% positive at 24 h; Hemoccult SENSA: 1.6% positive at 24 h | 0 positive when development delayed 48 or 72 h |
| Fludger et al,23 2002 | 10 | Healthy volunteers <35 y | Hemoccult | Challenge diet: one 7-oz black (blood) pudding | NC | NC | 40% of results were positive | Local delicacy in Bury, England |
CRC—colorectal cancer, FOBT—fecal occult blood test, NC—not clarified in publication, NS—no statistically significant difference between groups, SD—standard deviation.
*
Low-peroxidase diet involved eating no red meats and no high-peroxidase fruits or vegetables (horseradish, turnip, melon, etc).