Implementation of a 4-y, high-fiber, high-fruit-and-vegetable, low-fat dietary intervention: results of dietary changes in the Polyp Prevention Trial

BACKGROUND

The Polyp Prevention Trial (PPT) was a multicenter randomized clinical trial designed to determine the effects of a high-fiber (4.30 g/MJ), high-fruit-and-vegetable (0.84 servings/MJ), low-fat (20% of energy from fat) diet on the recurrence of adenomatous polyps in the large bowel.

OBJECTIVE

Our goal was to determine whether the PPT intervention plan could effect change in 3 dietary goals and to examine the intervention's effect on the intake of other food groups and nutrients.

DESIGN

Participants with large-bowel adenomatous polyps diagnosed in the past 6 mo were randomly assigned to either the intervention (n = 1037) or the control (n = 1042) group and remained in the trial for 4 y. Three dietary assessment instruments were used to measure dietary change: food-frequency questionnaires (in 100% of the sample), 4-d food records (in a 20% random cohort), and 24-h dietary recalls (in a 10% random sample).

RESULTS

Intervention participants made and sustained significant changes in all PPT goals as measured by the dietary assessment instruments; the control participants' intakes remained essentially the same throughout the trial. The absolute differences between the intervention and control groups over the 4-y period were 9.7% of energy from fat (95% CI: 9.0%, 10.3%), 1.65 g dietary fiber/MJ (95% CI: 1.53, 1.74), and 0.27 servings of fruit and vegetables/MJ (95% CI: 0.25, 0.29). Intervention participants also reported significant changes in the intake of other nutrients and food groups. The intervention group also had significantly higher serum carotenoid concentrations and lower body weights than did the control group.

CONCLUSION

Motivated, free-living individuals, given appropriate support, can make and sustain major dietary changes over a 4-y period.

Lack of effect of a low-fat, high-fiber diet on the recurrence of colorectal adenomas. Polyp Prevention Trial Study Group

BACKGROUND

We tested the hypothesis that dietary intervention can inhibit the development of recurrent colorectal adenomas, which are precursors of most large-bowel cancers.

METHODS

We randomly assigned 2079 men and women who were 35 years of age or older and who had had one or more histologically confirmed colorectal adenomas removed within six months before randomization to one of two groups: an intervention group given intensive counseling and assigned to follow a diet that was low in fat (20 percent of total calories) and high in fiber (18 g of dietary fiber per 1000 kcal) and fruits and vegetables (3.5 servings per 1000 kcal), and a control group given a standard brochure on healthy eating and assigned to follow their usual diet. Subjects entered the study after undergoing complete colonoscopy and removal of adenomatous polyps; they remained in the study for approximately four years, undergoing colonoscopy one and four years after randomization.

RESULTS

A total of 1905 of the randomized subjects (91.6 percent) completed the study. Of the 958 subjects in the intervention group and the 947 in the control group who completed the study, 39.7 percent and 39.5 percent, respectively, had at least one recurrent adenoma; the unadjusted risk ratio was 1.00 (95 percent confidence interval, 0.90 to 1.12). Among subjects with recurrent adenomas, the mean (+/-SE) number of such lesions was 1.85+/-0.08 in the intervention group and 1.84+/-0.07 in the control group. The rate of recurrence of large adenomas (with a maximal diameter of at least 1 cm) and advanced adenomas (defined as lesions that had a maximal diameter of at least 1 cm or at least 25 percent villous elements or evidence of high-grade dysplasia, including carcinoma) did not differ significantly between the two groups.

CONCLUSIONS

Adopting a diet that is low in fat and high in fiber, fruits, and vegetables does not influence the risk of recurrence of colorectal adenomas.

Is colonoscopy needed for the nonadvanced adenoma found on sigmoidoscopy? The Polyp Prevention Trial

BACKGROUND & AIMS

The need for colonoscopy when small tubular adenomas with low-grade dysplasia are found on sigmoidoscopy is uncertain. The aim of this study was to examine the prevalence and characteristics of proximal adenomas in patients with distal adenomas.

METHODS

We studied 981 subjects with distal adenomas found on the index colonoscopy before randomization in the Polyp Prevention Trial.

RESULTS

Four hundred sixty patients (46.9%) had >/=1 distal adenoma that was pathologically advanced (villous component, high-grade dysplasia, or >/=1 cm); 21.5% (211 of 981) had any proximal adenoma; and 4.3% (42 of 981) (95% confidence interval [CI], 3.0-5.5) had an advanced proximal adenoma. A greater percentage of patients with an advanced distal adenoma (5.9%) (95% CI, 3.7-8.0) had an advanced proximal adenoma compared with those with a nonadvanced distal adenoma (2.9%) (95% CI, 1.4-4.3) (OR, 2.1; 95% CI, 1.1-4.3; P = 0.03). Not performing a colonoscopy in patients with a nonadvanced distal adenoma would have missed 36% (15 of 42) of the advanced proximal adenomas.

CONCLUSIONS

Patients with an advanced distal adenoma are twice as likely to have an advanced proximal adenoma as patients with a nonadvanced distal adenoma. However, eschewing a colonoscopy in patients with a nonadvanced distal adenoma would result in not detecting a sizeable percentage of the prevalent advanced proximal adenomas. These data support performance of a colonoscopy in patients with a nonadvanced distal adenoma. Confirmation of these results in asymptomatic subjects undergoing screening sigmoidoscopy is advisable.

Effect of proxy-reported smoking status on population estimates of smoking prevalence

The use of proxy respondents in surveys designed to provide population estimates of smoking prevalence offers an inexpensive way to obtain these data. The accuracy of this information is examined in analyzing data from tobacco use surveys of adults conducted in 22 North American communities as part of the National Cancer Institute's Community Intervention Trial for Smoking Cessation. Proxy-reported smoking status was obtained in a cross-sectional telephone survey conducted from August 1993 to January 1994 (n = 99,682). Self-reported smoking status was obtained from an in-depth interview of a sample of the respondents aged 25-64 years enumerated from the telephone survey (n = 31,417). Discrepancy rates were calculated by comparing the proxy-reported and self-reported smoking statuses of a given individual (n = 10,226). In both surveys, respondents were categorized as current smokers (those who currently smoke and have smoked at least 100 cigarettes in their lifetime), recent quitters (< or = 8 years since cessation), long-term quitters (> 8 years since cessation), and never smokers. The overall discrepancy rate between the self-report and the proxy report was 5.4%. Self-respondents who were black, Hispanic, Asian, recent quitters, or aged 25-34 years were more likely to have inconsistent proxy reports. The authors estimate that the screener interview underestimated the true smoking prevalence by 0.1% when they corrected for smoking status discrepancies. These results confirm that proxy-reported smoking status is an accurate and effective means to monitor populationwide smoking prevalence of adults.

The polyp prevention trial II: dietary intervention program and participant baseline dietary characteristics

The Polyp Prevention Trial (PPT) is a multicenter randomized controlled trial to evaluate whether a low-fat, high-dietary fiber, high-fruit and -vegetable eating pattern will reduce the recurrence of adenomatous polyps of the large bowel. Men and women who had one or more adenomas removed recently were randomized into either the intervention (n = 1037) or control (n = 1042) arms. Food frequency questionnaire data indicate that PPT participants at the beginning of the trial consumed 36.8% of total energy from fat, 9.7 g of dietary fiber/1000 kcal, and 3.8 daily servings of fruits and vegetables. Baseline dietary characteristics, including intake of fat, fiber, and fruits and vegetables, as well as other macro- and micronutrients, were similar in the two study groups. The intervention participants receive extensive dietary and behavioral counseling to achieve the PPT dietary goals of 20% of total energy from fat, 18 g/1000 kcal of dietary fiber, and 5-8 daily servings (depending on total caloric intake) of fruits and vegetables. Control participants do not receive such counseling and are expected to continue their usual intake. Dietary intake in both groups is mentioned annually using a 4-day food record (also completed at 6 months by intervention participants only) and a food frequency questionnaire, with a 10% random sample of participants completing an annual unscheduled 24-h telephone recall. Blood specimens are drawn and analyzed annually for lipids and carotenoids. This article provides details on the rationale and design of the PPT dietary intervention program and describes the participant baseline dietary intake data characteristics.

Smokers' baseline characteristics in the COMMIT trial

BACKGROUND

Baseline telephone survey data from 10 COMMIT sites were submitted to statistical analyses to compare the smoking characteristics of non-Hispanic white (white), non-Hispanic black (black), Mexican-origin (Mexican), and Puerto Rican-origin (Puerto Rican) smokers.

RESULTS

White men and women were more likely to be classified as "heavy smokers" than members of other racial/ethnic groups, although black and Puerto Rican smokers were more likely than whites to increase their smoking rates on weekends. Whites were less likely to report stopping smoking in the past. White and Mexican smokers were most likely to smoke light or ultralight brands and least likely to smoke menthol cigarettes. Blacks were most likely to report smoking their first cigarette of the day within 10 min of waking.

CONCLUSION

The differences and similarities among different groups of smokers may have important implications for understanding patterns of tobacco-related disease in smokers from different racial/ethnic and sex groups.

Carcinoma of the gallbladder. Histologic types, stage of disease, grade, and survival rates

Data on patients with gallbladder cancer listed in the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute were reviewed. Between 1977 and 1986, 3038 patients were recorded in the Program. Histologic grade, histologic type, stage of disease, and vascular invasion were correlated with outcome. Compared with all other histologic types of cancer, papillary carcinomas had the most favorable prognosis. The 2-year survival rate for patients with papillary carcinoma was 47%. A correlation with survival existed between grade, stage of disease, and vascular invasion. The study confirmed that cancers of the gallbladder occur more often in older age groups and are more common in women. Almost 40% of cases are found at an advanced stage. For patients whose enolase tumor was limited to the gallbladder at the time of surgery, the 2-year survival rate was 45% and the 5-year rate was 32%.

Carcinoma of the extrahepatic bile ducts. Histologic types, stage of disease, grade, and survival rates

Data on patients with extrahepatic bile duct carcinomas recorded in the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute were reviewed. We analyzed the records of 1766 patients reported during a 10-year period (1977-1986). These tumors occurred primarily in older age groups and were slightly more common in males. Histologic grade, histologic types, and stage of disease are useful prognostic indicators. The 5-year survival rate for patients with Stage I disease was 11%. Although carcinomas of the extrahepatic bile ducts are better differentiated than carcinomas arising in the gallbladder, they have a less favorable prognosis.

Carcinoma of the gallbladder. Histologic types, stage of disease, grade, and survival rates

Data on patients with gallbladder cancer listed in the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute were reviewed. Between 1977 and 1986, 3038 patients were recorded in the Program. Histologic grade, histologic type, stage of disease, and vascular invasion were correlated with outcome. Compared with all other histologic types of cancer, papillary carcinomas had the most favorable prognosis. The 2-year survival rate for patients with papillary carcinoma was 47%. A correlation with survival existed between grade, stage of disease, and vascular invasion. The study confirmed that cancers of the gallbladder occur more often in older age groups and are more common in women. Almost 40% of cases are found at an advanced stage. For patients whose enolase tumor was limited to the gallbladder at the time of surgery, the 2-year survival rate was 45% and the 5-year rate was 32%.

Effect of long-term freezer storage, thawing, and refreezing on selected constituents of serum

We determined the effect of long-term freezer storage and repeated thawing and freezing of serum on concentrations of electrolytes (sodium, potassium, calcium, and phosphate), enzymes (aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, and creatine kinase), total protein, tumor markers (carcinoembryonic antigen and alpha-fetoprotein), and other substances. Vials (1 ml) of frozen serum from a single blood drawing from 40 women with no breast disease and 70 with benign breast disease were analyzed annually from 1983 to 1987. Blood had been obtained from 40 subjects in 1978, 40 in 1980, and 30 in 1983. Thawing and refreezing studies were done in two ways: (1) serum samples from 30 subjects with benign breast disease were thawed at weekly intervals for 6 weeks and (2) serum samples from 30 patients with stage IV breast cancer were analyzed for alpha-fetoprotein and carcinoembryonic antigen, and serum specimens from 23 patients with benign breast disease and 7 control subjects were analyzed for lactate dehydrogenase and creatine kinase after thawing and keeping the samples at room temperature for up to 4 hours and then refreezing them. For measuring laboratory variability, duplicate samples were processed. Long-term storage (up to 10 years) and repeated thawing and refreezing did not affect the results of any tested constituents of serum. Although most measurements showed statistically significant variability over test cycles, these differences were thought to be due to laboratory variability.

Comparison of pulsatile subcutaneous gonadotropin-releasing hormone and exogenous gonadotropins in the treatment of men with isolated hypogonadotropic hypogonadism

Eight men with isolated hypogonadotropic hypogonadism were treated with pulsatile gonadotropin-releasing hormone (GnRH) after maximal testicular growth and function had already been achieved with human chorionic gonadotropin (hCG) and human menopausal gonadotropin (hMG). Only four subjects could normalize plasma testosterone (T) levels (group A). After 18 months of GnRH therapy, testicular size of group A increased by 53% (P less than 0.01) over that previously attained with exogenous gonadotropins. However, despite further testicular growth, two men who were previously azoospermic on hCG/hMG remained so on GnRH. In the other two patients, total sperm count increased minimally. Thus, pulsatile gonadotropin levels achieved with GnRH are more effective in stimulating testicular growth, but not necessarily sperm output, than are stable gonadotropin concentrations obtained with hCG/hMG.

Serum bank for biological markers for breast cancer

A bank of serum specimens from women at varying risks of breast cancer has been established. Panels of test specimens can be secured by qualified investigators to evaluate newly discovered biological markers for breast cancer, to verify preliminary data, and to compare performance of established assays among different laboratories. Panels consisting of coded 1-ml vials of sera will be sent upon request to approved investigators. The procedure for application for serum panels is described.