Prospective study of fruit and vegetable consumption and incidence of colon and rectal cancers

BACKGROUND

Frequent consumption of fruit and vegetables has been associated with a reduced risk of colorectal cancer in many observational studies.

METHODS

We prospectively investigated the association between fruit and vegetable consumption and the incidence of colon and rectal cancers in two large cohorts: the Nurses' Health Study (88 764 women) and the Health Professionals' Follow-up Study (47 325 men). Diet was assessed and cumulatively updated in 1980, 1984, 1986, and 1990 among women and in 1986 and 1990 among men. The incidence of cancer of the colon and rectum was ascertained up to June or January of 1996, respectively. Relative risk (RR) estimates were calculated with the use of pooled logistic regression models accounting for various potential confounders. All statistical tests were two-sided.

RESULTS

With a follow-up including 1 743 645 person-years and 937 cases of colon cancer, we found little association of colon cancer incidence with fruit and vegetable consumption. For women and men combined, a difference in fruit and vegetable consumption of one additional serving per day was associated with a covariate-adjusted RR of 1.02 (95% confidence interval [CI] = 0.98-1.05). A difference in vegetable consumption of one additional serving per day was associated with an RR of 1.03 (95% CI = 0.97-1.09). Similar results were obtained for women and men considered separately. A difference in fruit consumption of one additional serving per day was associated with a covariate-adjusted RR for colon cancer of 0.96 (95% CI = 0.89-1.03) among women and 1. 08 (95% CI = 1.00-1.16) among men. For rectal cancer (total, 244 cases), a difference in fruit and vegetable consumption of one additional serving per day was associated with an RR of 1.02 (95% CI = 0.95-1.09) in men and women combined. None of these associations was modified by vitamin supplement use or smoking habits.

CONCLUSIONS

Although fruits and vegetables may confer protection against some chronic diseases, their frequent consumption does not appear to confer protection from colon or rectal cancer.

Follow-up in colorectal cancer: cost-effectiveness analysis of established and novel concepts

BACKGROUND

Follow-up programs in colorectal cancer have been under question recently due to their low efficacy. Some meta-analyses found a survival benefit and four randomized studies suggested the opposite. Therefore, this paper analyzes existing and proposed follow-up programs for costs and efficacy.

METHODS

One thousand and fifty-four colorectal cancer patients intensively followed-up in Ulm (endoscopy, chest radiography, abdominal ultrasound, computed tomography (CT) pelvis) were prospectively evaluated for recurrence, salvage surgery rate, survival and costs. Costs were compared among existing and proposed international follow-up programs retrieved by a MedLine search.

RESULTS

A total of 350/1,054 colorectal cancer patients (33.2%) relapsed asymptomatically, as detected by follow-up. 56/350 (local 47%, distant 53%) recurrences were resectable (16%), 21/350 patients survived (6%). The efficacy of follow-up was 21/1,054 patients (2%). Costs were, per patient, 2,220 euros (colon) or 4,851 euros (rectum). Costs in five randomized studies varied between 616 euros for minimal and 5,049 euros for intensive follow-up. Four proposed follow-up concepts include risk-adaption, which claim to reduce costs by 50-60% and range between 889 (colorectal) and 5,910 (high-risk, rectum) euros. The recommended German follow-up guideline costs 610 euros (low-risk, colorectal), 1,120 euros (high-risk, colon) or 2,252 euros (high-risk, rectum).

CONCLUSION

Follow-up concepts for colorectal cancer should aim at the identification of curable patients with recurrence. Evidence-based concepts, including life quality tests, remain to be defined, but currently abdominal ultrasound, endoscopy and carcino-embryonic antigen (CEA) determination at 6-month intervals for 2 years and annual intervals for 3 years seem to identify this patient sub-group.

Colorectal cancer update. Prevention, screening, treatment, and surveillance for high-risk groups

Great advances have been made in understanding the cause and molecular genesis of colorectal cancer. The disease can be prevented by a healthful diet and lifestyle or by resecting the precursor of most of these cancers, the advanced adenomatous polyp. Screening the average-risk population plus special surveillance for high-risk groups now is recommended by evidence-based guidelines. Surgery is highly curative for patients without distant metastases, and adjuvant therapy improves survival in selected patients with advanced cancers.

[Reducing incidence and mortality from rectal cancer by polypectomy: a prospective cohort study]

OBJECTIVE

To address the hypothesis that colorectal cancers often arise from precursor lesion(s), either adenomas or non-adenomatous polyps.

METHODS

A population-based mass screening for rectal cancer using 15cm rigid endoscopy was conducted in Haining County, Zhejiang province, from 1977 to 1980. Of over 230,000 participants, 4,076 of them were diagnosed with precursor lesions, either adenomas or non-adenomatous polyps, which were then removed. All individuals with precursor lesions were followed and re-examined by endoscopy every two to five years through 1998.

RESULTS

After the initial screening, 952 metachronous adenomas and 417 non-adenomatous polyps were detected and removed from the cohort. Furthermore, 27 cases of colorectal cancer were detected and treated. Log-rank tests showed that the years of survival significantly increased among those cancer patients who had undergone mass screening compared to other rectal cancer patients (P < 0.001). According to the population-based cancer registry in Haining County, both age-adjusted incidence and mortality rates from rectal cancer decreased from 1977 to 1996. Observed accumulative incidence and mortality rates decreased to 68.6% and 82.4% comparing with expected numbers during the last 20 years.

CONCLUSION

Mass rectal cancer screening in the general population followed by routine endoscopy for high-risk patients could decrease both rectal cancer incidence and mortality rates.

Screening for colorectal cancer

Colorectal cancer is the third most commonly diagnosed cancer and the second leading cause of cancer deaths in the United States. Fortunately, both the incidence and mortality associated with the disease have declined during the past 2 decades. This is likely due, at least in part, to improved efforts at screening and more aggressive removal of adenomatous polyps. However, colorectal cancer screening is still generally underutilized. This article reviews the current status and future outlook for colorectal cancer screening, including a discussion of risk factors for the disease, its anatomic distribution, proposed mechanisms of development from adenomatous polyps, rationale for screening, and screening options. Published literature concerning the cost-effectiveness of colorectal cancer screening is also summarized. The article concludes with a discussion of the emerging consensus regarding the importance of and approaches to screening.

Long-term treatment with sulindac in familial adenomatous polyposis: is there an actual efficacy in prevention of rectal cancer?

BACKGROUND AND OBJECTIVES

Ileorectal anastomosis (IRA) is still used in the treatment of familial adenomatous polyposis (FAP). Sulindac appears to induce regression of colorectal adenomas; however, its effects in long-term therapy and in preventing carcinoma remain unclear.

METHODS

Fifteen FAP patients treated by IRA received sulindac (200 mg/day) for a mean period of 48.6 +/- 28.7 (range 12-124) months. Number, size, and type of rectal polyps were assessed by endoscopic and histological evaluation every 6 months.

RESULTS

Significant regression of polyps was observed in all patients after 6 months (P < 0.02). However, after a mean of 48.6 +/- 28.7 months, both number and size of polyps increased again, showing no statistical difference with baseline values. Minute polyps appeared reddish, while the largest lesions were flat or slightly elevated. Endoscopic polypectomy was necessary in 9 patients and transanal surgical excision in 3. Two patients were submitted to restorative proctectomy because of a large polyp with severe dysplasia and a rectal cancer, respectively.

CONCLUSIONS

Sulindac appears to influence the morphological appearance of polyps in FAP patients, inducing apparent regression. However, at a dose of 200 mg, it does not influence the progression of polyps toward a malignant pattern.

Effect of subacute ibuprofen dosing on rectal mucosal prostaglandin E2 levels in healthy subjects with a history of resected polyps

Nonsteroidal antiinflammatory drugs are among the most promising chemopreventive agents for colorectal cancer. Although the mechanism by which nonsteroidal antiinflammatory drugs exert such effects remains to be further characterized, their best known pharmacological effect is inhibition of prostaglandin synthetase, which leads to decreases in tissue prostaglandin levels. We conducted a randomized, double-blind, controlled study to examine the effect of daily ibuprofen treatment on the rectal mucosal prostaglandin E2 (PGE2) levels in healthy subjects with a history of resected polyps. Study participants (n = 27) completed a 2-week run-in period and were then randomized to take a single, daily dose of ibuprofen (300 or 600 mg) or of a placebo for 4 weeks. Rectal biopsy specimens were taken before and after the run-in period and at 2 and 4 weeks after the ibuprofen/placebo treatment. Notably large between- and within-subject variability in the rectal mucosal PGE2 content was seen. The changes in PGE2 levels after ibuprofen/placebo treatment correlated with the baseline PGE2 content. After adjustment of the baseline values, 2 weeks of 300 mg/day of ibuprofen treatment resulted in significantly more suppression of PGE2 levels than that observed after the placebo treatment (55% versus 22% suppression from baseline; P = 0.033). Although other ibuprofen treatment schedules and doses appeared to result in suppression in the PGE2 levels, the suppression was not statistically significant because of the large variability in this measurement. Because lower doses are associated with fewer adverse effects, a dose of 300 mg of ibuprofen/day should be considered for future Phase II chemoprevention studies. Stratifying study participants, based on their baseline PGE2 levels and inclusion of a larger number of study subjects, are recommended for future trials where the rectal mucosal PGE2 level is to be used as a surrogate end point biomarker.

Do NSAIDs prevent colorectal cancer?

There is increasing evidence to suggest that acetylsalicylic acid (ASA) and other nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal cancer. This observation is supported by animal studies that show fewer tumours per animal and fewer animals with tumours after administration of several different NSAIDs. Studies in humans consistently support this hypothesis. Intervention data from familial adenomatosis coli establish that the process of human colonic adenoma polyp formation is affected. Supportive evidence comes from 21 of 23 human studies - both case-control and cohort. The reduced risk has been found in men and women, for cancers of the colon and the rectum and for the use of both ASA and the other NSAIDs. Earlier detection of lesions as a result of drug-induced bleeding does not seem to account for these findings. The molecular mechanisms responsible for the chemopreventive action of this class of drugs is not completely established. Protection may affect several pathways, including cell cycle arrest and induction of apoptosis. Because of the consistency of epidemiological, clinical and experimental data, there is no need for further placebo trials. At the same time, there is a need to establish the dose, duration and frequency of use required for cancer-preventive activity.

A case-control study of use of postmenopausal female hormone supplements in relation to the risk of large bowel cancer

Postmenopausal female hormone use has been associated with a reduced risk of colon cancer. We assessed the relation of use of these supplements to the risk of large bowel cancer. The data were collected in a case-control study of large bowel cancer conducted in Massachusetts. Control subjects were matched to incident cases of carcinoma of the colon or rectum on age, gender, and town precinct. The analysis was restricted to women who experienced a natural menopause or had had a hysterectomy with or without removal of the ovaries (292 colon cancer cases and 112 rectal cancer cases and their matched controls). Use of female hormone supplements was associated with a decreased risk of colon cancer among recent users (odds ratio, 0.6; 95% confidence interval, 0.4-1.0) and long duration (5+ years) of use (odds ratio, 0.5; 95% confidence interval, 0.3-0.9). The association with long duration of use appeared to be independent of recency of use and screening practices and was apparent for late-stage cancer. Hormone supplement use was not associated with a reduced risk of rectal cancer. Our results add to the evidence for a decreased risk of colon cancer associated with use of female hormone supplements.

Commentary on the Women's Health Initiative

The Women's Health Initiative (WHI), established by the National Institutes of Health in 1991, is a long-term national health study that focuses on strategies for preventing heart disease, breast and colorectal cancer and osteoporosis in postmenopausal women. These chronic diseases are the major causes of death, disability and frailty in older women of all races and socioeconomic backgrounds. The WHI a 15-year multi-million dollar endeavor, and one of the largest U.S. prevention studies of its kind. The study involves over 161,000 women aged 50-79, and is one of the most definitive, far reaching clinical trials of women's health ever undertaken in the U.S. The WHI Clinical Trial and Observational Study will attempt to address many of the inequities in women's health research and provide practical information to women and their physicians about hormone replacement therapy, dietary patterns and calcium/vitamin D supplements, and their effects on the prevention of heart disease, cancer and osteoporosis. Emerging information from the NIH Women's Health Initiative and other studies of women's health begun in the 1990's should be changing the landscape of options for older women in the years to come.

Education improves colorectal cancer screening by flexible sigmoidoscopy in an inner city population

OBJECTIVE

The District of Columbia General Hospital has a flexible sigmoidoscopy (FS) colorectal cancer screening program. We noted that this program was underused. The aim of this study was to determine whether education could improve use of a flexible sigmoidoscopy screening program in an inner city population.

METHODS

Patients undergoing screening FS 5 months before our educational initiative were compared to patients undergoing screening FS 5 months after implementation. A 1-month period was allowed for implementation. Procedure logs and GI charts were reviewed.

RESULTS

A total of 121 patients underwent FS screening during our study period. Of the patients, 97% were African-American; 58% were female; and the average age was 61 yr. A total of 50 patients underwent FS in the pre-education group, and 71 patients underwent FS after implementation of our educational initiative.

CONCLUSIONS

Education resulted in a 42% increase in FS screening in this inner city, predominantly African-American population. Larger scale educational initiatives should be conducted to determine whether these benefits can persist and can be improved upon.

Clinical practice guidelines. Review of the recommendations for colorectal screening

Data suggest that vigilant screening and polyp removal can help reduce mortality caused by colorectal cancer (CRC), the incidence of which increases with age. Although several screening methods are available, wide variation exists among them in accuracy, effectiveness of identifying cancerous lesions, potential complications, costs, ease of administration, and patient compliance. Moreover, a lack of direct evidence demonstrating the long-term benefits (compared with the costs and risks) of the individual screening methods complicates the decision of when and whether to screen. In 1994, an expert, multidisciplinary panel was convened to review the evidence and produce recommendations to help guide clinicians and patients with regard to CRC screening and surveillance. The resulting clinical practice guidelines, released in 1997, are examined.

Locally recurrent rectal cancer: role of composite resection of extensive pelvic tumors with strategies for minimizing risk of recurrence

Locally recurrent cancer of the rectum has been under-recognized as a complication, although it affects up to 40% of patients treated with surgery alone. Even in the best centers, rates average 25%. While radiotherapy may reduce recurrence, it is now apparent that total mesorectal excision is the most effective modality, with rates as low as 5%. The dramatic decrease in local recurrence can also be linked to increased survival in prospective studies, an effect more significant than any adjuvant therapy. The options, however, for patients with locally recurrent cancer are limited. Fifteen percent of patients with this complication die without systemic spread. Salvage by surgery offers potential cure. Other than anastomotic recurrences that can be locally resected, the best approach for long-term survival is an extensive surgical procedure requiring en bloc removal of adjacent organs and pelvic structures-so-called composite resection. With careful selection, 30% 5-year survival can be achieved and palliation is considerable, with 50% long-term local control. Intraoperative radiotherapy and brachytherapy, and/or preoperative chemoradiation may provide better results in future. Newer techniques of coloanal anastomosis, improved urinary diversion, and myocutaneous flaps for perineal reconstruction radically reduce the morbidity of these procedures. The approach to recurrent rectal cancer requires a sophisticated multidisciplinary team to obtain optimum results.

Colonoscopy

Colonoscopy and polypectomy are the most effective tools available to prevent colorectal cancer. The technical performance of colonoscopy can be improved by methods that make polyp detection easier and more reliable, facilitate cecal intubation, and reduce recurrence and complication rates after polypectomy. The state-of-the-art and possible future trends in patient preparation, indications, screening and surveillance intervals, sedation issues, and virtual colonoscopy are reviewed in this article.

American Cancer Society guidelines for the early detection of cancer

This issue of CA inaugurates a yearly report on American Cancer Society guidelines for early detection of cancer in asymptomatic individuals. The current recommendations, which reflect almost 20 years of updates, cover screening recommendations for breast, colorectal, prostate, and cervical cancers, as well as for other cancers, depending on patient age, history, environmental and/or occupational exposures, etc. A key concept for both the general public and health providers is the distinction between public health recommendations regarding screening and decisions about early detection tests that might be undertaken on an individual basis. Although it is likely that current screening protocols will be supplanted by newer technologies, such as genetic and molecular markers of risk and disease, greater utilization of the technologies at hand will improve efforts toward establishing an organized and systematic approach to early cancer detection.

World Cancer Research Fund/American Institute of Cancer Research 1997 recommendations: applicability to digestive tract cancer in Japan

OBJECTIVES

This paper reviewed analytic epidemiological studies of the major Japanese digestive tract cancers, i.e. esophageal, stomach, colon and rectal. The applicability of the recommendations for prevention of these cancers by the World Cancer Research Fund/American Institute of Cancer Research (W&A) to Japan is considered.

METHODS

Papers were searched by the MEDLINE for the period 1966 through 1997. Among them, 43 relevant papers including data from Japan were reviewed.

RESULTS

Results for 11 lifestyle-related factors were considered. Cigarette smoking was a strong and consistent, thus, convincing, risk factor for esophageal cancer, and a possible risk factor for stomach and colorectal cancer. Excessive consumption of alcohol was a convincing risk factor for esophageal cancer, and a possible risk factor for stomach and colorectal cancer. Excessive salt intake was a risk factor supported by some strong evidence but inconsistent; therefore, it is a probable risk factor for stomach cancer and a possible risk factor for colorectal cancer. Low physical activity was a probable risk factor for colorectal cancer. On the other hand, sufficient intake of vegetables, including green-yellow vegetables, and fruits was regarded as a possible protective factor for these cancers.

CONCLUSIONS

These observations were mostly consistent with those reported by W&A; therefore the recommendations by W&A for prevention of these cancers may be considered applicable to the current Japanese population.

[Hereditary colorectal cancer]

About 13% of all colorectal cancer may be dominantly inherited. This amounts to about 300 new cases a year in Norway. Colorectal cancer can be cured by early diagnosis and treatment. Coloscopy with polypectomy may prevent infiltrating cancer. Affected families should be offered genetic evaluation, and family members subjected to regular colonoscopy. The genetic bases of five colorectal cancer syndromes, accounting for most cases of hereditary early onset colorectal cancer, have now been determined. These are familial adenomatous polyposis, colon-endometrial cancer (hereditary non-polyposis colon cancer), Cowden's syndrome, Peutz-Jegher's syndrome and juvenile polyposis. These account for at most 3% of all colorectal cancers. In this group, predictive genetic testing may be employed in families with known mutation. Demonstration of mutation carriers by predictive testing must be based on health service available to the persons at risk. With regard to prophylactic measures, experimental and epidemiological data suggest a preventive effect of aspirin and resistant starch. Empirical information on the effect of intervention is insufficient; multicentre studies are needed.

Colorectal cancer screening: new opportunities

Colorectal cancer is the third most common cancer among men and women in the United States, and the third leading cause of cancer death. Strategies currently available to screen for colorectal cancer include fecal occult blood tests, sigmoidoscopy, or both tests used in combination. Colonoscopy and double contrast barium enema are potentially preferable options because they offer improved sensitivity over currently available tests, but the feasibility of these tests for population screening remains in doubt. Future opportunities for screening include focusing special efforts to deliver screening to higher risk individuals based on family history or age and the use of molecular or computer-aided radiographic techniques as alternatives to colonoscopy.

Colorectal cancer prevention by non-steroidal anti-inflammatory drugs: effects of dosage and timing

Epidemiological studies show that non-steroidal anti-inflammatory drugs (NSAIDs) reduce colorectal cancer incidence. We measured the rate ratio for colorectal adenocarcinoma according to dosage and the timing of exposure by means of a case-control study, nested in a non-concurrent cohort linkage study, using the population of beneficiaries of the Saskatchewan Prescription Drug Plan from 1981 to 1995 with no history of cancer since 1970 as the source population. Four controls per case, matched on age and gender and alive when the case was diagnosed, were randomly selected. Dispensing rates, calculated over successive time periods, characterized NSAID exposure. We accrued 3844 cases of colon cancer and 1971 cases of rectal cancer. For colon cancer a significant trend towards a decreasing rate ratio was associated with increasing exposure during the 6 months preceding diagnosis (P-trend = 0.002). For both cancers, significant trends were associated with exposure 11-15 years before diagnosis (colon: P-trend = 0.01; rectum: P-trend = 0.0001). At the highest exposure levels the rate ratio for colon cancer was 0.57 (95% confidence interval (CI) 0.36-0.89); for rectal cancer it was 0.26 (95% CI 0.11-0.61). No protection was associated with exposure during other periods. The timing of NSAID use must be considered in planning intervention trials to prevent colorectal cancer. There may be a 10-year delay before any preventive effect will appear.