Prospects for cancer prevention

Our plain-English summary of Prospects for cancer prevention, by L.R. Ferguson (Mutation Research, 1999).

The study

• Author: L.R. Ferguson
• Journal: Mutation Research
• Published: 1999;428(1-2):329-38
• Type of article: Review
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

As in many other countries, the New Zealand Cancer Society produces guidelines for cancer prevention. These recommend avoiding asbestos, smoking, sunlight, alcohol, fatty food and obesity. Women are advised to have a regular cervical smear test. Additional 'probably helpful' suggestions include eating plenty of fresh fruit and vegetables and dietary fibre. However, considerable data from animal studies and more slowly accumulating data from human intervention studies suggest additional and more specific advice may be appropriate. Fruit and vegetable servings should total a minimum of five each day. Some specific fruits and vegetables (e.g., tomato, broccoli, onions) may have particular benefits against individual cancer types. Positive human evidence on potential benefits of increasing dietary fibre comes from studies where wheat bran was added to the diet. This is not a dietary fibre per se, but merely a good fibre source. Indeed, our own studies suggest that it could be various phytochemicals in the bran, rather than dietary fibre, which is beneficial. An increase either in whole wheat or wheat bran, rather than fibre, would be a sounder recommendation. Although there is some evidence that multivitamin supplementation can protect against cancer, this may be only in the special situation where the population is already significantly vitamin-deficient. For example, a combination of beta-carotene, vitamin E and selenium significantly reduced cancer mortality in a Chinese population, whereas lung cancer risks (in already high risk groups) were increased in Finnish and American trials with high dose beta-carotene. Various other chemopreventive drugs are being actively developed and at various stages in clinical trials. The enhanced cancer incidence in the beta-carotene trial illustrates the potential benefit of utilising surrogate endpoints of malignant disease rather than incident cancer as a trial endpoint.

In plain English

This 1999 article was a review by the author, from the Auckland Cancer Society Research Centre in New Zealand, of evidence on preventing cancer, mainly through diet, vitamins and minerals, and chemopreventive drugs. It was not a study of asbestos. Asbestos came up in two contexts. First, the New Zealand Cancer Society's guidelines, listed in the abstract and a table, included "Avoid asbestos dust." Second, in describing an earlier trial called CARET, the review noted that more than 4000 of its 18,314 high-risk participants were asbestos-exposed men. As the review reported it, CARET tested daily beta-carotene plus retinyl palmitate (vitamin A) against placebo and was stopped 21 months early. Compared with the placebo group, the active group had a relative risk of 1.36 (95% CI 1.07–1.73) for weighted lung cancer incidence and 1.59 (95% CI 1.13–2.23) for weighted lung cancer mortality. The review gave no separate results for the asbestos-exposed men. The author suggested modified dietary recommendations. The author concluded that CARET and a Finnish beta-carotene trial illustrated the danger of using cancer as the endpoint of a prevention trial.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Narrative review of published cancer-prevention guidelines, human intervention trials and chemoprevention research (not an original study)
• Who was studied: No study population of its own. The review discussed published studies and the New Zealand Cancer Society's guidelines. Among the trials described was CARET (from a cited paper), with 18,314 men and women at high risk of lung cancer, more than 4000 of them asbestos-exposed men.
• Exposure: Mainly diet (fat, fruit and vegetables, fibre and wheat bran), vitamin and mineral supplements, and chemopreventive drugs. Asbestos was mentioned only in the New Zealand Cancer Society's guidelines (in the abstract and a table) and as a description of some CARET participants. No fiber type was named.
• Main results:
  • The New Zealand Cancer Society's guidelines, summarized in the abstract and reproduced in a table of firm guidelines, included avoiding asbestos dust.
  • CARET (a cited trial, not this article's own study) tested 30 mg beta-carotene plus 25,000 IU retinyl palmitate daily against placebo in high-risk participants, including more than 4000 asbestos-exposed men. The trial was stopped 21 months early because higher lung cancer risks appeared in the intervention group.
  • In CARET, as reported in the review, the active intervention group compared with the placebo group had a relative risk of 1.36 (95% confidence interval 1.07–1.73; P = 0.01) for weighted lung cancer incidence. No separate result was given for the asbestos-exposed men.
  • In CARET, as reported in the review, the relative risk for weighted lung cancer mortality in the active intervention group compared with placebo was 1.59 (95% confidence interval 1.13–2.23; P = 0.01).
  • In the Finnish ATBC trial (a cited study) of 29,133 male cigarette smokers aged 50–69, the beta-carotene groups had more cancers than the groups not given beta-carotene: lung 474 compared with 402, prostate 138 compared with 112, and stomach 70 compared with 56.
  • The author suggested modifying the New Zealand dietary guidelines: reduce fats to 20% or less of the diet, eat at least five and preferably eight servings of fruit and vegetables daily, choose whole cereals and brans over refined grains, and consider wheat bran as a supplement.
• The authors' conclusion: The author concluded that the CARET and ATBC trials illustrated the danger of using cancer as the endpoint of a prevention trial. The author considered that valid surrogate endpoints would allow shorter trials, and that new chemoprevention strategies need a stronger scientific basis.

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer, Clinical Trial.

Related studies

• Clinical Trials with Oncolytic Measles Virus: Current Status and Future Prospects — P. Msaouel, M. Opyrchal, et al. (2018)
• Clinical trials of vitamin and mineral supplements for cancer prevention — P. Greenwald, D. Anderson, et al. (2007)
• Cancer Prevention: Lessons Learned and Future Directions — B.K. Dunn, B.S. Kramer (2016)
• The potential role of antioxidant vitamins in preventing cardiovascular diseases and cancers — S. Hercberg, P. Galan, et al. (1998)
• Association between 8-hydroxy-2'-deoxyguanosine levels in DNA of workers highly exposed to asbestos and their clinical data, occupational and non-occupational confounding factors, and cancer — B. Marczynski, T. Kraus, et al. (2000)
• Targeting Inflammation in Cancer Prevention and Therapy — J. Todoric, L. Antonucci, et al. (2016)

Browse more research in Mutation Research, or return to medical research.