CONFERENCE SUMMARY Editor: Michael J. Glade, PhD

Nutrition After CancerAmerican Institute for Cancer ResearchChicago, Illinois, USAMay 8, 2002

I’m just lucky, I guess. Lucky I complied with my physician’surging to get the mammogram. And then it was lucky that I obeyedhis directive to get the colonoscopy. But it was my own idea toattend the conference, “Nutrition After Cancer.”

Richard S. Rivlin, MD, gave the keynote address, “The State ofthe Science on Nutrition and Cancer Survivorship.” Dr. Rivlininterwove prevention and treatment throughout his presentation,and that puzzled me at first. Then I remembered that cancersurvivors are the most probable candidates for becoming futurecancer victims. He addressed the intake of several specific dietaryagents and endorsed washed berries, but regretted that the resultsof a study on the relation of a low-fat (15% to 20% of totalcalories) diet to breast cancer survival was 2 y away. It seemed thatthe answers to most of the important issues lay in the future:determinants of patient behavior, compliance, and therapeuticchoices … factors that regulate cellular levels of endogenousantioxidants … interactions of phytochemicals, herbal products,and prescription drugs … relations of dietary factors to ameliorat-ing toxicity of chemotherapy and radiotherapy while enhancing ormaintaining efficacy … dose–response relations of dietaryagents.… All are important to me. In fact, I went to this conferencefor answers to these exact questions. Alas, there were no answers.As a survivor of cancer, I took cold comfort in Robert Browning’sopinion that “a man’s reach should exceed his grasp, or what’s aheaven for?” I do hope I won’t have to wait for heaven to obtainmy answers.

Diana Dyer, MS, RD, provided the perspective of a cancersurvivor as she addressed “Nutrition: Changes for Life.” Ms Dy-er’s goals after cancer were remarkably similar to those of mostsurvivors: “Reduce my risk for recurrence … rebuild and improvemy immune system … not be plagued by debilitating fatigue.…”Come to think of it, they’re probably similar to the goals ofeveryone, everywhere, cancer survivor or not. As all speakers did,Ms Dyer endorsed the American Institute for Cancer Research’sCancer Prevention Diet Guidelines of 1995, but she went further:“Make sure every bite will protect!” Every bite? Yes, EVERY bite.In shotgun fashion, she addressed and advised on such topics as fatintake, animal products, cold-water fish, fiber, legumes, herbs andspices, flaxseeds, green tea, and soy. Lots of soy. You can’t arguewith success; after three bouts of cancer, Ms Dyer professed tohave “more energy than [she] knows what to do with.” (Her website, www.CancerRD.com, contains “family-tested menus” for thecancer survivor.)

Mark Messina, PhD, spoke on “Soy and the Cancer Survivor.”I was curious to know why the consumption of soy-based foodshas been touted as the road to salvation for over a decade. Ac-cording to Dr Messina, soy is the only realistic source of theisoflavones that can inhibit the enzymes that regulate the repro-duction of cells, including cancer cells. Dr Messina’s evaluation ofthe literature has led him to conclude that an increase in soyconsumption leads to a decrease in risk for cancer, all other thingsbeing equal. The trick, it seems, is to find out which things areequal. For example, because people in Asian countries consumemore soy foods than Americans and have lower rates of breast andprostrate cancer than Americans, it’s logical to suspect that achemopreventive relation exists between soy and these two can-

cers. Indeed, some data are very encouraging: women who con-sumed 11 g of soy daily during their developmental (teenage)years had a 50% reduction in their risk of developing breast canceras adults, compared with women who did not eat any soy products.But no mention was made of the effect of soy when taken beforeor after ages 13 to 15 y. Does this 3-y period represent a solitarywindow of opportunity? What is the effect of soy on women whoalready have developed breast cancer? That is a very importantquestion, because isoflavones (sometimes calledplant estrogens orphytoestrogens) can mimic estrogen in some tissues. Becausesome breast cancers react positively to estrogen and grow, it makessense for women with those tumors to avoid soy products. Butlaboratory studies have indicated that, although moderate doses ofthe isoflavone “genistein” stimulates cell growth, higher dosesactually inhibit growth of cancer cells. How high a dose is requiredbefore the threshold for this beneficial response is reached? I’m notsure anyone knows. To further complicate the issue, tamoxifan, thedrug of choice given to cancer patients to inhibit the growth oftumors, should be weakened in the presence of estrogen-like soy.But animal studies have indicated that the combination of soy andtamoxifan works better than tamoxifan alone! The fact that thestudy was done on animals, not humans, compromises the data, butthis possibility certainly warrants further investigation. In fact,although it’s safe to say that two servings of soy products a day(about 50 mg of isoflavones) can play a role in preventing cancer,no firm data exist to advise cancer survivors, except a generalimpression that soy foods should be more beneficial than soy pills.

Wendy Demark-Wahnefried, PhD, RD, LDN, presented a com-prehensive discussion of “Flaxseed and the Cancer Survivor.”According to Dr Demark-Wahnefried, flaxseed contains�-3 fattyacids, which inhibit the metabolism of�-6 fatty acids. Because�-6 fatty acids appear to stimulate the growth and metastasis ofbreast cancers, it makes sense to consume�-3 fatty acids on aregular basis. In addition, flaxseed contains large amounts oflignans, a form of dietary fiber. Lignans are converted by largeintestinal bacteria to chemicals that resemble estrogen and thatmay possess mildly estrogenic properties. As with soy products, itwould seem prudent for cancer survivors with estrogen-positivetumors to avoid flaxseed, but data presented on 25 men withprostrate cancer seemed to show that a low-fat diet (20% of totalcalories as fat) combined with 30 g of flaxseed daily reduced allindicators of cancer after only about a month of treatment. Asidefrom the questionable fat component and the lack of placebo in thistrial, it must be pointed out that lignans act as a laxative, and 30 g(about 3 tablespoons) is a lot! How much is necessary? Even morethan soy products, flaxseed holds some tantalizing promises toreduce not only cancer rates but also the rates of other humanconditions, such as hypercholesterolemia and a compromised im-mune system. But when should flaxseed be consumed? For howlong? How much? In what form? I wish good health and God’sspeed to the researchers who will bring us the answers to thesequestions.

Rowan Chlebowski, MD, PhD, delineated the relation between“Weight Management and the Cancer Survivor.” “Body massincrease has a direct relation to breast cancer recurrence.… Obe-sity leads to an increase in hormones that encourage cancer.” DrChlebowski confirmed that weight loss is a viable approach to theprevention of cancer. The next question was: How, and howmuch? Unfortunately, the studies he quoted were not based oncancer survivors, but it doesn’t take much of a leap of faith toextrapolate the results. What I found interesting was the docu-mented need for constant medical supervision during weight-management programs. I guess those weekly weigh-ins are neces-

0899-9007/03/$30.00Nutrition 19:698–699, 2003©Elsevier Inc., 2003. Printed in the United States. All rights reserved.

sary! Equally necessary is exercise, which reduces insulinsecretion (insulin has been shown to stimulate breast cell growth).Dr Chlebowski suggested that physical movement, coupled with adiet that reduces the need for estrogen and insulin, will result in abody that is truer to the 10 000-y-old model that has stood the testof time and supports us today. How much weight to lose? I wassurprised to hear that even a 5% decrease in body weight results ina 50% decrease in the chances of suffering from diabetes, heartdisease, or cancer.

Kerry S. Courneya, PhD, considered whether cancer survival isa matter of the “Survival of the Fittest? The Potential Role ofExercise in Reducing Recurrence and Mortality After Cancer.”According to Dr Courneya, exercise optimizes everything goodand ameliorates everything bad. I wasn’ t surprised to hear thatvalid studies on cancer survivors don’ t exist. Nonetheless, for thefirst time in the conference, data were presented that reflected verylarge numbers of people, routinely in the thousands. In thosestudies, over and over, exercise led to fitness, and fitness led tobetter resistance to cancer. But what about those who had suc-cumbed to cancer? The answer was the most heartening of theentire conference. Exercise after cancer diagnosis or treatmentimproves the QUALITY OF LIFE of a patient. (I’m using capitalletters because it’s so important.) What good is a “cure” that isworse than the disease? Don’ t we all want to regain our formervibrancy? “Quality of life” as a survivor is much more important

than length of life. Dr Courneya’s message: “Walking is good!Preferably, every day, at least 10 min at a time. It is important torealize that ‘walking’ does not mean ‘strolling.’ Walk like you’ relate for an appointment.” But start slowly and walk in an area “ thatengages the mind and spirit”— in other words, walk in the woods,not in the basement on a treadmill.

John R. Prince, in his final remarks, “Agenda for Action,”touched on the need for more and, in some cases, better research.But there already is a huge body of information available. Forexample, no literate person in the entire world can claim ignoranceof the value of a diet high in fresh plant-based foods and low inmeats.

I would like to see more investigation of the “ time factor” in therelation of nutrition to cancer. When most people are unavoidablyconfronted by their own mortality, they become instant converts toa healthy lifestyle, only to regret not having started earlier. Howmuch earlier in life should they have started? It’s not helpful tosay, “start at conception.” Is there some period when exposure tocertain foods is most crucial? If so, when is that time and what arethose foods?

Kathleen KingGurnee, Illinois, USA

doi:10.1016/S0899-9007(03)00110-2

Nutrition Volume 19, Numbers 7/8, 2003 699Nutrition After Cancer