Dietary and Physical Activity Factors Affecting Risk for Certain Cancers
Breast cancer is the most commonly diagnosed cancer among women in the United States and has the second highest mortality rate after lung cancer.201 For breast cancer, well-established, non-dietary risk factors include the use of estrogen therapy (hormone replacement therapy) menopausal symptoms, and exposure to ionizing radiation, especially during adolescence. Some reproductive and other factors that are difficult to modify increase the risk of breast cancer: first menstruation before the age of 12 years, not having had a child or having a first child older than 30 years, late age at menopause, and a family history of breast cancer. For breast cancer, the risk factors for diagnosis before and after menopause are different.2 These factors may differ because of the positive and negative hormone receptors for breast cancer.202 203 Whether early exposure, including in utero exposure during adolescence, has a significant impact on breast cancer risk in the latter half of life is of increasing concern. The higher the body height, the higher the risk of breast cancer in adults, implying the influence of nutritional factors on breast cancer in the first half of life.204 205
There is consistent evidence that increased body weight and weight gain in adulthood are associated with an increased risk of breast cancer in postmenopausal women (but not premenopausal).76 206-208 The increased satellite may be due in part to the high levels of estrogen produced by excess adipose tissue after menopause. Women who take postmenopausal hormone therapy are less likely to detect the deleterious effects of increased weight because higher levels of exogenous estrogen may obscure the deleterious effects of increased weight.
Among dietary factors, alcohol consumption is recognized as one of the behaviors most consistently associated with an increased risk of breast cancer. Since their relationship was first reported in the 1980s,209 210 a large number of trials have also validated their relationship.91 211 212 A comprehensive analysis of these findings clearly demonstrates that increased alcohol intake increases the risk of breast cancer, and that small amounts of alcohol intake appropriately increase the risk of breast cancer.2 14 213 214 However, the exact mechanism of action of alcohol as a carcinogen on breast tissue remains unclear and is perhaps related to the effects of alcohol on sex hormone metabolism.
Although the initial benefits of physical activity in breast cancer patients may have weight and hormone metabolism related215 216 , the effects of physical activity as an independent risk factor have become a hot area in its own right over the past 20 years. A large number of studies have consistently concluded that for premenopausal and postmenopausal women, moderate to vigorous physical activity is associated with a reduced risk of breast cancer, with women who exercise more having an approximately 25％14 217 lower risk of breast cancer than women who exercise less.
In observational studies, dietary patterns of hearty fruits and vegetables, poultry, fish and low-fat dairy products were found to reduce the risk of breast cancer.2 114 However, studies of fruits and vegetables and breast cancer have found that fruits and vegetables do not reduce breast cancer risk.14 Some recent studies have found that they can reduce tumors that are more difficult to treat with estrogen-negative receptors.218-220 One recent study found that higher blood higher levels of carotenoids in the blood may reduce breast cancer risk, supporting the recommendation to consume dark plant foods to prevent breast cancer.114 221
Although whether lowering fat intake to a very low level may reduce breast cancer risk remains a hot topic, this has not been found in the pooled findings of several prospective cohort studies.222 The Women’s Health Advocacy Dietary Improvement Trial found that in postmenopausal women, a low-fat dietary intervention that lowered fat intake to approximately 29％ calories had only a small effect on reducing breast cancer risk by only a small amount (a 9％ risk reduction).155
The best nutrition- and exercise-related recommendations for reducing breast cancer risk are to engage in daily, purposeful physical activity; to minimize weight gain through a combination of energy restriction (in part through a dietary pattern high in fruits and vegetables) and daily physical activity; and to avoid or control the intake of alcoholic beverages.
Bowel Cancer
Bowel cancer ranks as the second leading cancer factor causing death in the U.S. population.201 A family history of bowel cancer or adenomatous polyps, a precancerous lesion, increases the risk of bowel cancer. Chronic smoking and excessive alcohol consumption may also increase the risk of bowel cancer. As with breast cancer, height in adults increases the risk of bowel cancer.15 This may be partly a response to nutritional status during growth.
Many studies have verified whether overweight and obesity increase bowel cancer risk, most of which found that being overweight increases bowel cancer risk in both men and women, but more so in men.15 63 224 The results of these studies confirm the strong association between body fat distribution and bowel cancer risk, and also confirm that abdominal fat, such as a larger waist circumference or high waist-to-hip ratio, increases bowel cancer risk.15
Studies validating the relationship between physical activity and bowel cancer risk have been highly consistent, finding that increased physical activity can see an increased risk of bowel cancer.225 226 Trials examining physical activity and colon adenomas or polyps have found that increased physical activity can also reduce their risk.227 Also, moderate daily exercise can reduce the risk of bowel cancer, and vigorous exercise may provide greater benefits.15 101 227 228.
As early as the 1970s, it was found that geographically correlated meat intake and bowel cancer incidence implied a role for red and processed meats in increasing bowel cancer risk. Numerous case-control and cohort studies have subsequently confirmed the association between red meat intake and bowel cancer risk, and the WCRF/AICR places great confidence in this evidence. A recent meta-analysis of cohort studies estimated that approximately 100 grams of red meat or 50 grams of processed meat can increase the risk of bowel cancer by approximately 15％-20％.15 135 Several mechanisms have been proposed to explain the increased risk of bowel cancer from red meat. Grilled meat increases the carcinogens heterocyclic amines and polycyclic aromatic hydrocarbons.2 In addition, the iron content of red meat may be a catalyst for the formation of nitrosamines,17 which generate DNA-damaging free radicals.
The role of dietary fiber in bowel cancer risk has been studied for many years. However, results from interventional trials that increased fiber intake did not find an association between fiber and polyp recurrence.153 174 A pooled analysis of prospective studies also found no role for fiber in bowel cancer risk. However, in recent years, a large number of other prospective cohort studies have provided evidence that fiber, especially from whole grain cereals,168 can reduce the risk of bowel cancer.230 231 Although the basis is changing, it is reasonable that fiber and whole grain intake can reduce the risk of bowel cancer.15 232 In conclusion, high vegetable and fruit and whole grain foods (low in red and processed meats) can reduce the risk of bowel cancer.233 risk233.
Some studies have found that vitamin D234-236 or a combination of vitamin D, as well as calcium237, is associated with a reduced risk of bowel cancer. High levels of vitamin D in the blood may reduce the risk of bowel cancer.235 236 Adequate vitamin D is required for calcium absorption. calcium and dairy products have been found to be associated with a reduced risk of bowel cancer in some studies.235 238 A growing number of studies have found a protective role for calcium in bowel cancer and intestinal polyp adenomas.239 However, because high calcium intake increases the risk of prostate cancer,2 240 the American Cancer Society does not specifically recommend calcium supplements or increased intake of calcium or dairy products for cancer prevention, although calcium is likely to help reduce the risk of bowel cancer.
Studies on alcohol consumption and bowel cancer risk confirm that increased alcohol consumption increases bowel cancer risk, especially in men15 226.
To reduce the risk of bowel cancer, the best combination of nutrition and physical activity is recommended to increase exercise intensity and duration, limit the use of red and processed meats, consume the recommended dose of calcium, ensure adequate vitamin D status, eat more fruits and vegetables, avoid obesity and central weight gain, and avoid excessive alcohol consumption. In addition, it is important to follow the American Cancer Society guidelines for routine bowel cancer screening because identifying and ruling out precancerous lesions can prevent bowel cancer.
Endometrial Cancer
Endometrial cancer is the most common gynecologic cancer in women in the United States, ranking fourth in the incidence of cancer in women after age-adjusted incidence.201 The relationship between obesity and endometrial cancer is well established.242-245 Being overweight or obese leads to a 2-3.5-fold increased risk of developing the disease, and in the United States, approximately 60％ of the disease is due to obesity.246 For premenopausal premenopausal women, the association of insulin resistance, elevated ovarian androgens, cessation of ovulation, and luteinizing hormone deficiency with overweight could explain the increased risk.247 For postmenopausal women, high levels of estrogens, which are converted from androstenedione in adipose tissue, contribute to increased risk of endometrial cancer242; it has been observed that compared to those on or previously using hormone therapy and postmenopausal never Obesity can pose a greater risk for endometrial cancer than women who are on or have previously received hormone therapy.248 In the European Prospective Study on Cancer and Nutrition, a large number of prospective studies conducted in nine European countries found a clear relationship between waist circumference predicting obesity and abdominal fat.244
Epidemiological studies have consistently reported an inverse association between physical activity and endometrial cancer risk242 245 249 250, but some studies have limited subgroups, such as non-menopausal women251 or overweight and obese women252 253. In another study, longer sedentary time was associated with a high risk of endometrial cancer, independent of physical activity level254. An active lifestyle can reduce the risk of endometrial cancer and indirectly help maintain a healthy weight as well as reduce the risk of diabetes and hypertension, both of which are risk factors for the disease.255
Unlike obesity and physical activity, the basis for dietary factors is different for each individual. Case-control studies generally support an inverse association between intake of fruits and vegetables and endometrial cancer.256 However, 2 cohort studies did not find an association between all fruit intake, all vegetable intake, or any vegetarian population and endometrial cancer.256 257 Similarly, case-control studies found that diets high in fiber258 and antioxidants259 reduced endometrial cancer risk with red meat260 Total fat, saturated fatty acid and animal fat intake258 increased endometrial cancer risk, and cohort studies were unable to replicate these findings.261-264 In the Women’s Health Advocacy Dietary Improvement Trial, dietary interventions (reduced total fat intake and increased vegetable and fruit and grain intake) had no effect on endometrial cancer risk.265 In a meta-analysis of four cohort studies, it was found that a high glycemic loading diet increased the risk of endometrial cancer.266
The theoretical basis for the association between alcohol consumption and endometrial cancer risk remains inconsistent. Recently, a meta-analysis of seven cohort studies found a nonlinear relationship between daily alcohol consumption and endometrial cancer risk, in which a maximum of one drink per day slightly reduced endometrial cancer risk and an excess of two drinks per day increased endometrial cancer risk267.
Currently, the best nutrition and physical activity-related recommendations for reducing endometrial cancer are to maintain a healthy weight and to engage in daily physical activity.
Kidney Cancer
In the United States, kidney cancer (including pelvic cancer), accounts for 5％of new cancer cases and 3％of cancer deaths among men and 3％of new cancer cases and 2％of cancer deaths among women. Over the past 10 years, the incidence of kidney cancer has increased by 3.2％201 per year. approximately 92％ of kidney cancers are renal cell carcinomas. The etiology of renal cell carcinoma is largely unknown; however, most of the identified modifiable risk factors include obesity and smoking.In 2002, the International Agency for Research in Oncology concluded that there is sufficient evidence that excessive obesity is a cause of renal cell carcinoma.268 Results on the relationship between dietary factors and renal cell carcinoma risk are limited or inconsistent.2 Although there is no evidence on detecting the effects of physical activity on renal cell carcinoma and its effect on other major sites of cancer (e.g., breast cancer, bowel cancer) compared with each other, relatively few studies have found that physical activity reduces renal cell cancer risk.
The best nutritional and physical activity-related advice for reducing kidney cancer is to maintain a healthy weight and avoid smoking.
Lung Cancer
Lung cancer is the leading cause of cancer mortality in the United States.2 205 More than 85％ of lung cancers are due to smoking, and 10％-14％ of smoking addictions are due to radon exposure. Because smoking is a very important factor in lung cancer, smoking is associated with other poor behaviors, including lack of exercise and unhealthy dietary patterns, and isolating the effects of these factors on cancer risk is difficult. For example, some evidence suggests that physical activity may reduce lung cancer risk.271-273 In a study monitoring the relationship between lung cancer and smoking, high levels of physical activity were found to reduce lung cancer risk in smokers and those who had quit smoking.273
Many studies have found a relatively low risk of lung cancer in both smokers and nonsmokers who ate five vegetables and fruits per day. A recent review of reviews found that a higher intake of fruit significantly reduced lung cancer risk.2 While a healthy diet may reduce lung cancer risk, the risk from smoking is still significant. For smokers, high doses of beta-carotene and/or vitamin A supplements increase (but do not decrease) the risk of lung cancer (see “Beta-carotene”)129 130.
The best advice for reducing the risk of lung cancer is to avoid smoking and environmental tobacco smoke and to avoid exposure to radon.
Ovarian cancer
Ovarian cancer is the second most common gynecologic cancer and the leading cause of death among gynecologic cancers.201 Although the cause of ovarian cancer is not well understood, it is associated with hormonal, environmental, and genetic factors. Approximately 10％ of ovarian cancers are due to genetic factors274.
Nutritional risk factors for ovarian cancer are not well defined.2 275 The overall rationale for obesity, however, is inconsistent, favoring the adverse effects of obesity on ovarian cancer. A meta-analysis that included 8 human-based case-control studies and 8 cohort studies found that obese women have an increased risk of ovarian cancer.276 The association between obesity and ovarian cancer has also been confirmed by 2 recent cohort studies. The National Institutes of Health AARP (NIH-AARP) cohort study found that among women who had not used menopausal hormone therapy, obese women had an 83％ increased risk of ovarian cancer compared to normal weight women; obesity was not associated with ovarian cancer in women who had used hormone therapy after menopause.277 The EPIC study showed that in postmenopausal women, ovarian cancer and obesity is very closely related278.
The IARC report on weight control and physical activity242 and the 2007 WCRF report concluded that the role of physical activity and obesity in ovarian cancer risk is not determinative.2 Although a meta-analysis of observational research trials found an appropriate inverse relationship between levels of recreational activity and ovarian cancer risk, because no association was subsequently found between the two, 2 additional A cohort study trial278.
Evidence that higher intake of fruits and vegetables reduces ovarian cancer risk is limited.2 Recent cohort studies have consistently given little support for this relationship.280-282 The Nurses’ Health Study found that adolescent intake of fruits and vegetables reduces ovarian cancer risk, predicting a possible association with early dietary factors.
Intake of animal foods, including meat, eggs, and dairy products, has been found to be associated with ovarian cancer risk.264 284-286 There was no indication that milk/dairy product or calcium intake was associated with ovarian cancer in the prospective cohort study, which included a pooled analysis of data from 12 cohort studies287 and other studies.288 289 The bases associated with vitamin D intake are also inconsistent.
Some bases suggest that increased ovarian cancer risk is associated with higher intake of saturated fat.286 290 This was further confirmed by a recent randomized clinical trial265 which found that a low-fat dietary intervention reduced the incidence of ovarian cancer. Studies have provided little support for alcohol consumption and ovarian cancer risk by and large291.
Some evidence also suggests that legumes may reduce ovarian cancer risk.292 Some trials assessing the relationship between legume/soy isoflavone intake and ovarian cancer have also shown an inverse relationship.293-296 A recent cohort study in Sweden, however, found no relationship between phytoestrogens and ovarian cancer.297 Some meta-analyses have provided evidence that tea consumption may reduce ovarian cancer risk 298-300, especially green tea301.
Currently, the evidence on nutrition and physical activity on ovarian cancer risk is inconsistent or limited, although some areas of active research may be promising. There are no very credible recommendations for ovarian cancer.
Pancreatic cancer
Pancreatic cancer ranks fourth in cancer deaths in the United States.201 A large number of studies have shown that smoking, type 2 diabetes, and impaired glucose tolerance increase the risk of pancreatic cancer.302 The relatively low incidence and survival of pancreatic cancer compared with other breast or bowel cancers has hindered research on lifestyle factors for pancreatic cancer. In recent years, because of the availability of follow-up cohort studies, there is a large body of evidence on the relationship between overweight and obesity and pancreatic cancer risk. One prospective meta-analysis study found that an increase in BMI increased the risk of pancreatic cancer, as did the results of several other cohort studies and a pooled analysis of the results of recent meta-analyses.64 304 Several later studies have also shown that abdominal fat increases the risk of pancreatic cancer, especially in women. Similar results were found in the large Advocates for Women’s Health305 and EPIC306 studies, which found that abdominal obesity was more significantly associated with pancreatic cancer risk than BMI. These findings are consistent with risk factors for abnormal glucose tolerance and type 2 diabetes.
Fewer studies have investigated the relationship between physical activity or dietary factors and pancreatic cancer risk, including alcohol consumption.2 A recent meta-analysis on physical activity suggests that high levels of exercise may reduce pancreatic cancer risk, especially with work activity.307 Higher intake of red and processed meats and lower intake of vegetables and fruits are associated with increased pancreatic cancer risk,2 308 309 but the relationship has not been further clarified. Recent studies have found that high levels of vitamin D (25-hydroxyvitamin D >100 nmol/L) may be associated with an increased risk of pancreatic cancer310.
The best advice for reducing the risk of pancreatic cancer is to quit smoking and maintain a healthy weight. It is also beneficial to follow the American Cancer Society guidelines for physical activity recommendations.
Prostate Cancer
Prostate cancer is the most common in American men and ranks second in cancer mortality.201 Although prostate cancer is associated with age, family history of pancreatic cancer and androgens, the mechanism of the role of nutritional factors in this process is unclear.311 Because research on prostate cancer has matured, it is important to be able to diagnose malignant prostate cancer, common nonmalignant and early stage prostate cancers. For example, the AARP Diet and Health from the National Institutes of Health has shown that there is an inverse relationship between BMI and prostate cancer incidence, mainly because it has an inverse relationship with the incidence of limited prostate cancer312. Conversely, the same study reported a strong hierarchical association between BMI and increased risk of prostate cancer mortality.312 Recent data found an association between overweight and poor prognosis for prostate cancer patients on diagnosis and treatment.70 313 The role of obesity in fatal prostate cancer may be a poor prognostic response to diagnosis and treatment, or it may lead to diagnosis at an advanced stage, or both. . The relationship between obesity and fatal prostate cancer has been confirmed in a number of meta-analytic studies of prospective studies314.
Recently, a meta-analysis of 19 cohort studies and 24 case-control studies examined the relationship between physical activity and prostate cancer.315 In general, this meta-analysis suggests that daily physical activity may be appropriate to reduce the risk of prostate cancer. There is also some basis to suggest that physical activity, especially vigorous physical activity, may reduce the risk of prostate cancer, especially for advanced prostate cancer.95 268
Some studies have shown that a diet rich in certain vegetables (including tomatoes/tomato products, cruciferous vegetables, soybeans, legumes, or other legumes) or fish is associated with a reduced risk of prostate cancer; then, these bases are not entirely plausible. As with body size, the literature can be confusing because of the different roles of limited prostate cancer and frontal prostate cancer. As an example, in the Prostate, Lung, Bowel, and Ovarian Cancer Screening Trial (PLCO),316 no association was found between vegetable intake and prostate cancer incidence; however, vegetable intake significantly reduced advanced prostate cancer.316 What is particularly clear from the findings on advanced prostate cancer is the intake of cruciferous vegetables.316 A recent meta-analysis of legumes also found that that increasing cruciferous vegetables reduces the risk of malignant prostate cancer.317 318
Based on the findings of other studies and the biological basis for the effects of antioxidant nutrients, the SELECT trial was designed to examine the effects of the supplements selenium, vitamin E, or their combination on the prevention of prostate cancer. The results were disappointing, finding no effect; if there was an effect, there was a slight increase in prostate cancer risk in those taking vitamin E supplements120.
Many studies have validated the relationship between calcium and dairy intake and prostate cancer risk. However, the literature is evolving, and some studies suggest that a high-calcium diet increases prostate cancer risk, with the increased risk likely coming from intake of dairy products.2 319-321 Whether this is related to the calcium content of dairy products is unclear, although the observation from Chinese Singaporeans with low dairy intake that increased calcium intake increases prostate cancer risk suggests that the effect of calcium may not fully reflect the the effect of dairy intake.
The best nutritional and related physical activity recommendation to reduce prostate cancer risk is to eat at least 2.5 cups of a variety of fruits and vegetables daily, combined with physical activity to achieve a healthy weight. It may be wiser to limit calcium supplementation to no more than the recommended level of calcium intake through food and beverages. However, because calcium and dairy products may reduce the risk of bowel cancer, the American Cancer Society has not developed specific recommendations for calcium and dairy intake for cancer prevention.
Stomach Cancer
Gastric cancer is the fourth most common cancer worldwide and ranks second in cancer mortality.201 However, gastric cancer is relatively uncommon in the United States. There is much credible evidence that chronic gastric disease with H. pylori infection increases the risk of gastric cancer.322 323 Although the overall incidence of gastric cancer continues to decline in most parts of the world, recent years have seen an increasing trend in the incidence of gastric cancer at the spout in the United States and some countries in Europe.324 The reasons for the increase are under active investigation, but may be related to low-grade esophageal cancer, which is due to abdominal obesity caused by gastric reflux324.
There are relatively few studies on the effect of body size or obesity on gastric cancer. A recent meta-analysis of 10 cohort studies found that higher BMI led to a higher risk of gastric cancer, ignoring the effects of gender or geographic location, and also found a similar relationship for this effect.325 Similarly, a number of studies have examined the effect of physical activity on gastric cancer. More recently, a large number of cohort studies have found an association between increased physical activity and reduced risk of gastric cancer326 327.
Many studies have found that consuming large amounts of fruits and vegetables is associated with a lower risk of stomach cancer, but consuming large amounts of salt and salt-cured foods is associated with an increased risk of stomach cancer, with salt-cured foods most likely being meat2 322 323.
The best recommendations for reducing the risk of stomach cancer are to consume at least 2.5 cups of fruits and vegetables per day; reduce the intake of processed meats, salt and salt-cured foods; engage in physical activity; and maintain a healthy weight.
Upper respiratory and digestive tract cancers
In the United States, upper respiratory and digestive tract cancers are more prevalent in men. Smoking alone (including cigarettes, chewing tobacco, and snuff) or drinking alcohol, but especially both together, increases the risk of oral, pharyngeal, laryngeal, and esophageal cancers; these exposures contribute to the gender differences in these cancers.
Obesity increases the incidence of adenocarcinoma of the lower esophagus at the gastroesophageal junction, most likely due to acid reflux caused by epithelial cell damage, metaplasia, and dysplasia. There is some evidence that the intake of hot beverages and foods may increase the risk of oral and esophageal cancers, most likely due to damage to contact tissues caused by high temperatures. Consumption of vegetables and fruits may reduce the risk of oral and esophageal cancers.
The best advice for reducing upper respiratory and digestive tract cancer is to quit smoking, limit alcohol consumption, avoid obesity, and eat at least 2.5 cups of diverse fruits and vegetables 328-330 per day.