American Cancer Society (ACS), World Cancer Research Fund (WCRF) and American Institute of Cancer Research (AICR) jointly made several recommendations for cancer prevention as follows, most of which have been evidenced by latest research.
Each recommendation links to more details.
1. To maintain normal weight.
To prevent from breast cancer, ACS suggests that women should involve at least 150 minutes moderate exercise every week, take a glass of alcoholic drink at most every day and keep BMI (body mass index) less than 25kg/m2. In a clinical trial including 2905 breast cancer high risk women, risk of breast cancer for women who followed ACS suggestions lowered 44%.
Women's Health Initiative Observational Study which included 64,000 women found that a healthy diet (more vegetable, fruits, less meats and less alcoholic drinks) can significantly lower the risk of breast cancer. For women whose BMI less than 25kg/m2 , the onset risk of breast cancer lowered 20%. For women whose BMI about 25 to 29.9kg/m2, the risk of breast cancer lowered 30%. However, what is worth noting is that a healthy diet cannot lower the risk of breast cancer in terms of obese women.
That is because BMI itself is a risk factor for the development of cancer. Excess weight triggers insulin resistance while increase in insulin and growth factor promotes the development of cancer. Obesity promotes the generation of estrogen, which in turn promotes the development of various cancers. Moreover, fat also secrets cytokins that
A recent dose responses meta-analysis (including 50 prospective observational studies) found that maintaining normal weight can help adults prevent certain types of cancer, especially cancers that are not suitable for hormone replacement therapy (HRT). Studies found that for adult women, each additional 5 kg in weight will increase the risk of breast cancer by 11%, endometrial cancer by 39% and ovarian cancer by 13%. For adult men, each additional 5 kg increase the risk of colon cancer by 9%. The risk of kidney cancer is 1.42 times of normal weight men. The most difficult problem we are facing is that adults will gain weight as they grow older.
Dr. Harvie said, “The most difficult problem is that people will gain weight as they grow older”.
2. Be physically active for at least 30 minutes every day.
Several observational studies have found that physical exercise can lower the risk of breast cancer, colorectal cancer and endometrium cancer. A prospective study targeting American and Europeans showed that compared with people who are exercise deficient, the risk of cancer will be lowered by 20% for those whose exercise reached minimally recommended exercise (MET from 7.5-15 per week).
In 2015 ASCO annual meeting, Prof. Donald Abrams from California University pointed out that exercise can improve the prognosis of cancer patients. A recent meta-analysis about breast cancer and colorectal cancer survivors (including 16 researches on breast cancer and 7 researches on colorectal cancer and covering 50,000 cancer survivors) found that exercise can reduce the fatality rate of breast cancer and colorectal cancer patients. Therefore, after treatment, cancer patients are advised to adopt relevant cancer prevention recommendations.
3. Eat more vegetables, fruits, whole grains such as beans.
Dietary habits also have impacts on risk of cancer besides weight control and exercise. A recent meta-analysis of prospective cohort studies including 10m population found that more fruits and vegetable can reduce all-cause mortality rate and cardiovascular mortality rate but not cancer-related mortality rate.
4. Limit consumption of red meat (such as beef, pork and lamb) and avoid processed meats
Moreover, studies showed that red meat is not that bad as we thought as least in terms of cancer development. EPIC conducted a survey involving 450,000 participants, the result of which showed that people are concerned whether processed meat can increase risk of cancer. Research found that daily intake of 50g processed meat will increase the risk of cancer by 11%. However, the research showed no relation between red meat and risk of cancer. Thus it can be seen that people should be wary of processed meat but not red meat.
5. Limit daily intake of alcoholic drinks
Excessive drinking (over 5 standards drinks per day) is strongly linked to 10 types of cancer: oropharyngeal cancer (HR, 5.13), esophagus squamous cell carcinoma (HR, 4.95), prostate cancer (HR, 1.61), throat cancer (HR, 2.65), colorectal cancer (HR, 1.44), liver cancer (HR, 2.07), gastric cancer (HR, 1.2), gallbladder cancer (HR, 2.07), prostate cancer (HR,1.19), and lung cancer (HR, 1.11). Even moderate drinking (one standard drink per day) can increases the risk of oropharyngeal cancer (HR, 1.17), esophagus squamous cell carcinoma (HR, 1.3), and breast cancer (HR, 1.05).
6. Avoid indiscriminate use of vitamin supplements
A recent randomized clinical trial is carried out to study whether risk of cancer can be reduced by taking vitamin supplements while the research result is thought-provoking. Folic acid can increase the risk of cancer(HR, 1.07), especially prostate cancer (HR, 1.24) and colorectal cancer (HR, 1.28); β-carotene can increase the risk of lung cancer (HR, 1.07) and gastric cancer (HR, 1.54.); selenium can increase the risk of non-melanoma skin cancer (HR, 1.44); vitamin E can increase the risk of prostate cancer (HR, 1.17).
In conclusion, obesity, lack of exercise, over intake of alcohol are factors that we should pay attention to. As influence of dietary habit on cancer is not evident, further in-depth research needs to be done to confirm their relationship.