Certain lifestyle factors are associated with developing prostate, breast, colon, pancreatic and many other cancers, and changing these same lifestyle factors should be part of every treatment for people who are diagnosed with any type of cancer.  Up to 40 percent of human cancers are at least partially caused by modifiable lifestyle factors (British Journal of Cancer, March 23, 2018;118:1130–1141).  Lack of exercise, excess body fat or diets high in refined carbohydrates, red meat or processed meats increase risk for cancers of the stomach, colon, biliary tract, pancreas, lung, breast, prostate, endometrium and others (British Journal of Cancer, Jan 4,2011;104 (1): 6–11; European Journal of Clinical Nutrition, 2007;61(Suppl 1):S112–S121).
Today, major university cancer treatment centers recommend that, within reason, all cancer patients should avoid known cancer-causing lifestyle factors:
• Smoking
• Alcohol
• Chronic inflammation
• Various infections
• Certain hormones
• Immunosuppression
• Exposure to radiation (cumulative over lifetime)
• Exposure to various toxins (cumulative over lifetime)
• Obesity
• Sugar-added foods and drinks and other refined carbohydrates
• Processed meats and meat from mammals
• Fried foods and grilled or charred foods
• Lack of plants (fruits, vegetables, beans, whole grains and other seeds)
• Lack of exercise
How Inflammation Increases Risk for Cancer Recurrences
When germs get into your body, your immunity recognizes that the germ cells have proteins on their outer surfaces that are different from your body’s own cells, and your immunity produces cells and proteins that attack and kill the invading germs. As soon as the invading germs are gone, your immunity is supposed to slow down and stop producing all the proteins and cells that did the attacking and killing. Inflammation means that your immunity stays active and starts to attack and damage your own cells and the DNA genetic material inside them.
Normal cells undergo apoptosis, which means that they live only a certain number of days and then die. If your immunity damages their DNA, the cells may be changed so they forget to die and try to live forever, which is cancer. The “immortal” cancer cells may overgrow and invade other tissues to destroy them and kill you. For example, breast cancer cells do not kill you as long as they stay in the breast, but the breast cancer cells can become so numerous that they spread to your brain, lungs, bones and other tissues and kill you by destroying these essential tissues.
High Blood Sugar Causes Inflammation
The same cells and chemicals that kill germs also start the healing process, so damage to any tissue in your body turns on your immunity in the same way that infections do and therefore can cause inflammation. When blood sugar levels rise too high, sugar sticks to the outer membranes of all types of cells in your body and damages them to turn on your immunity. All the harmful effects of diabetes, such as impotence, dementia, blindness, deafness, heart attacks and cancers, are caused by high blood sugar turning on your immunity, and you don’t have to be diabetic to suffer this damage. A review of the world’s literature shows that non-diabetics with high blood sugar levels suffer a marked increase in breast, colon, liver, stomach, pancreatic and endometrial cancers (Diabetologia, September 8, 2014). Furthermore, high blood sugar levels cause high insulin levels that also increase cancer risk (JCI, May 2013;4(3)). High blood sugar levels can be caused by foods such as sugared drinks, sugar-added foods, foods made from flour, white rice, potatoes and yams, and so forth (Cancer Epidemiology, Biomarkers & Prevention, March 3, 2016). Other studies show that high blood sugar levels are associated with increased risk for prostate cancer (Horm Cancer, April 2016;7(2):75-83) and breast cancer by causing inflammation through the 12-Lipoxygenase (12-HETE) pathway (Cancer Res, Jan 1, 2016;76(1);24–29).
Studies Showing that Lifestyle Changes Treat Cancer 
Lifestyle factors help to prevent prostate cancer recurrences (J of Urology, Sept, 2005;174(1065–1070).  Men with prostate cancer who adopted a heart-healthy, plant-based diet rich in vegetables, fruit, beans, fish and whole grains were far less likely to die from their prostate cancer cancer patients who continued to eat red meat, processed meat, eggs, potatoes, high-fat dairy products, butter, processed grains found in bakery products and pastas, snacks, sweets and desserts (Cancer Prevention Research, published online June 1, 2015).  A Mediterranean-type diet based on fruits and vegetables prolonged the lives of men previously diagnosed with prostate cancer (European Urology, May 2014; 65(5):887-894) and reduced risk for recurrence in men already diagnosed with prostate cancer (Int J Cancer, 2012, 131:201-210). Avoiding alcohol and overweight also helped to prevent prostate cancer recurrence (Cancer Causes & Control, January 6, 2015).  A seven-year study of almost 1000 patients with colon cancer that had already spread to their bellies (Abstract 10006, 2017 Annual Meeting of the American Society of Clinical Oncologists, May 17, 2017) had a 42 percent reduction in death rate and a 31 percent reduction in recurrence of their cancer when they:
• avoided overweight,
• exercised regularly (one hour of walking per day),
• ate a diet rich in whole grains, vegetables and fruits, and low in red meat and processed meat, and
• restricted alcohol.
A review of the world’s literature showed that the lifestyle changes listed above can help to prolong the lives of patients who have already been diagnosed with cancer (Acta Oncol, Feb 2011;50(2):167-78), causing the World Cancer Research Fund, the American Institute for Cancer Research and the American Cancer Society to recommend that cancer patients follow a largely plant-based diet with limited consumption of meat, restriction of alcohol, maintenance of a healthy weight and a regular exercise program (Maturitas, May 19, 2017).
The Clinical Oncology Society of Australia (COSA) cites more than 30 journal references to show that regular exercise before, during and following cancer treatment decreases the severity of other adverse side effects and is associated with reduced risk of developing new cancers and comorbid conditions such as cardiovascular disease, diabetes and osteoporosis (Med J Aust, May 7, 2018).  They recommend that:
• Doctors should prescribe exercise within physical limitations as part of cancer care.
• Cancer care should include referral to an accredited exercise physiologist or physiotherapist with experience in cancer care.
• All health professionals should discuss with their cancer patients the role of exercise in cancer recovery, to avoid inactivity and progress towards at least 150 minutes of moderate intensity aerobic exercise and two to three moderate intensity resistance exercise sessions each week.
A study of 15,450 adult survivors of childhood cancer showed that regular exercisers gained a 40 percent reduction in death rate eight years after treatment(compared to non-exercisers), and the highest survival rate was in those who exercised 15 to 18 metabolic-equivalent-task (MET) hours per week, equal to brisk walking for about 60 minutes a day, 5 days a week (JAMA Oncology, June 3, 2018).   National physical activity guidelines for cancer survivors recommend five days a week for 30 minutes per session.
Many studies have shown that the typical Western diet that is high in sugar, red meat, processed meats and fried foods is associated with a marked increased risk for colon cancer (JAMA, Aug 15, 2007;298(7):754-64).  Nuts may help to prevent colon cancer recurrences after treatment by lowering high blood sugar levels, which are a major risk factor for developing colon cancer in the first place (J Natl Cancer Inst, 2012 Nov 21;104(22):1702-11; J Clin Oncol, 2018 Apr 10;36(11):1112-1120).  A pro-inflammatory diet that raises un-conjugated estrogen levels can increase post-menopausal breast cancer risk (Int J Cancer, Mar 25, 2018). Reduced estrogen levels and breast cancer risk were found in women who: exercised regularly, avoided alcohol, were not overweight, ate a lot of fruits, vegetables and whole grains, and restricted processed food high in fat and sugars, refined grains, red meat and processed meat.  A study from Spain showed that women on a high-vegetable Mediterranean-type diet had close to one third the rate of breast cancer when compared to a control group that was only given advice to reduce fat intake (AMA Oncol, January 21, 2016; JAMA Intern Med, Nov 1, 2015;175(11):1752-60).  The Nurses Study showed that women who ate a lot of fiber in their teens (fruits, vegetables and seeds) had significantly reduced rates of breast cancer when they grew older (Pediatrics, February 1, 2016;137(3):).  Post-menopausal women who followed a traditional Mediterranean diet in Greece had lower breast cancer rates (Am J Clin Nutr, Sept 2010;92(3):620-5).  Women who ate the most calories, exercised the least and had the most body fat were at increased risk for breast cancer (Breast Cancer Res Treat, May 2006;97(1):97-106). Eating large amounts of foods that cause high rises in blood sugar increased breast cancer risk among postmenopausal women, regardless of whether they were overweight, exercised vigorously or took female hormones (Int J Cancer, May 1, 2006;118(9):2372).
Obese people are at significantly increased risk for developing many different cancers (JAMA, 2017;318(20):1975-6).  The American Cancer Society reports that obesity is linked to increased death risk from the most common forms of cancer in men (prostate, kidney, colorectal, esophagus, stomach, pancreas and liver) and women (colorectal, ovary, breast, cervical, kidney and uterus). Obesity turns on your immunity and keeps it active to cause inflammation that is associated with increased death rates after cancer diagnosis. Harvard University researchers show that being overweight increases risk for most cancers (American Society of Clinical Oncology conference in Chicago, May 29, 2015).
Nobody knows exactly why overweight is associated with increased risk for so many types of cancer, but the most likely explanation is that storing fat in your belly means that you store excess fat in your liver. Your liver controls blood sugar levels. When blood sugar levels rise too high, the pancreas releases insulin which lowers blood sugar levels by driving sugar from the bloodstream into your liver. Having extra fat in your liver prevents sugar from entering the liver to keep blood sugar levels high. This raises blood insulin and insulin-like growth factor-1 (IGF-1) levels even higher to overstimulate cells, which can lead to cancer (Annual Review of Medicine, 2010; 61:301–316). Extra fat in your liver also turns on your immunity to cause inflammation, which is associated with increased risk for many cancers (Cell, 2010;140(6):883–899).  Storing fat in the belly is a major risk factor for colon and rectal cancers (PLoS One, 2013;8(1):e53916).
Breast Cancer: Fatty tissue produces large amounts of the female hormone, estrogen. Estrogen stimulates the breast to grow and too much estrogen overstimulates the breast which can lead to cause cancer. The riskiest time to have too much estrogen is after the menopause (BMJ, 2007 Dec 1;335(7630):1134). Taking estrogen after menopause increases cancer risk, and taking estrogen with the second female hormone, progesterone, increases breast cancer risk even more. Women who have a delayed menopause and go into menopause after age 55 are at increased risk for breast cancer because of their prolonged exposure to estrogen. Gaining a lot of weight from age 18 to 50 also increases breast cancer risk after the menopause. Women who start menstruating before age 10 are at increased risk for breast cancer because of their prolonged lifetime exposure to estrogen. A program of diet and exercise that gets women to lose weight after treatment for breast cancer helps to prevent recurrences (Journal of the National Cancer Institute, 2009; 101(9):630–643).
Endometrial Cancer: Women who are overweight are two to four times more likely to suffer cancer of the inner lining of the uterus, and the more overweight a woman is, the more likely she is to suffer endometrial cancer (Int J Cancer, Jan 15, 2007;120(2):378-83). Women who are given estrogen without also receiving the second female hormone, progesterone, are at high risk for uterine cancer. Estrogen stimulates the inner lining of the uterus to grow, while progesterone stops the stimulation. Taking estrogen without also taking progesterone stimulates growth of the inner lining of the uterus all the time to cause cancer. Anything that raises blood sugar levels increases risk for endometrial cancer: diabetes, lack of exercise, eating and drinking foods and fluids with added sugar, and so forth.
Kidney Cancer: Storing fat in the belly is associated with renal cell cancer, the most common form of kidney cancer (Br J Cancer, 2001 Sep 28;85(7):984-90). Having extra belly fat raises blood insulin levels. Insulin constricts arteries to raise blood pressure. High blood pressure is associated with increased risk for kidney cancer.
Esophageal Cancer: Being overweight is associated with increased risk for esophageal adenocarcinoma, but not esophageal squamous cell cancer (Ann Oncol, Mar,  2013;24(3):609-17). Overweight can cause reflux of acid from the stomach to the esophagus, and the esophagus is damaged by the acid. This can cause inflammation that leads to a precancerous condition called Barrett’s esophagus.
Pancreatic Cancer: Obesity is associated with increased risk for pancreatic cancer (Ann Oncol, Apr, 2012;23(4):843-52). Storing fat in the belly raises blood sugar levels, which causes the pancreas to constantly make more insulin that overstimulates the pancreas.
Thyroid Cancer: Patients who are overweight tend to have increased risk for thyroid cancer, particularly the types that kill (Archives of Surgery, published online May 21, 2012).
Gall Bladder Cancer: Being overweight increases risk for having gall stones, and gall stones are associated with increased risk for gall bladder cancers (Br J Cancer, 2007 May 7;96(9):1457-61).
Prostate Cancer: Obesity is associated with a slight increased risk of prostate cancer, but it is strongly associated with increased risk for the aggressive type of prostate cancer that can kill (World Cancer Research Fund International. Continuous Update Project Report: Diet, Nutrition Physical Activity, and Prostate Cancer, 2014). Obesity increases levels of growth factors such as Insulin-Like Growth Factor-1 that can stimulate normal cells to become cancerous.
Ovarian Cancer: Being overweight is associated with a slight increased risk for premenopausal ovarian cancer, but not for ovarian cancer after menopause.
Liver Cancer: The most common known causes of liver cancer are chronic infections with the hepatitis viruses. However, being overweight is associated with increased risk for liver cancer in people who are not infected with these viruses (Eur J Cancer, 2012 Sep;48(14):2137-45). Storing extra fat in your liver, called a fatty liver, turns on your immunity to cause inflammation, which increases risk for liver cancer and many other cancers.
Thirty percent of all alcohol–related deaths are caused by cancer, with 60 percent of these deaths from breast cancer, and one third of these deaths were associated with an average of fewer than two drinks a day (Drug Alcohol Rev, June 16, 2016). A review of scientific articles showed that drinking even one glass of wine a day raises the risk of cancers of the throat, esophagus, liver, colon, rectum and breast (Addiction. Jul 21, 2016). The more you drink, the greater your risk for developing these cancers. Alcohol has also been associated with cancers of the skin (Am J Clin Nutr, Nov 2015;102(5):1158-66), prostate and pancreas. Another review of 27 studies showed that taking up to two drinks a day is associated with a 23 percent increased risk for prostate cancer (BMC Cancer, Nov 5, 2016).  A review of 222 scientific papers that followed 92,000 light drinkers and 60,000 non-drinkers showed that taking just one alcoholic drink a day is associated with increased risk for cancer of the mouth and throat, esophagus and breast (Annals of Oncology, Feb 2013; 24(2):301-308). Several studies show that mouth, throat and liver cancer patients who stop drinking have a reduced chance of recurrence of their cancers compared to those who continue to drink.
My Recommendations
Every person diagnosed with cancer should talk with his or her physicians about the lifestyle factors associated with increased cancer risk and the very strong evidence that changing these inflammatory lifestyle factors can help to prolong their lives.