There were attempts to link various cancer-related risk factors to one another. It is estimated that 43 per cent of all new cancer cases could be avoided by modifying the risk factors for cancer that individuals can affect through their own actions. Smoking is the largest single cause, accounting for up to 20 per cent of all new cases of cancer. [1, 2] It should be noted that the influence of the different population-level variables would vary depending on regional conditions and population health and socio-economic behaviour.
Cancer risk factors can be roughly divided into the following categories:
Most cancers are associated with aging. The longer a person lives, the more likely it is that these cells develop cancer that causes lesions. The ability of cells to avoid and recover from these defects weakens with age.
There are significant differences between men and women in the incidence of also other cancers than gender-related ones (such as Ovarian Cancer and prostate cancer). For example, in men, the age-adjusted morbidity of laryngeal cancer is almost ten times that of women. The disparity is now less than three-fold in lung and lip cancers, although it was 15-fold until the 1960s. These developments can be explained primarily by the fact that men and women's smoking patterns have changed over the last decades over different ways.
The use of Tobacco products is the single most important factor in increasing cancer risk. The hazards of Tobacco are due to a large number of carcinogenic compounds: those which are already in the Tobacco product and those that form during smoking.
It is well understood what effect smoking has on the production of Lung Cancer. The greater the risk of getting lung cancer, the younger people start smoking, the more they smoke regularly, and the longer they continue to smoke. [4, 5] If a person has smoked 20 cigarettes a day for 50 years, his or her risk of developing Lung Cancer is nearly 50 times greater than that of non-smokers. The risk of lung cancer, after quitting smoking, exceeds those of non-smokers of the same age quite rapidly but it does not fall to the same level. People who have smoked the longest benefit from giving up. Smoking is a major cause of larynx cancer, and also has an impact on oral, pharyngeal, kidney, pancreatic, oesophageal, cervical, and bladder cancer. Smoking could increase Breast Cancer risk slightly, too. 
In recent years, strong evidence has accumulated in studies about the carcinogenic potential of using snus. The risk of developing oral and pharyngeal cancer, pancreatic and gastric cancer and oesophageal cancer is significantly higher for those who use snus than for those who do not use Tobacco products. [7-9] Over the last few years, electronic smoking has increased significantly. It is studying its impact on health.
With the combination of smoking and other factors, the risk of cancer also increases considerably. Smoking and outdoor work together, for example, increase the risk of lip cancer by as much as 15-fold, while outdoor work or smoking alone only doubles the risk of lip cancer.  Smoking increases the effect of asbestos and other chemicals used in the workplace, which are not especially harmful by themselves.
There is a direct causal link between alcoholic beverage use and many cancer types. There is compelling evidence that heavy Alcohol consumption raises the risk of cancers of the throat, pharynx, larynx, oesophagus, liver, bowel and breast. 
For example, four regular doses of Alcohol (50 grams of ethanol) roughly double the risk of oral and pharyngeal cancer. Other factors that contribute to the Alcohol impact. Drinking Alcohol and smoking together, for example, very significantly increase the risk of nasal, pharynx and larynx cancers.
There is no safe level of Alcohol intake about breast cancer, although the risk of cancer is increased in direct proportion to the amount of Alcohol consumed on a daily basis. The biggest risk factor is the volume of ethanol consumed. Strong Alcohol consumption raises cancer risk and causes many apparent health issues. The type of alcoholic drinks consumed does not affect cancer risk significantly.
Diet is a dynamic combination of components, having joint and opposite effects that are hard to accurately predict. Food is known to have the greatest effect on the occurrence of oesophagus, colon, rectum, kidney, prostate, lung, and Breast Cancer.
Nutritional fat increases the risk of breast, colon and Pancreatic Cancer according to a number of animal tests. However, information about people is not yet sufficiently convincing to allow for a definite judgment of the effects of fat on cancer risk. Cancer tissue requires energy and minerals, so nutrition can have an effect not only on cancer production but also on its growth.
It is probable that dietary fibres can protect against Colorectal Cancer.  In addition, diets high in fruits and vegetables lower the risk of many cancers.
There was a comprehensive study of the effect of red and processed meat on the incidence of some types of cancer. High processed meat intake is associated with increased risk of colorectal and gastric cancer. Red meat is also a potential risk factor for both colorectal and pancreatic and Prostate Cancer. 
The key interest in the vitamin and cancer connection has been in carotenoids, vitamins A, E, C , and D, and folate. Vitamin products have also been tested for cancer prevention, but none of these have yet been shown to prevent cancer alone or in any combination.  Therefore, the key factor for cancer prevention appears to be a healthy overall lifestyle, not specific dietary factors.
Some processes in food preparation cause chemical changes which lead to the formation of cancer-causing substances in the food. Smoking and grilling fatty foods over an open fire or other high temperature will produce small quantities of polycyclic aromatic hydrocarbons ( PAHs) on the food's surface, which will increase cancer risk. High salt and salt-conserving foods raise the risk of gastric cancer.
There are several studies that have identified the correlation between physical activity and cancer risk. Accumulated scientific evidence suggesting that physical activity especially protects against breast, colon, endometrial, and Prostate Cancer.
Moderate physical activity affects the metabolism of certain hormones and improves the general mechanisms of body defence. Exercise reduces the amount of fat tissue and balances the situation of different growth factors in the body. People who exercise more regularly often have more safe ingredients for cancer in their diets.
A total amount of about one hour of daily physical activity in the form of everyday or beneficial exercise, such as walking or biking to work or to the shop, climbing the stairs or working the yard, is sufficient according to recent studies. Specifically, people who do sedentary work can frequently exercise to stop overweight. Swift workout several days a week will increase the protective impact of physical activity on cancer. 
There is a strong connection between female genital cancer and Breast Cancer and sexual and reproductive behaviour. If a woman has multiple sexual partners, she may have a greater risk of developing Cervical Cancer. The number of their male partner's sexual partners also affects the risk of developing Cervical Cancer between women. This may be explained by the fact that sexual contact with infectious viruses is significant in Cervical Cancer pathogenesis.
To give birth at an early age and to have several children protects against Breast Cancer. If the woman has a very large number of children, the protective effect is emphasised.  Infertility also constitutes a risk factor for ovarian and endometrial cancers. Early sexual maturity and late menopause increase menstrual cycles and the incidence of the above cancers.
Breast, endometrial and ovarian cancers are more frequently diagnosed during menopause in women who use long-term Hormone therapy. [17-19] Progesterone, combined with replacement oestrogen therapy, increases the risk of Breast Cancer but, in turn, protects against endometrial cancer. [17, 18, 20] Accordingly, the effects of oestrogen replacement therapy in the treatment of menopause should be assessed individually in relation to the risk of cancer, inter alia.
For men, elevated levels of male hormone, i.e. androgen, are likely to be associated with an increased risk of Prostate Cancer.
In everyday life, we are exposed, involuntarily or accidentally, to a wide range of chemicals. In several studies, inter alia, links with the use of deodorants and hair dyes to cancer risk were investigated. Some studies have found that the use of hair dyes increases the incidence of, for example, bladder and Breast Cancer slightly, but there is insufficient evidence of their definite role as a potential risk factor for cancer.
Some viral infections increase the risk of developing cancer. Bacteria-infections may also raise the risk of certain cancers. The most widely studied family of cancer-causing viruses are papillomaviruses (HPV, human papilloma virus), some of which contribute to chronic inflammation and eventually Cervical Cancer.  In addition, papillomaviruses can cause other cancers, such as pharyngeal cancer.  Long-term follow-up studies are underway to determine to what degree HPV vaccines often prevent cancer. 
The Helicobacter pylori bacterium raises the risk of gastric cancer.  Chronic inflammation of the liver (infections with hepatitis B and C viruses) is associated with increased risk of Liver Cancer. A vaccination program for hepatitis B virus ( HBV), initiated in Taiwan in 1984, led first to a decrease in HBV prevalence, and subsequently to a substantial reduction in the incidence of Liver Cancer in vaccinated age groups.