Smoking cigarette releases hundreds of toxic chemicals into air. Of those chemicals, about 70 % can cause cancer. Even second-hand smoke is said to be a cause of cancer. Cigars are even worse because a large one emits about the same amount of second-hand smoke as an entire pack of cigarettes. There is no “safe amount” of second-hand smoke as even low levels can be harmful.
Extra fat tissue produces excess amounts of estrogen and other hormones that may stimulate cell growth and proliferation, thereby increasing chances of developing cancer. Obesity may also cause chronic inflammation, which over time can damage DNA causing cancer. Obesity is associated with an increased risk of colon, breast in post menopausal women, and endometrial cancer, among several others.
#3 Exposure to sunlight
Excessive exposure to sun may lead to skin cancer. Using sunscreen can help prevent skin cancer but it should be of right kind, broad-spectrum, SPF 30 or higher and water resistant.
One quarter of new cancer cases are diagnosed in people between age 65 and 74, according to the National Cancer Institute. Though this is a non-modifiable factor, strong evidence shows that a diet filled with a variety of plant foods such as vegetables, fruits, whole grains, and beans helps lower risk for many cancers.
#5 Sedentary lifestyle
It can lead to the development of cancer. Scientists in Germany analyzed 43 observational studies, which included more than 4 million people and almost 70,000 cancer cases, found an additional two hours a day of sedentary behavior was linked to an 8 percent increase in colon cancer risk, a 10 percent increase in endometrial cancer risk, and a 6 percent increase in risk for lung cancer, even among people who were otherwise physically active.
#6 Exposure to artificial light at night
The scientists have found exposing our bodies to artificial light at night increases risk for certain cancers, such as breast and prostate which require hormones to grow. One possible explanation is that exposure to artificial light at night suppresses the production of melatonin, a hormone that helps control the sleep cycle and is also a powerful antioxidant. Lower levels of melatonin are linked to a higher risk of breast cancer as there is some evidence that women, who work night shifts, have shown slightly higher rates of breast cancer.