Why cancer has increased so much nowadays when it isn’t an infectious disease?

Answer 1

Cancer CAN be caused by, or associated with infectious diseases. For example, Helicobacter pylori can increase risk for stomach cancer. HPV can increase your risk of cervical cancer!

But, broadly speaking, the shift in a high prevalence of infectious diseases to a high prevalence of "chronic diseases" has a lot to do with societal changes. As medicine improves, people can live longer with chronic diseases like cancer, and so the prevalence is increasing (See the graphic linked below). Carcinogenic environmental exposures to pesticides, air pollution, and other chemicals are increasing due to industrialization, urbanization, and large-scale farming associated with population increases. Increased age is also a risk factor for cancer, and people are living much longer than they used to. Lastly, cultural changes in health behaviors (especially in developed countries) such as poor diet and inactive lifestyles can increase risk of cancer, and as we know we are in the midst of a huge rise in these behaviors!

https://www.google.com/url?sa=i&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjbi_3XxbzjAhUQh-AKHXm9BkcQjRx6BAgBEAQ&url=https%3A%2F%2Fneoreviews.aappublications.org%2Fcontent%2F16%2F2%2Fe94&psig=AOvVaw38VkJtbySD-PLHJyg-npmB&ust=1563473177163028