People who spend the bulk of their day sitting may have an increased risk for certain kinds of cancers, according to a recent study HealthDay reported.

Researchers from the University of Regensburg in Germany found a consistent relationship between hours spent sitting - whether behind the wheel, in front of the TV or working at a computer --and an increased risk for colon and endometrial cancers.

"Prolonged sitting time lowers energy expenditure and displaces time spent in light physical activities, which consequently leads to weight gain over time," researchers Daniela Schmid and Michael Leitzmann wrote in their study. "Moreover, TV viewing is accompanied by increased consumption of unhealthy foods, such as sugar-sweetened beverages, sweets, and fast food."

For every two hours spent sitting in front of the computer or television, the average person raises his or her risk of colon cancer by 8 percent, or endometrial cancer by 10 percent and of lung cancer by 6 percent.

For the study, researchers examined 43 studies that involved nearly 4 million people. These studies specifically looked at the link between sitting and nearly 70,000 cases of cancer.

Researchers found no link between the amounts of time spent sitting and breast, ovarian, testicular or prostate cancers, or cancers of the stomach, esophagus and kidneys, or non-Hodgkin lymphoma.

Researchers said the risks remained even for "active couch potatoes,' or folks who squeeze in some time at the gym but still spend the day off their feet. This finding suggests that regular exercise can't offset the risks of too much sitting.

It is still unclear to researchers what it is about sitting that raise cancer risk.

Researchers said "It could be as simple as obesity, which itself is a major cause of cancer. Or it could be more complicated," NBC News reported.

The findings were recently published in the Journal of the National Cancer Institute.