Middle-aged men who stayed fit were less likely to die from three common cancers after being diagnosed than those who were out of shape, research found.

In a study of 17,049 men, those with good respiratory and cardiovascular fitness were more likely to survive prostate, lung or colorectal cancer, and avoid developing lung or colorectal cancers. The results were released Wednesday by the American Society of Clinical Oncology in advance of the group’s meeting set to begin May 31 in Chicago.

The research is among the first to show the benefit of fitness in cancer prevention and survival, adding to well-known advantages against heart disease, breathing ailments and metabolic conditions such as diabetes, said Susan Lakoski, the study’s lead author and the director of Cardiovascular Prevention for Cancer Patients at the Vermont Cancer Center. Lakoski said the study controlled for well-known factors like smoking and obesity.

“It’s important to be fit in midlife to avoid the adverse consequences of cancer and dying from cancer,” Lakoski said. “It’s a very strong relationship.”

Lung cancer is the most lethal cancer in the U.S., causing 158,081 deaths in 2009, according to the Centers for Disease Control and Prevention in Atlanta. Colorectal cancer is the second-biggest killer, with 136,717 people diagnosed and 51,848 deaths. Prostate cancer is the most common malignancy in men, though less deadly. In 2009, 206,640 men in the U.S. were diagnosed and 28,088 died, according to the CDC.

Just a slight increase in fitness correlated with a 14 percent reduction in dying from the cancers, the study found. The fittest one-fourth of men in the study were also 68 percent less likely to develop lung cancer and 38 percent less likely to get colorectal cancer than the least fit.

— Drew Armstrong, Bloomberg News