A study of nine trials of 7,50,000 people showed a reduced risk of seven types of cancers with the amount of physical activity during leisure time. Many types of cancer have a relationship of 'dose/response' from the seven cancers identified in the report.
The study was conducted by researchers of Harvard T.H. Chan School of Public Health and National Cancer Institute from the American Cancer Society and is published in the Journal -- Clinical Oncology.
"Physical activity guidelines have largely been based on their impact on chronic diseases like cardiovascular disease and diabetes," said Alpa Patel, senior scientific director of epidemiology research of the American Cancer Society.
The guidelines for activity stated that 2.5 to 5 hours of moderate-intensity workout in a week or 1.25 to 2.5 hours of vigorous activity is the ideal amount of physical activity for sustaining a healthy lifestyle.
Researchers after the study found engaging in recommended amounts of activity (7.5 to 15 MET-hours/week) was associated with a statistically significant lower risk of seven of the 15 cancer types studied, with the reduction increasing with more MET-hours.
Physical activity was associated with a lower risk of colon cancer in men (8 per cent for 7.5 MET-hours/week; 14 per cent for 15 MET-hours/week), female breast cancer (6-10 per cent), endometrial cancer (10-18 per cent), kidney cancer (11-17 per cent), myeloma (14-19 per cent), liver cancer (18-27 per cent), and non-Hodgkin lymphoma (11-18 per cent in women).
"These data provide strong support that these recommended levels are important to cancer prevention, as well," said Patel.
The researchers' results have directly supported the activity levels suggested for cancer prevention.