The research on more than 200,000 women from nine European countries found doing household chores was far more cancer protective than playing sport. Dusting, mopping and vacuuming was also better than having a physical job.
The women in the Cancer Research UK-funded study spent an average of 16 to 17 hours a week cooking, cleaning and doing the washing. Experts have long known that physical exercise can reduce the risk of breast cancer, probably through hormonal and metabolic changes.
But it has been less clear how much and what types of exercise are necessary for this risk reduction.