Obesity and lack of exercise could be putting many cancer survivors at risk, research has suggested.
A study found that breast cancer survivors were among those likely to be fat, which could make their prognosis worse.
Obesity and taking little exercise is generally linked to poor disease outcomes, the authors said.
In cancer patients, studies have linked inactivity and being fat with recurrence of the disease, death and a reduced quality of life.
More than 114,000 people were questioned for the study, published in the journal Cancer, and asked if they had participated in any activities from a list in the past three months.
They were also asked how often they took part in the activity and how long each session lasted.
The authors found that fewer than 22% of survivors were physically active at the ideal level.
Just over 18% of all cancer survivors reported being obese, with little variation among the cancer survivor groups.
Obese breast cancer survivors were less likely to be active than obese women without a history of cancer.
The Canadian authors, from the University of Alberta, said: "Obesity itself is strongly associated with poorer disease outcomes and obese breast cancer survivors may particularly benefit from higher physical activity levels in terms of disease outcomes.