The patients took part in a psychological "intervention" designed to reduce stress and promote a healthy lifestyle, and the analysis revealed that the women survived longer and were less likely to relapse than those who did not, according to the study published in the journal Cancer.
Starting in 1994, researcher Barbara Andersen and her colleagues selected 227 women recovering from breast cancer surgery and about to undergo chemotherapy, reports New Scientist.
Half received a year-long intervention that included encouragement to relax, delegate stressful tasks, exercise, eat healthily and stick to medication.
Twenty-four per cent of women who received the intervention relapsed within a follow-up period lasting for 11 years on average, compared with 29 per cent of those who did not.
But, by taking into account how long remission lasted, and controlling for factors affecting the risk of relapse, such as age and cancer severity, Andersen's team calculates that the intervention reduced the risk of relapsing by 45 per cent and of dying by 55 per cent.