A new prospective study has reported that smoking and obesity are associated with reduced survival after breast cancer diagnosis, whereas alcohol consumption and use of hormone replacement therapy (HRT) do not reduce survival, and exercise does not increase it. The study was designed to examine the impact of smoking, body mass index (BMI), alcohol consumption, HRT, and physical activity on survival after breast cancer diagnosis. It included 528 women diagnosed with primary breast cancer and enrolled in the Copenhagen City Heart Study. Self-reported information concerning the factors included in the study was collected a total of four times during 1976-1978, 1981-1983, 1991-1994, and 2001-2003.

Smoking was found to be associated with 16% higher total mortality after breast cancer diagnosis. Total mortality refers to death from all causes, including non-breast cancer specific causes. Obesity was found to be associated with a 61% increase in total mortality and an 82% increase in breast cancer-specific mortality. Neither consuming 1 to 6 alcoholic drinks per week, nor 7 to 14 drinks per week reduced survival, nor did using HRT. Neither moderate physical activity (two to four hours per week) nor a higher level of physical activity (more than four hours per week) increased survival after breast cancer diagnosis. The results provide evidence that some factors known to influence risk of breast cancer do not have similar effects on survival once breast cancer has been established.