Background: Overweight/obesity are strongly implicated in breast cancer development, and weight gain pre- and post-diagnosis are associated with greater morbidity and all-cause mortality. The aim of this study was to describe the prevalence of overweight/obesity and the pattern of weight gain after diagnosis of breast cancer amongst Australian women.
Methods: We collected sociodemographic, medical, weight and lifestyle data using an anonymous, self-administered online cross-sectional survey between November 2017 and January 2018 from women with breast cancer living in Australia. The sample consisted mainly of members of the Breast Cancer Network Australia (BCNA) Review and Survey Group.
Results: From a total of 309 responses to the survey, we obtained complete pre/post diagnosis weight data in 277 women, and calculated pre/post BMI for 270 women. Proportion of women with overweight/obesity rose from 48.52% at diagnosis (131/270) to 67.37% (192/285). Most women were Caucasian with stage I-III breast cancer (n=255) or ductal carcinoma in situ (DCIS) (n=34) and mean age of 59.1 years . The majority of women (63.82%) reported they had gained weight after diagnosis, with an average of 9.07 kg in this group. Half of all women gained 5 kg or more, with 16.97% gaining in excess of 20 kg, and 60.74% experiencing an increase in BMI of >1kg/m2. Over half of women rated their concern about weight as high. Of women who gained weight, more than half reported that this occurred during the first year after diagnosis.
Conclusions: Women in Australia gain a considerable amount of weight after a diagnosis of breast cancer/DCIS and report high levels of concern about their weight. Because weight gain after breast cancer may lead to poorer outcomes, efforts to prevent and manage weight gain must be prioritised and accelerated particularly in the first year after diagnosis. Limitations of this study include its self-report nature.