Are weight changes after breast cancer diagnosis associated with poorer survival?

The aim of this study was to assess whether weight changes after diagnosis of breast cancer (BC) were associated with survival. The study found that a weight changes of over 10% were associated with a poorer outcome when compared to weight maintenance (within 5%). 

BC remains one of the most commonly diagnosed cancers in women. More women are surviving breast cancer than ever due to early detection and modern treatments. Bodyweight in women with cancer remains a key factor that influences survival in women with BC. Weight change is common in women with BC. It can be a consequence of the BC or anti-cancer treatments such as surgery, chemotherapy, or radiation.

There is evidence from previous studies that weight changes in the periods during the progression of BC has an impact on the survival of patients with BC. Body mass index (BMI) is a measure of weight in relation to height. A healthy BMI is between 18.5 and 24.9. It is important to evaluate whether changes in bodyweight impact the outcomes of women with BC.

There were 2216 postmenopausal BC survivors included in this study. The weight and height at the beginning of the study (at an average of 3.9 months after diagnosis) were recorded for all patients. Patients were followed up with telephone interviews for an average of 5.5 years. 

Compared to weight-maintenance (within 5% of initial body weight) a weight-loss of greater than 10% resulted in a 2.49 times increased risk of all-cause mortality (ACM). A more than 10% weight loss was also associated with a 3.09 times higher risk of mortality due to BC.

Weight gain of over 10% was associated with a 1.64 times higher risk of ACM and a 2.24 times higher risk of mortality due to BC. These associations were stronger for women with normal BMI at the start of the study than those who were overweight. These risks were also higher for women who lost or gained weight fast (more than 1% body weight per year). 

The authors concluded that weight changes may reduce survival in BC patients. They suggested that weight maintenance within 5% of body weight may help improve outcomes in BC patients. 

This study was carried out exclusively in Germany. This study may not be translatable to other populations due to European lifestyles not being comparable to the United States and Asia. Also, weight and height were obtained through interviews, meaning they were self-reported. Errors in reporting these numbers may influence the results.