Does obesity or diabetes have an effect on breast cancer survival?

This study evaluated whether obesity and diabetes mellitus were associated with survival in early stage breast cancer patients.

Roughly two-thirds of the US population and one-third of the world population are considered to be overweight or obese. Diabetes mellitus (DM) has also become very common, particularly among older individuals. DM is a condition in which patients have high blood sugar levels caused by a lack of insulin from the pancreas. DM is highly associated with obesity. Both conditions have been shown to increase the risk of breast cancer (BC). The current study examined the association between obesity, DM and survival in early-stage BC patients who received modern treatments.

This study examined 6342 patients who were treated for BC between 1996 and 2005. 40% of patients were of normal weight, 30% were overweight, and 30% were obese. 8% of the patients also had DM. Three main outcomes measured were recurrence-free survival or RFS (defined as the time patients survived without the cancer returning), overall survival or OS (defined as the time patients survived with or without the disease) and breast cancer specific survival or BCSS (defined as the time patients survived breast cancer).

After approximately 5 years of follow up, the authors of the study found that overweight and obese patients had lower survival rates compared to normal weight patients. RFS, OS and BCSS were decreased by 18%, 20% and 21% respectively in overweight patients and by 13%, 24% and 23% respectively in obese patients. These results were more significant for patients with estrogen receptor positive (ER+) BC (BC that grows in response to estrogen, the main female sex hormone). Patients with DM also had a lower RFS and OS, by 21% and 39% respectively.

In summary, both obesity and DM had a negative impact on survival rates in patients with early-stage breast cancer.

This was a retrospective study (it followed patients who were treated in the past rather than following them throughout their treatment and measuring their outcomes). These studies are known to provide weak statistical information. Also, there was a small number of patients with DM in this group of patients.

Talk to your doctor about the most appropriate way for you to control your weight and to maintain normal blood sugar levels.