Having diabetes is not linked to five-year survival in metastatic breast cancer but may affect long-term survival, according to a new study presented at ENDO 2022, the annual conference of the Endocrine Society, and described in an article at MedPage Today.
Diabetes and cancer are both common health conditions in the United States, and they’re related in certain ways — including sharing some common risk factors. For example, regularly drinking sugar-sweetened beverages is linked to a higher risk of developing type 2 diabetes as well as colorectal cancer. Having type 2 diabetes may also raise the risk for certain cancers, and undergoing bariatric surgery leading to diabetes remission is linked to a lower cancer risk. At the same time, breast cancer survivors may be at higher risk for developing diabetes.
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Some past research has shown that diabetes is not linked to overall cancer survival. But for the latest study, researchers were interested specifically in whether having diabetes was linked to outcomes in metastatic breast cancer. To do this, they looked at data from 244 people with diabetes, and an equal number without diabetes, who underwent treatment for metastatic breast cancer at two different U.S. health systems in the Northeast. The average age of study participants was 57 when they started treatment, and 84% were white. In the group with diabetes, the average A1C level (a measure of long-term blood glucose control) was 6.6% — indicating good blood glucose control — and the average random blood glucose level was 123 mg/dl.
Diabetes linked to lower long-term survival rates after metastatic breast cancer
The researchers found that participants with and without diabetes had similar five-year survival rates — 54% for those with diabetes, and 56% for those without diabetes. Both groups also had a similar time to next cancer treatment, with 56% of both groups trying another treatment a year later. But for participants who were still living after eight years, having diabetes was linked to lower long-term survival. Within this group, at year 10, 67% of participants with diabetes were still living, compared with 87% of those without diabetes.
Regardless of diabetes status, random blood glucose was linked to both five-year and long-term survival. For participants with a random glucose level of 180 mg/dl or lower, five-year survival was 55%, while it dropped to 48% for those with a random glucose level above 180 mg/dl but less than 200 mg/dl, and to 23% for those with a random glucose level of 200 mg/dl or higher. Among those who survived at least eight years, the 10-year survival rate was 83% for participants with a random glucose level of 180 mg/dl or lower, compared with 63% for those with a random glucose level above 180 mg/dl.
The researchers concluded that since diabetes and blood glucose control were more closely linked to long-term survival than to five-year survival in metastatic breast cancer, it may be especially important to optimize blood glucose control in people with diabetes who have a better prognosis for their metastatic breast cancer.
Want to learn more about diabetes and breast cancer? Read “No Increased Breast Cancer Risk Found With GLP-1 Agonists,” “Aspirin, Breast Cancer, and Type 2 Diabetes,” and “Breast Cancer Survivors See Higher Risk for Diabetes, High Blood Pressure.”