Antidiabetic treatment is associated with a reduced risk of blood cancer

People using metformin are less likely to develop myeloproliferative neoplasm (MPN) over time, indicating that the treatment may help prevent the development of some types of cancer, according to a study published in Blood Advances magazine.

Metformin is a therapy used to treat high blood sugar in people with type 2 diabetes, which increases the effect of insulin, reduces the amount of glucose secreted by the liver , and helps the body absorb glucose. A meta-analysis of previous studies linked this therapy to a reduced risk of gastrointestinal, breast and urological cancers, and a retrospective study among US veterans found that metformin users had a reduced risk of developing both solid, and hematological cancers.

“Our team was interested in understanding other effects that we see with commonly prescribed drugs such as metformin,” said Anne Stidsholt Rug, MD, chief physician at Aarhus University Hospital and clinical assistant professor at Aalborg University Hospital in Denmark.

"We were interested in the anti-inflammatory effect of metformin because MPNs are highly inflammatory diseases. This is the first study to examine the relationship between metformin use and the risk of developing MPNs."

Myeloproliferative diseases are a group of diseases that affect how the bone marrow produces blood cells, leading to an overproduction of red blood cells, white blood cells, or platelets, which can lead to bleeding problems, an increased risk of stroke or heart attack and organ damage.

Researchers compared metformin use among patients diagnosed with MPN and a matched group from the general Danish population between 2010 and 2018.

Of the 3,816 cases of MPN identified in the sample, a total of 268 (7.0%) people with MPN were taking metformin, compared with 8.2% (1,573 of 19,080) of people in the control group who were taking metformin but were not diagnosed with MPN. Only 1.1% of MPN cases had been taking metformin for more than five years, compared with 2.0% of controls. The protective effect of metformin was observed in all MPN subtypes when adjusted for possible confounding factors.

“We were surprised by the magnitude of the association we observed in the data,” said Daniel Tuiet Christensen, MD, PhD, a graduate student at Aalborg University Hospital and lead author of the study.

"We saw the strongest effect in people who took metformin for more than five years compared to those who took treatment for less than a year," Dr. Christensen added, noting that this makes clinical sense since MPNs are diseases that develop over a long period of time, like other types of cancer.

The researchers noted that although the protective effect of long-term metformin use was observed in all MPN subtypes, the study was limited by a retrospective registry-based design. In addition, they could not account for lifestyle factors that may influence cancer risk, such as smoking, obesity and dietary habits.

Dr. Rugh noted that although the research team was not able to accurately assess why metformin appears to protect against the development of MPN, they hope that more research will be conducted to better understand this phenomenon. In the future, the researchers intend to identify similar trends with myelodysplastic syndromes and acute myeloid leukemia in population-level data for further study.