Chemotherapy drugs, often used as a first line of defense for a prevalent form of adult leukemia, could actually be causing relapses in patients, according to a new study.

The research, published Wednesday in the online edition of Nature details the results of research samples taken from eight patients diagnosed with acute myeloid leukemia (AML).

Although the study results are shocking, not getting chemo is not a good option. Patients diagnosed with AML who refuse chemotherapy treatment usually die within a few months. Those who choose to undergo chemotherapy live longer, but still have an 80 percent rate of relapse and death within the five years.

“The purpose of this study was to try to begin to understand what happens at relapse,” Dr. Timothy Ley, co-author of the study, told FoxNews.com. “Does the tumor change? Does it evolve? Is it even the same tumor coming back?”

Ley said that the findings were surprising. Out of the eight patients tested, the same tumor always came back, but with a slight mutation added to the original tumor. The rate of these mutations, medically known as transversions, were much greater in patients who relapsed.

This startling find, according to researchers, means that the chemotherapy drugs may in fact be causing relapses.

Although the study may give patients and loved ones pause, Ley still advocates for chemotherapy treatment.

“Without the initial chemotherapy, all of these patients would be dead in a few months. We know that from history,” Ley said. “So the therapy that we use, even though it has problems, it’s necessary at this point. But we need to improve it because it’s contributing to the relapse.”