Weight Loss Surgery May Negatively Impact Leukemia Treatment

Bariatric surgery may negatively affect treatment outcomes for patients with chronic myeloid leukemia (CML), according to recent research published in Cancer, the journal for the American Cancer Society.

A recent study showed that prior bariatric surgery may negatively impact treatment outcomes in patients with chronic myeloid leukemia.

Bariatric surgeries — which include gastric bypass and other procedures — involve altering the stomach and/or intestines to help a person lose weight. Despite being the most effective and sustained weight loss option for patients with morbid obesity, according to the study authors these digestive adjustments may affect how well the body can process oral drugs used to treat CML, the researchers noted.

“Bariatric surgery could affect bioavailability via decreased absorption after altered gastric emptying and decreased intestinal transit time where these drugs are absorbed,” the study authors wrote.

The study authors compared the outcomes of two groups of patients with CLL who were being treated with oral tyrosine kinase inhibitors (TKIs): 22 underwent prior bariatric surgery, while 44 did not.

Findings showed that 68% of patients who underwent bariatric surgery had an early molecular response — a marker of the treatment working and a better prognosis — at three months, compared with 91% of patients with no history of weight loss surgery.

Patients in the bariatric surgery group also tended to take longer to reach a complete cytogenic response (meaning that between 0 and 1% of cells express the Philadelphia chromosome, which is associated with the disease) and major molecular response.

“Notably, two patients in the bariatric surgery group had an improvement in their response following an increase in TKI dosing after response failure by milestones,” the authors wrote.

At the five-year mark, 60% of patients in the bariatric surgery group lived without disease-related events or symptoms, compared to 77% of patients who did not undergo bariatric surgery. Additionally, at this time point, 32% of patients who underwent bariatric surgery were void of relapse, death or the addition of another therapy (a statistic known as “failure-free survival”), compared with 63% in the non-bariatric surgery group.

Prior research has also shown that patients who underwent a sleeve gastrectomy saw a 60% decrease in the CML drug Gleevec (imatibib) in blood levels compare to baseline. Similarly, researchers saw an 83% decrease in the drug after patients underwent gastric bypass surgery.

Considering these findings, the researchers on this study recommended the following for patients with CML who underwent bariatric surgery and the clinicians treating them:

• Monitoring of drug levels in the blood stream. “Optimal (Gleevec) blood levels correlate with cytogenic and molecular responses and could be a solution for monitoring therapy in patients with a history of bariatric surgery,” they explained.
• However, since means of measuring the amount of TKI drugs in the blood are not easily available, the researchers also said that the dosing of the drugs can be increased once a patient does not respond or stops responding to the treatment, something that “is in line with a previous report showing that TKI dose escalation may improve response after signs of resistance.” Patients can also be switched to different TKIs, they said.
• For patients who are already undergoing treatment for CML and are candidates for or are considering bariatric surgery, the researchers recommend patients achieve a deep remission before the surgery. This decision should be a joint effort between the patient, CML specialist, surgeon and pharmacist, the researchers emphasized.

More research is needed to optimize outcomes for patients with CML who underwent bariatric surgery, the researchers concluded.

“Given the growing use of this surgery, there is an unmet need to design specifically adapted treatment strategies for these patients,” the study authors wrote.

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