SEATTLE – Metformin use before surgery for stage I and II non–small cell lung cancer (NSCLC) was associated with improved progression-free survival at 5 years in a retrospective database study of 138 patients who also had type 2 diabetes.
The patients were treated for stage I and II NSCLC at Rush University Medical Center, Chicago. They also had type 2 diabetes; 81 (59%) were on metformin in the 6 months before pulmonary resection, and 57 (41%) were not, reported Rush medical student Robert Medairos, who is one of the study researchers.
Robert Medairos
At 5 years follow-up, progression-free survival was 60% in the metformin group, but about 35% in the no-metformin group (P = .01). Overall survival was about 90% at 5 years in both study arms.
A larger study or longer follow-up may show overall survival benefits for metformin users, Mr. Medairos said at the annual meeting of the American Association for Thoracic Surgery.
Patients were about 70 years old on average in both groups, with 35 pack-year smoking histories, and an average body mass index of about 30 kg/m2. Both study arms had slightly more men than women, and were otherwise balanced for ethnicity and comorbidities.
About 12% of patients in the metformin group and 40% in the no-metformin group, were on insulin prior to surgery. Mean preoperative creatinine was 1 mg/dL in the metformin group, and 1.7 mg/dL in the no-metformin group. There were trends towards higher-stage disease and more lymph node involvement in the no-metformin group. About half the patients in both arms had adenocarcinomas, but a greater proportion of patients in the no-metformin group had squamous cell carcinomas.
The Rush study might be the first to look into metformin for early NSCLC, but there have been several studies in advanced disease. A recent retrospective analysis of 750 diabetes patients with stage IV NSCLC found a median survival of 5 months for the 61% on metformin at diagnosis, but 3 months for those who were not (Am. J. Respir. Crit. Care. Med. 2015;191:448-54).
Currently, there are about a dozen ongoing trials of the drug for lung cancer, and scores more for prostate, breast, brain, uterine, colorectal, thyroid, and other cancers.
Metformin’s metabolic effects might reduce the ability of cancers to grow and metabolize, or the drug might somehow boost the antineoplastic effects of chemotherapeutics. “Our next step is to look at histological and tissues samples to see if metformin changes gene transcription in lung cancer cells,” Mr. Medairos said.
Mr. Medairos has no disclosures.