Author Topic: metformin--2 studies on growth of VS - 2 different results??  (Read 867 times)


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metformin--2 studies on growth of VS - 2 different results??
« on: March 10, 2020, 10:28:34 am »
Metformin Potential Impact on the Growth of Vestibular Schwannomas

Austin Y Feng  1 , Alejandro Enriquez-Marulanda  2 , Ali Kouhi  1   3 , Noor-E-Seher Ali  1 , Justin M Moore  2 , Yona Vaisbuch  1
Affiliations  expand
PMID: 31913209  DOI: 10.1097/MAO.0000000000002545

Objective: Previous work has suggested that metformin may possess antineoplastic properties. This study aims to assess the effect of metformin on the growth of sporadic vestibular schwannomas.

Methods: A retrospective cohort study was performed on patients presenting with radiologically confirmed vestibular schwannomas to Stanford medical center between January 1990 and October 2018. Patients who received metformin during the follow-up period were included and were compared with the control group who were not receiving metformin. Tumor progression and hearing loss are primary and secondary outcomes, respectively.

Results: A total of 149 patients were analyzed, with 42 patients receiving metformin. The mean age at presentation is 69.6 (±11.7) years. There are 69 (46.3%) females and 80 (53.7%) males and there is no significant age difference between the groups. Tumor size at presentation is similar between both groups, 8 mm (4-13) in control group and 7.5 mm (4-14) in metformin group. The average follow-up period is 34.2 months (18.3-57.8) and 30.3 months (13.6-69.8) in the metformin and control cohorts, respectively, and they are not significantly different. No significant differences between both groups were found in final American Academy of Otolaryngology - Head and Neck Surgery hearing outcome or poor audiogram outcome. Metformin users are significantly less likely to present with tumor growth at final follow-up compared with nonmetformin users (28.6 versus 49.5%, respectively; p = 0.02).

Conclusions: This preliminary result suggests metformin may reduce vestibular schwannoma tumor growth rate and shows potential promise as a novel chemotherapeutic agent. Further studies are needed to validate this finding.
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Exploring Whether Statins or Metformin Influence the Growth of Vestibular Schwannomas
February 2020Journal of Neurological Surgery, Part B: Skull Base 81
DOI: 10.1055/s-0040-1702458
Conference: 30th Annual Meeting North American Skull Base Society
Shafeen QaziSophia TranSanjana BalachandraShow all 5 authorsJacob B HunterJacob B Hunter
Objective: This study aims to assess whether statins and or metformin impact the growth of vestibular schwannomas (VS).

Study Design: Retrospective case series.

Setting: Single, tertiary care academic hospital.

Patients: Patients diagnosed with a sporadic VS, with at least two MRI studies at least 6 months apart prior to any intervention.

Intervention: Serial MRI studies. Using Brainlab cranial planning software, a combination of three reviewers measured the greatest linear diameter on axial imaging, in addition to manually segmenting each tumor to calculate volumes in serial MRI studies.

Main Outcome Measure: The VS tumor growth, defined as either ≥2 mm increase in tumor size when measuring the greatest axial diameter, or a 20% increase in tumor volume, between consecutive MRI studies, or between the first and last available MRI study. Growth rates in patients, who had evidence per their electronic medical record (EMR) of having been prescribed either a statin or metformin, were compared with growth rates in patients on neither medication.

Results: A total of 426 patients met inclusion criteria, 53.4% of which were women. For all patients, the median age was 61.5 years (IQR: 53.5–68.2 years), the median linear tumor diameter at diagnosis was 11.3 mm (IQR: 6.5–16.4 mm), and the median tumor volume was 0.31 cm3 (IQR: 0.12–0.79 cm3). Reviewing the EMR, 48 patients (11.3%) were taking metformin; 146 patients (34.3%) were taking a statin; and the remainder 232 patients were considered controls. Comparing tumor measurements between raters, the intraclass correlation coefficient (ICC) for linear measurements was 0.934 (95% CI: 0.865–0.967) while for volumetric measurements, it was 0.902 (95% CI: 0.802–0.952). In assessing metformin, utilizing linear measurements, 17.0% of patients demonstrated growth compared with 19.1% of controls (p = 0.844). Utilizing volumetric measurements, 48.9% of patients demonstrated growth as compared with 61.9% of controls (p = 0.112). With regard to statin use, utilizing linear measurements, 13.1% of patients demonstrated growth, which was significantly fewer than the control group in which 22.2% of controls demonstrated growth. (p = 0.032). When utilizing volumetric analysis, 57.2% of statin users demonstrated volumetric growth compared with 62.1% of controls (p = 0.393).

Conclusion: Utilizing linear measurements, VS patients taking a statin demonstrated significantly less VS growth as compared with controls. However, when assessing tumor volumes, there was no significant growth rate between statin users and controls. In regard to metformin usage, neither linear nor volumetric measurements demonstrate any difference in VS growth between patients and controls.


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Re: metformin--2 studies on growth of VS - 2 different results??
« Reply #1 on: March 10, 2020, 03:55:14 pm »
Interesting find Rocky.

Both these papers were published last month and both were published in the Journal of Neurological Surgery.

The first paper states "Metformin users are significantly less likely to present with tumor growth at final follow-up compared with nonmetformin users (28.6 versus 49.5%, respectively; p = 0.02)" This is a nice result to read.

The second paper, did show lower growth for metformin users, but it appears it was not significant. This is not so nice to read.

The first paper had a mean follow-up period if 34.2 months, while I could not find the follow-up period for the second paper. The longer the study period the better.

The first paper states, "Patients who received metformin during the follow-up period were included", while the second paper states, "having been prescribed either a statin or metformin" and "48 patients (11.3%) were taking metformin" . While the first paper talks about recieved, the second paper. Maybe it's arguing about semantics, but could it be that the first paper had patients that verified they were taking, metformin while the second paper's group were prescribed and there may have been a compliance issue.

I think it's worth doing some more studies. There needs to be control over compliance and results can be published on a yearly basis. After 5 years we'll have a pretty good picture.

Thanks for finding these abstracts Rocky.