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Association Between Metformin Use and Risk of Esophageal Squamous Cell Carcinoma in a Population-Based Cohort Study

Wang QL, Santoni G, Ness-Jensen E, Lagergren J, Xie SH

The American journal of gastroenterology, 2020

4,116,030 participants · 31 citations

Abstract

OBJECTIVES

Esophageal cancer is a highly fatal malignant neoplasm, with 2 etiologically different histological types. A large prospective study is expected to elucidate the specific risk of the 90% subtype of esophageal cancer, esophageal squamous cell carcinoma (ESCC), with metformin therapy. This study aims to determine the association between metformin use and incident ESCC risk.

METHODS

This was a nationwide population-based prospective cohort study conducted in Sweden in 2005-2015. Among 8.4 million participants identified in the cohort, 411,603 (5%) were metformin users. The users were compared with 10 times as many frequency-matched nonusers of metformin (n = 4,116,030) by age and sex. Metformin use was treated as a time-varying variate, and multivariable cause-specific proportional hazards model was used to calculate hazard ratios (HR) with 95% confidence intervals (CI) for ESCC, adjusted for age, sex, calendar year, residence area, tobacco smoking, alcohol overconsumption, and use of nonsteroidal anti-inflammatory drugs or statins.

RESULTS

The incidence rates of ESCC were 3.5 per 100,000 person-years among the metformin users and 5.3 per 100,000 person-years in the nonusers. Metformin users overall were at a decreased risk of ESCC compared with nonusers (HR 0.68, 95% CI 0.54-0.85). The decrease in risk was more pronounced in new metformin users (HR 0.44, 95% CI 0.28-0.64) and participants aged 60-69 years (HR 0.45, 95% CI 0.31-0.66).

DISCUSSION

Metformin use…

How strong is the evidence?

Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 4,116,030 participants or records.

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