Background: Gastroesophageal reflux disease (GERD) is a highly prevalent gastrointestinal disorder worldwide. Management strategies include lifestyle modification, pharmacologic therapy, and surgical interventions. Diaphragmatic breathing exercises have been proposed as a non-pharmacological treatment aimed at improving lower esophageal sphincter function and reducing reflux episodes. Methods: A systematic search of PubMed/MEDLINE, Scopus, ScienceDirect, Google Scholar, and ClinicalTrials.gov was conducted from database inception to 10 March 2026 to identify randomized controlled trials evaluating diaphragmatic breathing in patients with GERD. Two reviewers independently screened studies, extracted data, and assessed risk of bias using the Cochrane Risk of Bias 2.0 tool. Random-effects meta-analyses were performed to estimate pooled mean differences for symptom scores and quality-of-life outcomes. Results: Ten randomized controlled trials including 476 patients were analyzed (mean age: 39.9 ± 11.3 years). Diaphragmatic breathing interventions were performed in 229 participants, with an average duration of 20.36 min per session over approximately 5.1 weeks. Meta-analysis demonstrated a modest improvement in GERD symptom scores favoring diaphragmatic breathing (SMD −0.74; 95% CI −1.36 to −0.12; p = 0.019), with substantial heterogeneity (I² = 79.7%). Subgroup analyses comparing breathing with medication and sham breathing controls produced similar trends. Quality-of-life outcomes did not demonstrate statistically significant improvement (MD −2.35; 95% CI −6.35 to 1.65; p = 0.25) and showed considerable heterogeneity (I² = 85.3%). Risk-of-bias assessment revealed “some concerns” in several studies, primarily related to randomization procedures and outcome reporting. Conclusions: Although pooled results demonstrated a statistically significant reduction in GERD symptom scores favoring diaphragmatic breathing, this finding must be interpreted with considerable caution given the substantial heterogeneity observed. The current evidence remains limited by methodological heterogeneity, and inconsistent outcome assessment is insufficient to support definitive clinical recommendations, and the observed benefit may not be generalizable across patient populations or clinical settings. Larger standardized randomized trials are required to determine the clinical role of diaphragmatic breathing in GERD management.

Background: Gastroesophageal reflux disease (GERD) is a common problem that affects patients. The constant irritation of the esophageal mucosa, in addition to the potential aspiration, has been suggested as a predisposing factor for lung cancer (LC). This study aims to investigate the association between GERD and LC. Methods: An electronic search was conducted on EMBASE, CENTRAL, and PubMed databases from inception through November 2025. Studies evaluating the association between GERD and lung cancer in adult populations were included. Reviews, non-English articles, pediatric studies, and non-human studies were excluded. Twelve studies involving 2,900,965 patients met the inclusion criteria. Three types of common and random effect meta-analyses were utilized, namely meta-analysis of proportion, log(HR) and log(OR) models. Included studies were examined for risk of bias using the Newcastle–Ottawa scale. Results: Twelve articles describing 2,900,965 patients were found to be fit for inclusion. Male and female sexes were equally represented. On average, patients were 57.67 ± 10.02 years of age. Pooled proportion of co-occurring LC and GERD in patients was estimated at 64% [95% C.I.: 15–95%; p = 0.02], with significant heterogeneity (I² = 96.8%, p < 0.01). Among studies calculating for hazard ratio (HR), an estimated pooled log(HR) of 1.01 [95% C.I.: 0.36–2.8; p = 0.98] with significant data heterogeneity (I² = 88%, p < 0.01) was found. In comparison, five studies included estimates of odds ratio (OR), which resulted in a pooled log(OR) of 1.32 [95% C.I.: 1.2–1.46; p < 0.01], with less heterogeneity (I² = 59.1%) which was marginally significant (p = 0.04). Conclusions: Our findings may suggest a possible association between LC and GERD; however, estimates were discordant across effect measures and heterogeneity was substantial, so this association should be interpreted with caution.