How Obesity Complicates Breast Cancer Care: Insights From a Systematic Review of Case Reports

The global rise in obesity has intersected with increasing breast cancer incidence, generating a critical need to understand how excess adiposity affects diagnostic accuracy, treatment delivery, and patient outcomes. Although large epidemiologic studies have established associations between obesity and worse breast cancer prognosis, individual-level clinical nuances remain underrepresented. This review systematically evaluates case-based evidence to identify how obesity contributes to diagnostic delays and treatment complications in breast cancer care. This systematic review was conducted according to PRISMA 2020 guidelines and registered with PROSPERO. Databases searched included PubMed, Embase, Scopus, and Google Scholar through April 2025, using terms related to breast cancer, obesity, and case reports. Eligible studies included English-language case reports or series describing diagnostic or therapeutic complications in obese women with breast cancer. The Joanna Briggs Institute checklist was used to assess methodological quality. Nine patients from eight reports met inclusion criteria. Thematic analysis revealed four key domains in which obesity affected care: delayed or misattributed diagnosis, increased risk of surgical site infections and reconstructive failure, altered metabolism and pharmacokinetics leading to treatment toxicity or underdosing, and compounded clinical complexity due to multimorbidity. Cases included rare infections, malabsorption of endocrine therapy post-bariatric surgery, and fatal toxicities amplified by obesity-related comorbidities. Obesity introduces clinically significant barriers throughout breast cancer diagnosis and treatment. This review emphasizes how real-world patient cases echo trends from population studies while revealing additional mechanistic and procedural challenges. Greater awareness of obesity-specific risks can inform personalized strategies to mitigate diagnostic errors, optimize treatment efficacy, and improve outcomes amid the ongoing obesity epidemic.