Oral paraneoplastic manifestations and findings associated with extra-oral surgically treated malignancies: a prospective cross-sectional study of 300 cases

To assess the prevalence of oral paraneoplastic manifestations in patients with biopsy-confirmed extra-oral malignancies and to identify oral findings with potential paraneoplastic significance that could serve as new targets for dental screening. A single-center prospective cross-sectional study was performed. A total of 300 consecutive surgical oncology patients (April 2024–September 2025) underwent standardized oral examinations one day prior to planned oncologic surgery. Extraoral and intraoral findings—including mucosal changes, perfusion abnormalities, tongue morphology, and candidal colonization—were evaluated by oral medicine specialists. Only primary extra-oral malignancies were included and categorized into upper gastrointestinal, colorectal, hepatopancreatic, lung, and breast cancer. Mycological cultures were obtained in all patients. Statistical assessment used Chi-square test, multivariate stepwise selection logistic regression models and univariate models of selected confounders (SAS software). Classical paraneoplastic oral syndromes (e.g., paraneoplastic pemphigus, acanthosis nigricans) were not detected. Oral candidiasis was uncommon and appeared mainly in patients with advanced disease, suggesting limited usefulness as an early indicator. In contrast, labial and lingual hypoperfusion occurred significantly more often in gastrointestinal cancers (p ≤ 0.0001, labial hypoperfusion was differentiated in 25.5% (24/94) of gastrointestinal malignancies). Patients with breast cancer showed a markedly higher prevalence of tongue enlargement and dental impressions (both p < 0.0001, with tongue enlargement detected in 51,3% (80/159) of cases), as well as lateral deviation during protrusion (p = 0.0152). Traditional oral paraneoplastic manifestations were virtually absent in this cohort. However, simple clinical findings—particularly perfusion changes and tongue morphology—showed frequent tumor-specific associations and may merit further investigation for the verification as potential early paraneoplastic indicators. As a pilot study, the results should be interpreted as hypothesis-generating. Following validation in large multicenter studies, these findings may bring a promising opportunity to strengthen the role of dentists in multidisciplinary prevention programs.