This study of patients under investigation for lung cancer (LC) aims to: 1) examine the prevalence of self-reported taste and smell alterations (TSAs) and their relationships with demographic and clinical characteristics; and 2) explore nutritional importance of TSAs by examining their associations with patient-reported weight loss, symptoms interfering with food intake, and changes in food intake.MethodsPatients were recruited consecutively during investigation for LC from one university hospital in Sweden. Patient-reported information on TSAs, demographics, six-month weight history, symptoms interfering with food intake, and changes in food intake was obtained. Relationships between TSAs and other variables were examined using two-tailed significance tests. In addition, putative explanatory factors for weight loss were explored in those patients diagnosed with LC, since a relationship between TSAs and weight loss was found in this group.ResultsThe final sample consisted of 215 patients, of which 117 were diagnosed with primary LC within four months of study inclusion and 98 did not receive a cancer diagnosis. The 38% prevalence of TSAs was identical in both groups, and were generally reported as mild and not interfering with food intake. However, a statistically significant relationship between TSAs and weight loss was found among patients with LC, with a median weight change of − 5.5% and a higher frequency of weight loss ≥ 10%. Patients with LC and weight loss ≥ 10%, had higher frequency of reporting TSAs, of decreased food intake and of ≥ 1 symptom interfering with food intake compared with those with less weight loss.Conclusion TSAs, although relatively mild, were present in 38% of patients with and without LC. Relationships between TSAs and weight loss were found among patients with LC, but not fully explained by decreased food intake. This highlights the complexity of cancer-related weight loss.