BACKGROUND AND AIM: Positron Emission Tomography/Computed Tomography (PET/CT) is utilized as a guide for sampling lung lesions and for staging lung cancer. In this study, we examined the importance of mass size and Standardized Uptake Value maximum (SUVmax) values in predicting cancer in lesions identified on PET/CT.

METHODS: We analyzed PET/CT results from patients diagnosed with newly discovered lung cancer or those presenting lung lesions in other radiological imaging. The lesion’s longest diameter and the areas with the highest SUVmax values were recorded. Lesion-nodule categorization, as well as benign-malignant differentiation and cancer subtypes, were separately examined with
respect to diameter and SUVmax involvement.

RESULTS: Separate diameter and SUVmax cut-off values were determined for predicting cancer in lesions and nodules. For all lesions, the likelihood of malignancy increases when the
size exceeds 27.5 mm and the SUVmax value surpasses 5.428 (p<0.001, p<0.001). Concerning nodules, the malignancy threshold lies at a size of 15.5 mm and an SUVmax value of 4.54 (p<0.001, p=0.022). It was observed that lesion size and SUVmax value in primary lung cancers were significantly higher than in metastatic lung cancers (p=0.002, p=0.04). SUVmax uptake was lower in small cell lung cancer (SCLC) lesions compared to non-small cell lung cancer (NSCLC) lesions (p=0.001). The longest diameter was higher in adenocarcinoma than in squamous cell carcinoma (p=0.028).

CONCLUSIONS: PET/CT plays a crucial role in staging patients diagnosed with lung cancer. In cases where cancer is suspected but diagnosis is challenging, PET/CT findings, along with the individual’s risk factors, will aid in clinical decision-making.