Abstract
Purpose Intratumor metabolic heterogeneity parameters on 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) have been proven to be predictors of the clinical prognosis of cancer patients. The study aimed to examine the correlation between 18F-FDG PET-CT-defined heterogeneity parameters and the prognostic significance in patients with colorectal cancer. Methods The study included 188 patients with colorectal cancer who received surgery and 18F-FDG PET/CT examinations. Preoperative 18F-FDG PET/CT conventional and metabolic heterogeneity parameters were collected, including maximum, peak, and mean standardized uptake value (SUVmax, SUVpeak, and SUVmean), metabolic tumor volume (MTV), total lesion glycolysis (TLG), heterogeneity index-1 (HI-1) and heterogeneity index-2 (HI-2), and clinicopathological information. Correlations between these parameters and patient survival outcomes were inferred. Results The associations between 18F-FDG PET/CT parameters and clinical outcomes were analyzed. Tumor thrombus (P < 0.001), tumor stage (P=0.001), MTV (P=0.003), HI-1 (P=0.032), and HI-2 (P=0.001) differed between the two groups with and without recurrence. Multivariate analysis showed that, in the radical surgery group, HI-2 (HR = 1.10, 95% CI: 1.04–1.17, P=0.001), tumor stage (HR = 20.65, 95% CI: 4.81–88.62, P < 0.001), and regional lymph nodes status (HR = 0.16, 95% CI: 0.04–0.57, P=0.005) were independent variables significantly correlated with progression-free survival (PFS) and HI-2 (HR = 1.16, 95% CI: 1.07–1.26, P < 0.001) was an independent variable affecting overall survival (OS). In the palliative surgery group, HI-2 (HR = 1.03, 95% CI: 1.01–1.06, P=0.020) was an independent variable affecting PFS, and all the parameters were not statistically significant for OS. Conclusion HI-2, tumor stage, and regional lymph nodes status might predict the outcomes of colorectal cancer more effectively than other 18F-FDG PET/CT defined parameters.
Highlights
Colorectal cancer is one of the most common malignancies worldwide, with a dismal prognosis
This study enrolled 188 patients (Figure 1). e inclusion criteria were as follows: (1) colorectal cancer was pathologically confirmed as adenocarcinoma, mucinous adenocarcinoma, or signet ring cell carcinoma; pathological tumor features were obtained from the surgical pathology report; (2) serum carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) levels were detected within one week of positron emission tomography-computed tomography (PET/CT) examination; (3) without any treatment before PET/CT examination, radical or palliative surgery was performed within two weeks after the examination; (4) the tumor tissue showed positive FDG metabolism. e exclusion criteria for the subjects were as follows: (1) colorectal cancer of other pathological types; (2) colorectal cancer accompanying a second primary malignant tumor. e research protocol was approved by the Medical Ethics Committee of the First Affiliated Hospital of USTC (2021-RE-002)
In the univariate analysis for overall survival (OS), all the parameters were not statistically significant (Table 4). This is the first study to explore the predictive value of 18F-FDG PET/CT intratumoral HI in colorectal cancer patients. e current research indicates that the intratumoral heterogeneity index-2 (HI-2) of 18F-FDG uptake is an important prognostic factor for progression-free survival (PFS) and OS in patients with colorectal cancer
Summary
Colorectal cancer is one of the most common malignancies worldwide, with a dismal prognosis. For nonmetastasized colorectal cancer (T14N0-2M0), radical surgical resection is the most effective treatment, but for locally advanced middle and lower rectal cancer with CT3-4 and/or N+, neoadjuvant. For late period colorectal cancer, surgery, radiotherapy, chemotherapy, or targeted therapy can be chosen according to the patient’s condition [3, 4]. Despite considerable advances in colorectal cancer treatment, the 5-year survival rate of colorectal cancer patients treated with surgery is still less than 50% [1]. E death of colorectal cancer is mainly related to distant metastasis at the time of diagnosis or after the cancerfree period [5]. The tumor-node-metastasis (TNM) staging system of the American Joint Committee on Cancer (AJCC) is the most common predictive model for colorectal cancer. The predictive effect of biological markers and molecular markers, including CEA, the RAS gene, BRAF, and HER-2, plays a critical role in clinical practice in recent years
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