Sensitivity of 2-[18F]fluoro-2-deoxyglucose positron emission tomography for advanced colorectal neoplasms: a large-scale analysis of 7505 asymptomatic screening individuals

Predictive value of 18F-fluorodeoxyglucose PET/CT in histological grade of incidental colorectal adenoma

BACKGROUND

18F-fluorodeoxyglucose (18F-FDG) positron-emission tomography/computed tomography (PET/CT) as an imaging modality for the whole body has shown its value in detecting incidental colorectal adenoma. In clinical practice, adenomatous polyps can be divided into three groups: low-grade intraepithelial neoplasia (LGIN), high-grade intraepithelial neoplasia (HGIN) and cancer, which can lead to different clinical management. However, the relationship between the 18F-FDG PET/CT SUVmax and the histological grade of adenomatous polyps is still not established, which is a challenging but valuable task.

METHODS

This retrospective study included 255 patients with colorectal adenoma (CRA) or colorectal adenocarcinomas (AC) who had corresponding 18F-FDG uptake incidentally found on PET/CT. The correlations of SUVmax with pathological characteristics and tumor size were assessed. Neoplasms were divided into LGIN, HGIN, and AC according to histological grade. Receiver operating characteristic (ROC) analysis was applied to evaluate the predictive value of the SUVmax-only model and comprehensive models which were established with imaging and clinical predictors identified by univariate and multivariate analysis.

RESULTS

The SUVmax was positively correlated with histological grades (r=0.529, P<0.001). Univariate and multivariate analysis showed that SUVmax was an independent risk factor among all groups except between HGIN and AC. The area under the curves (AUCs) of the comprehensive model for distinguishing between AC and adenoma, LGIN and HIGN, LGIN and AC, and HGIN and AC were 0.886, 0.780, 0.945, 0.733, respectively, which is statistically higher than the AUCs of the SUVmax-only model with 0.812, 0.733, 0.863, and 0.688, respectively.

CONCLUSIONS

As an independent risk factor, SUVmax based on 18F-FDG PET/CT is highly associated with the histological grade of CRA. Thus, 18F-FDG PET/CT can serve as a noninvasive tool for precise diagnosis and assist in the preoperative formulation of treatment strategies for patients with incidental CRA.

Combined SUVmax and localized colonic wall thickening parameters to identify high-risk lesions from incidental focal colorectal 18F-FDG uptake foci

Objective

To evaluate the detection ability of 18F-FDG PET/CT for identifying high-risk lesions (high-risk adenomas and adenocarcinoma) from incidental focal colorectal 18F-FDG uptake foci combining maximum standard uptake value (SUVmax) and localized colonic wall thickening (CWT). The secondary objective was to investigate the factors of missed detection of high-risk adenomas by 18F-FDG PET/CT.

Patients and methods

A total of 6394 patients who underwent 18F-FDG PET/CT in our hospital from August 2019 to December 2021 were retrospectively analysed, and 145 patients with incidental focal colorectal 18F-FDG uptake foci were identified. The optimal cut-off value of SUVmax for 18F-FDG PET/CT diagnosis of high-risk lesions was determined by receiver operating characteristic (ROC) curves. SUVmax and localized CWT were combined to identify high-risk lesions from incidental focal colorectal 18F-FDG uptake foci. The characteristics of incidental adenomas detected and high-risk adenomas missed by 18F-FDG PET/CT were compared.

Results

Of the 6394 patients, 145 patients were found to have incidental focal colorectal FDG uptake foci (2.3%), and 44 patients underwent colonoscopy and pathological examination at the same time. In fact, 45 lesions, including 12 low-risk lesions and 33 high-risk lesions (22 high-risk adenomas, 11 adenocarcinoma), were found by colonoscopy. The area under the ROC curve of SUVmax for low-risk lesions and high-risk lesions was 0.737, and the optimal cut-off value was 6.45 (with a sensitivity of 87.9% and specificity of 58.3%). When SUVmax ≥6.45, the combination of localized CWT parameters has little influence on the sensitivity and specificity of detection; when SUVmax &lt;6.45, the combination of localized CWT parameters can improve the specificity of detection of high-risk lesions, but the sensitivity has little change. In addition, the size of high-risk adenomas discovered incidentally by 18F-FDG PET/CT was larger than that of high-risk adenomas missed, but there was no significant difference in lesion location, pathological type or intraepithelial neoplasia between the two groups.

Conclusions

The combination of SUVmax and localized CWT parameters of 18F-FDG PET/CT helped identify high-risk lesions from incidental focal colorectal 18F-FDG uptake foci, especially for lesions with SUVmax &lt;6.45. Lesion size may be the only factor in 18F-FDG PET/CT missing high-risk adenomas.

Limited usefulness of serum carcinoembryonic antigen and carbohydrate antigen 19-9 levels for gastrointestinal and whole-body cancer screening

The diagnostic performance of serum carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 levels for multiple-organ cancer screening has not been fully elucidated. However, they are widely used for real-world opportunistic screening of multiple-organ cancers. This study aimed to examine the diagnostic performance of these serum markers in multiple-organ cancer screening. Data from asymptomatic individuals subjected to opportunistic cancer screening were analyzed. The diagnostic performance of CEA and CA 19-9 was assessed for (A) upper/lower gastrointestinal cancers and (B) whole-body cancers (including both gastrointestinal and other organ cancers) using the results of upper/lower gastrointestinal endoscopy and whole-body imaging as reference. Data from 12,349 and 7616 screened individuals were used to assess the diagnostic performance of CEA and CA 19-9 for (A) and (B), respectively. For (A), the sensitivity and positive predictive value (PPV) of CEA (cut-off: 5 ng/mL) were 7.8% and 3.7%, respectively; those of CA19-9 (cut-off: 37 U/mL) were 7.4% and 2.7%, respectively. For (B), the sensitivity and PPV of CEA were 6.6% and 4.1%, respectively, and those of CA19-9 were 10.8% and 5.8%, respectively. Considering even multiple cancers, the sensitivity and PPV of CEA and CA 19-9 were low, thus confirming their limited usefulness in multiple-organ cancer screening.

Feasibility of observational screening colonoscopy followed by deferred polypectomy

BACKGROUND AND AIM

With the increasing necessity of colorectal cancer screening, observational screening colonoscopy during which only endoscopic observation and diagnosis is performed is worth consideration. However, whether detected lesions can be correctly identified at secondary colonoscopy performed for polypectomy is unclear. Further, whether new neoplastic lesions can be detected at secondary colonoscopy has not been fully examined. This study was performed to investigate the detectability of adenomatous polyps and advanced colorectal neoplasia (ACN) at secondary colonoscopy.

METHODS

Data were analyzed from individuals who underwent initial observational screening colonoscopy followed by secondary colonoscopy for polypectomy. The proportion of correct detection at secondary colonoscopy of the lesions detected at initial colonoscopy was assessed. The number and characteristics of lesions that were newly detected at secondary colonoscopy were also evaluated.

RESULTS

Data of 587 individuals were assessed. Among the 1 331 lesions detected at the initial colonoscopy, 1 151 (86.5%) were properly detected at the secondary colonoscopy. The proportions of correct detection at the secondary colonoscopy for ACN, non-advanced adenomas sized 5 to 9 mm, and non-advanced adenomas sized 1 to 4 mm were 100%, 95.4%, and 70.3%, respectively. In total, 175 adenomatous polyps and ACNs were newly detected at secondary colonoscopy in 112 individuals (19.1% of all individuals). Most of the lesions (165 lesions, 94.3%) were non-advanced adenomas, while advanced adenomas (5.7%) were also found.

CONCLUSION

Screening by observational colonoscopy followed by deferred polypectomy is a feasible option in terms of lesion detectability, particularly when lesions sized ≥ 5 mm are the treatment target.

Incidence of Advanced Colorectal Neoplasia in Individuals With Untreated Diminutive Colorectal Adenomas Diagnosed by Magnifying Image-Enhanced Endoscopy

OBJECTIVES

Because of the increasing number of detected diminutive colorectal adenomas, the "diagnose-and-do-not-resect" approach has recently attracted attention as an alternative to resection. We evaluated the cumulative incidence of advanced colorectal neoplasia (ACN) in individuals with untreated diminutive adenomas and compared this incidence in individuals without adenomas.

METHODS

Data from 1,378 individuals who underwent first screening colonoscopy (CS) and at least one follow-up CS without polypectomy were analyzed. Patients with no adenomas or with only nonadvanced diminutive adenomas (<5 mm) diagnosed by magnifying image-enhanced endoscopy were scheduled to undergo a follow-up CS within 5 years after the initial CS without treatment. The participants were divided into 2 groups: those with untreated diminutive adenomas (group A) and those with no adenomas (group B). The cumulative incidence of ACN and the hazard ratio were assessed using Gray's test and the Fine and Gray model.

RESULTS

During the median follow-up period of 60.9 months, 21 ACNs were detected. The 5-year cumulative incidences of ACN in group A (n = 361) and group B (n = 1,017) were 1.4% (95% confidence interval [CI]: 0.5-3.4) and 0.8% (95% CI: 0.3-1.7), respectively, without a statistically significant difference (P = 0.23). No ACNs developed from unresected adenomas. The smoking status was significantly associated with the incidence of ACN, and the hazard ratio for ACN in group A vs group B adjusted for smoking status was 1.43 (95% CI: 0.52-3.90; P = 0.48).

DISCUSSION

The low 5-year cumulative incidence of ACN suggests the potential to adopt the "diagnose-and-do-not-resect" strategy as an alternative option for diminutive adenomas not requiring excessive surveillance.

A scoring model for predicting advanced colorectal neoplasia in a screened population of asymptomatic Japanese individuals

BACKGROUND

Risk stratification of screened populations could help improve colorectal cancer (CRC) screening. Use of the modified Asia-Pacific Colorectal Screening (APCS) score has been proposed in the Asia-Pacific region. This study was performed to build a new useful scoring model for CRC screening.

METHODS

Data were reviewed from 5218 asymptomatic Japanese individuals who underwent their first screening colonoscopy. Multivariate logistic regression was used to investigate risk factors for advanced colorectal neoplasia (ACN), and a new scoring model for the prediction of ACN was developed based on the results. The discriminatory capability of the new model and the modified APCS score were assessed and compared. Internal validation was also performed.

RESULTS

ACN was detected in 225 participants. An 8-point scoring model for the prediction of ACN was developed using five independent risk factors for ACN (male sex, higher age, presence of two or more first-degree relatives with CRC, body mass index of > 22.5 kg/m², and smoking history of > 18.5 pack-years). The prevalence of ACN was 1.6% (34/2172), 5.3% (127/2419), and 10.2% (64/627) in participants with scores of < 3, ≥ 3 to < 5, and ≥ 5, respectively. The c-statistic of the scoring model was 0.70 (95% confidence interval, 0.67-0.73) in both the development and internal validation sets, and this value was higher than that of the modified APCS score [0.68 (95% confidence interval, 0.65-0.71), P = 0.03].

CONCLUSIONS

We built a new simple scoring model for prediction of ACN in a Japanese population that could stratify the screened population into low-, moderate-, and high-risk groups.

Efficacy of 18-fluoro deoxy glucose-positron emission tomography computed tomography for the detection of colonic neoplasia proximal to obstructing colorectal cancer

Identification of secondary colonic neoplasia proximal to obstructing colorectal cancer is essential for determining the range of colorectal resection.We examined the accuracy of 18-fluoro deoxy glucose-positron emission tomography (FDG-PET) for detection of colonic neoplasia.We recruited patients with obstructing colorectal cancer from our registry. Preoperative FDG-PET was performed, and the detection rate for colonic neoplasia was estimated. Preoperative colonoscopy or postoperative colonoscopy within a year after operation was employed as the indexed standard.Ninety-three patients were included in this study. Colonic neoplasia proximal to obstruction was confirmed in 83 cases. The sensitivity and positive predictive value of FDG-PET were 25.3% and 77.8%, respectively. The sensitivity was higher in larger lesions (3.2% for <5 mm, 29.4% for 6-10 mm, 45.5% for 11-20 mm, and 71.4% for >21 mm) and in higher pathological grade lesions (14.6% for low-grade adenoma, 38.5% for high-grade adenoma, 66.7% for carcinoma in situ, and 100% for invasive carcinoma). The round shape in PET images was a predictor for neoplasia, with an area under the curve of 0.75293 at an aspect ratio of 1.70.FDG-PET should be used as a screening modality for invasive colorectal cancer (CRC) proximal to obstructing colorectal cancer.

A Novel Theranostic Combination of Near-infrared Fluorescence Imaging and Laser Irradiation Targeting c-KIT for Gastrointestinal Stromal Tumors

It is difficult to distinguish gastrointestinal stromal tumors (GISTs) from other types of submucosal tumors under conventional gastrointestinal endoscopy. We aimed to detect GISTs by molecular fluorescence imaging using a near-infrared (NIR) photosensitizer (IR700)-conjugated anti-c-KIT antibody and to treat GISTs by photoimmunotherapy with NIR irradiation as a non-invasive theranostic procedure. We also investigated the therapeutic mechanisms. Methods: Human GIST cell lines GIST-T1 and GIST-882M were incubated with IR700-conjugated anti-c-KIT antibody, IR700-12A8, and observed by confocal laser microscopy. Mice with GIST-T1 xenografts or rats with orthotopic xenografts were injected with IR700-12A8 or AF488-conjugated antibody, and observed under IVIS or autofluorescence imaging (AFI) endoscopy. GIST cells were treated with IR700-12A8 and NIR light in vitro and vivo, and cell viability, histology and apoptosis were evaluated. Results: Strong red fluorescence of IR700-12A8 was observed on the cell membrane of GIST cells and was gradually internalized into the cytoplasm. Tumor-specific accumulation of IR700-12A8 was observed in GIST-T1 xenografts in mice. Under AFI endoscopy, a strong fluorescence signal was observed in orthotopic GIST xenografts in rats through the normal mucosa covering the tumor. The percentage of dead cells significantly increased in a light-dose-dependent manner and both acute necrotic and late apoptotic cell death was observed with annexin/PI staining. Cleaved PARP expression was significantly increased after IR700-12A8-mediated NIR irradiation, which was almost completely reversed by NaN₃. All xenograft tumors (7/7) immediately regressed and 4/7 tumors completely disappeared after IR700-12A8-mediated NIR irradiation. Histologic assessment and TUNEL staining revealed apoptosis in the tumors. Conclusion: NIR fluorescence imaging using IR700-12A8 and subsequent NIR irradiation could be a very effective theranostic technology for GIST, the underlying mechanism of which appears to involve acute necrosis and supposedly late apoptosis induced by singlet oxygen.

Performance of 18-fluoro-2-deoxyglucose positron emission tomography for esophageal cancer screening

AIM

To evaluate the performance of 18-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) for esophageal cancer (EC) screening.

METHODS

We retrospectively analyzed the data of consecutive asymptomatic individuals who underwent FDG-PET and esophagogastroduodenoscopy (EGD) simultaneously for cancer screening at our institution from February 2004 to March 2013. In total, 14790 FDG-PET and EGD procedures performed for 8468 individuals were included in this study, and the performance of FDG-PET for EC screening was assessed by comparing the results of FDG-PET and EGD, considering the latter as the reference.

RESULTS

Thirty-two EC lesions were detected in 28 individuals (31 squamous cell carcinomas and 1 adenocarcinoma). The median tumor size was 12.5 mm, and the depths of the lesions were as follows: Tis (n = 12), T1a (n = 15), and T1b (n = 5). Among the 14790 FDG-PET procedures, 51 examinations (0.3%) showed positive findings in the esophagus; only 1 was a true-positive finding. The screen sensitivity, specificity, positive predictive value, and negative predictive value of FDG-PET for ECs were 3.6% (95%CI: 0.1-18.3), 99.7% (95%CI: 99.6-99.7), 2.0% (95%CI: 0.0-10.4), and 99.8% (95%CI: 99.7-99.9), respectively. Of the 50 FDG-PET false-positive cases, 31 were observed in the lower esophagus, and gastroesophageal reflux disease was observed in 17 of these 31 cases.

CONCLUSION

This study is the first to clarify the FDG-PET performance for EC screening. Based on the low screen sensitivity, FDG-PET is considered to be difficult to use as a screening modality for ECs.

Can positron emission tomography detect colorectal adenomas and cancers?

BACKGROUND AND AIM

Fluorine-18 2-fluoro-2-deoxy-d-glucose positron emission tomography (PET) is effective and less invasive than other modalities used to diagnose tumors, including colorectal cancer (CRC). However, the detectability of adenomas and CRCs, especially in the early stages, is unclear.

METHODS

We evaluated the records of 2323 consecutive eligible patients who underwent both a total colonoscopy (TCS) and PET between October 2002 and September 2012 at a tertiary cancer center. The PET findings were verified by TCS performed independently within 1 year. Target lesions were defined as CRCs and adenomas that were 6 mm or larger in size.

RESULTS

Total colonoscopy detected 532 target lesions ≥ 6 mm in size: 56 T2-T4 CRCs, 39 T1 CRCs, 223 advanced adenomas, and 214 low-grade adenomas. Of the 532 lesions, 216 (40.6%) were PET positive. Of the 369 cases with positive uptakes, PET detected target lesions in the matched segments for 58.5% (216/369). Sensitivity of PET to T2-T4 CRCs, T1 CRCs, advanced adenomas, and low-grade adenomas was 92.9%, 79.5%, 50.7%, and 9.3%, respectively. PET could detect 76.5% (13/17) of T1 CRCs whose size is 10 to 19 mm and 85.0% (17/20) of T1 CRCs equal or larger than 20 mm. The multivariate analysis excluding T2-T4 CRCs showed malignant histology, larger size, protruded lesions, villous histology, and lesions in distal colon were significant factors.

CONCLUSIONS

Sensitivity of PET for detecting T2-T4 and even T1 cancers are promising. However, sensitivity of PET to adenomas, even advanced adenomas, is limited.