Routine use of positron-emission tomography/computed tomography for staging of primary colorectal cancer: does it affect clinical management?

Colon cancer: the 2023 Korean clinical practice guidelines for diagnosis and treatment

Colorectal cancer is the third most common cancer in Korea and the third leading cause of death from cancer. Treatment outcomes for colon cancer are steadily improving due to national health screening programs with advances in diagnostic methods, surgical techniques, and therapeutic agents.. The Korea Colon Cancer Multidisciplinary (KCCM) Committee intends to provide professionals who treat colon cancer with the most up-to-date, evidence-based practice guidelines to improve outcomes and help them make decisions that reflect their patients' values and preferences. These guidelines have been established by consensus reached by the KCCM Guideline Committee based on a systematic literature review and evidence synthesis and by considering the national health insurance system in real clinical practice settings. Each recommendation is presented with a recommendation strength and level of evidence based on the consensus of the committee.

PET/CT in assessment of colorectal liver metastases: a comprehensive review with emphasis on 18F-FDG

Approximately 25% of those who are diagnosed with colorectal cancer will develop colorectal liver metastases (CRLM) as their illness advances. Despite major improvements in both diagnostic and treatment methods, the prognosis for patients with CRLM is still poor, with low survival rates. Accurate employment of imaging methods is critical in identifying the most effective treatment approach for CRLM. Different imaging modalities are used to evaluate CRLM, including positron emission tomography (PET)/computed tomography (CT). Among the PET radiotracers, fluoro-18-deoxyglucose (18F-FDG), a glucose analog, is commonly used as the primary radiotracer in assessment of CRLM. As the importance of 18F-FDG-PET/CT continues to grow in assessment of CRLM, developing a comprehensive understanding of this subject becomes imperative for healthcare professionals from diverse disciplines. The primary aim of this article is to offer a simplified and comprehensive explanation of PET/CT in the evaluation of CRLM, with a deliberate effort to minimize the use of technical nuclear medicine terminology. This approach intends to provide various healthcare professionals and researchers with a thorough understanding of the subject matter.

Accuracy of pre-operative 18-fluoride fluorodeoxyglucose positron emission tomography (FDG-PET) in predicting lymph node involvement in colon cancer

BACKGROUND

Accurate staging of colon cancer is imperative in directing treatment and prognostication. Existing literature on pre-operative accuracy of FDG-PET/CT in detecting lymph node disease often combines colon and rectal cancer, examines rectal cancers alone, and rarely assesses colon cancer in isolation. Our aim was to assess pre-operative utility of FDG-PET/CT in detecting lymph node disease in colon cancer.

METHODS

A retrospective cohort analysis was performed at a single Australian institution between 2017 and 2022 to identify treatment naive primary colonic tumours. Primary outcome was sensitivity and specificity using formal surgical histopathology as gold standard. Secondary outcomes were patient and tumour factors predictive of FDG-PET/CT positive disease including pre-operative CEA, mismatch repair status, duration to surgery, and tumour T-stage.

RESULTS

Three hundred and thirty-nine patients were identified. Thirty-four had pre-operative FDG-PET/CT without neoadjuvant therapy. The mean surgical lymph node harvest was 18 nodes. Twenty-five patients had moderately differentiated tumours. The median duration between FDG-PET/CT and operation was 17 days. Pre-operative FDG-PET/CT suggested positive lymph node involvement in 12 patients. Compared to final lymph node histopathology, FDG-PET/CT had a sensitivity of 53%, specificity of 82%, positive predictive value of 75%, negative predictive value of 64% and accuracy of 68%. There was no significant difference between groups for secondary outcomes.

CONCLUSION

FDG-PET/CT has moderate specificity but poor sensitivity in the detection of lymph node involvement in colon cancer. Its utility should likely remain isolated to investigating equivocal lesions or follow up of known PET avid disease.

Imaging and its Impact on Defining the Oligometastatic State

Successful treatment of oligometastatic disease (OMD) is facilitated through timely detection and localization of disease, both at the time of initial diagnosis (synchronous OMD) and following the initial therapy (metachronous OMD). Hence, imaging plays an indispensable role in management of patients with OMD. However, the challenges and complexities of OMD management are also reflected in the imaging of this entity. While innovations and advances in imaging technology have made a tremendous impact in disease detection and management, there remain substantial and unaddressed challenges for earlier and more accurate establishment of OMD state. This review will provide an overview of the available imaging modalities and their inherent strengths and weaknesses, with a focus on their role and potential in detection and evaluation of OMD in different organ systems. Furthermore, we will review the role of imaging in evaluation of OMD for malignancies of various primary organs, such as the lung, prostate, colon/rectum, breast, kidney, as well as neuroendocrine tumors and gynecologic malignancies. We aim to provide a practical overview about the utilization of imaging for clinicians who play a role in the care of those with, or at risk for OMD.

Colorectal liver metastases: Current management and future perspectives

The liver is the commonest site of metastatic disease for patients with colorectal cancer, with at least 25% developing colorectal liver metastases (CRLM) during the course of their illness. The management of CRLM has evolved into a complex field requiring input from experienced members of a multi-disciplinary team involving radiology (cross sectional, nuclear medicine and interventional), Oncology, Liver surgery, Colorectal surgery, and Histopathology. Patient management is based on assessment of sophisticated clinical, radiological and biomarker information. Despite incomplete evidence in this very heterogeneous patient group, maximising resection of CRLM using all available techniques remains a key objective and provides the best chance of long-term survival and cure. To this end, liver resection is maximised by the use of downsizing chemotherapy, optimisation of liver remnant by portal vein embolization, associating liver partition and portal vein ligation for staged hepatectomy, and combining resection with ablation, in the context of improvements in the functional assessment of the future remnant liver. Liver resection may safely be carried out laparoscopically or open, and synchronously with, or before, colorectal surgery in selected patients. For unresectable patients, treatment options including systemic chemotherapy, targeted biological agents, intra-arterial infusion or bead delivered chemotherapy, tumour ablation, stereotactic radiotherapy, and selective internal radiotherapy contribute to improve survival and may convert initially unresectable patients to operability. Currently evolving areas include biomarker characterisation of tumours, the development of novel systemic agents targeting specific oncogenic pathways, and the potential re-emergence of radical surgical options such as liver transplantation.

Lateral pelvic lymph node dissection in the management of locally advanced low rectal cancer: Summary of the current evidence

Lateral pelvic lymph nodes (LPLN) are a major site for local recurrence following curative resection for low locally advanced rectal cancer. Ongoing advances in imaging techniques have improved predicting LPLN metastasis (LPLNM) during pre-operative staging. However, there is ongoing debate on optimal management of this subgroup of patients with variation between guidance of different societies. In Japan, LPLNM is considered as local disease and addressed by lateral pelvic node dissection (LPLND) in addition to total mesorectal excision (TME). However, in the west, LPLNM is considered as metastatic disease and those patients are offered neoadjuvant chemoradiotherapy (nCRT) followed by TME surgery. The potential surgical risks and morbidity associated with LPLND as well as the uncertainty of the oncological outcome have raised the concern that patients with locally advanced low rectal cancer with LPLNM could be over or under-treated. A comprehensive review of literature was performed, summarizing the current evidence on available modalities for predicting LPLNM, the role of LPLND in the management of advanced low rectal cancer and the available surgical approaches with their impact on surgical and oncological outcomes. LPLND is associated with increased operative time, blood loss and post-operative morbidity. The potential benefits for local disease control and survival still awaits high quality studies. There has been increasing number of reports of the use minimally invasive approaches in LPLND in an attempt to reduce post-operative complications. There is need for high quality evidence to define the role of LPLND in management of patients with advanced low rectal cancer.

Effect of PET-CT on disease recurrence and management in patients with potentially resectable colorectal cancer liver metastases. Long-term results of a randomized controlled trial

BACKGROUND

Preoperative evaluation of resectable colorectal cancer liver metastases with positron emission tomography (PET) combined with computed tomography (PET-CT) is used extensively. The PETCAM trial evaluated the effect of PET-CT (intervention) vs no PET-CT (control) on surgical management. PET-CT resulted in 8% change in surgical management, therefore, we aimed to compare long-term outcomes (disease-free [DFS], overall survival [OS]).

METHODS

Trial recruitment (2005-2010) had prospective follow-up until 2013. Events from 2013 to 2017 were collected retrospectively. Survival was described by the Kaplan-Meier method and compared with log-rank test. Oncologic risk factors were calculated using Cox proportional hazard models.

RESULTS

Among 404 patients randomized, there were no differences in DFS (hazard ratio [HR] = 1.13; 95% confidence interval [CI], 0.89 to 1.43) or OS (HR, 1.02; 95% CI, 0.78-1.32) between groups. For all patients randomized, median DFS (PET-CT vs no PET-CT) was 16 months (95% CI, 13-18) and 15 months (95% CI, 11-22), P = .33. For patients who underwent liver resection (n = 368), DFS (17 vs 16 months, P = .51) and OS (58 months vs 52 months, P = .90) were similar between groups, respectively. Risk factors for DFS and OS were age, tumor size, node-positive disease, extrahepatic metastases and disease-free duration.

CONCLUSION

Preoperative PET-CT changes surgical management in a small percentage of cases, without effect on recurrence rates or long-term survival.

Morphological predictors for lymph node metastases on computed tomography in colon cancer

INTRODUCTION/BACKGROUND

The aim of the study was to assess morphological predictors for lymph node metastases (Stage III disease) in colon cancer on computed tomography.

METHODS AND MATERIALS

Ninety-four patients with histology-proven colon cancer (adenocarcinoma) who underwent elective primary curative resection between the years 2012 and 2014 were included. Contrast-enhanced CT examinations were independently reviewed by two blinded observers regarding tumor location, depth of tumor invasion, and presence of lymph node metastases. Ocular presence of internal heterogeneity and presence of irregular outer border were used as morphological criteria for lymph node involvement. Protocol-based histopathology after curative surgery served as reference standard. Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values, and accuracy for each morphological criterion for prediction of stage III disease were calculated. Inter-observer agreement was compared using Kappa statistics.

RESULTS

According to histopathology, 59 patients were staged as I-II disease and 35 patients were staged as stage III disease. The presence of internal heterogeneity in a lymph node on CT resulted in moderate sensitivity (66-77%) but high specificity (95-95%) for prediction of Stage III disease by both observers. The presence of irregular outer border also resulted in poor sensitivity (49-54%) but high specificity (97-97%). The combination of either internal heterogeneity and/or irregular outer border per patient resulted in a moderate sensitivity (67-77%) and high specificity (95-95%), PPV (89-96%), and NPV (84-88%). Inter-observer agreement (Cohens Kappa) was 0.72. Consensus reading for the combined criteria resulted in sensitivity and specificity of 69% and 100%, respectively.

CONCLUSION

Using morphological criteria for lymph node metastases on CT examination in patients with colon cancer results in high specificity but moderate sensitivity in predicting stage III disease.

Metformin Discontinuation prior to FDG PET/CT: A Randomized Controlled Study to Compare 24- and 48-hour Bowel Activity

Purpose To investigate the relationship of 24- and 48-hour metformin discontinuation to bowel uptake of fluorine 18 fluorodeoxyglucose (FDG) on PET/CT scans. Materials and Methods Patients with diabetes who were treated with metformin and referred for FDG PET/CT were randomized to three equal groups based on duration of metformin discontinuation: 24 hours, 48 hours, and no discontinuation (control group). Two interpreters blinded to the study groups assessed FDG uptake in multiple segments of small and large bowel qualitatively and semiquantitatively by using maximum standardized uptake values (SUVs_max). Differences in age, sex, weight, dose of metformin, duration of metformin treatment, blood glucose levels, and FDG dose injected were assessed. Data were analyzed with analysis of variance when passing normality, and by nonparametric testing when not. Results Ninety study participants (62 male, 28 female; median age, 70 years) were enrolled from July 2010 through March 2012. There were no differences between study groups in weight, blood glucose levels 3 days prior to scanning, or normal organ uptake. Large bowel SUV_max was lower after 24 hours (4.10 ± 2.00 vs 5.42 ± 2.36; P = .020) and 48 hours (2.63 ± 0.88 vs 5.42 ± 2.36; P ˂ .001) of metformin discontinuation than for no discontinuation (control), and for 48 hours versus 24 hours of discontinuation (P = .0015). Small bowel SUV_max was lower after 24 hours (2.86 ± 0.67 vs 3.73 ± 1.08 [control]; P ˂ .001) and 48 hours (2.78 ± 0.73 vs 3.73 ± 1.08 [control]; P ˂ .001) of metformin discontinuation versus no metformin discontinuation, but not for 48 hours versus 24 hours of discontinuation (P = .57). Examination-day blood glucose levels increased after 48-hour withdrawal of metformin (8.41 mmol/L ± 2.86 vs 6.83 mmol/L ± 2.13 [control]; P = .002). Conclusion Metformin discontinuation for 48 hours prior to PET/CT was associated with lower accumulation of fluorodeoxyglucose in the bowel, compared to when there was no discontinuation (control group) or 24-hour discontinuation of metformin. © RSNA, 2018.

Patterns of recurrence in patients achieving pathologic complete response after neoadjuvant chemoradiotherapy for rectal cancer

PURPOSE

The aim of this study was to characterize the patterns of recurrence in patients achieving pathologic complete response (pCR) after neoadjuvant chemoradiotherapy (CRT) for locally advanced rectal cancer.

METHODS

Patients with locally advanced rectal cancer treated with neoadjuvant CRT and who achieved pCR from January 2004 to December 2012 were collected. The primary outcome measurement was the patterns of recurrence.

RESULTS

Among 195 patients who achieved pCR, 18 developed recurrence. Furthermore, local recurrence occurred in 1.5% of patients (3/195), while distant metastases occurred in 7.7% of patients (15/195), which included 7 lung metastases, 1 liver metastasis, and 8 metastases in other locations.

CONCLUSIONS

Our study indicated that patients achieving pCR following neoadjuvant CRT have a favorable prognosis, with distant metastases predominating in all recurrences. Among patients with distant metastases, non-liver metastases were the predominant pattern.

Diagnostic and prognostic value of preoperative 18F-fluorodeoxyglucose positron emission tomography/computed tomography for colorectal cancer: comparison with conventional computed tomography

BACKGROUND/AIMS

18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has been used for preoperative staging of colorectal cancer (CRC). However, the diagnostic accuracy of FDG-PET/CT for detection of lymph node or distant metastasis and its prognostic role have not been well established. We therefore evaluated the diagnostic and prognostic value of FDG-PET/CT in comparison with conventional CT for CRC.

METHODS

We investigated 220 patients who underwent preoperative FDG-PET/CT and CT, followed by curative surgery for CRC. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG-PET/CT and CT for detection of lymph node metastasis and distant metastasis were evaluated. In addition, we assessed the findings of FDG-PET/CT and CT according to outcomes, including cancer recurrence and cancer-related death, for evaluation of prognostic value.

RESULTS

For detection of lymph node metastasis, FDG-PET/CT had a sensitivity of 44%, a specificity of 84%, and an accuracy of 67%, compared with 59%, 65%, and 62%, respectively, for CT (P=0.029, P=0.000, and P=0.022). For distant metastasis, FDG-PET/CT had a sensitivity of 79%, a specificity of 94%, and an accuracy of 93%, compared with 79%, 87%, and 86%, respectively, for CT (P=1.000, P=0.004, and P=0.037). In addition, positive findings of lymph node metastasis and distant metastasis on FDG-PET/CT were associated significantly with cancer recurrence or cancer-related death (P=0.009, P=0.001, respectively).

CONCLUSIONS

Preoperative FDG-PET/CT had a higher specificity and accuracy compared to CT for detection of lymph node metastasis and distant metastasis of CRC. In addition, FDG-PET/CT could be a valuable prognostic tool for CRC.

Current clinical status of 18F-FLT PET or PET/CT in digestive and abdominal organ oncology

Positron emission tomography (PET) or PET/computed tomography (CT) using ¹⁸F-3'-fluoro-3'-deoxythymidine (¹⁸F-FLT) offers noninvasive assessment of cell proliferation in human cancers in vivo. The present review discusses the current status on clinical applications of ¹⁸F-FLT-PET (or PET/CT) in digestive and abdominal oncology by comparing with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG)-PET (or PET/CT). The results of this review show that although ¹⁸F-FLT uptake is lower in most cases of digestive and abdominal malignancies compared with ¹⁸F-FDG uptake, ¹⁸F-FLT-PET can be used to detect primary tumors. ¹⁸F-FLT-PET has shown greater specificity for N staging than ¹⁸F-FDG-PET which can show false-positive uptake in areas of inflammation. However, because of the high background uptake in the liver and bone marrow, it has a limited role of assessing liver and bone metastases. Instead, ¹⁸F-FLT-PET will be a powerful tool for monitoring response to treatment and provide prognostic information in digestive and abdominal oncology.

Assessment and diagnostic accuracy of lymph node status to predict stage III colon cancer using computed tomography

Background

To study different imaging criteria for prediction of lymph node metastases (Stage III disease) in colon cancer using CT.

Methods

In a retrospective setting, 483 consecutive patients with histology proven colon cancer underwent elective primary resection during 2008–2011, a cohort of 119 patients were included. Contrast enhanced CT examinations, in portal-venous phase, were reviewed with assessment of the number of lymph nodes, their anatomical distribution, size, size ratio, internal heterogeneity, presence of irregular outer border and attenuation values. Sensitivity, specificity, PPV and NPV for each studied criteria for prediction of stage III disease was calculated.

Results

According to histopathology 80 patients were stage I-II and 39 were stage III. Of the studied CT-criteria for lymph node metastases per patient, internal heterogeneity in at least one lymph node resulted in the best performance with sensitivity, specificity, PPV and NPV of 79, 84, 70 and 89%, Odds ratio (OR) 20. Presence of irregular outer border resulted in a sensitivity, specificity, PPV and NPV of 59, 81, 61 and 82%, OR 6.2. If both internal heterogeneity and/or irregular outer border was used as a criterion this resulted in a sensitivity, specificity, PPV and NPV of 85, 75, 62 and 91%, OR 16.5. None of the size criteria used were predictive for stage III disease.

Conclusions

When performing preoperative CT in patients with colon cancer, the imaging criteria that allow best prediction of stage III disease on CT are either presence of at least one lymph node with internal heterogeneity or internal heterogeneity and/or irregular outer border. These criteria have to be validated in a prospective study.

Pre-operative TNM staging of primary colorectal cancer by (18)F-FDG PET-CT or PET: a meta-analysis including 2283 patients

The aim of the present study was to perform a meta-analysis to assess the diagnostic value of fluorine-18 fluorodeoxyglucose ((18)F-FDG) PET-CT/PET in the pre-operative evaluation of TNM staging in patients with primary colorectal cancer (CRC). The Medline, Embase and Web of Knowledge were searched for studies assessing the diagnostic value of (18)F-FDG PET-CT/PET in the pre-operative evaluation of TNM staging in CRC patients. We pooled the sensitivity, specificity, positive and negative Likelihood ratio (LR+ and LR-) and Diagnostic Odds Ratio (DOR) and constructed summary receiver operating characteristic curves. A total of 28 studies including 2283 CRC patients were analyzed. The pre-operative tumor detecting rate of PET-CT was 95.35%, which was superior to CT (P < 0.05). The pooled sensitivity and specificity of pre-operative T staging by PET-CT/PET was 0.73 (95% CI: 0.65-0.81) and 0.99 (95% CI: 0.98-0.99), which the AUC and Q* were 0.96 and 0.91, respectively. Concerning pre-operative N staging, the pooled sensitivity and specificity of PET-CT/PET were 0.62 and 0.70, which the AUC and Q* were 0.76 and 0.70, respectively. As for M staging, the pooled sensitivity and specificity of PET-CT/PET were 0.91 (95% CI: 0.80-0.96) and 0.95 (95% CI: 0.91-0.98), which the AUC and Q* were 0.96 and 0.91, respectively. (18)F-FDG PET-CT/PET had good performance in the pre-operative tumor detecting rate, T staging and M staging in patients with primary CRC, which might alter the therapeutic strategy. However, the diagnostic value of (18)F-FDG PET-CT/PET in pre-operative N staging in CRC patients was not ideal.

Surgery with versus without preoperative concurrent chemoradiotherapy for mid/low rectal cancer: an interim analysis of a prospective, randomized trial

INTRODUCTION

Multimodality therapy, including preoperative chemoradiotherapy (CRT) and total mesorectal excision (TME), has effectively reduced local recurrence rates of rectal cancer over the past decade. However, the benefits and risks of the addition of neoadjuvant CRT to surgery need to be evaluated. This study was to compare the efficacy of TME with versus without preoperative concurrent chemoradiotherapy (CCRT) involving XELOX regimen (oxaliplatin plus capecitabine) in Chinese patients with stages II and III mid/low rectal adenocarcinoma.

METHODS

We randomly assigned patients to the TME group (TME without preoperative CCRT) or CCRT + TME group (TME with preoperative CCRT). The primary endpoint was disease-free survival (DFS); the secondary endpoints were overall survival (OS), local and distant recurrence, tumor response to CRT, toxicity, sphincter preservation, and surgical complications. An interim analysis of the potential inferiority of DFS in the CCRT + TME group was planned when the first 180 patients had been followed up for at least 6 months.

RESULTS

A total of 94 patients in the TME group and 90 patients in the CCRT + TME group were able to be evaluated. The 3-year DFS and OS rates were 86.3 % and 91.5 % in the whole cohort, respectively. The 3-year DFS rates of the TME and CCRT + TME groups were 85.7% and 87.9 % (P = 0.766), respectively, and the 3-year OS rates were 90.7 % and 92.3 % (P = 0.855), respectively. The functional sphincter preservation rates of the TME and CCRT + TME groups were 71.3 % and 70.0 % (P = 0.849), respectively. In the TME group, 16 (17.0 %) patients were proven to have pTNM stage I disease after surgery. In the CCRT + TME group, 32 (35.6 %) patients achieved a pathologic complete response (pCR).

CONCLUSIONS

Preliminary results indicated no significant differences in the DFS, OS, or functional sphincter preservation rates between the TME and CCRT + TME groups. However, preoperative CCRT with XELOX yielded a high pCR rate. Newer techniques are needed to improve the staging accuracy, and further investigation is warranted.

CLINICAL TRIAL REGISTRATION NUMBER

Chi CTR-TRC-08000122.

Role of fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography in gastrointestinal cancers

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has become a routine imaging modality for many malignancies and its use is currently increasing. In the present review article, we will summarize the evidence for FDG-PET/CT use in digestive cancers (excluding neuroendocrine tumours), and review the existing recommendations. While PET/CT is nowadays considered to be an important tool in the initial workup of oesophageal and anal cancers, new data are emerging regarding its use in assessing therapeutic efficacy, radiotherapy treatment planning, and detection of recurrence in case of isolated tumour marker elevation. Moreover, PET/CT may help decision making by detecting distant metastatic sites especially in potentially resectable metastatic colorectal cancer and, to a lesser extent, in localized gastric and pancreatic cancers. Finally, incidental focal colonic FDG uptakes require exploration by colonoscopy, as they are often associated with premalignant or malignant lesions.

Imaging in rectal cancer with emphasis on local staging with MRI

Imaging in rectal cancer has a vital role in staging disease, and in selecting and optimizing treatment planning. High-resolution MRI (HR-MRI) is the recommended method of first choice for local staging of rectal cancer for both primary staging and for restaging after preoperative chemoradiation (CT-RT). HR-MRI helps decide between upfront surgery and preoperative CT-RT. It provides high accuracy for prediction of circumferential resection margin at surgery, T category, and nodal status in that order. MRI also helps assess resectability after preoperative CT-RT and decide between sphincter saving or more radical surgery. Accurate technique is crucial for obtaining high-resolution images in the appropriate planes for correct staging. The phased array external coil has replaced the endorectal coil that is no longer recommended. Non-fat suppressed 2D T2-weighted (T2W) sequences in orthogonal planes to the tumor are sufficient for primary staging. Contrast-enhanced MRI is considered inappropriate for both primary staging and restaging. Diffusion-weighted sequence may be of value in restaging. Multidetector CT cannot replace MRI in local staging, but has an important role for evaluating distant metastases. Positron emission tomography-computed tomography (PET/CT) has a limited role in the initial staging of rectal cancer and is reserved for cases with resectable metastatic disease before contemplating surgery. This article briefly reviews the comprehensive role of imaging in rectal cancer, describes the role of MRI in local staging in detail, discusses the optimal MRI technique, and provides a synoptic report for both primary staging and restaging after CT-RT in routine practice.

Clinical impact of FDG-PET/CT on colorectal cancer staging and treatment strategy

FDG-PET/CT is rarely used for initial staging of patients with colorectal cancer (CRC). Surgical resection of primary tumor and isolated metastases may result in long-term survival or presumed cure, whereas disseminated disease contraindicates operation. We analyzed a retrospective material to elucidate the potential value of FDG-PET/CT for staging of CRC. Data were retrieved from 67 consecutive patients (24-84 years) with histopathologically proven CRC who had undergone FDG-PET/CT in addition to conventional imaging for initial staging. Treatment plans before and after FDG-PET/CT were compared and patients divided as follows: (A) Patients with a change in therapy following FDG-PET/CT and (B) Patients without a change following FDG-PET/CT. Sixty-two patients had colon and five had rectal cancer. Of these, 20 (30%; CI 20.2-41.7) belonged to group A, whereas 47 (70%; CI 58.3-79.8) fell in group B. In conclusion, FDG-PET/CT changed treatment plan in 30% of cases. In ⅓ of these there was either a change from intended curative to palliative therapy or vice versa, while in the remaining ⅔ the pattern was more mixed. Thus, even in a retrospective routine material there were substantial changes in management strategy following FDG-PET/CT for staging in CRC.

Evaluation of lateral pelvic nodes in patients with advanced rectal cancer

OBJECTIVE

The purpose of this article is to discuss the importance of lateral pelvic lymph node metastasis as a predictor of local recurrence and survival in patients with advanced rectal cancer.

CONCLUSION

Prediction of lateral pelvic nodal staging on MRI shows high accuracy compared with the other imaging modalities. Diffusion-weighted MRI or (18)F-FDG PET/CT may be helpful to assesses lateral pelvic lymph node metastasis.

Positron emission tomography/computed tomography in the staging of colon cancer

Purpose

Accurate preoperative staging of colon cancer is essential for providing the optimal treatment strategy and evaluating the expected prognosis. The aim of this study is to assess the value of positron emission tomography/computed tomography (PET/CT) over conventional studies in the staging of colon cancer.

Methods

A total of 266 colon cancer patients diagnosed between January 2008 and December 2010 were assessed with both PET/CT and conventional studies. Discordance with PET/CT and conventional studies were evaluated, and changes in the management strategy were assessed for each stage. Discordant findings were verified by using intraoperative examination, pathology reports, and follow-up imaging studies.

Results

Multidetector computed tomography (MDCT) and PET/CT showed similar accuracy in detecting lymph node metastasis in patients with clinical stage III (36.2% vs. 42%, P = 0.822) and stage IV (60.3% vs. 63.5%, P = 0.509) disease. PET/CT led to a change in management strategy for 1 of 40 patients (2.5%) with clinical stage I, 0 of 25 patients (0%) with stage II, 9 of 138 patients (6.5%) with stage III, and 8 of 63 patients (12.7%) with stage IV disease.

Conclusion

PET/CT changed the management plan in 6.5% of patients with clinical stage III and 12.7% of patients with clinical stage IV colon cancer. Our findings suggest that PET/CT may be considered as a routine staging tool for clinical stage III and IV colon cancers.

Positron emission tomography/computed tomography for optimized colon cancer staging and follow up

OBJECTIVES

Optimal management of colon cancer (CC) requires detailed assessment of extent of disease. This study prospectively investigates the diagnostic accuracy of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (PET/CT) for staging and detection of recurrence in primary CC.

MATERIAL AND METHODS

PET/CT for preoperative staging was performed in 66 prospectively included patients with primary CC. Diagnostic accuracy for PET/CT and CT was analyzed. In addition to routine follow up, 42 stages I-III CC patients had postoperative PET/CT examinations every 6 months for 2 years. Serological levels of tissue inhibitor of metalloproteinase-1 (TIMP-1), carcinoembryonic antigen, and liberated domain I of urokinase plasminogen activator receptor were analyzed.

RESULTS

Accuracy for tumor, nodal, and metastases staging by PET/CT were 82% (95% confidence interval [CI]: 70; 91), 66% (CI: 51; 78), and 89% (CI: 79; 96); for CT the accuracy was 77% (CI: 64; 87), 60% (CI: 46; 73), and 69% (CI: 57; 80). Cumulative relapse incidences for stages I-III CC at 6, 12, 18, and 24 months were 7.1% (CI: 0; 15); 14.3% (CI: 4; 25); 19% (CI: 7; 31), and 21.4% (CI: 9; 34). PET/CT diagnosed all relapses detected during the first 2 years. High preoperative TIMP-1 levels were associated with significant hazards toward risk of recurrence and shorter overall survival.

CONCLUSIONS

This study indicates PET/CT as a valuable tool for staging and follow up in CC. TIMP-1 provided prognostic information potentially useful in selection of patients for intensive follow up.

The role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in the primary staging of rectal cancer

Background

In this study we aimed to determine the need for ¹⁸F-flourodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in the preoperative staging of rectal carcinoma in our large patient group according to level and location of tumor.

Method

Totally, 97 patients diagnosed with primary rectal adenocarcinoma between May 2009 and July 2011 were included in the study. Preoperative staging was performed by evaluating contrast-enhanced thoracic, abdominal, and pelvic computed tomographies. After staging by conventional methods, all patients underwent an ¹⁸F-FDG PET/CT. In all cases, the relationship between ¹⁸F-FDG uptake and gender, tumor height at the anal canal, localization in the rectal wall, plasma carcinoembryonic antigen levels, histopathological tumor type, and tumor stage were examined.

Results

While the ceCT was normal in 4 (4%) patients, it was positive for the rectum in 93 (95%), pelvic lymph nodes in 22 (22%), and distant metastases in 14 (14%) (liver (8), lung (8), bone (2), distant lymph nodes (6), and uterus (1)). Using computed tomography, disease stages were determined as stage 0, 1, 2, 3, and 4 in 4, 8, 48, 23, and 14 patients, respectively; ¹⁸F-FDG PET/CT was normal in two (2%) patients. The mean SUVmax of FDG-positive rectal tumors was calculated as 17.31 ± 9.37. Additionally, 18F-FDG uptake was seen in pelvic lymph nodes in 15 (15%) patients and in distant organs in 24 (24%) patients (liver (9), lung (12), bone (5), distant lymph nodes (11), uterus (1), and sigmoid colon (1)). According to an ¹⁸F-FDG PET/CT, 2, 7, 47, 20, and 21 patients were staged as stage 0, 1, 2, 3, and 4, respectively. In 14 patients (14.4%), the stage of the disease was either changed, and there was a need to make adjustments to the patient’s treatment strategy (n = 10), or the type of operation was changed (n = 4). In seven patients (0.7%), findings from ¹⁸F-FDG PET/CT images did not require any changes of the treatment plan.

Conclusion

F-FDG PET/CT provides new findings in addition to conventional techniques in the staging of primary rectal cancer. These findings could change the patients’ treatment strategies.