Distribution of FDG-avid nodes in esophageal cancer: implications for radiotherapy target delineation

The Role of MRI and PET/CT in Radiotherapy Target Volume Determination in Gastrointestinal Cancers-Review of the Literature

Positron emission tomography with computed tomography (PET/CT) and magnetic resonance imaging (MRI) could improve accuracy in target volume determination for gastrointestinal cancers. A systematic search of the PubMed database was performed, focusing on studies published within the last 20 years. Articles were considered eligible for the review if they included patients with anal canal, esophageal, rectal or pancreatic cancer, as well as PET/CT or MRI for radiotherapy treatment planning, and if they reported interobserver variability or changes in treatment planning volume due to different imaging modalities or correlation between the imaging modality and histopathologic specimen. The search of the literature retrieved 1396 articles. We retrieved six articles from an additional search of the reference lists of related articles. Forty-one studies were included in the final review. PET/CT seems indispensable for target volume determination of pathological lymph nodes in esophageal and anal canal cancer. MRI seems appropriate for the delineation of primary tumors in the pelvis as rectal and anal canal cancer. Delineation of the target volumes for radiotherapy of pancreatic cancer remains challenging, and additional studies are needed.

18F-FDG-PET/CT Imaging for Gastrointestinal Malignancies

Gastrointestinal malignancies encompass a variety of primary tumor sites, each with different staging criteria and treatment approaches. In this review we discuss technical aspects of 18F-FDG-PET/CT scanning to optimize information from both the PET and computed tomography components. Specific applications for 18F-FDG-PET/CT are summarized for initial staging and follow-up of the major disease sites, including esophagus, stomach, hepatobiliary system, pancreas, colon, rectum, and anus.

Impact of 18F-FDG-PET/CT on the identification of regional lymph node metastases and delineation of the primary tumor in esophageal squamous cell carcinoma patients

Purpose

In patients undergoing chemoradiation for esophageal squamous cell carcinoma (ESCC), the extent of elective nodal irradiation (ENI) is still discussed controversially. This study aimed to analyze patterns of lymph node metastases and their correlation with the primary tumor using ¹⁸F‑fludeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scans.

Methods

102 ESCC patients with pre-treatment FDG-PET/CT scans were evaluated retrospectively. After exclusion of patients with low FDG uptake and patients without FDG-PET-positive lymph node metastases (LNM), 76 patients were included in the final analysis. All LNM were assigned to 16 pre-defined anatomical regions and classified according to their position relative to the primary tumor (above, at the same height, or below the primary tumor). In addition, the longitudinal distance to the primary tumor was measured for all LNM above or below the primary tumor. The craniocaudal extent (i.e., length) of the primary tumor was measured using FDG-PET imaging (L_PET) and also based on all other available clinical and imaging data (endoscopy, computed tomography, biopsy results) except FDG-PET (L_CT/EUS).

Results

Significantly more LNM were identified with ¹⁸F‑FDG-PET/CT (177 LNM) compared to CT alone (131 LNM, p < 0.001). The most common sites of LNM were paraesophageal (63% of patients, 37% of LNM) and paratracheal (33% of patients, 20% of LNM), while less than 5% of patients had supraclavicular, subaortic, diaphragmatic, or hilar LNM. With regard to the primary tumor, 51% of LNM were at the same height, while 25% and 24% of lymph node metastases were above and below the primary tumor, respectively. For thirty-three LNM (19%), the distance to the primary tumor was larger than 4 cm. No significant difference was seen between L_CT/EUS (median 6 cm) and L_PET (median 6 cm, p = 0.846)

Conclusion

¹⁸F‑FDG-PET can help to identify subclinical lymph node metastases which are located outside of recommended radiation fields. PET-based involved-field irradiation might be the ideal compromise between small treatment volumes and decreasing the risk of undertreatment of subclinical metastatic lymph nodes and should be further evaluated.

Esophageal cancer lymph node metastasis-associated gene signature optimizes overall survival prediction of esophageal cancer

Esophageal cancer (EC) is characteristic of early regional lymph node metastasis (LNM) and most patients with metastasis have a poor prognosis. However, the current diagnostic techniques do not enable precise differentiation of EC LNM, prognostic stratification, and individual survival estimation. To identify potential molecular biomarkers for EC patients with LNM, we explored differently expressed genes in The Cancer Genome Atlas database between 77 non-LNM cases and 88 LNM cases by limma package R. Then, according to univariate and multivariate Cox regression analyses, we constructed an 8-messenger RNA (mRNA) prognostic signature model, which could predict the outcome in a more exact way. The area under the curve of the risk score is significantly higher than other clinical information, indicating that the 8-mRNA-based risk score is a good indicator for prognosis. Then, combined with other individual risk factors, such as age, sex, T stage, M stage, etc, we could precisely calculate the individual 1-, 3-, and 5-year survival rates. The Gene Set Enrichment Analysis, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes analysis indicate that the risk model is mainly associated with cancer-related pathways, such as cell division, cellular meiosis, and cell cycle regulation. In summary, the 8-mRNA-based risk score model that we developed successfully predicts the survival of EC. It is independent of clinical information and performing better than other clinical information for prognosis.

Efficacy comparison of transcervical video-assisted mediastinoscopic lymphadenectomy combined with left transthoracic esophagectomy versus right transthoracic esophagectomy for esophageal cancer treatment

Background

This study aimed to propose a new surgical strategy, i.e., the transcervical video-assisted mediastinoscopic lymphadenectomy (VAMLA) with esophagectomy via the left transthoracic approach for patients with esophageal cancer (EC), and to compare the outcomes with those of esophagectomy via the right thoracic approach.

Methods

From December 2014 to March 2016, 49 cases were enrolled in this non-randomized concurrent control study. Twenty-eight patients with EC who underwent transcervical VAMLA with esophagectomy via the left transthoracic approach were assigned into the study group, while 21 EC patients undergoing esophagectomy via the right transthoracic approach during the same period were enrolled into the control group. Operative outcomes including operative time, the numbers of removed lymph nodes, intraoperative blood loss, the length of hospital stay, and postoperative complications in both groups were evaluated and compared.

Results

There were no significant differences in the baseline profiles between the two groups, and all patients in the two groups successfully underwent the surgery. There was a significant difference between transcervical VAMLA with esophagectomy via the left thoracic approach and esophagectomy via the right thoracic approach with regard to the number of all dissected lymph nodes [(29.0 ± 8.7) vs. (17.8 ± 8.1), p < 0.05], dissected superior mediastinal lymph nodes [(11.2 ± 5.0) vs. (3.7 ± 2.9), p < 0.05], and dissected in the recurrent laryngeal nerve lymph nodes [(5.6 ± 3.5) vs. (2.3 ± 2.1), p < 0.05]. No significant differences were observed in the operative time, intraoperative blood loss, length of postoperative hospital stay, number of dissected abdominal lymph nodes, postoperative pulmonary complications (pneumonia and atelectasis), anastomotic fistula, chylothorax, and vocal cord paralysis (p > 0.05).

Conclusion

Transcervical VAMLA combined with esophagectomy via the left thoracic approach appears technically feasible and safe and shows advantages in the number of dissected superior mediastinal lymph nodes, suggesting that it may serve as a new treatment option for patients with esophageal carcinoma.