Residual Tumor After Neoadjuvant Chemoradiation Outside the Radiation Therapy Target Volume: A New Prognostic Factor for Survival in Esophageal Cancer

The Key Clinical Questions of Neoadjuvant Chemoradiotherapy for Resectable Esophageal Cancer—A Review

Over 50% of individuals with esophageal cancer (EC) present with advanced stages of the disease; therefore, their outcome following surgery alone is poor, with only 25%–36% being alive 5 years post-surgery. Based on the evidence that the CROSS and NEOCRTEC5010 trials provided, neoadjuvant chemoradiotherapy (nCRT) is now the standard therapy for patients with locally advanced EC. However, there are still many concerning clinical questions that remain controversial such as radiation dose, appropriate patient selection, the design of the radiation field, the time interval between chemoradiotherapy (CRT) and surgery, and esophageal retention. With immune checkpoint inhibitors (ICIs) rapidly becoming a mainstay of cancer therapy, along with radiation, chemotherapy, and surgery, the combination mode of immunotherapy is also becoming a hot topic of discussion. Here, we try to provide constructive suggestions to answer the perplexing problems and clinical concerns for the progress of nCRT for EC in the future.

Comparable Clinical Outcome Using Small or Large Gross Tumor Volume-to-Clinical Target Volume Margin Expansion in Neoadjuvant Chemoradiotherapy for Esophageal Squamous Cell Carcinoma

The purpose of this study was to evaluate the feasibility of small primary gross tumor volume (GTV)-to-clinical target volume (CTV) margin expansion in neoadjuvant chemoradiation for esophageal squamous cell carcinoma. Medical records of 139 patients with locally advanced esophageal squamous cell carcinoma who underwent neoadjuvant chemoradiation and radical esophagectomy were retrospectively reviewed. Patients treated with longitudinal primary GTV-to-CTV margin expansion of 2 cm and no additional expansion of the CTV through the esophagus were classified into a small margin (SM) group (37 patients). The remaining 102 patients were classified as a large margin (LM) group. Patterns of recurrence including local and out-field regional recurrence rates were compared between the two groups. Clinical outcomes including rates of local control, regional control, failure-free survival, and overall survival were also compared. More patients in the SM group underwent paclitaxel + carboplatin, Mckeown esophagectomy, and intensity-modulated radiation therapy than in the LM group. With a median follow-up of 25.6 months, there was no significant difference in the crude rate of local recurrence (10.8% vs. 6.9%, P=0.694), out-field regional recurrence (27.0% vs. 19.6%, P=0.480), or out-field regional recurrence without in-field recurrence (10.8% vs. 12.7%, P=0.988) between the two groups. There was no significant difference in failure-free survival (5-year, 34.4% vs. 30.6%, P=0.652) or overall survival (44.1% vs. 38.5%, P=1.000), either. Esophageal fistula was not reported in the SM group (0.0% vs. 7.9%, P=0.176). In conclusion, a radiation field with 2 cm of longitudinal primary GTV-to-CTV was feasible in the neoadjuvant setting for esophageal squamous cell carcinoma treatment.

Inter-Observer and Intra-Observer Variability in Gross Tumor Volume Delineation of Primary Esophageal Carcinomas Based on Different Combinations of Diagnostic Multimodal Images

Background and Purpose

This study aimed to investigate inter-/intra-observer delineation variability in GTVs of primary esophageal carcinomas (ECs) based on planning CT with reference to different combinations of diagnostic multimodal images from endoscopy/EUS, esophagography and FDG-PET/CT.

Materials and Methods

Fifty patients with pathologically proven thoracic EC who underwent diagnostic multimodal images before concurrent chemoradiotherapy were enrolled. Five radiation oncologist independently delineated the GTVs based on planning CT only (GTV_C), CT combined with endoscopy/EUS (GTV_CE), CT combined with endoscopy/EUS and esophagography (X-ray) (GTV_CEX), and CT combined with endoscopy/EUS, esophagography, and FDG-PET/CT (GTV_CEXP). The intra-/inter-observer variability in the volume, longitudinal length, generalized CI (CI_gen), and position of the GTVs were assessed.

Results

The intra-/inter-observer variability in the volume and longitudinal length of the GTVs showed no significant differences (p>0.05). The mean intra-observer CI_gen values for all observers was 0.73 ± 0.15. The mean inter-observer CI_gen values for the four multimodal image combinations was 0.67 ± 0.11. The inter-observer CI_gen for the four combined images was the largest, showing significant differences with those for the other three combinations. The intra-observer CI_gen among different observers and inter-observer CI_gen among different combinations of multimodal images showed significant differences (p<0.001). The intra-observer CI_gen for the senior radiotherapists was larger than that for the junior radiotherapists (p<0.001).

Conclusion

For radiation oncologists with advanced medical imaging training and clinical experience, using diagnostic multimodal images from endoscopy/EUS, esophagography, and FDG-PET/CT could reduce the intra-/inter-observer variability and increase the accuracy of target delineation in primary esophageal carcinomas.

Prognostic value of visual residual tumour cells (VRTC) for patients with esophageal squamous cell carcinomas after neoadjuvant therapy followed by surgery

Background

We assessed visual residual tumour cells (VRTC) with both Becker’s tumour regression grading (TRG) system and Japanese TRG system in esophageal squamous cell carcinoma (ESCC) patients treated with neoadjuvant therapy followed by surgery.

Methods

We compared Becker system and Japanese system in 175 ESCC patients treated between 2009 and 2015.

Results

According to Becker system, the 5-year DFS/DSS rates were 70.0%/89.3, 53.8%/56.7, 43.0%/49.0, and 42.4%/39.1% for TRG 1a (VRTC 0), TRG 1b (1–10%), TRG 2 (11–50%), and TRG 3 (> 50%). According to Japanese system, the rates were 38.8%/34.1, 49.5%/58.7, 50.2%/49.0 and 70.0%/89.3% for Grade 0-1a (VRTC> 66.6%), Grade 1b (33.3–66.6%), Grade 2 (1–33.3%) and Grade 3 (0). TRG according to two systems significantly discriminate the patients’ prognosis. TRG according to Becker system (HR 2.662, 95% CI 1.151–6.157), and lymph node metastasis (HR 2.567, 95% CI 1.442–4.570) were independent parameters of DSS.

Conclusions

Both Becker and Japanese system had their advantage in risk stratification of these ESCC patients. It was speculated that dividing 1–10% VRTC into a group might contribute to independently prognostic significance of Becker’s TRG system. Therefore, in addition to TRG of different systems, the percentage of VRTC might be recommended in the pathologic report, which could make the results more comparable among different researches, and more understandable for oncologists in the clinical practice.

Proposal for the delineation of neoadjuvant target volumes in oesophageal cancer

PURPOSE

To define instructions for delineation of target volumes in the neoadjuvant setting in oesophageal cancer.

MATERIALS AND METHODS

Radiation oncologists of five European centres participated in the following consensus process: [1] revision of published (MEDLINE) and national/institutional delineation guidelines; [2] first delineation round of five cases (patient 1-5) according to national/institutional guidelines; [3] consensus meeting to discuss the results of step 1 and 2, followed by a target volume delineation proposal; [4] circulation of proposed instructions for target volume delineation and atlas for feedback; [5] second delineation round of five new cases (patient 6-10) to peer review and validate (two additional centres) the agreed delineation guidelines and atlas; [6] final consensus on the delineation guidelines depicted in an atlas. Target volumes of the delineation rounds were compared between centres by Dice similarity coefficient (DSC) and maximum/mean undirected Hausdorff distances (H_max/H_mean).

RESULTS

In the first delineation round, the consistency between centres was moderate (CTVtotal: DSC = 0.59-0.88; H_mean = 0.2-0.4 cm). Delineations in the second round were much more consistent. Lowest variability was obtained between centres participating in the consensus meeting (CTVtotal: DSC: p < 0.050 between rounds for patients 6/7/8/10; H_mean: p < 0.050 for patients 7/8/10), compared to validation centres (CTVtotal: DSC: p < 0.050 between validation and consensus meeting centres for patients 6/7/8; H_mean: p < 0.050 for patients 7/10). A proposal for delineation of target volumes and an atlas were generated.

CONCLUSION

We proposed instructions for target volume delineation and an atlas for the neoadjuvant radiation treatment in oesophageal cancer. These will enable a more uniform delineation of patients in clinical practice and clinical trials.

Locoregional Residual Esophageal Cancer after Neo-adjuvant Chemoradiotherapy and Surgery Regarding Anatomic Site and Radiation Target Fields: A Histopathologic Evaluation Study

OBJECTIVE

Neoadjuvant chemoradiotherapy followed by surgery establishes a considerable pathologic complete response (pCR) in EC. The aim was to determine site of residual tumor and its prognostic impact.

SUMMARY BACKGROUND DATA

High rates of residual tumor in the adventitial region even inside the radiation fields will influence current decision-making.

METHODS

We evaluated resection specimens with marked target fields from 151 consecutive EC patients treated with carboplatin/paclitaxel and 41.4Gy between 2009 and 2018.

RESULTS

In radically resected (R0) specimens 19.8% (27/136) had a pCR (ypT0N0) and 14% nearly no response (tumor regression grade: tumor regression grade 4-5). Residual tumor commonly extended in or restricted to the adventitia (43.1%; 47/109), whereas 7.3% was in the mucosa (ypT1a), 16.5% in the submucosa (ypT1b) and 6.4% only in lymph nodes (ypT0N+). Macroscopic residues in R0-specimens of partial responders (tumor regression grade 2-3: N = 90) were found in- and outside the gross tumor volume (GTV) in 33.3% and 8.9%, and only microscopic in- and outside the clinical target volume in 58.9% and 1.1%, respectively. Residual nodal disease was observed proximally and distally to the clinical target volume in 2 and 5 patients, respectively. Disease Free Survival decreased significantly if macroscopic tumor was outside the GTV and in ypT2-4aN+.

CONCLUSIONS

After neoadjuvant chemoradiotherapy, pCR and ypT1aN0 were seen in a limited number of R0 resected specimens (19.8% and 7.3%, respectively), whereas 6.4% had only nodal disease (yT0N+). Disease Free Survival decreased significantly if macroscopic residue was outside the GTV and in responders with only nodal disease. Therefore, we should be cautious in applying wait and see strategies.

Comparison of nodal irradiation dose using radiotherapy for patients with thoracic esophageal cancer

The present study aimed to compare incidental nodal irradiation (INI) doses using volume-modulated arc therapy (VMAT), 5-field intensity-modulated radiotherapy (5F-IMRT) and 3D-conformal radiotherapy (3D-CRT) treatment plans for patients with thoracic esophageal cancer (EC). A total of 15 patients with thoracic EC were selected for participation between October 2016 and July 2017 at the Hangzhou Cancer Hospital. Regional lymph nodal stations were contoured according to 3D CT-based images of the Japan Esophageal Society Guidelines. All patients were treated with 60 Gy using VMAT, 5F-IMRT and 3D-CRT plans. Dose-volume histograms of planning target volume (PTV), lung, heart, spinal cord and incidental nodal irradiation were compared between the three plans. 5F-IMRT was superior in PTV_V95% (the volume of the PTV receiving 95% of the prescription dose, P=0.003) and the VMAT plan was best in terms of conformal index (P=0.005). V20 and V30 were reduced by 10.7-22.6% (P=0.002) and 12.8-21% (P=0.026), respectively, in normal lung tissue using the VMAT plan. 5F-IMRT demonstrated the lowest maximum dose (Dmax) for the spinal cord (P=0.037). For the INI, 3D-CRT exhibited the highest equivalent uniform dose (EUD) values for 106pre (P=0.014) and 106tb-L (P=0.03) in upper-thoracic EC. The mean EUD of all lymph nodal regions in middle-thoracic EC were >40 Gy in VMAT and 5F-IMRT plans; the VMAT plan had higher EUD values in lower-thoracic EC compared with 5F-IMRT, 3D-CRT plans for INI. VMAT were comparable to the 5F-IMRT plan with respect to dosimetric characteristics for planning and INI doses to thoracic nodal levels NO 105-112 are considerable for thoracic EC.

Microscopic tumor spread beyond (echo)endoscopically determined tumor borders in esophageal cancer

OBJECTIVE

The microscopic tumor spread (MS) beyond the macroscopic tumor borders of esophageal tumors is crucial for determining the clinical target volume (CTV) in radiotherapy. The question arises whether current voluminous CTV margins of 3-5 cm around the macroscopic gross tumor volume (GTV) to account for MS are still accurate when fiducial markers are used for GTV determination. We aimed to pathologically validate the use of fiducial markers placed on the (echo)endoscopically determined tumor border (EDTB) as a surrogate for macroscopic tumor borders and to analyse the MS beyond EDTBs.

METHODS

Thirty-three consecutive esophageal cancer patients treated with neo-adjuvant chemoradiotherapy after (echo)endoscopic fiducial marker implantation at cranial and caudal EDTB were included in this study. Fiducial marker positions were detected in the surgical specimens under CT guidance and demarcated with beads, and subsequently analysed for macroscopic tumor spread and MS beyond the demarcations. A logistic regression analysis was performed to determine predicting factors for MS beyond EDTB.

RESULTS

A total of 60 EDTBs were examined in 32 patients. In 50% of patients no or only partial regression of tumor in response to therapy (≥Mandard 3) or higher was seen (i.e., residual tumor group) and included for MS analysis. None had macroscopic tumor spread beyond EDTBs. In the residual tumor group, only 20 and 21% of the cranial and caudal EDTBs were crossed with a maximum of 9 mm and 16 mm MS, respectively. This MS was corrected for each individual determined contraction rate (mean: 93%). Presence of MS beyond EDTB was significantly associated with initial tumor length (p = 0.028).

CONCLUSION

Our results validate the use of fiducial markers on EDTB as a surrogate for macroscopic tumor and indicate that CTV margins around the GTV to compensate for MS along the esophageal wall can be limited to 1-1.5 cm, when the GTV is determined with fiducial markers.

Reliability of clinical nodal status regarding response to neoadjuvant chemoradiotherapy compared with surgery alone and prognosis in esophageal cancer patients

Background: Clinical nodal (cN) staging is a key element in treatment decisions in patients with esophageal cancer (EC). The reliability of cN status regarding the effect on response and survival after neoadjuvant chemoradiotherapy (nCRT) with esophagectomy was evaluated in determining the up- and downstaged pathological nodal (pN) status after surgery alone. Material and methods: From a prospective database, we included all 395 EC patients who had surgery with curative intent with or without nCRT between 2000 and 2015. All patients were staged by a standard pretreatment protocol: 16-64 mdCT, 18 F-FDG-PET or 18 F-FDG-PET/CT and EUS ± FNA. After propensity score matching on baseline clinical tumor and nodal (cT/N) stage and histopathology, a surgery-alone and nCRT group (each N = 135) were formed. Clinical and pathological N stage was scored as equal (cN = pN), downstaged (cN > pN) or upstaged (cN < pN). Prognostic impact on disease free survival (DFS) was assessed with multivariable Cox regression analysis (factors with p value <.1 on univariable analysis). Results: The surgery-alone and nCRT group did not differ in cT/N status. Pathologic examination revealed equal staging (32 vs. 27%), nodal up (43 vs. 16%) and downstaging (25 vs. 56%), respectively (p < .001). Nodal up-staging was common in cT3-4a tumors and adenocarcinomas in the surgery-alone group, while nodal downstaging was found in half of cT1-2 and cT3-4 regardless of tumortype after nCRT. Prognostic factors for DFS were pN (p = .002) and lymph-angioinvasion (p = .016) in surgery-alone, and upper abdominal cN metastases (p = .012) and lymph node ratio (p = .034) in the nCRT group. Conclusions: Despite modern staging methods, correct cN staging remains difficult in EC. Nodal overstaging (cN > pN) occurred more often than understaging impeding an adequate assessment of pathologic complete response and prognosis after nCRT.

Impact of Age and Comorbidity on Choice and Outcome of Two Different Treatment Options for Patients with Potentially Curable Esophageal Cancer

Purpose

This study was designed to assess the impact of age and comorbidity on choice and outcome of definitive chemoradiotherapy (dCRT) or neoadjuvant chemoradiotherapy plus surgery.

Methods

In this population-based study, all patients with potentially curable EC (cT1N+/cT2-3, TX, any cN, cM0) diagnosed in the South East of the Netherlands between 2004 and 2014 were included. Kaplan–Meier method with log-rank tests and multivariable Cox regression analysis were used to compare overall survival (OS).

Results

A total of 702 patients was included. Age ≥ 75 years and multiple comorbidities were associated with a higher probability for dCRT (odds ratio [OR] 8.58; 95% confidence interval [CI] 4.72–15.58; and OR 3.09; 95% CI 1.93–4.93). The strongest associations were found for the combination of hypertension plus diabetes (OR 3.80; 95% CI 1.97–7.32) and the combination of cardiovascular with pulmonary comorbidity (OR 3.18; 95% CI 1.57–6.46). Patients with EC who underwent dCRT had a poorer prognosis than those who underwent nCRT plus surgery, irrespective of age, number, and type of comorbidities. In contrast, for patients with squamous cell carcinoma with ≥ 2 comorbidities or age ≥ 75 years, OS was comparable between both groups (hazard ratio [HR] 1.52; 95% CI 0.78–2.97; and HR 0.73; 95% CI 0.13–4.14).

Conclusions

Histological tumor type should be acknowledged in treatment choices for patients with esophageal cancer. Neoadjuvant chemoradiotherapy plus surgery should basically be advised as treatment of choice for operable esophageal adenocarcinoma patients. For patients with esophageal squamous cell carcinoma with ≥ 2 comorbidities or age ≥ 75 years, dCRT may be the preferred strategy.

Management of Patients With Adenocarcinoma or Squamous Cancer of the Esophagus

Esophageal cancer is characterized by early and frequent metastasis. Surgery is the primary treatment for early-stage disease, whereas patients with patients with locally advanced disease receive perioperative chemotherapy or chemoradiotherapy. Squamous cancers can be treated with primary chemoradiotherapy without surgery, depending on their response to therapy and patient tolerance for subsequent surgery. Chemotherapy with a fluorinated pyrimidine and a platinum agent, followed by later treatment with taxanes and irinotecan, provides some benefit. Agents that inhibit the erb-b2 receptor tyrosine kinase 2 (ERBB2 or HER2), or vascular endothelial growth factor, including trastuzumab, ramucirumab, and apatinib, increase response and survival times. Esophageal adenocarcinomas have mutations in tumor protein p53 and mutations that activate receptor-associated tyrosine kinase, vascular endothelial growth factor, and cell cycle pathways, whereas esophageal squamous tumors have a distinct set of mutations. Esophageal cancers develop systems to evade anti-tumor immune responses, but studies are needed to determine how immune checkpoint modification contributes to esophageal tumor development.

Radiation to the Gastric Fundus Increases the Risk of Anastomotic Leakage After Esophagectomy

BACKGROUND

Concerns have been raised regarding the toxicity of neoadjuvant chemoradiotherapy (nCRT) for esophageal cancer that could contribute to an increased risk of postoperative complications. The aim of this study was to determine the influence of the radiation dose to the gastric fundus on the risk of postoperative anastomotic leakage in patients undergoing nCRT followed by transthoracic esophagectomy.

METHODS

Between January 2012 and July 2015, 97 consecutive patients who underwent nCRT followed by transthoracic esophagectomy were included in this single-center cohort study. The gastric fundus was contoured on the pretreatment planning computed tomography. Within this contour, dose-volume histogram variables were calculated, and logistic regression analysis was used to determine their influence on the risk of anastomotic leakage.

RESULTS

In 25 of 97 patients (26%) anastomotic leakage occurred. The mean radiation dose to the gastric fundus was significantly higher in patients with than without leakage (median 35.6 Gy versus 24.9 Gy, respectively, p = 0.047). A mean dose more than versus less than 31.4 Gy was associated with leakage rates of 43% versus 15%, respectively. Adjusted for tumor location, clinical T stage, and radiation method, the mean radiation dose to the gastric fundus remained significantly and independently associated with an increased risk of anastomotic leakage (adjusted odds ratio 1.05 per 1-Gy increase, 95% confidence interval: 1.002 to 1.10, p = 0.043).

CONCLUSIONS

Efforts should be made to minimize the radiation dose to the gastric fundus when planning nCRT for esophageal cancer, because higher dose levels to the gastric fundus are associated with an increased risk of anastomotic leakage after subsequent transthoracic esophagectomy and cervical anastomosis.

Radiation field size and dose determine oncologic outcome in esophageal cancer

Background

Locoregional recurrence is a major problem in esophageal cancer patients treated with definitive concomitant chemoradiotherapy. Approximately half of the patients fail locoregionally. We analyzed the impact of enlarged radiation field size and higher radiation dose incorporated to chemoradiotherapy on oncologic outcome.

Methods

Seventy-four consecutive patients with histologically proven nonmetastatic squamous or adenocarcinoma of the esophagus were included in this retrospective analysis. All patients were locally advanced cT3–T4 and/or cN0-1. Treatment consisted of either definitive concomitant chemoradiotherapy (Def-CRT) (n = 49, 66 %) or preoperative concomitant chemoradiotherapy (Pre-CRT) followed by surgical resection (n = 25, 34 %). Patients were treated with longer radiation fields. Clinical target volume (CTV) was obtained by giving 8–10 cm margins to the craniocaudal borders of gross tumor volume (GTV) instead of 4–5 cm globally accepted margins, and some patients in Def-CRT group received radiation doses higher than 50 Gy.

Results

Isolated locoregional recurrences were observed in 9 out of 49 patients (18 %) in the Def-CRT group and in 1 out of 25 patients (3.8 %) in the Pre-CRT group (p = 0.15). The 5-year survival rate was 59 % in the Def-CRT group and 50 % in the Pre-CRT group (p = 0.72). Radiation dose was important in the Def-CRT group. Patients treated with >50 Gy (11 out of 49 patients) had better survival with respect to patients treated with 50 Gy (38 out of 49 patients). Five-year survivals were 91 and 50 %, respectively (p = 0.013).

Conclusions

Radiation treatment planning by enlarged radiation fields in esophageal cancer decreases locoregional recurrences considerably with respect to the results reported in the literature by standard radiation fields (18 vs >50 %). Radiation dose is as important as radiation field size; patients in the Def-CRT group treated with ≥50 Gy had better survival in comparison to patients treated with 50 Gy.

Predicting Response to Neoadjuvant Chemoradiotherapy in Esophageal Cancer with Textural Features Derived from Pretreatment 18F-FDG PET/CT Imaging

Adequate prediction of tumor response to neoadjuvant chemoradiotherapy (nCRT) in esophageal cancer (EC) patients is important in a more personalized treatment. The current best clinical method to predict pathologic complete response is SUV_max in ¹⁸F-FDG PET/CT imaging. To improve the prediction of response, we constructed a model to predict complete response to nCRT in EC based on pretreatment clinical parameters and ¹⁸F-FDG PET/CT-derived textural features. Methods: From a prospectively maintained single-institution database, we reviewed 97 consecutive patients with locally advanced EC and a pretreatment ¹⁸F-FDG PET/CT scan between 2009 and 2015. All patients were treated with nCRT (carboplatin/paclitaxel/41.4 Gy) followed by esophagectomy. We analyzed clinical, geometric, and pretreatment textural features extracted from both ¹⁸F-FDG PET and CT. The current most accurate prediction model with SUV_max as a predictor variable was compared with 6 different response prediction models constructed using least absolute shrinkage and selection operator regularized logistic regression. Internal validation was performed to estimate the model's performances. Pathologic response was defined as complete versus incomplete response (Mandard tumor regression grade system 1 vs. 2-5). Results: Pathologic examination revealed 19 (19.6%) complete and 78 (80.4%) incomplete responders. Least absolute shrinkage and selection operator regularization selected the clinical parameters: histologic type and clinical T stage, the ¹⁸F-FDG PET-derived textural feature long run low gray level emphasis, and the CT-derived textural feature run percentage. Introducing these variables to a logistic regression analysis showed areas under the receiver-operating-characteristic curve (AUCs) of 0.78 compared with 0.58 in the SUV_max model. The discrimination slopes were 0.17 compared with 0.01, respectively. After internal validation, the AUCs decreased to 0.74 and 0.54, respectively. Conclusion: The predictive values of the constructed models were superior to the standard method (SUV_max). These results can be considered as an initial step in predicting tumor response to nCRT in locally advanced EC. Further research in refining the predictive value of these models is needed to justify omission of surgery.

Superiority of Deformable Image Co-registration in the Integration of Diagnostic Positron Emission Tomography-Computed Tomography to the Radiotherapy Treatment Planning Pathway for Oesophageal Carcinoma

AIMS

To investigate the use of image co-registration in incorporating diagnostic positron emission tomography-computed tomography (PET-CT) directly into the radiotherapy treatment planning pathway, and to describe the pattern of local recurrence relative to the PET-avid volume.

MATERIALS AND METHODS

Fourteen patients were retrospectively identified, six of whom had local recurrence. The accuracy of deformable image registration (DIR) and rigid registration of the diagnostic PET-CT and recurrence CT, to the planning CT, were quantitatively assessed by comparing co-registration of oesophagus, trachea and aorta contours. DIR was used to examine the correlation between PET-avid volumes, dosimetry and site of recurrence.

RESULTS

Positional metrics including the dice similarity coefficient (DSC) and conformity index (CI), showed DIR to be superior to rigid registration in the co-registration of diagnostic and recurrence imaging to the planning CT. For diagnostic PET-CT, DIR was superior to rigid registration in the transfer of oesophagus (DSC=0.75 versus 0.65, P<0.009 and CI=0.59 versus 0.48, P<0.003), trachea (DSC=0.88 versus 0.65, P<0.004 and CI=0.78 versus 0.51, P<0.0001) and aorta structures (DSC=0.93 versus 0.86, P<0.006 and CI=0.86 versus 0.76, P<0.006). For recurrence imaging, DIR was superior to rigid registration in the transfer of trachea (DSC=0.91 versus 0.66, P<0.03 and CI=0.83 versus 0.51, P<0.02) and oesophagus structures (DSC=0.74 versus 0.51, P<0.004 and CI=0.61 versus 0.37, P<0.006) with a non-significant trend for the aorta (DSC=0.91 versus 0.75, P<0.08 and CI=0.83 versus 0.63, P<0.06) structure. A mean inclusivity index of 0.93 (range 0.79-1) showed that the relapse volume was within the planning target volume (PTVPET-CT); all relapses occurred within the high dose region.

CONCLUSION

DIR is superior to rigid registration in the co-registration of PET-CT and recurrence CT to the planning CT, and can be considered in the direct integration of PET-CT to the treatment planning process. Local recurrences occur within the PTVPET-CT, suggesting that this is a suitable target for dose-escalation strategies.

Prognostic Value of the Circumferential Resection Margin in Esophageal Cancer Patients After Neoadjuvant Chemoradiotherapy

Background

Circumferential resection margins (CRM) for esophageal cancer (EC), defined by the College of American Pathologists (CAP; >0 mm) or the Royal College of Pathologists (RCP; >1 mm) as tumor-free (R0), are based on a surgery-alone approach. We evaluated the usefulness of both definitions in current practice with neoadjuvant chemoradiotherapy (nCRT).

Methods

CRMs were measured in 209 patients (104 with nCRT) with locally advanced EC after transthoracic esophagectomy. Local recurrence and cancer related death were scored as events. Patients were followed for at least 2 years or until death. Prognostic factors (P < 0.1 in univariate analyses) for 2-year disease-free survival (DFS) and local recurrence-free survival (LRFS) were incorporated in multivariate Cox regression analyses. Both CRM measurements were analyzed separately and prognostic cutoff values (0–1.0 mm) were assessed in both groups.

Results

Independent prognostic factors (P < 0.05) for 2-year DFS were tumor length, lymph node ratio, angioinvasion, and CAP R0 in the surgery-alone group and pN stage (P < 0.01) in the nCRT group. Prognostic factors (P < 0.05) for 2-year LRFS were CAP, lymph node ratio, and tumor length in the surgery-alone group, and CAP and grade in the nCRT group. Optimal CRM cutoff values between 0.0 and 0.2 mm were prognostic for 2-year DFS in the surgery-alone and at 0.3 mm for the nCRT group.

Conclusions

nCRT affected the CRM cutoff values. After nCRT, the CRM R0 according to the CAP was only prognostic for 2-year LRFS. However, in the surgery-alone group, it was prognostic for both the 2-year DFS and LRFS.

Expert Consensus Contouring Guidelines for Intensity Modulated Radiation Therapy in Esophageal and Gastroesophageal Junction Cancer

PURPOSE/OBJECTIVE(S)

Current guidelines for esophageal cancer contouring are derived from traditional 2-dimensional fields based on bony landmarks, and they do not provide sufficient anatomic detail to ensure consistent contouring for more conformal radiation therapy techniques such as intensity modulated radiation therapy (IMRT). Therefore, we convened an expert panel with the specific aim to derive contouring guidelines and generate an atlas for the clinical target volume (CTV) in esophageal or gastroesophageal junction (GEJ) cancer.

METHODS AND MATERIALS

Eight expert academically based gastrointestinal radiation oncologists participated. Three sample cases were chosen: a GEJ cancer, a distal esophageal cancer, and a mid-upper esophageal cancer. Uniform computed tomographic (CT) simulation datasets and accompanying diagnostic positron emission tomographic/CT images were distributed to each expert, and the expert was instructed to generate gross tumor volume (GTV) and CTV contours for each case. All contours were aggregated and subjected to quantitative analysis to assess the degree of concordance between experts and to generate draft consensus contours. The panel then refined these contours to generate the contouring atlas.

RESULTS

The κ statistics indicated substantial agreement between panelists for each of the 3 test cases. A consensus CTV atlas was generated for the 3 test cases, each representing common anatomic presentations of esophageal cancer. The panel agreed on guidelines and principles to facilitate the generalizability of the atlas to individual cases.

CONCLUSIONS

This expert panel successfully reached agreement on contouring guidelines for esophageal and GEJ IMRT and generated a reference CTV atlas. This atlas will serve as a reference for IMRT contours for clinical practice and prospective trial design. Subsequent patterns of failure analyses of clinical datasets using these guidelines may require modification in the future.

Clinical validation of FDG-PET/CT in the radiation treatment planning for patients with oesophageal cancer

BACKGROUND

The aim of this prospective study was to determine the proportion of locoregional recurrences (LRRs) that could have been prevented if radiotherapy treatment planning for oesophageal cancer was based on PET/CT instead of CT.

MATERIALS AND METHODS

Ninety oesophageal cancer patients, eligible for high dose (neo-adjuvant) (chemo)radiotherapy, were included. All patients underwent a planning FDG-PET/CT-scan. Radiotherapy target volumes (TVs) were delineated on CT and patients were treated according to the CT-based treatment plans. The PET images remained blinded. After treatment, TVs were adjusted based on PET/CT, when appropriate. Follow up included CT-thorax/abdomen every 6months. If LRR was suspected, a PET/CT was conducted and the site of recurrence was compared to the original TVs. If the LRR was located outside the CT-based clinical TV (CTV) and inside the PET/CT-based CTV, we considered this LRR possibly preventable.

RESULTS

Based on PET/CT, the gross tumour volume (GTV) was larger in 23% and smaller in 27% of the cases. In 32 patients (36%), >5% of the PET/CT-based GTV would be missed if the treatment planning was based on CT. The median follow up was 29months. LRRs were seen in 10 patients (11%). There were 3 in-field recurrences, 4 regional recurrences outside both CT-based and PET/CT-based CTV and 3 recurrences at the anastomosis without changes in TV by PET/CT; none of these recurrences were considered preventable by PET/CT.

CONCLUSION

No LRR was found after CT-based radiotherapy that could have been prevented by PET/CT. The value of PET/CT for radiotherapy seems limited.