The influence of gastric filling instructions on dose delivery in patients with oesophageal cancer: A prospective study

Principle and progress of radical treatment for locally advanced esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma is one of the most common malignant tumors in the digestive system in China and the world. Most patients are diagnosed as locally advanced or advanced stage. Concurrent chemoradiotherapy is the standard treatment for locally advanced esophageal squamous cell carcinoma. This study intends to summarize the evidence-based medical evidence of the treatment principle of locally advanced esophageal squamous cell carcinoma, the selection of radiotherapy dose, the outline of radiotherapy target and the selection of chemotherapy scheme. As a result, the effect of radiotherapy and chemotherapy is equivalent to that of surgery for the radical treatment of esophageal squamous cell carcinoma. In the era of immunization, it is recommended to use involved field irradiation. Fluorouracil plus cisplatin regimen is the standard chemotherapy regimen. FOLFOX regimen and paclitaxel plus fluorouracil regimen are optional concurrent chemotherapy regimens. The toxic and side effects of different chemotherapy regimens are different, which can be selected according to the actual situation of patients.

Assessment and validation of the internal gross tumour volume of gastroesophageal junction cancer during simultaneous integrated boost radiotherapy

Background

Respiratory motion may introduce errors during radiotherapy. This study aims to assess and validate internal gross tumour volume (IGTV) margins in proximal and distal borders of gastroesophageal junction (GEJ) tumours during simultaneous integrated boost radiotherapy.

Methods

We enrolled 10 patients in group A and 9 patients in group B. For all patients, two markers were placed at the upper and lower borders of the tumour before treatment. In group A, within the simulation and every 5 fractions of radiotherapy, we used 4-dimensional computed tomography (4DCT) to record the intrafractional displacement of the proximal and distal markers. By fusing the average image of each repeated 4DCT with the simulation image based on the lumbar vertebra, the interfractional displacement could be obtained. We calculated the IGTV margin in the proximal and distal borders of the GEJ tumour. In group B, by referring to the simulation images and cone-beam computed tomography (CBCT) images, the range of tumour displacement in proximal and distal borders of GEJ tumour was estimated. We calculated the proportion of marker displacement range in group B lay within the IGTV margin calculated based on the data obtained in group A to estimate the accuracy of the IGTV margin.

Results

The intrafractional displacement in the cranial–caudal (CC) direction was significantly larger than that in the anterior–posterior (AP) and left–right (LR) directions for both the proximal and distal markers of the tumour. The interfractional displacement in the AP and LR directions was larger than that in the CC direction (p = 0.001, p = 0.017) based on the distal marker. The IGTV margins in the LR, AP and CC directions were 9 mm, 8.5 mm and 12.1 mm for the proximal marker and 15.8 mm, 12.7 mm and 11.5 mm for the distal marker, respectively. In group B, the proportions of markers that located within the IGTV margin in the LR, AP and CC directions were 96.5%, 91.3% and 96.5% for the proximal marker and 100%, 96.5%, 93.1% for the distal marker, respectively.

Conclusions

Our study proposed individualized IGTV margins for proximal and distal borders of GEJ tumours during neoadjuvant radiotherapy. The IGTV margin determined in this study was acceptable. This margin could be a reference in clinical practice.

Radiotherapy for cancers of the oesophagus, cardia and stomach

We present the updated recommendations of the French society for radiation oncology on radiotherapy of oesophageal cancer. Oesophageal cancer still remains a malignant tumour with a poor prognosis. Surgery remains the standard treatment for localized cancers, regardless of histology. For locally advanced stages, surgery remains a standard for adenocarcinomas after neoadjuvant treatment with chemotherapy or chemoradiotherapy. However, it is a therapeutic option after initial chemoradiotherapy for stage III squamous cell carcinomas, given the increased morbidity and mortality with a multimodal treatment, which results in an equivalent overall survival with or without surgery. Preoperative or exclusive chemoradiotherapy should be delivered according to validated regimens with an effective total dose (50Gy), if surgery is not planned or if the tumour is deemed resectable before chemoradiotherapy. Intensity-modulated radiotherapy significantly reduces irradiation of the lungs and heart and may reduce the morbidity of this treatment, especially in combination with surgery. In case of exclusive chemoradiotherapy, dose escalation beyond 50Gy is not currently recommended. Some technical considerations still remain questionable, such as the place of prophylactic lymph node irradiation, adaptive radiotherapy, evaluation of response during and after chemoradiotherapy and the value of proton therapy.

Impact of histology classification on pathologic treatment response and overall survival in distal esophageal cancer patients: a propensity matched analysis

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) has been linked to superior pathologic treatment response compared to esophageal adenocarcinoma (EAC) after neoadjuvant chemoradiation. However, the impact of histology on survival remains unclear. It has been suggested, based on epidemiologic similarities, that distal EAC should be grouped with gastric cancers as an entity distinct from distal ESCC, but there is little data to support this recommendation. We therefore aim to compare pathologic treatment response (PTR) and overall survival (OS) in patients with distal EAC versus distal ESCC.

METHODS

This retrospective cohort study included patients who underwent esophagectomy for distal esophageal malignancy. Histologic sub-groups were matched (1:1) using a propensity-score matching approach. Pre-operative clinical parameters, oncologic outcomes and survival were compared between groups.

RESULTS

1031 distal EC patients, with a median age of 64.4 years and a male preponderance (86.5%), underwent esophagectomy at our institution between 1999 and 2019. 939 (91.1%) patients had a diagnosis of EAC and 92 (8.9%) had ESCC. A higher proportion of ESCC patients were female (26.1% vs. 12.1%; P < 0.01) and non-white (12.0% vs. 3.8%; P < 0.01). Propensity-score sub-analysis identified 75 matched pairs. Rates of pathologic complete response (58.0% vs. 48.9%; P = 0.67) and OS (43.0 vs. 52.0 months; P = 0.808) were not significantly different between matched groups.

CONCLUSIONS

Although traditionally known to have a better overall PTR compared to EAC, ESCC patients in our large series did not show any improvement in PTR or OS. Treatment recommendations for patients with EAC and ESCC should consider tumor location in addition to histology.

MRI evaluation of normal tissue deformation and breathing motion under an abdominal compression device

Purpose

Abdominal compression can minimize breathing motion in stereotactic radiotherapy, though it may impact the positioning of dose‐limiting normal tissues. This study quantified the reproducibility of abdominal normal tissues and respiratory motion with the use of an abdominal compression device using MR imaging.

Methods

Twenty healthy volunteers had repeat MR over 3 days under an abdominal compression plate device. Normal tissues were delineated on daily axial T2‐weighted MR and compared on days 2 and 3 relative to day 1, after adjusting for baseline shifts relative to bony anatomy. Inter‐fraction organ deformation was computed using deformable registration of axial T2 images. Deformation > 5 mm was assumed to be clinically relevant. Inter‐fraction respiratory amplitude changes and intra‐fraction baseline drifts during imaging were quantified on daily orthogonal cine‐MR (70 s each), and changes > 3 mm were assumed to be relevant.

Results

On axial MR, the mean inter‐fraction normal tissue deformation was > 5 mm for all organs (range 5.1–13.4 mm). Inter‐fraction compression device misplacements > 5 mm and changes in stomach volume > 50% occurred at a rate of 93% and 38%, respectively, in one or more directions and were associated with larger adjacent organ deformation, in particular for the duodenum. On cine‐MR, inter‐fraction amplitude changes > 3 mm on day 2 and 3 relative to day 1 occurred at a rate of < 12.5% (mean superior–inferior change was 1.6 mm). Intra‐fraction baseline drifts > 3 mm during any cine‐MR acquisition occurred at a rate of 23% (mean superior–inferior changes was 2.4 mm).

Conclusions

Respiratory motion under abdominal compression is reproducible in most subjects within 3 mm. However, inter‐fraction deformations greater than 5 mm in normal tissues were common and larger than inter‐ and intra‐fraction respiratory changes. Deformations were driven mostly by variable stomach contents and device positioning. The magnitude of this motion may impact normal tissue dosimetry during stereotactic radiotherapy.

Density override in treatment planning to mitigate the dosimetric effect induced by gastrointestinal gas in esophageal cancer radiation therapy

PURPOSE

To investigate the dosimetric effect of variable gas volume in esophageal cancer radiation therapy (RT) and whether a density override (DO) in treatment planning can effectively mitigate this dosimetric effect.

MATERIAL AND METHODS

Nine patients with gastrointestinal gas pockets in the planning computed tomography (pCT) were retrospectively included. Per patient, the intensity-modulated RT (IMRT) and volumetric-modulated arc therapy (VMAT) plans associated with no DO, DO = 0.5, and DO = 1 in the gas pockets were made. Initial and follow-up gas volumes were assessed from the pCTs and cone-beam CTs (CBCTs), respectively. Fractional CTs were created based on the pCT and CBCTs to calculate the fractional doses using all six plans. We then investigated for all six plans the correlation between the gas volume difference (relative to initial gas volume) and the dose difference (relative to planned dose). We also calculated and compared the accumulated dose by summing the fractional doses using two strategies: single-plan strategy (i.e. using each of the six plans separately) and plan-selection strategy (i.e. selecting one of the three plans depending on the fractional gas volume for IMRT and VMAT planning separately).

RESULTS

The dose difference was approximately linearly correlated to the gas volume difference. Underdoses of >3.5% and overdoses of >7% were found for gas volume decreases >160 mL/330 mL and increases >260 mL/370 mL for IMRT/VMAT planning, respectively. Moreover, for most patients, the single-plan strategy with the use of DO = 0.5 resulted in neither undesired underdose nor much overdose. The plan-selection strategy, however, can always ensure sufficient target coverage and minimize high dose regions to the most extent.

CONCLUSIONS

The variation in gas volume during the treatment course can result in clinically undesired underdose or overdose. The DO-based plan-selection strategy can effectively mitigate the gas-induced underdose and minimize the overdose for esophageal cancer RT.

Comparison of carina-based versus bony anatomy-based registration for setup verification in esophageal cancer radiotherapy

Background

To investigate the feasibility and geometric accuracy of carina-based registration for CBCT-guided setup verification in esophageal cancer IGRT, compared with current practice bony anatomy-based registration.

Methods

Included were 24 esophageal cancer patients with 65 implanted fiducial markers, visible on planning CTs and follow-up CBCTs. All available CBCT scans (n = 236) were rigidly registered to the planning CT with respect to the bony anatomy and the carina. Target coverage was visually inspected and marker position variation was quantified relative to both registration approaches; the variation of systematic (Σ) and random errors (σ) was estimated.

Results

Automatic carina-based registration was feasible in 94.9% of the CBCT scans, with an adequate target coverage in 91.1% compared to 100% after bony anatomy-based registration. Overall, Σ (σ) in the LR/CC/AP direction was 2.9(2.4)/4.1(2.4)/2.2(1.8) mm using the bony anatomy registration compared to 3.3(3.0)/3.6(2.6)/3.9(3.1) mm for the carina. Mid-thoracic placed markers showed a non-significant but smaller Σ in CC and AP direction when using the carina-based registration.

Conclusions

Compared with a bony anatomy-based registration, carina-based registration for esophageal cancer IGRT results in inadequate target coverage in 8.9% of cases. Furthermore, large Σ and σ, requiring larger anisotropic margins, were seen after carina-based registration. Only for tumors entirely confined to the mid-thoracic region the carina-based registration might be slightly favorable.

Electronic supplementary material

The online version of this article (10.1186/s13014-018-0986-1) contains supplementary material, which is available to authorized users.

Dosimetric impact of gastrointestinal air column in radiation treatment of pancreatic cancer

OBJECTIVE

Dosimetric evaluation of air column in gastrointestinal (GI) structures in intensity modulated radiation therapy (IMRT) of pancreatic cancer.

METHODS

Nine sequential patients were retrospectively chosen for dosimetric analysis of air column in the GI apparatus in pancreatic cancer using cone beam CT (CBCT). The four-dimensional CT (4DCT) was used for target and organs at risk (OARs) and non-coplanar IMRT was used for treatment. Once a week, these patients underwent CBCT for air filling, isocentre verification and dose calculations retrospectively.

RESULTS

Abdominal air column variation was as great as ±80% between weekly CBCT and 4DCT. Even with such a large air column in the treatment path for pancreatic cancer, changes in anteroposterior dimension were minimal (2.8%). Using IMRT, variations in air column did not correlate dosimetrically with large changes in target volume. An average dosimetric deviation of mere -3.3% and a maximum of -5.5% was observed.

CONCLUSION

CBCT revealed large air column in GI structures; however, its impact is minimal for target coverage. Because of the inherent advantage of segmentation in IMRT, where only a small fraction of a given beam passes through the air column, this technique might have an advantage over 3DCRT in treating upper GI malignancies where the daily air column can have significant impact. Advances in knowledge: Radiation treatment of pancreatic cancer has significant challenges due to positioning, imaging of soft tissues and variability of air column in bowels. The dosimetric impact of variable air column is retrospectively studied using CBCT. Even though, the volume of air column changes by ± 80%, its dosimetric impact in IMRT is minimum.