Radiotherapy and chemoradiotherapy as a novel option for the treatment of locally advanced inoperable gastric adenocarcinoma: A phase II study

Reconsidering the Role of Radiotherapy for Inoperable Gastric Cancer: A Systematic Review of Gastric Radiotherapy Given With Definitive and Palliative Intent

AIMS

The role of radiotherapy (RT) for inoperable gastric cancer (IGC) is commonly low-dose, given reactively for symptoms (e.g. bleeding), in contrast to the oesophagus, where high quality evidence exists for higher doses of RT. This systematic review aims to evaluate the use of, and evidence for, definitive and high-dose palliative RT for IGC and whether a change in practice is warranted.

MATERIALS AND METHODS

Following registration with PROSPERO (CRD42022297080), MEDLINE, EMBASE and The Cochrane Library were searched in accordance with PRISMA standards for studies evaluating definitive (non-metastatic disease, BED10 >45Gy) or high-dose palliative RT (for symptom/local control, minimum BED10 >30Gy). A manual search of meeting proceedings and clinical trial registries was also performed.

RESULTS

31 studies were selected for analysis. 10 definitive studies totalling n = 354 patients receiving RT with 45-50.4Gy/25-28#, showed median overall survival ranging between 11 and 26.4 months, clinical complete response range 12%-45%, G3 gastrointestinal toxicity 0-31% (range) and RT completion rates ranging from 81% to 100%. 21 high-dose palliative studies (n = 955) mostly evaluated haemostatic control and reported 38 different RT regimens (most commonly 30Gy/10#). Bleeding response rate (RR) was 59.6%-90%, pain RR 45.5-100%, obstruction RR 52.9%-100%, G3 gastrointestinal toxicity <5% and RT completion 68%-100%. An additional American National Cancer Database review >4700 non metastatic IGC patients which combined both definitive and palliative doses found significant benefit to RT in addition to chemotherapy. Evidence regarding a dose-response relationship is conflicting, limited by retrospective data. Two studies report high quality -of-life (QOL) scores following gastric RT.

CONCLUSION

There is a body of mainly non-randomised, observational evidence showing high-dose RT is efficacious, safe and may maintain QOL for patients with IGC. A change in practice will require a prospective randomised controlled trial, which should explore the role of prophylactic, high-BED RT combined with optimal systemic therapy using modern IMRT techniques and RT quality assurance.

Definitive Chemoradiation With Dose Escalation for Locally Advanced Gastric Cancer: Case Studies

Gastric cancer is a prevalent cancer with a predilection for Asian ethnicity and male patients. In early and locally advanced gastric cancer, without significant comorbidities, surgery is a part of the treatment management of this cancer. However, with concurrent comorbidities, surgery may not be recommended and alternative treatment options such as palliative chemotherapy and/or radiation and definitive chemoradiation can be considered to reduce morbidity. We present three cases of gastric cancer where definitive chemoradiation with dose escalation was utilized due to underlying comorbidities and poor performance status. The treatment was generally well tolerated by patients and resulted in substantial reduction in gastric mass size in two patients with median overall survival of 10 months.

Between evidence and new perspectives on the current state of the multimodal approach to gastric cancer: Is there still a role for radiation therapy?

In patients affected by gastric cancer (GC), especially those in advanced stage, the multidisciplinary approach of treatment is fundamental to obtain a good disease control and quality of life. Although many chemotherapeutics in combination to radiotherapy are adopted in the peri- or postoperative setting, the most optimal timing, regimens and doses remains controversial. In the era of radical surgery performed with D2-lymphadenectomy, the role of radiation therapy remains to be better defined. Categories of patients, who could benefit more from an intensified local treatment rather than more toxic systemic therapy, are still under investigation. Evidence and recent updates of the randomized trials, meta-analysis and prospective trials show that the postoperative radiotherapy plays a fundamental role in reducing the loco-regional recurrence and in turn the disease-free survival in operable advanced GC patients, also after a well performed D2 surgery. Therapeutic decisions should be taken considering the individual patients, but the multimodal approach is necessary to guarantee a longer survival and a good quality of life. Ongoing randomized trials could better define the timing and the combination of radiotherapy and systemic therapy.

18-Fluorodeoxy-Glucose Positron Emission Tomography- Computed Tomography (18-FDG-PET/CT) for Gross Tumor Volume (GTV) Delineation in Gastric Cancer Radiotherapy

Purpose:

Evaluation of the 18-fluorodeoxy-glucose positron emission tomography-computed tomography (18-FDG-PET/_CT) for gross tumor volume (GTV) delineation in gastric cancer patients undergoing radiotherapy.

Methods:

In this study, 29 gastric cancer patients (17 unresectable and 7 inoperable) were initially enrolled for radical chemoradiotherapy (45Gy/25 fractions + chemotherapy based on 5 fluorouracil) or radiotherapy alone (45Gy/25 fractions) with planning based on the 18-FDG-PET/CT images. Five patients were excluded due to excess blood glucose levels (1), false-negative positron emission tomography (1) and distant metastases revealed by 18-FDG-PET/CT (3). The analysis involved measurement of metabolic tumor volumes (MTVs) performed on PET/CT workstations. Different threshold levels of the standardized uptake value (SUV) and liver uptake were set to obtain MTVs. Secondly, GTV_PET values were derived manually using the positron emission tomography (PET) dataset blinded to the computed tomography (CT) data. Subsequently, GTV_CT values were delineated using a radiotherapy planning system based on the CT scans blinded to the PET data. The referenced GTV_CT values were correlated with the GTV_PET and were compared with a conformality index (CI).

Results:

The mean CI was 0.52 (range, 0.12-0.85). In 13/24 patients (54%), the GTV_PET was larger than GTV_CT, and in the remainder, GTV_PET was smaller. Moreover, the cranio-caudal diameter of GTV_PET in 16 cases (64%) was larger than that of GTV_CT, smaller in 7 cases (29%), and unchanged in one case. Manual PET delineation (GTVPET) achieved the best correlation with GTV_CT (Pearson correlation = 0.76, p <0.0001). Among the analyzed MTVs, a statistically significant correlation with GTV_CT was revealed for MTV_10%SUVmax (r = 0.63; p = 0.0014), MTV_liv (r = 0.60; p = 0.0021), MTV_SUV2.5 (r = 0.54; p = 0.0063); MTV_20%SUVmax (r = 0.44; p = 0.0344); MTV_30%SUVmax (r = 0.44; p = 0.0373).

Conclusion:

18-FDG-PET/_CT in gastric cancer radiotherapy planning may affect the GTV delineation.

Multicenter Phase 2 Study of Peri-Irradiation Chemotherapy Plus Intensity Modulated Radiation Therapy With Concurrent Weekly Docetaxel for Inoperable or Medically Unresectable Nonmetastatic Gastric Cancer

PURPOSE

To assess the efficacy and feasibility of concurrent chemoradiation therapy (CCRT) plus preradiation and postradiation chemotherapy for patients with nonmetastatic gastric carcinoma who do not undergo surgery.

METHODS AND MATERIALS

Patients with inoperable (due to medical comorbid conditions or patient's refusal to undergo surgery) or unresectable gastric cancer received up to 2 21-day cycles of preradiation and postradiation chemotherapy (docetaxel 37.5 mg/m² on days 1 and 8, cisplatin 25 mg/m² on days 1-3, and a continuous infusion of fluorouracil [FU] 750 mg/m² on days 1-5), respectively. CCRT between preradiation and postradiation chemotherapy was initiated on day 43 and consisted of intensity modulated radiation therapy (50.4 Gy) plus concurrent docetaxel 20 mg/m² weekly for 6 weeks.

RESULTS

36 patients were evaluable; 21 patients with comorbid conditions were unsuitable for surgery (group 1), 8 had unresectable disease (group 2), and 7 refused surgery (group 3). The clinical complete response (cCR) rate for the 36 evaluable patients was 36% (95% confidence interval [CI], 19%-53%) and the overall response rate was 83% (95% CI, 75%-97%). The median survival time and estimated 2-year survival rate were 25.8 months (95% CI, 7.1-44.5 months) and 52% (95% CI, 38%-67%), respectively. The estimated median OS and 2-year OS rates for groups 1, 2, and 3 were 37.0 months (95% CI, 7.9-66.1 months) and 52% (95% CI, 31%-73%), 17.7 months (95% CI, 7.8-27.6 months) and 20% (95% CI, 0%-49%), and 38.9 months (95% CI, 16.6-58.3 months) and 67% (95% CI, 30%-100%), respectively. Achieving a cCR was associated with significantly better overall survival (P=.004) and progression-free survival (P=.003). The most common grade 3 or greater toxicity during the chemotherapy phase was neutropenia. Common grade 3/4 toxicities during CCRT were nausea and vomiting.

CONCLUSIONS

This regimen is tolerable and shows promising efficacy in inoperable or medically unresectable GC.

Delineation of Margins for the Planning Target Volume (PTV) for Image-Guided Radiotherapy (IGRT) of Gastric Cancer Based on Intrafraction Motion

Background: Application of the image-guided radiotherapy (IGRT) system for gastric cancer involving daily verification of patient positioning on the treatment machine allows minimisation of geometrical errors as a consequence of intra- and inter-fraction motion. The purpose of this study was to define the intrafraction motion in gastric cancer patients during a treatment session based on the IGRT system and designation of margins around the clinical target volume CTV (internal target volume ITV) necessary to delineate the planning target volume (PTV). Methods: Twenty gastric cancer patients were analysed. The total radiation dose for each was 45Gy in 25 fractions within 5 weeks. The margins for the PTV were calculated according to van Herk (2004), Stroom and Heijmen (2002) and the International Commission on Radiation Units and Measurements (ICRU) Report 62 formulas based on craniocaudal (Y axis), laterolateral (X axis) and anteroposterior (Z axis) shifts. Results: Delineated margins for the PTV in gastric cancer with the three formulas applied were respectively 0.2, 0.2, and 0.2cm in the lateral plane, 0.3, 0.3, and 0.3cm in the craniocaudal plane and 0.3, 0.3, and 0.2cm in the anteroposterior plane. Conclusions: Recommended margins for the PTV in gastric cancer calculated in this study based on intrafraction motion are 0.3cm, 0.2cm and 0.3cm in the craniocaudal, lateral and anterioposterior directions, respectively. Use of the IGRT system corrects for the motions between factions and allows reduction in ITV-PTV margins. The main advantage of the smaller margins in comparison to the non-IGRT radiotherapy is a reduction in the probability of radiation complications.