Impact of hybrid FDG-PET/CT on gross tumor volume definition of cervical esophageal cancer: reducing interobserver variation

PET/CT and MR Improve Interobserver Agreement in Primary Tumor Determination for Radiotherapy in Esophageal Squamous Cell Cancer

Background/Objectives: The aim of the study was to evaluate interobserver variability in the determination of the primary tumor for radiotherapy treatment planning in esophageal squamous cell carcinoma (ESCC). Methods: Sixteen patients with locally advanced ESCC were included in the analysis. In all patients positron emission tomography with computed tomography (PETC/CT) and magnetic resonance (MR) scans for radiotherapy planning were performed. Five experienced radiation oncologists delineated the primary tumor based on CT alone, MR alone, PET/CT, CT with fused MR and PET/CT with fused MR. Mean tumor volumes were calculated for each patient and imaging modality. The generalized conformity index (CIgen) was calculated to assess agreement in tumor determination. Results: The mean tumor volumes and CIgen for CT alone, MR alone, PET/CT, CT with fused MR and PET/CT with fused MR were 33.1 cm3, 30.2 cm3, 38.1 cm3, 31.9 cm3, 36.2 cm3 and 0.59, 0.64, 0.66, 0.63, 0.71, respectively. CIgen was significantly higher using PET/CT with fused MR compared to CT (p < 0.001) and PET/CT (p = 0.002) and using PET/CT compared to CT (alone) (p = 0.003). Conclusions: Our study showed higher agreement in primary tumor determination in ESCC using PET/CT compared to CT alone. Higher agreement was also found using PET/CT with fused MR compared to CT alone and PET/CT.

Inter-observer variation in gross tumour volume delineation of oesophageal cancer on MR, CT and PET/CT

BACKGROUND

The aim of our study was to assess the inter-observer variability in delineation of the gross tumour volume (GTV) of oesophageal cancer on magnetic resonance (MR) in comparison to computed tomography (CT) and positron emission tomography and CT (PET/CT).

PATIENTS AND METHODS

Twenty-three consecutive patients with oesophageal cancer treated with chemo-radiotherapy were enrolled. All patients had PET/CT and MR imaging in treatment position. Five observers independently delineated the GTV on CT alone, MR alone, CT with co-registered MR, PET/CT alone and MR with co-registered PET/CT. Volumes of GTV were measured per patient and imaging modality. Inter-observer agreement, expressed in generalized conformity index (CIgen), volumetric conformity index (VCI), planar conformity index (PCI) and inter-delineation distance (IDD) were calculated per patient and imaging modality. Linear mixed models were used for statistical analysis.

RESULTS

GTV volume was significantly lower on MR (33.03 cm3) compared to CT (37.1 cm3; p = 0.002) and on PET/CT MR (35.2 cm3; p = 0.018) compared to PET/CT (39.1 cm3). The CIgen was lowest on CT (0.56) and highest on PET/CT MR (0.67). The difference in CIgen between MR (0.61) and CT was borderline significant (p = 0.048). The VCI was significantly higher on MR (0.71; p = 0.007) and on CT MR (0.71; p = 0.004) compared to CT (0.67). The PCI was significantly higher on CT MR (0.67; p = 0.031) compared to CT (0.64). The largest differences were observed in the cranio-caudal direction.

CONCLUSIONS

The highest inter-observer agreement was found for PET/CT MR and the lowest for CT. MR could reduce the difference in delineation between observers and provide additional information about the local extent of the tumour.

Additional chemoradiotherapy for superficial esophageal squamous cell carcinoma after near-circumferential or full-circumferential noncurative endoscopic submucosal dissection: a retrospective study

BACKGROUND

Endoscopic submucosal dissection (ESD) is a potentially efficient therapeutic intervention for superficial esophageal cancer. Additional treatment such as chemoradiotherapy (CRT) or esophagectomy is recommended in cases of muscularis mucosa invasion with positive resection margins or lymphovascular invasion or submucosal layer invasion, which are considered noncurative ESD, due to an increased risk of lymph node metastasis. However, the adequacy of additional CRT after near-circumferential or full-circumferential noncurative ESD has not been fully discussed. In this study, we retrospectively evaluated the efficacy and toxicity of additional CRT for superficial esophageal squamous cell carcinoma (SCC) after near-circumferential or full-circumferential noncurative ESD, which was defined as a mucosal defect measuring ≥ 3/4 of the esophageal circumference.

METHODS

We retrospectively evaluated 24 patients who received additional CRT for superficial esophageal SCC after near-circumferential or full-circumferential noncurative ESD between 2012 and 2018. Elective nodal irradiation (ENI) was performed in all patients and boost irradiation (BI) was performed after ENI in 4 patients with positive resection margins. The prescription doses of ENI and BI were 41.4 Gy in 23 fractions and 9 Gy in 5 fractions, respectively. Concurrent chemotherapy (a combination of cisplatin or nedaplatin and 5-fluorouracil) was administered to all patients.

RESULTS

The 3-year and 5-year overall survival rates were 92% and 78%, respectively, while the 3-year and 5-year progression-free survival rates were 83% and 70%, respectively. Grade 2 esophageal stenosis occurred in 8 (33%) patients. There was no case of Grade 3 or worse esophageal stenosis. Among them, 4 (17%) patients developed stenosis before additional CRT, which persisted after the completion of additional CRT. The remaining 4 (17%) patients developed de novo stenosis within 5 months following the completion of additional CRT. One patient (4%) still requires regular bougie dilation. Grade 3 and Grade 4 acute toxicity, including anemia, neutropenia, thrombocytopenia, and esophagitis occurred in 1 (4%) and 0 (0%), 6 (25%) and 1 (4%), 1 (4%) and 0 (0%), and 1 (4%) and 0 (0%) patients, respectively. One (4%) patient who underwent salvage CRT for the out-of-field lymph node recurrence died with acute myeloid leukemia.

CONCLUSIONS

Additional CRT is a viable treatment option even in patients who have undergone near-circumferential or full-circumferential noncurative ESD. Esophageal stenosis after additional CRT following near-circumferential or full-circumferential noncurative ESD is manageable and acceptable.

Advances in the Imaging of Esophageal and Gastroesophageal Junction Malignancies

Accurate imaging is key for the diagnosis and treatment of esophageal and gastroesophageal junction cancers . Current imaging modalities, such as computed tomography (CT) and 18F-FDG (2-deoxy-2-[18F]fluoro-D-glucose) positron emission tomography (PET)/CT, have limitations in accurately staging these cancers. MRI shows promise for T staging and residual disease assessment. Novel PET tracers, like FAPI, FLT, and hypoxia markers, offer potential improvements in diagnostic accuracy. 18F-FDG PET/MRI combines metabolic and anatomic information, enhancing disease evaluation. Radiomics and artificial intelligence hold promise for early detection, treatment planning, and response assessment. Theranostic nanoparticles and personalized medicine approaches offer new avenues for cancer therapy.

Prevalence and risk factors for retropharyngeal and retro-styloid lymph node metastasis in hypopharyngeal carcinoma

BACKGROUND

We evaluated the prevalence and identified the risk factors for retropharyngeal and retro-styloid lymph node metastasis (LNM) in patients with hypopharyngeal carcinoma (HPC). This was achieved using a combination of magnetic resonance (MR) and [18 F]-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) images.

METHODS

Two board-certified radiation oncologists retrospectively reviewed pretreatment FDG-PET/CT images and contrast-enhanced thin-slice CT and MR images of 155 patients with HPC who underwent radiotherapy. Fisher's exact tests and logistic regression analyses were performed to assess the risk factors for LNM.

RESULTS

Retropharyngeal LNM (RPLNM) was confirmed in 20 (13%) patients. Posterior wall (PW) tumors (odds ratio [OR]: 4.128, 95% confidence interval [CI]: 1.339-12.727; p = 0.014) and bilateral or contralateral cervical LNM (OR: 11.577, 95% CI: 2.135-62.789; p = 0.005) were significantly correlated with RPLNM. The RPLNM was found in 9 (32%) of the 28 patients with PW tumors. Of these 9 patients, 2 (7%) had ipsilateral RPLNM, 3 (11%) had contralateral RPLNM, and 4 (14%) had bilateral RPLNM. The PW tumors were significantly associated with contralateral RPLNM (p < 0.001). Retro-styloid LNM (RSLNM) was confirmed in two (1%) patients, both of whom had ipsilateral RSLNM with lymph nodes (LNs) of ≥ 15 mm in the upper limit of ipsilateral level II. A significant association was found between LNs of ≥ 15 mm in the upper limit of ipsilateral level II and ipsilateral RSLNM (p = 0.001).

CONCLUSIONS

The RPLNM was identified in 13% of patients with HPC. The PW tumors and bilateral or contralateral cervical LNM were risk factors for RPLNM; particularly, PW tumors were a specific risk factor for contralateral RPLNM. Although the RSLNM was rare, LNs of ≥ 15 mm in the upper limit of ipsilateral level II were a risk factor for ipsilateral RSLNM.

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.

Assessing Interobserver Variability in the Delineation of Structures in Radiation Oncology: A Systematic Review

PURPOSE

The delineation of target volumes and organs at risk is the main source of uncertainty in radiation therapy. Numerous interobserver variability (IOV) studies have been conducted, often with unclear methodology and nonstandardized reporting. We aimed to identify the parameters chosen in conducting delineation IOV studies and assess their performances and limits.

METHODS AND MATERIALS

We conducted a systematic literature review to highlight major points of heterogeneity and missing data in IOV studies published between 2018 and 2021. For the main used metrics, we did in silico analyses to assess their limits in specific clinical situations.

RESULTS

All disease sites were represented in the 66 studies examined. Organs at risk were studied independently of tumor site in 29% of reviewed IOV studies. In 65% of studies, statistical analyses were performed. No gold standard (GS; ie, reference) was defined in 36% of studies. A single expert was considered as the GS in 21% of studies, without testing intraobserver variability. All studies reported both absolute and relative indices, including the Dice similarity coefficient (DSC) in 68% and the Hausdorff distance (HD) in 42%. Limitations were shown in silico for small structures when using the DSC and dependence on irregular shapes when using the HD. Variations in DSC values were large between studies, and their thresholds were inconsistent. Most studies (51%) included 1 to 10 cases. The median number of observers or experts was 7 (range, 2-35). The intraclass correlation coefficient was reported in only 9% of cases. Investigating the feasibility of studying IOV in delineation, a minimum of 8 observers with 3 cases, or 11 observers with 2 cases, was required to demonstrate moderate reproducibility.

CONCLUSIONS

Implementation of future IOV studies would benefit from a more standardized methodology: clear definitions of the gold standard and metrics and a justification of the tradeoffs made in the choice of the number of observers and number of delineated cases should be provided.

Prevalence and risk factors of retro-styloid lymph node metastasis in oropharyngeal carcinoma

BACKGROUND

Supporting data defining the selection criteria of level VIIb for inclusion in the target volume in radiotherapy (RT) planning are insufficient. We evaluated the prevalence of level VIIb retro-styloid lymph node metastasis (RSLNM) and associated risk factors in patients with oropharyngeal carcinoma (OPC).

MATERIALS AND METHODS

We retrospectively reviewed pre-treatment [18F]-fluoro-2-deoxy-d-glucose-positron emission tomography/computed tomography (CT) along with contrast-enhanced thin slice CT and magnetic resonance (MR) images of 137 patients pathologically confirmed as having OPC who underwent RT. The location of lymph nodes (LNs) was confirmed on the planning CT images. Fisher's exact test and logistic regression analyses were made to determine the risk factors of RSLNM.

RESULTS

RSLNM was confirmed in 18 (13%) patients. All RSLNMs were located within level VIIb on the planning CT images. No patients exhibited LNM in contralateral level VIIb. Furthermore, no patients with negative or single ipsilateral cervical LNM had RSLNM. Fisher's exact test revealed that smoking status (p=.027), multiple ipsilateral cervical LNM (p=.045) and LN ≥15 mm in the upper limit of ipsilateral level II (p<.001) were significantly associated with RSLNM. Logistic regression analyses revealed that the presence of LNs ≥15 mm in upper limit of ipsilateral level II was significantly associated with RSLNM (odds ratio: 977.297; 95% confidence interval: 57.629-16573.308; p<.001).

CONCLUSIONS

RSLNM is relatively common in patients with OPC with a prevalence rate of approximately 10%. The prevalence of RSLNM in patients with negative or single ipsilateral cervical LNM and contralateral RSLNM is extremely low; therefore, level VIIb can be excluded from the target volume in such patients. LN ≥15 mm in the upper limit of ipsilateral level II is a risk factor for RSLNM. Ipsilateral level VIIb should be included in the target volume for patients with this risk factor.KEY MESSAGERetro-styloid lymph node metastasis (RSLNM) prevalence is ∼10% in oropharyngeal carcinoma.Lymph node ≥15 mm in ipsilateral level II upper limit is a risk factor for RSLNM.

Impact of metal artifact reduction algorithm on gross tumor volume delineation in tonsillar cancer: reducing the interobserver variation

BACKGROUND

Patients with tonsillar cancer (TC) often have dental fillings that can significantly degrade the quality of computed tomography (CT) simulator images due to metal artifacts. We evaluated whether the use of the metal artifact reduction (MAR) algorithm reduced the interobserver variation in delineating gross tumor volume (GTV) of TC.

METHODS

Eighteen patients with TC with dental fillings were enrolled in this study. Contrast-enhanced CT simulator images were reconstructed using the conventional (CTCONV) and MAR algorithm (CTMAR). Four board-certified radiation oncologists delineated the GTV of primary tumors using routine clinical data first on CTCONV image datasets (GTVCONV), followed by CTCONV and CTMAR fused image datasets (GTVMAR) at least 2 weeks apart. Intermodality differences in GTV values and Dice similarity coefficient (DSC) were compared using Wilcoxon's signed-rank test.

RESULTS

GTVMAR was significantly smaller than GTVCONV for three observers. The other observer showed no significant difference between GTVCONV and GTVMAR values. For all four observers, the mean GTVCONV and GTVMAR values were 14.0 (standard deviation [SD]: 7.4) cm3 and 12.1 (SD: 6.4) cm3, respectively, with the latter significantly lower than the former (p < 0.001). The mean DSC of GTVCONV and GTVMAR was 0.74 (SD: 0.10) and 0.77 (SD: 0.10), respectively, with the latter significantly higher than that of the former (p < 0.001).

CONCLUSIONS

The use of the MAR algorithm led to the delineation of smaller GTVs and reduced interobserver variations in delineating GTV of the primary tumors in patients with TC.

Immunomodulatory function of the active ingredients in traditional Chinese prescriptions on early stage esophageal cancer with dysplasia

OBJECTIVE

To explore the effects of the ingredients in a traditional Chinese prescription on the immune regulation of esophageal cancer in patients with early atypical hyperplasia.

METHODS

A total of 60 C57BL mice were randomly selected as the positive control group; another 240 C57BL mice were randomly divided into a blank control group (n=30), a 4NQO group (n=60) and an experimental group (n=120). The experimental group was divided into the prevention group which received carcinogens and the prescription composition simultaneously, and the treatment group which received carcinogens first and the prescription composition second. The lymphocyte proliferation responses in peripheral blood and spleen cells were determined, and the changes of CD4⁺, CD8⁺, B7H4, CD4⁺CD25⁺ before and after administration were measured.

RESULTS

The CD4⁺ cell concentration in the 4NQO group was significantly higher than that in the other four groups (P<0.05). No significant difference was found in the CD4⁺B7H4⁺ cell concentration among the five groups (P>0.05); the CD8⁺ concentration in the 4NQO and the prevention groups was significantly higher than that in the other three groups (P<0.05).

CONCLUSION

The composition of traditional Chinese prescriptions can improve antitumor immunity and slow down the development of esophageal precancerous lesions by inhibiting the expression of T cells on lymphocytes and the positive expression of B7H4 and CD4⁺ in esophageal cancer.

Prognostic Value of CT Imaging-Based Tumor Volume in Patients With Non-Surgical Esophageal Squamous Cell Carcinoma

BACKGROUND

The American Joint Committee on Cancer-Tumor (AJCC-T) staging system for esophageal carcinoma patients, which is based on the depth of tumor invasion, is not applicable in some cases. This study aims to assess the prognostic value of CT imaging-based tumor volume and its usefulness for T staging in patients with non-surgical esophageal squamous cell carcinoma (ESCC).

METHODS

We retrospectively reviewed the records of 158 ESCC patients undergoing definitive (chemo) radiotherapy from two hospitals. Tumor volume based on the CT imaging was calculated using the formula: V = πabc / 6. Three cutoff points for tumor volume were obtained with the X-tile software. Overall survival (OS) was analyzed using the Kaplan-Meier method. The -2 log-likelihood ratio and Akaike Information Criterion (AIC) value were evaluated to compare the AJCC-T staging system with the proposed T staging method.

RESULTS

The median tumor volume was 19.8 cm³ (range from 1.0 to 319.5 cm³). The three optimal cutoff points of tumor volume were 12.7, 22.8, and 51.9 cm³, and the patients were divided into four groups named as proposed T1-T4 stages. The 3-year OS rates in patients with proposed T1 to T4 stages were 67.9%, 30.6%, 21.3%, and 5.3%, respectively. The -2 log-likelihood ratios of the AJCC-T stage and proposed T stage were 1,068.060 and 1,047.418, respectively. The difference in the AIC value between the two T staging systems was 18.642.

CONCLUSION

CT imaging-based tumor volume was superior to the depth of tumor invasion for T staging in predicting the prognosis of non-surgical ESCC patient.

[F18] FDG-PET/CT for manual or semiautomated GTV delineation of the primary tumor for radiation therapy planning in patients with esophageal cancer: is it useful?

Background

Target volume definition of the primary tumor in esophageal cancer is usually based on computed tomography (CT) supported by endoscopy and/or endoscopic ultrasound and can be difficult given the low soft-tissue contrast of CT resulting in large interobserver variability. We evaluated the value of a dedicated planning [F18] FDG-Positron emission tomography/computer tomography (PET/CT) for harmonization of gross tumor volume (GTV) delineation and the feasibility of semiautomated structures for planning purposes in a large cohort.

Methods

Patients receiving a dedicated planning [F18] FDG-PET/CT (06/2011–03/2016) were included. GTV was delineated on CT and on PET/CT (GTV_CT and GTV_PET/CT, respectively) by three independent radiation oncologists. Interobserver variability was evaluated by comparison of mean GTV and mean tumor lengths, and via Sørensen–Dice coefficients (DSC) for spatial overlap. Semiautomated volumes were constructed based on PET/CT using fixed standardized uptake values (SUV) thresholds (SUV30, 35, and 40) or background- and metabolically corrected PERCIST-TLG and Schaefer algorithms, and compared to manually delineated volumes.

Results

45 cases were evaluated. Mean GTV_CT and GTV_PET/CT were 59.2/58.0 ml, 65.4/64.1 ml, and 60.4/59.2 ml for observers A–C. No significant difference between CT- and PET/CT-based delineation was found comparing the mean volumes or lengths. Mean Dice coefficients on CT and PET/CT were 0.79/0.77, 0.81/0.78, and 0.8/0.78 for observer pairs AB, AC, and BC, respectively, with no significant differences. Mean GTV volumes delineated semiautomatically with SUV30/SUV35/SUV40/Schaefer’s and PERCIST-TLG threshold were 69.1/23.9/18.8/18.6 and 70.9 ml. The best concordance of a semiautomatically delineated structure with the manually delineated GTV_CT/GTV_PET/CT was observed for PERCIST-TLG.

Conclusion

We were not able to show that the integration of PET/CT for GTV delineation of the primary tumor resulted in reduced interobserver variability. The PERCIST-TLG algorithm seemed most promising compared to other thresholds for further evaluation of semiautomated delineation of esophageal cancer.

Comparison of gross target volumes based on four-dimensional CT, positron emission tomography-computed tomography, and magnetic resonance imaging in thoracic esophageal cancer

PURPOSE

The application value of ¹⁸ F-FDG PET-CT combined with MRI in the radiotherapy of esophageal carcinoma was discussed by comparing the differences in position, volume, and the length of GTVs delineated on the end-expiration (EE) phase of 4DCT, ¹⁸ F-FDG PET-CT, and T₂ W-MRI.

METHODS

A total of 26 patients with thoracic esophageal cancer sequentially performed 3DCT, 4DCT, ¹⁸ F-FDG PET-CT, and MRI simulation for thoracic localization. All images were fused with the 3DCT images by deformable registration. GTV_CT and GTV_50% were delineated on 3DCT and the EE phase of 4DCT images, respectively. The GTV based on PET-CT images was determined by thresholds of SUV ≥ 2.5 and designated as GTV_PET2.5 . The images of T₂ -weighted sequence and diffusion-weighted sequence were referred as GTV_MRI and GTV_DWI , respectively. The length of the abnormality seen on the 4DCT, PET-CT, and DWI was compared.

RESULTS

GTV_PET2.5 was significantly larger than GTV_50% and GTV_MRI (P = .000 and 0.008, respectively), and the volume of GTV_MRI was similar to that of GTV_50% (P = .439). Significant differences were observed between the CI of GTV_MRI to GTV_50% and GTV_PET2.5 to GTV_50% (P = .004). The CI of GTV_MRI to GTV_CT and GTV_PET2.5 to GTV_CT were statistically significant (P = .039). The CI of GTV_MRI to GTV_PET2.5 was significantly lower than that of GTV_MRI to GTV_50% , GTV_MRI to GTV_CT , GTV_PET2.5 to GTV_50% , and GTV_PET2.5 to GTV_CT (P = .000-0.021). Tumor length measurements by endoscopy were similar to the tumor length as measured by PET and DWI scan (P > .05), and there was no significant difference between the longitudinal length of GTV_PET2.5 and GTV_DWI (P = .072).

CONCLUSION

The volumes of GTV_MRI and GTV_50% were similar. However, GTV_MRI has different volumes and poor spatial matching compared with GTV_PET2.5 .The MRI imaging could not include entire respiration. It may be a good choice to guide target delineation and construction of esophageal carcinoma by combining 4DCT with MRI imaging. Utilization of DWI in treatment planning for esophageal cancer may provide further information to assist with target delineation. Further studies are needed to determine if this technology will translate into meaningful differences in clinical outcome.

The Role of Positron Emission Tomography Imaging in Radiotherapy Target Delineation

Positron emission tomography (PET) is an advanced functional imaging modality in oncology care for the diagnosis, staging, prognostication, and surveillance of numerous malignancies. PET can also offer considerable advantages for target volume delineation as part of radiation treatment planning. In this review, data and clinical practice from 6 general oncology disease sites are assessed to descriptively evaluate the role of PET in target volume delineation. Also highlighted are several specific and practical utilities for PET imaging in radiation treatment planning. Publication of several ongoing prospective trials in the future may further expand the utility of PET for target delineation and patient care.

Hypofractionated palliative volumetric modulated arc radiotherapy with the Radiation Oncology Study Group 8502 "QUAD shot" regimen for incurable head and neck cancer

BACKGROUND

To review a single institutional experience of the Radiation Therapy Oncology Group (RTOG) 8502 "QUAD shot" regimen using volumetric modulated arc radiotherapy (VMAT) for incurable head and neck cancer (HNC).

METHODS

Thirty-four consecutive patients with HNC were treated with at least one cycle of the RTOG 8502 regimen. Treatment plans included the use of VMAT with 6 MV photons generated by a linear accelerator. Two daily fractions of 3.7 Gy were delivered with an interval of at least 6 h for 2 consecutive days, totaling 14.8 Gy over 4 fractions. This was repeated every 3-4 weeks for a total of three cycles. No concurrent systemic therapy was performed.

RESULTS

The number of completed cycles was 1 in 6 (18%) patients, 2 in 5 (15%), and 3 in 23 (68%). Tumor response was achieved in 29 (85%) patients and symptom relief in 20 (77%) of 26 patients. Overall response (tumor response or symptom relief) was achieved in 32 (94%) patients. All patients who received 2 or more treatment cycles achieved overall response. Median overall survival (OS) was 5.7 months. Multivariate analysis revealed that completion of all three treatment cycles was significantly associated with better OS (P = 0.002). Grade 2 toxicity was observed in four (12%) patients, but no acute Grade ≥ 3 or late toxicity was observed.

CONCLUSIONS

The RTOG 8502 "QUAD shot" regimen using VMAT is effective for incurable HNC with highly reduced toxicity. Treatment with multiple cycles is recommended for better treatment response and/or survival.