Radiotherapy for Oropharyngeal Carcinoma With an Uninvolved Contralateral Neck: The Safety of Omission of Contralateral High Level II and Retropharyngeal Lymph Nodes From Elective Target Volumes.

AIMS: To analyse outcomes and patterns of failure in patients with oropharyngeal carcinoma (OPC) treated with definitive volumetric modulated arc therapy with omission of contralateral high level II lymph nodes (HLII) and retropharyngeal lymph nodes (RPLN) in the contralateral uninvolved neck. MATERIALS AND METHODS: Patients with OPC treated between January 2016 and July 2019 were retrospectively identified. In the absence of contralateral neck disease, institutional protocols allowed omission of contralateral HLII and contralateral RPLN in the additional absence of ipsilateral RPLN, soft palate/posterior pharyngeal wall primary. RESULTS: In total, 238 patients with OPC and an uninvolved contralateral neck received definitive (chemo)radiotherapy with bilateral neck treatment. The median follow-up was 30.6 months. Two-year local control, regional control and overall survival were 91.0, 91.6 and 86.5%, respectively. Contralateral HLII were omitted in 159/238 (66.8%) patients; this included 106 patients in whom the primary tumour was at/crossed the midline. The contralateral RPLN region was omitted from elective target volumes for 175/238 (73.5%); this included 114 patients with a primary tumour at/crossed the midline. The mean contralateral parotid dose when contralateral HLII and RPLN were both omitted was 24.4 Gy, compared with 28.3 Gy without HLII/RPLN omission (P < 0.001). Regional progression occurred in 18/238 (7.6%) patients, all involving the ipsilateral neck with one bilateral. There were no recurrences in the contralateral HLII or RPLN regions. CONCLUSION: In patients with OPC and an uninvolved contralateral neck receiving bilateral (chemo)radiotherapy, the omission of contralateral RPLN and HLII from elective target volumes was safe and could lead to reduced contralateral parotid doses.

Evaluation of Locoregional Recurrence Patterns Following Adjuvant (Chemo)Radiotherapy for Oral Cavity Carcinoma.

AIMS: To evaluate patterns of locoregional recurrence following adjuvant (chemo)radiotherapy for oral cavity squamous cell carcinomas. MATERIALS AND METHODS: One hundred and one patients who received adjuvant radiotherapy ± chemotherapy for oral cavity squamous cell carcinoma between 2013 and 2016 were analysed. For documented locoregional recurrence, recurrence imaging was deformably co-registered to the planning computed tomography scan. The volume of recurrence was delineated (Vrec). Vrec coverage by 95% of the corresponding planning target volume prescription dose was determined and the location compared with planning target volumes. Sites of recurrence were classified using a combined volume and centroid-based method: (A) central high dose, (B) peripheral high dose, (C) central low dose, (D) central peripheral dose, (E) extraneous. RESULTS: The median follow-up was 36 months. Forty-three per cent and 53% of patients received radiotherapy to the ipsilateral neck only and bilateral neck, respectively. Three-year overall survival, disease-free survival, local control, regional control and distant metastases-free survival were 63.0, 65.6, 88.0, 85.1 and 85.3%, respectively. Of 10 episodes of primary site recurrences, five were type A, four type B and one was type E. Of 14 episodes of regional recurrence, five were type A, two type C, two type D and five type E. Five of 21 (24%) patients with oral tongue carcinoma with an undissected/unirradiated contralateral neck had a type E contralateral neck recurrence, including 2/11 with pN0, 1/4 with pN1 and 2/6 with pN2 disease. CONCLUSIONS: Marginal and out-of-field recurrences remain a significant pattern of failure. We advocate generous target delineation postoperatively and, for oral tongue carcinomas, a comprehensive approach with bilateral neck irradiation.

Quality Assurance Peer Review for Radiotherapy for Haematological Malignancies.

AIMS: To assess the impact of weekly scheduled peer review of radiotherapy planning contours for definitive treatment of haematological malignancies based on rates of recommended changes. MATERIALS AND METHODS: Analysis of a prospective database of contour-based peer review at weekly scheduled meetings for patients undergoing definitive radiotherapy for haematological malignancies at a single large cancer centre between January and December 2018. Recommended changes were prospectively classified as involving the gross tumour volume (GTV), clinical target volume (CTV), planning target volume (PTV), organs at risk or dose fractionation. A univariate analysis was carried out to explore the associations between recommended changes and disease, treatment characteristics and consultant experience. RESULTS: In total, 158/171 (92%) of all cases of haematological malignancy undergoing definitive radiotherapy were prospectively peer reviewed over a 12-month period. Overall, 26/158 (16.5%) changes were recommended within the peer review meetings. This included a total of 27 contour changes (GTV, CTV or PTV) in 25 patients. An increase in CTV was the most common change, occurring in 20/158 (12.7%) cases. One dose-fractionation change was recommended. Additional advice regarding planning technique/set-up was documented in 5/158 (3.2%) patients. There were no significant associations between rates of recommended change and disease type, stage, prior chemotherapy, first line versus refractory/relapse, anatomical site, radiotherapy technique or consultant experience. CONCLUSIONS: Weekly contour-based peer review meetings resulted in a high rate of recommended changes. Compliance was high. Peer review was potentially beneficial for all disease and treatment characteristics and for any degree of clinician experience.

Quality Assurance Peer Review of Head and Neck Contours in a Large Cancer Centre via a Weekly Meeting Approach.

AIMS: To assess the impact of weekly scheduled peer review of head and neck contours for definitive and adjuvant radiotherapy cases based on rates of recommended changes. MATERIALS AND METHODS: Retrospective analysis of a prospective database. Recommended changes were prospectively classified as 'major' (change in gross tumour volume and/or high-dose clinical target volume, dose/fractionation) or 'minor' (change in intermediate or elective dose clinical target volumes or organs at risk). Univariate analysis to explore associations between recommended changes and tumour site/stage and radical/adjuvant indication. RESULTS: In total, 307/375 (82%) head and neck cases treated with volumetric-modulated arc therapy were prospectively peer reviewed over a 12-month period; 195 (64%) cases received definitive and 112 (36%) received adjuvant radiotherapy. Overall, 43/307 (14.0%) changes were recommended within the peer review meetings. This comprised 27/307 (8.8%) major changes and 16/307 (5.2%) minor changes; 33/43 (77%) changes were in the clinical target volume. Rates of recommended changes were significantly higher for adjuvant versus definitive radiotherapy (odds ratio 2.26, P = 0.014) and for larynx compared with oropharynx (odds ratio 3.02, P = 0.02). There was no overall correlation between clinician experience and rates of change (P = 0.62). CONCLUSION: Routine weekly meeting contour-based peer review resulted in a number of major and minor changes to treatment. Compliance was high. Peer review was potentially beneficial for all tumour sites/stages/indications and any degree of clinician experience.

Accuracy of Response Assessment Positron Emission Tomography-Computed Tomography Following Definitive Radiotherapy Without Chemotherapy for Head and Neck Squamous Cell Carcinoma.

AIM: There are few data to inform on the use of response assessment 2-[fluorine-18]-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography-computed tomography (PET-CT) following radical radiotherapy without chemotherapy for head and neck squamous cell carcinoma (HNSCC). This retrospective study evaluated the accuracy of PET-CT in HNSCC following radical radiotherapy. MATERIALS AND METHODS: In total, 138 patients with HNSCC treated with radical radiotherapy without chemotherapy who underwent a baseline and response assessment FDG PET-CT were identified. FDG PET-CT outcomes were analysed with reference to clinicopathological outcomes. RESULTS: The median follow-up was 26 months. FDG-avid disease at baseline was present for the primary site and lymph nodes in 118 and 86 patients, respectively. With regard to the primary tumour, the negative predictive value (NPV) of a complete metabolic response (CMR) was 95%; the positive predictive value (PPV) of equivocal uptake and a positive scan were 6% and 82%, respectively. The likelihood ratios for a CMR, equivocal and positive scans of the primary site were 0.19, 0.22, 14.8, respectively. With regard to lymph node disease, the NPV of a CMR was 91%, the PPV of equivocal uptake and a positive scan were 33% and 88%, respectively. Likelihood ratios for lymph node disease for CMR, equivocal and positive scans were 0.19, 0.97 and 15.1, respectively. CONCLUSION: Compared with the accuracy reported in the literature following chemoradiotherapy, response assessment FDG PET-CT following radical radiotherapy without chemotherapy had a similarly high NPV, whereas the PPV following a positive scan was higher.

Changes in Patient-reported Swallow Function in the Long Term After Chemoradiotherapy for Oropharyngeal Carcinoma.

AIMS: To assess long-term patient-reported swallow function after chemoradiotherapy for oropharyngeal carcinoma and to evaluate the frequency of deterioration/improvement over years. MATERIALS AND METHODS: Fifty-nine patients with oropharyngeal carcinoma treated with parotid-sparing intensity-modulated radiotherapy and concurrent chemotherapy between 2010 and 2012 had previously completed the MD Anderson Dysphagia Inventory (MDADI) at a median of 34 months (range 24-59) after treatment. An MDADI was posted to 55 alive and disease-free patients after a 30 month interval; 52/55 replies were received, a median of 64 months (range 52-88) after treatment; 27/52 (52%) had been managed with a prophylactic gastrostomy. A 10 point or greater change in the MDADI scores was defined as clinically significant. RESULTS: Overall, in the whole cohort, patient-reported swallow function showed a small absolute improvement in MDADI composite score on the second MDADI questionnaire (>5 years after treatment) compared with the first MDADI (>2 years after treatment); mean 68.0 (standard deviation 19.3) versus 64.0 (standard deviation 16.3), P = 0.021. Using the composite score, swallow function was stable over time in 29/52 (56%) patients; a clinically significant improvement in swallow function over time was noted in 17/52 (33%) patients; conversely 6/52 (12%) patients experienced a clinically significant deterioration with time. Abnormality of pre-treatment diet and a prophylactic gastrostomy correlated with an inferior MDADI composite score on the later questionnaire (P = 0.029 and P = 0.044, respectively). CONCLUSIONS: Long-term dysphagia is prevalent >5 years after treatment. Although long-term swallow function is stable in most patients, it is not static in a minority. On MDADI composite summary scores, 33% of patients experienced an improvement, whereas 12% deteriorated with time. Further investigation is needed to determine underlying mechanisms behind these divergent outcomes.

Postoperative (Chemo)Radiotherapy for Oral Cavity Squamous Cell Carcinomas: Outcomes and Patterns of Failure.

AIMS: To determine outcomes after adjuvant radiotherapy for squamous cell carcinoma of the oral cavity and to correlate locoregional recurrence patterns with radiotherapy target volumes. MATERIALS AND METHODS: All patients receiving adjuvant radiotherapy±chemotherapy after surgery with curative intent for oral cavity squamous cell carcinoma between 2007 and 2012 were retrospectively analysed. Locoregional recurrences were reconstructed on the planning computed tomography scan by both deformable image co-registration and by visual assessment. Recurrences were categorised as in-field, marginal or out-of-field if >95%, 20-95%, and <20% of the recurrence volume was encompassed by 95% of the prescription isodose, respectively. RESULTS: In total, 106 patients with a median follow-up of 42 months were included. Oral cavity subsites included oral tongue (54%) and floor of mouth (32%). Thirty (28%) patients received concurrent chemotherapy. Fifty-five (52%) patients received bilateral neck radiotherapy. Two year overall, disease-free, local disease-free, regional disease-free and distant metastases-free survival were 72, 83, 92, 89, 94%, respectively. On multivariate analysis, extracapsular nodal spread was the only factor significantly associated with inferior overall survival. Fourteen (13%) patients have experienced locoregional failure. Of the eight local recurrences at the primary tumour site, four, three and one were classified as in-field, marginal and out-of-field, respectively. Of 10 regional recurrences, one, one and eight were in-field, marginal and out-of-field. There were 7/21 (33%) contralateral regional recurrences in patients with pN2a/b disease who did not receive contralateral neck irradiation; there were 0/21 (0%) and 0/9 (0%) contralateral regional recurrences in patients with pN0 or pN1 disease, respectively, who did not receive contralateral neck irradiation. CONCLUSION: Marginal recurrences highlight the need for generous target volume delineation. Based upon rates of contralateral regional recurrences, a comprehensive approach to target volume selection should be advised for tumour subsites with bilateral lymphatic drainage in the presence of pN2a/b disease.

Functional Imaging Biomarkers: Potential to Guide an Individualised Approach to Radiotherapy.

The identification of robust prognostic and predictive biomarkers would transform the ability to implement an individualised approach to radiotherapy. In this regard, there has been a surge of interest in the use of functional imaging to assess key underlying biological processes within tumours and their response to therapy. Importantly, functional imaging biomarkers hold the potential to evaluate tumour heterogeneity/biology both spatially and temporally. An ever-increasing range of functional imaging techniques is now available primarily involving positron emission tomography and magnetic resonance imaging. Small-scale studies across multiple tumour types have consistently been able to correlate changes in functional imaging parameters during radiotherapy with disease outcomes. Considerable challenges remain before the implementation of functional imaging biomarkers into routine clinical practice, including the inherent temporal variability of biological processes within tumours, reproducibility of imaging, determination of optimal imaging technique/combinations, timing during treatment and design of appropriate validation studies.

Assessment of outcomes with delayed (18)F-FDG PET-CT response assessment in head and neck squamous cell carcinoma.

OBJECTIVE: To assess the accuracy of a 4-month post-(chemo)radiotherapy 18-fludeoxyglucose ((18)F-FDG) positron emission tomography (PET)-CT for head and neck squamous cell carcinoma (HNSCC). METHODS: 105 patients who underwent a baseline and response assessment (18)F-FDG PET-CT scan between 2008 and April 2013 were identified. (18)F-FDG PET-CT outcomes were analysed with reference to clinicopathological outcomes. RESULTS: 79 of 105 (75%) (18)F-FDG PET-CT scans demonstrated a complete metabolic response; 19 of 101 (19%) for assessable primary tumours were positive; and 19 of 93 (20%) for patients with nodal disease were equivocal (n = 10) or positive (n = 9). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for primary and nodal disease were 90%, 89%, 47%, 99% and 91%, 89%, 53% and 99%, respectively. Eight of nine patients with a positive nodal response scan had clinicopathological evidence of residual nodal disease (PPV, 89%). 2 of 10 patients with equivocal nodal responses had clinicopathological evidence of residual nodal disease (PPV, 20%). CONCLUSION: (18)F-FDG PET-CT 4 months post treatment has a very high NPV. A positive (18)F-FDG PET-CT has a high PPV for residual nodal disease. By contrast, patients who have an equivocal nodal response have a low PPV. ADVANCES IN KNOWLEDGE: Response assessment (18)F-FDG PET-CT is a valuable tool in guiding the selective use of neck dissection following (chemo)radiotherapy for HNSCC. An equivocal lymph node response has a limited predictive value for persistent disease, and optimal management remains a clinical challenge.

Involved Node, Site, Field and Residual Volume Radiotherapy for Lymphoma: A Comparison of Organ at Risk Dosimetry and Second Malignancy Risks.

AIMS: Recent radiotherapy guidelines for lymphoma have included involved site radiotherapy (ISRT), involved node radiotherapy (INRT) and irradiation of residual volume after full-course chemotherapy. In the absence of late toxicity data, we aim to compare organ at risk (OAR) dose-metrics and calculated second malignancy risks. MATERIALS AND METHODS: Fifteen consecutive patients who had received mediastinal radiotherapy were included. Four radiotherapy plans were generated for each patient using a parallel pair photon technique: (i) involved field radiotherapy (IFRT), (ii) ISRT, (iii) INRT, (iv) residual post-chemotherapy volume. The radiotherapy dose was 30 Gy in 15 fractions. The OARs evaluated were: breasts, lungs, thyroid, heart, oesophagus. Relative and absolute second malignancy rates were estimated using the concept of organ equivalent dose. Significance was defined as P < 0.005. RESULTS: Compared with ISRT, IFRT significantly increased doses to lung, thyroid, heart and oesophagus, whereas INRT and residual volume techniques significantly reduced doses to all OARs. The relative risks of second cancers were significantly higher with IFRT compared with ISRT for lung, breast and thyroid; INRT and residual volume resulted in significantly lower relative risks compared with ISRT for lung, breast and thyroid. The median excess absolute risks of second cancers were consistently lowest for the residual technique and highest for IFRT in terms of thyroid, lung and breast cancers. The risk of oesophageal cancer was similar for all four techniques. Overall, the absolute risk of second cancers was very similar for ISRT and INRT. CONCLUSIONS: Decreasing treatment volumes from IFRT to ISRT, INRT or residual volume reduces radiation exposure to OARs. Second malignancy modelling suggests that this reduction in treatment volumes will lead to a reduction in absolute excess second malignancy. Little difference was observed in second malignancy risks between ISRT and INRT, supporting the use of ISRT in the absence of a pre-chemotherapy positron emission tomography scan in the radiotherapy treatment position.

Patterns of failure after intensity-modulated radiotherapy in head and neck squamous cell carcinoma using compartmental clinical target volume delineation.

AIMS: To determine the pattern of disease recurrence in non-nasopharyngeal head and neck squamous cell carcinoma (HNSCC) patients treated with radical intensity-modulated radiotherapy (IMRT) with or without chemotherapy, and to correlate the sites of locoregional recurrence with radiotherapy target volumes. MATERIALS AND METHODS: In total, 136 patients treated with radical IMRT with or without chemotherapy between 2008 and 2011 for non-nasopharyngeal HNSCC were retrospectively identified. A compartmental approach to clinical target volume (CTV) delineation was routinely utilised during this period and IMRT was delivered using a 5-7 angle step and shoot technique. Locoregional recurrences were reconstructed on the planning computed tomography scan by both deformable image coregistration and by visual assessment, and were analysed in relation to target volumes and dosimetry. RESULTS: The median follow-up was 31 (range 3-53) months. Two year local control, regional control, disease-free survival, distant metastasis-free survival and overall survival were 86, 93, 78, 89 and 79%, respectively. One hundred and twenty of 136 (88%) patients achieved a complete response to treatment and 7/120 (6%) have subsequently had a locoregional recurrence. Analysis of these recurrences revealed five to be infield; one to be marginal to the high-dose CTV; one to be out-of-field. Overall the marginal/out-of-field recurrence rate was 2/136 (1.5%). CONCLUSIONS: IMRT utilising a compartmental approach to CTV delineation was associated with a low rate of marginal/out-of-field recurrence.

Long-term swallow function after chemoradiotherapy for oropharyngeal cancer: the influence of a prophylactic gastrostomy or reactive nasogastric tube.

AIMS: Two contrasting approaches of a prophylactic gastrostomy or a nasogastric tube as needed are widely used to support patients receiving chemoradiotherapy for head and neck cancer. The influence of the type and timing of enteral feeding tube support upon long-term swallowing is uncertain. This study analysed the patients' perspective on long-term swallowing, comparing two groups of patients who received chemoradiotherapy for oropharyngeal cancer managed with the two approaches. MATERIALS AND METHODS: The MD Anderson Dysphagia Inventory (MDADI) was posted to 63 consecutive patients with oropharyngeal squamous cell cancer treated with concurrent chemoradiotherapy between January 2007 and June 2009, who had not required therapeutic enteral feeding before treatment and who were disease free on follow-up at least 2 years after treatment. RESULTS: In total, 56/63 patients completed questionnaires; 43 had been managed with a prophylactic gastrostomy and 13 with a policy of nasogastric tube as needed. There were no significant differences in all global, emotional, physical or functional domains of the MDADI according to enteral feeding strategy. Diet at 6 months after treatment was significantly correlated with better MDADI scores. CONCLUSIONS: In this study, the choice of a prophylactic gastrostomy or nasogastric tube as needed did not seem to influence long-term swallowing function.

The efficacy of induction chemotherapy with docetaxel, cisplatin and 5-fluorouracil combined with cisplatin concurrent chemoradiotherapy for locally advanced head and neck squamous cell carcinoma: a matched pair analysis.

AIMS: The role of induction chemotherapy (ICT) for head and neck squamous cell carcinoma (HNSCC) is controversial. The aim of the study was to assess the benefit of ICT with docetaxel, cisplatin and 5-fluorouracil (5-FU) (TPF) when combined with concurrent cisplatin chemoradiotherapy (CRT) for HNSCC. MATERIALS AND METHODS: Patients with HNSCC treated between January 2005 and December 2010 with radical intent with either TPF or cisplatin and 5-FU (PF) ICT and documented intention to proceed with concurrent cisplatin CRT were identified retrospectively. The use and choice of ICT regimen was at the clinician's discretion. In total, 68 patients treated with TPF were identified and were matched for T and N stage and tumour site to 68 patients treated with PF. A survival analysis was carried out using Kaplan-Meier and the Cox proportional hazards model. RESULTS: The median follow-up was 29.9 versus 36.3 months for the TPF and PF groups, respectively. Three year locoregional relapse-free survival (RFS), distant RFS, RFS, cancer-specific survival and overall survival rates for the TPF and PF groups were 84.2, 91.6, 82.6, 81.3 and 74.9% versus 73.7, 84.9, 71.9, 72.1 and 62.9%, respectively. On multivariate analysis, treatment with TPF predicted for improved locoregional RFS (P = 0.03) and overall survival (P = 0.05). CONCLUSION: The addition of docetaxel to a cisplatin doublet ICT regimen before concurrent CRT may improve disease control for locally advanced HNSCC.

Increasing the yield of recombinant thyroid-stimulating hormone-stimulated 2-(18-fluoride)-flu-2-deoxy-D-glucose positron emission tomography-CT in patients with differentiated thyroid carcinoma.

OBJECTIVE: The aim of this study was to assess the accuracy of recombinant thyroid-stimulating hormone (rTSH)-stimulated 2-(18-fluoride)-flu-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography (PET)-CT in detecting recurrence in patients with differentiated thyroid cancer. METHODS: Consecutive (18)F-FDG PET-CT scans performed with rTSH stimulation between 2007 and 2010 in patients with a history of papillary or follicular thyroid carcinoma were reviewed. PET-CT findings were correlated with thyroglobulin levels, and histological, clinical and radiological follow-up. RESULTS: 58 rTSH PET-CT scans were performed in 47 patients with a previous thyroidectomy and radioiodine ablation. The only indication for PET-CT was a raised thyroglobulin level in 46 of 58 scans, with the remainder for characterisation of equivocal radiology or staging. 25 (43%) of PET-CT scans were positive for recurrent disease. Histological correlation was available for 21 (36%) scans. The overall sensitivity, specificity, positive predictive value and negative predictive value were 69%, 76%, 72% and 73%, respectively. Median unstimulated thyroglobulin in true-positive scans was 33 µg l(-1) and 2.2 µg l(-1) in the remainder (p=0.12). 4 of 35 (11%) patients with unstimulated thyroglobulin levels <10 µg l(-1) had true-positive scans. Median stimulated thyroglobulin in true-positive scans was 320 µg l(-1), and 10 µg l(-1) in the remainder (p=0.046), with no positive scans with a stimulated thyroglobulin <8 µg l(-1). PET-CT directly influenced patient management in 17/58 (29%) scans. CONCLUSION: rTSH PET-CT is a useful imaging technique for detecting disease recurrence in patients with iodine-resistant differentiated thyroid cancer. Low stimulated thyroglobulin levels are potentially useful in identifying patients unlikely to benefit from a PET-CT scan.

Delayed response assessment with FDG-PET-CT following (chemo) radiotherapy for locally advanced head and neck squamous cell carcinoma.

AIMS: To analyse the diagnostic accuracy of delayed response assessment 2-[¹8F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography-computed tomography (PET-CT) following (chemo)radiation for locally advanced head and neck squamous cell carcinoma (HNSCC). MATERIAL AND METHODS: Forty-four consecutive patients who underwent a baseline and response assessment using FDG PET-CT for HNSCC following (chemo)radiation between August 2008 and April 2011 were identified retrospectively. Clinicopathological findings and serial clinical follow-up provided the reference standard. RESULTS: Median follow-up was 14 months (range 5-43 months). Response assessment FDG PET-CT was performed at 16.8 weeks (inter-quartile range 15.8-18.6 weeks). Thirty-one out of 44 (70%) response assessment examinations showed a complete metabolic response. Seven out of 40 (18%) assessable primary tumours were positive. Eight out of 41 (20%) patients with pre-treatment nodal disease had equivocal or positive FDG uptake at response assessment. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for primary disease and nodal disease were 100, 89, 43, 100, and 100%, and 92, 63, and 100%, respectively. Seven patients had residual FDG-negative soft tissue detectable on the unenhanced CT component of the response assessment images; all remained disease free after clinical observation. Distant metastases were detected on response assessment FDG PET-CT in four out of the 44 patients (10%). CONCLUSION: The diagnostic accuracy of response assessment with FDG PET-CT performed at approximately 16 weeks post-(chemo)radiotherapy is good. The very high NPV of a complete metabolic response can be used to guide management decisions. Although the PPV is limited for local residual disease, FDG PET-CT is a powerful screening tool for the detection of interim metastatic disease.

Improving target definition for head and neck radiotherapy: a place for magnetic resonance imaging and 18-fluoride fluorodeoxyglucose positron emission tomography?

Defining the target for head and neck radiotherapy is a critical issue with the introduction of steep dose gradients associated with intensity-modulated radiotherapy. Tumour delineation inaccuracies are a major source of error in radiotherapy planning. The integration of 18-fluoride fluorodeoxyglucose positron emission tomography ((18)FDG-PET) and magnetic resonance imaging directly into the radiotherapy planning process has the potential to greatly improve target identification/selection and delineation. This raises a range of new issues surrounding image co-registration, delineation methodology and the use of functional data and treatment adaptation. This overview will discuss the practical aspects of integrating (18)FDG-PET and magnetic resonance imaging into head and neck radiotherapy planning.