The Effects of Human Papillomavirus Status and Treatment on the Positive Predictive Value of Post-radiotherapy 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography in Advanced Head and Neck Squamous Cell Carcinoma

AIMS

The high negative predictive value of post-chemoradiation (CRT) positron emission tomography-computed tomography (PET-CT) is well established in head and neck squamous cell cancers (HNSCC). The positive predictive value (PPV) remains under scrutiny, with increasing evidence that it is affected by several factors. The aim of this study was to assess the PPV of post-treatment PET-CT for residual nodal disease when stratified by treatment modality and tumour human papillomavirus (HPV) status.

MATERIALS AND METHODS

This was a retrospective cohort study in a tertiary oncology centre carried out between January 2013 and December 2019. Patients were radically treated with radiotherapy only/CRT for node-positive HNSCC. PET-CT nodal responses were categorised as complete, equivocal (EQR) or incomplete (ICR), and outcomes extracted from electronic records.

RESULTS

In total, 480 patients were evaluated, all had a minimum potential follow-up of 2 years, with a median of 39.2 months. The PPV of 12-week PET-CT was significantly different between HPV-positive (22.5%) and HPV-unrelated (52.7%) disease, P < 0.001. It was also significantly different between the CRT (24.8%) and radiotherapy-only (51.1%) groups, P = 0.001. The PPV of an EQR was significantly less than an ICR, irrespective of HPV status and primary treatment modality. In HPV-positive disease, the PPV of an EQR was 9.0% for the CRT group compared with 21.4% for radiotherapy only, P = 0.278. The PPV in those who achieved an ICR was 34.2% in the CRT group, significantly lower than 70.0% in the radiotherapy-only group, P = 0.03.

CONCLUSION

The PPV of 12-week PET-CT is significantly lower for HPV-positive compared with HPV-unrelated HNSCC. It is poorer in patients with HPV-positive disease treated with CRT compared with radiotherapy alone.

Positron Emission Tomography-Computed Tomography Surveillance after (Chemo)Radiotherapy in Advanced Head and Neck Squamous Cell Cancer: Beyond the PET-NECK Protocol

AIMS

To evaluate the implementation of 18-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) surveillance after (chemo)radiotherapy, to compare outcomes for those who achieved a complete (CR), equivocal (EQR) and incomplete (ICR) nodal response on 12-week PET-CT according to their human papillomavirus (HPV) status, and to assess the safety of ongoing surveillance beyond 12 weeks in the HPV-positive EQR group.

MATERIALS AND METHODS

All patients with node-positive head and neck squamous cell carcinoma (HNSCC) treated with (chemo)radiotherapy between January 2013 and September 2017 were identified. PET-CT responses were classified as CR, ICR or EQR. Patient outcomes were obtained from electronic records.

RESULTS

In total, 236 patients with a minimum of 2 years of follow-up were identified. The mean age was 59 years; 79.3% had N2 disease; 77.1% of patients had oropharyngeal cancer and 10.1% had squamous cell carcinoma of unknown primary, of whom 82.0% (169) were HPV positive; 78.0% received chemoradiotherapy. The median time from the end of radiotherapy to PET-CT was 91 days. Of the HPV-related HNSCC, 60.4% achieved CR, 29.0% EQR and 10.6% ICR. With a median follow-up of 41.7 months, there was no difference in survival between patients with HPV-related HNSCC achieving CR and EQR (median overall survival not reached for both, P = 0.67) despite the omission of immediate neck dissection in 98.0% of the EQR group.

CONCLUSION

Patients with HPV-positive HNSCC who have achieved EQR have comparable survival outcomes to those who achieved a CR despite the omission of immediate neck dissections; this shows the safety of ongoing surveillance beyond 12 weeks in this group of patients.

Effect of intradermal anaesthesia on success rate and pain of intravenous cannulation: a randomized non-blind crossover study

Intravenous cannulation is a commonly performed procedure. This study aimed to determine whether the success rate and pain of intravenous cannulation is affected by prior injection of intradermal lidocaine. Intravenous cannulation was performed twice in 45 healthy volunteers. Intradermal lidocaine was administered prior to one of these cannulations. The outcome measures were success or failure of cannulation, and pain of cannulation, measured with a 100 mm visual analogue pain scale. The success rate of intravenous cannulation with and without prior intradermal lidocaine was 54% and 76%, respectively. The difference was 22.0% (95% CI 1.5-27.8%; P = 0.03). Log-linear analysis for three-way interaction between the variables (outcome, vascular condition and use of lidocaine) showed a significant influence of vascular condition on outcome (G(2) 24.6, P < 0.001). The mean (SD) pain scores in the control and intervention group were 34.8 (21.0) and 13.6 (13.2) mm, respectively. The difference between the mean pain scores was 21.2 mm (95% CI 15.1-27.3 mm). In conclusion, the success rate of intravenous cannulation may be reduced with the use of intradermal lidocaine, but success rate is primarily dependent on vascular condition. Intradermal lidocaine achieves a clinically significant reduction in the pain of intravenous cannulation.