Long-Term Outcomes of De-Intensified Chemoradiotherapy for Human Papillomavirus-Associated Oropharyngeal Squamous Cell Carcinoma

PURPOSE/OBJECTIVE(S)

To report long-term oncologic outcomes among patients with human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) treated with definitive de-intensified chemoradiotherapy.

MATERIALS/METHODS

Major criteria for de-intensification were (1) AJCC 7th edition T0-T3, N0-N2c, M0 (AJCC 8th edition T0-T3, N0-N2, M0), (2) pathologically confirmed p16 positive, and (3) no or minimal/remote smoking history (non-mutated p53 if ≥30 pack-years). Treatment was 60 Gy intensity-modulated radiotherapy with first-choice concurrent cisplatin 30 mg/m2 once per week (alternative regimens permissible for cisplatin ineligible patients). Patients with T0-T2 N0-1 (AJCC 7th edition) were recommended 60 Gy radiation alone. Systemic therapy received included: cisplatin 30 mg/m2 (n = 122), cetuximab (n = 15), cisplatin 40 mg/m2 (n = 12), carboplatin/paclitaxel (n = 2), and radiation alone (n = 25). Kaplan Meier estimates for overall survival (OS), progression-free survival (PFS), locoregional control (LRC), and freedom from distant metastasis (FFDM) were calculated. Cox regression models were used for comparisons among subgroups.

RESULTS

A total 176 patients received de-intensified treatment (n = 153 prospective protocol, n = 23 off-protocol). Median follow-up was 52.6 months (range 5.3 - 102.0, 90.8% with minimum 2-year follow-up); 56.8% (n = 100) were never smokers and 43.2% (n = 76) former smokers; former smokers had median 9 pack-years smoking history (range 0.25 - 50) with 46% ≥10 pack-years. Outcomes were as follows: 2-year OS 99.4% and 5-year OS 91.8%; 2-year PFS 94.1% and 5-year PFS 84.3%; 2-year LRC 98.3% and 5-year LRC 95.8%; 2-year FFDM 95.8% and 5-year FFDM 93.2%. Median time to progression events were 21.1 months (range, 7.2 - 54.1) with 37.5% (6 of 16) of recurrences occurring after 24 months. Six total locoregional events occurred (five recurrences and one site of persistent disease), within the 60 Gy planning target volume. Twenty-three patients with T0-T2 N0-1 disease received radiation alone with 2-year PFS 92.9% (5-year 83.8%) and 2-year LRC 100% (5-year 95.2%). Outcomes for former smokers with ≥10 pack-years were comparable to patients with less or no smoking history (2-year PFS 94.1% vs 94.1%; 5-year PFS 90.6% vs 82.7%; HR 0.58, p = 0.38). Early results suggest similar oncologic outcomes among those treated off-protocol (median follow-up 25.6 months) with 1 of 23 patients experiencing locoregional recurrence.

CONCLUSION

Dose de-intensification of 60 Gy radiotherapy with weekly cisplatin results in favorable long-term tumor control in patients with HPV-associated OPSCC. De-intensified 60 Gy alone may be efficacious in carefully selected patients with T0-T2 N0-1 (AJCC 7th edition) disease. Inclusion of biologically favorable patients with more extensive former smoking history in de-intensification clinical trials may be warranted.

Definitive Chemoradiation Treatment Response Evaluation Using NI-RADS and ctHPVDNA for HPV-Associated Oropharyngeal Squamous Cell Carcinoma

PURPOSE/OBJECTIVE(S)

To compare the evaluation of treatment response among patients with human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) treated with definitive (chemo)radiotherapy (CRT).

MATERIALS/METHODS

Patients with locally advanced HPV-associated OPSCC treated with definitive radiotherapy (RT) or CRT from 2019 to 2022 at a single institution were reviewed. Patients underwent standard 3-month post-CRT positron emission tomography/computed tomography (PET/CT) scan with or without contrast enhanced CT (CECT) of the head and neck. Plasma circulating tumor HPV DNA (ctHPVDNA) was collected from 2-8 months post-CRT. Equivocal findings on post-CRT imaging prompted repeat evaluation. Imaging response was assessed via NI-RADS (Neck Imaging Reporting and Data System) risk classification and independently reviewed by two board certified radiologists, both blinded to outcomes and ctHPVDNA values.

RESULTS

Our cohort of 52 patients included: 87% males; median age 61.5; 63% never smokers, 31% former smokers, 6% current smokers; 44% tonsil primary, 46% base of tongue; 4% T0, 25% T1, 40% T2, 12% T3, 17% T4; 6% N0, 15% N1, 2% N2a, 44% N2b, 25% N2c, 8% N3 (AJCC 7th edition). Concurrent systemic therapy was received in 90%. During this period 71 PET/CTs and 15 CECTs were reviewed for treatment response evaluation; 44% (23/52) patients required additional imaging for equivocal findings; 62 ctHPVDNA blood samples were co-analyzed for treatment evaluation. The highest risk classification score between mucosa, primary, and/or neck site was: 42% NI-RADS 1, 48% NI-RADS 2, and 10% NI-RADS 3. Only patients with locoregional disease recurrence/progression were included for evaluation comparison between imaging and circulating biomarkers. No cancer events occurred without imaging and/or ctHPVDNA detection. Patients with NI-RADS score ≥2 during first post-CRT imaging evaluation more frequently underwent additional imaging (70% vs 30%, p<0.001). NI-RADS risk classification suggested 5 locoregional events (2 true positives, 3 false positives) resulting in 100% sensitivity, 94% specificity, 40% positive predictive value (PPV), and 100% negative predictive value (NPV). Circulating tumor HPV-DNA identified 2 locoregional events (2 true positives, 0 false positives) resulting in 100% sensitivity, 100% specificity, 100% PPV, and 100% NPV. Salvage operations were performed in 2 of 3 patients with false positive disease by NI-RADS classification without any evidence of cancer on final pathology.

CONCLUSION

While limited by the small number of recurrence events in this cohort, ctHPVDNA for HPV-associated OPSCC in conjunction with post-treatment imaging evaluation may limit the need for repeat imaging and unwarranted salvage operations that increase patient worry, morbidity, and financial toxicity. Additional prospective study is warranted.

Solar superstorm of AD 774 recorded subannually by Arctic tree rings

Recently, a rapid increase in radiocarbon (¹⁴C) was observed in Japanese tree rings at AD 774/775. Various explanations for the anomaly have been offered, such as a supernova, a γ-ray burst, a cometary impact, or an exceptionally large Solar Particle Event (SPE). However, evidence of the origin and exact timing of the event remains incomplete. In particular, a key issue of latitudinal dependence of the ¹⁴C intensity has not been addressed yet. Here, we show that the event was most likely caused by the Sun and occurred during the spring of AD 774. Particularly, the event intensities from various locations show a strong correlation with the latitude, demonstrating a particle-induced ¹⁴C poleward increase, in accord with the solar origin of the event. Furthermore, both annual ¹⁴C data and carbon cycle modelling, and separate earlywood and latewood ¹⁴C measurements, confine the photosynthetic carbon fixation to around the midsummer.

Tree rings retain information of sudden variations of ancient radiocarbon (¹⁴C) content, however the origin and exact timing of these events often remain uncertain. Here, the authors analyze a set of Arctic tree rings and link a rapid increase in ¹⁴C to a solar event that occurred during the spring of AD 774.

Positron emission tomography imaging for herpes virus infection: Implications for oncolytic viral treatments of cancer

Molecular therapy using viruses would benefit greatly from a non-invasive modality for assessing dissemination of viruses. Here we investigated whether positron emission tomography (PET) scanning using [(124)I]-5-iodo-2'-fluoro-1-beta-d-arabinofuranosyl-uracil (FIAU) could image cells infected with herpes simplex viruses (HSV). Using replication-competent HSV-1 oncolytic viruses with thymidine kinase (TK) under control of different promoters, we demonstrate that viral infection, proliferation and promoter characteristics all interact to influence FIAU accumulation and imaging. In vivo, as few as 1 x 107 viral particles injected into a 0.5-cm human colorectal tumor can be detected by [(124)I]FIAU PET imaging. PET signal intensity is significantly greater at 48 hours compared with that at 8 hours after viral injection, demonstrating that PET scanning can detect changes in TK activity resulting from local viral proliferation. We also show the ability of FIAU-PET scanning to detect differences in viral infectivity at 0.5 log increments. Non-invasive imaging might be useful in assessing biologically relevant distribution of virus in therapies using replication-competent HSV.