HPV-related oropharyngeal cancer: Risk factors for treatment failure in patients managed with primary transoral robotic surgery

Transoral robotic surgery for oropharyngeal cancer: a systematic review on the role of margin status

INTRODUCTION

Nowadays, robotic surgery finds application in the field of head and neck in the treatment of oropharyngeal tumors. The aim of this work is to examine the efficacy of transoral robotic surgery (TORS) in performing safe oncological resections of oropharyngeal squamous cell carcinoma (OPSCC), with particular attention to the status of margins.

EVIDENCE ACQUISITION

Literature search of English-language studies focused on TORS through PubMed, the Cochrane Library and EMBASE databases. A total of 431 papers returned to search, but only 24 met the inclusion criteria. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Guidelines.

EVIDENCE SYNTHESIS

Within the selected studies, the overall rate of OPSCC positive margins following TORS is minimal, especially when patient selection is adequate and when TORS is used by high volume centers.

CONCLUSIONS

TORS is a very precise and viable therapeutic tool that provides good results in terms of surgical radicality with low positive margin rates and good results in terms of overall survival and disease-free survival; however, there is still a great heterogeneity in margins definition within the available literature. Consequently, even if this surgical approach is very promising, it is still challenging to draw firm conclusions nowadays.

Predictors for Success and Failure in Transoral Robotic Surgery-A Retrospective Study in the North of the Netherlands

Transoral Robotic Surgery (TORS) is utilized for treating various malignancies, such as early-stage oropharyngeal cancer and lymph node metastasis of an unknown primary tumor (CUP), and also benign conditions, like obstructive sleep apnea (OSA) and chronic lingual tonsillitis. However, the success and failure of TORS have not been analyzed to date. In this retrospective observational multicenter cohort study, we evaluated patients treated with TORS using the da Vinci surgical system. Success criteria were defined as identification of the primary tumor for CUP, >2 mm resection margin for malignant conditions, and improvement on respiratory polygraphy and tonsillitis complaints for benign conditions. A total of 220 interventions in 211 patients were included. We identified predictors of success, such as low comorbidity status ACE-27, positive P16 status, and lower age for CUP, and female gender and OSA severity for benign conditions. For other malignancies, no predictors for success were found. Predictors of failure based on postoperative complications included high comorbidity scores (ASA) and anticoagulant use, and for postoperative pain, younger age and female gender were identified. This study provides valuable insights into the outcomes and predictors of success and failure in TORS procedures across various conditions and may also help in patient selection and counseling.

Diagnostic challenges and prognostic implications of extranodal extension in head and neck cancer: a state of the art review and gap analysis

Extranodal extension (ENE) is a pattern of cancer growth from within the lymph node (LN) outward into perinodal tissues, critically defined by disruption and penetration of the tumor through the entire thickness of the LN capsule. The presence of ENE is often associated with an aggressive cancer phenotype in various malignancies including head and neck squamous cell carcinoma (HNSCC). In HNSCC, ENE is associated with increased risk of distant metastasis and lower rates of locoregional control. ENE detected on histopathology (pathologic ENE; pENE) is now incorporated as a risk-stratification factor in human papillomavirus (HPV)-negative HNSCC in the eighth edition of the American Joint Committee on Cancer (AJCC) and the Union for International Cancer Control (UICC) TNM classification. Although ENE was first described almost a century ago, several issues remain unresolved, including lack of consensus on definitions, terminology, and widely accepted assessment criteria and grading systems for both pENE and ENE detected on radiological imaging (imaging-detected ENE; iENE). Moreover, there is conflicting data on the prognostic significance of iENE and pENE, particularly in the context of HPV-associated HNSCC. Herein, we review the existing literature on ENE in HNSCC, highlighting areas of controversy and identifying critical gaps requiring concerted research efforts.

Trans oral robotic surgery for oropharyngeal cancer: A multi institutional experience

OBJECTIVES

Trans Oral Robotic Surgery (TORS) has proved to be a safe and feasible treatment for oropharyngeal squamous cell carcinoma (OPSCC). The aim of this study is to analyse oncological outcomes of OPSCC patients treated with TORS.

MATERIALS AND METHODS

This study involved 139 patients with OPSCC, treated with TORS between 2008 and 2020. Clinicopathological characteristics, treatment details and oncological outcomes were evaluated retrospectively.

RESULTS

The management strategies included TORS alone in 42.5%, TORS-RT in 25.2% and TORS-CRT in 30.9%. The ENE was noted in 28.8% of neck dissections. In 19 patients clinically classified as unknown primaries, the primary was found in 73.7%. Rates of local, regional relapses and distant metastasis were 8.6%, 7.2%, and 6.5%, respectively. The 5 year- Overall Survival and Disease Free Survival were 69.6% and 71.3%, respectively.

CONCLUSION

TORS fits well in the modern management of OPSCC. Although definitive CRT remains a milestone, TORS is proving to be a valid and safe treatment option. The choice of the therapeutic strategy requires evaluation by a multidisciplinary team.

Predictive Value of 18F-Fluorodeoxyglucose Positron-Emission Tomography Metabolic and Volumetric Parameters for Systemic Metastasis in Tonsillar Cancer

Although the prognosis of tonsillar cancer (human papillomavirus-positive oropharyngeal squamous cell carcinoma) is improving, disease control failure (distant metastasis) still occurs in some cases. We explored whether several 18F-fluorodeoxyglucose (FDG) positron-emission tomography (PET) parameters can predict metastasis. We retrospectively reviewed the medical records of 55 patients with tonsil squamous cell carcinoma who underwent pretreatment 18F-FDG positron-emission tomography/computed tomography (PET/CT) followed by primary surgery. During the follow-up period, systemic metastases were found in 7 of the 55 patients. The most common sites were the lungs (33%), bone (22%), brain/skull base (22%), small bowel (11%), and liver (11%). Pathologically, P53 mutation was less common in patients with systemic metastasis (41.7% vs. 14.3%, p = 0.054) than without systemic metastasis. In terms of PET parameters, the metabolic tumor volume (MTV2.5) and total lesion glycolysis (TLG2.5) values were lower in the primary tumor, and higher in the metastatic lymph nodes, of human papillomavirus (HPV)-positive compared to HPV-negative patients (all p < 0.05). The MTV2.5, TLG2.5, and tumor−to−liver uptake ratio were 36.07 ± 54.24 cm3, 183.46 ± 298.62, and 4.90 ± 2.77, respectively, in the systemic metastasis group, respectively; all of these values were higher than those of the patients without systemic metastasis (all p < 0.05). The MTV2.5 value was significantly different between the groups even when the values for the primary tumor and metastatic lymph nodes were summed (53.53 ± 57.78 cm3, p = 0.036). The cut-off value, area under the curve (95% confidence interval), sensitivity, and specificity of MTV2.5 for predicting systemic metastasis were 11.250 cm3, 0.584 (0.036−0.832), 0.571, and 0.565, respectively. The MTV2.5 of metastatic lymph nodes and summed MTV2.5 values of the primary tumor and metastatic lymph nodes were significantly higher in tonsillar cancer patients with than without systemic metastases. We suggest PET/CT scanning for pre-treatment cancer work-up and post-treatment surveillance to consider additional systemic therapy in patients with a high risk of disease control failure.

Revision Transoral Robotic Surgery for Early Stage HPV Positive Oropharyngeal Squamous Cell Carcinoma, it's Timing and Margins: Past and Present- a Prospective Single Centre Observational Study

To review cohort of patients with HPV positive early stage oropharyngeal cancer that underwent revision trans oral robotic surgery for positive or close margin for evidence of residual disease, its impact on survival and discussion about clear margin. This is a prospective observational study. Our TORS revision rate was 20.6%. 91.7% did not need radiotherapy to primary site; mean recurrence free survival is 31 months and no mortality in this cohort due to the primary disease. There is no consensus on what is clear margin. The surgical margins are a surrogate marker for later recurrences or long-term survival and this is what guides our treatment but equally attempts should be made to preserve their function and not increase the morbidity.

Human Papillomavirus-Related Non-Metastatic Oropharyngeal Carcinoma: Current Local Treatment Options and Future Perspectives

Over the last two decades, human papillomavirus (HPV) has caused a new pandemic of cancer in many urban areas across the world. The new entity, HPV-associated oropharyngeal squamous cell carcinoma (OPSCC), has been at the center of scientific attention ever since, not only due to its distinct biological behavior, but also because of its significantly better prognosis than observed in its HPV-negative counterpart. The very good treatment outcomes of the disease after primary therapy (minimally-invasive surgery, radiation therapy with or without chemotherapy) resulted in the creation of a separate staging system, reflecting this excellent prognosis. A substantial proportion of newly diagnosed HPV-driven OPSCC is diagnosed in stage I or II, where long-term survival is observed worldwide. Deintensification of the primary therapeutic methods, aiming at a reduction of long-term toxicity in survivors, has emerged, and the quality of life of the patient after treatment has become a key-point in many clinical trials. Current treatment recommendations for the treatment of HPV-driven OPSCC do not differ significantly from HPV-negative OPSCC; however, the results of randomized trials are eagerly awaited and deemed necessary, in order to include deintensification into standard clinical practice.

Adjuvant Radiotherapy in Surgically Treated HPV-Positive Oropharyngeal Carcinoma with Adverse Pathological Features

Purpose: HPV-positive oropharyngeal carcinoma (HPV-OPC) is increasingly treated with primary surgery. The National Comprehensive Cancer Network (NCCN) recommends adjuvant therapy for surgically treated HPV-OPC displaying adverse pathological features (AF). We evaluated adjuvant radiotherapy patterns and outcomes in surgically treated AF-positive HPV-OPC (AF-HPV-OPC). Methods: The National Cancer Database was interrogated for patients ≥ 18 years with early-stage HPV-OPC from 2010 to 2017 who underwent definitive resection. Patients that had an NCCN-defined AF indication for adjuvant radiotherapy were assessed, including positive surgical margins (PSM), extranodal extension (ENE), lymphovascular invasion, and level 4/5 cervical lymph nodes. Overall survival (OS) was evaluated using Cox proportional hazards models and Kaplan−Meier analysis in whole and propensity score matched (PM) cohorts. Results: Of 15,036 patients meeting inclusion criteria, 55.7% were positive for at least one AF. Presence of any AF was associated with worse OS (hazard ratio (HR) = 1.56, p < 0.001). In isolation, each AF was associated with worse OS. On PM analysis, insurance status, T2 category, Charlson-Deyo comorbidity score, ENE (HR = 1.81, p < 0.001), and PSM (HR = 1.58, p = 0.002) were associated with worse OS. Median 3-year OS was 92.0% among AF-HPV-OPC patients undergoing adjuvant radiotherapy and 84.2% for those who did not receive adjuvant radiotherapy (p < 0.001, n = 1678). The overall rate of patients with AF-HPV-OPC who did not receive adjuvant radiotherapy was 13% and increased from 10% in 2010 to 17% in 2017 (ptrend = 0.007). Conclusions: In patients with AF-HPV-OPC, adjuvant radiotherapy is associated with improved survival. In the era of de-escalation therapy for HPV-OPC, our findings demonstrate the persistent prognostic benefit of post-operative radiotherapy in the setting of commonly identified adverse features. Ongoing clinical trials will better elucidate optimized patient selection for de-escalated therapy.

Transoral Robotic Surgery for Oropharyngeal Squamous Cell Carcinoma of the Tonsil versus Base of Tongue: A Systematic Review and Meta-Analysis

Simple Summary

Transoral Robotic Surgery (TORS) has become widely adopted for the surgical removal of oropharyngeal squamous cell carcinoma (OPSCC). However, it is currently unknown if TORS has equal efficacy and outcomes in patients with tonsillar or base of tongue (BOT) OPSCC. Therefore, we performed a systematic review, including articles describing the surgical management of OPSCC with TORS that compared margin status, complications, and recurrence between tonsil and BOT. BOT OPSCC had a higher rate of positive margins compared to tonsillar OPSCC. However, no differences were seen in the recurrence or postoperative hemorrhage rates of BOT and tonsillar OPSCC. While a higher rate of positive margins was seen in BOT OPSCC when compared to tonsillar OPSCC, this did not translate to a higher recurrence rate in the BOT group. Future research on which subset of patients with BOT is more likely to have positive margins is warranted to improve the utility of TORS further.

Abstract

Transoral Robotic Surgery (TORS) has become widely adopted for the surgical removal of oropharyngeal squamous cell carcinoma (OPSCC), with the most common locations being in the tonsil and base of tongue (BOT). However, it is currently unknown if TORS has equal efficacy and outcomes in patients with tonsillar or BOT OPSCC. Therefore, the aim of this study was to compare the margin status and recurrence rates of tonsillar and BOT OPSCC after TORS. Per PRISMA guidelines, PubMed, Scopus, and CINAHL were systematically searched from inception to 2/28/2022. Articles including the surgical management of OPSCC with TORS that compared margin status, complications, and recurrence between tonsil and BOT were included. Meta-analyses of proportions and odds ratios were performed. A total of 28 studies were included, comprising 1769 patients with tonsillar OPSCC and 1139 patients with BOT OPSCC. HPV positivity was seen in 92.3% of tumors. BOT OPSCC had a higher rate of positive margins compared to tonsillar OPSCC (28.1% [95%CI 15.1–43.3] vs. 7.5% [95%CI 3.3–13.3]). No differences were seen in recurrence between BOT and tonsillar OPSCC (OR 1.1 [95%CI 0.8–1.5], p = 0.480). In addition, no differences in postoperative hemorrhage were seen between tonsillar and BOT OPSCC (10.7% [95%CI 6.1–16.5] vs. 8.8% [95% CI 1.5–21.3]). While a higher rate of positive margins was seen in BOT OPSCC when compared to tonsil OPSCC, this did not translate to a higher recurrence rate in the BOT group. Future research on which subset of patients with BOT is more likely to have positive margins is warranted to improve the utility of TORS further.

Multicentre study on resection margins in carcinoma of the oral cavity, oro-hypopharynx and larynx

Objective

The prognostic significance of the resection margins is still subject of conflicting opinions. The purpose of this paper is to report the results of a study on the margins in carcinoma of the oral cavity, oro-hypopharynx and larynx.

Methods

A multicentre prospective study was carried out between 2015 and 2018 with the participation of 10 Italian reference hospitals. The primary objective was to evaluate local control in patients with well-defined clinical characteristics and comprehensive histopathological information.

Results

During the study period, 455 patients were enrolled; the minimum follow-up was 2 years. Previous treatment, grading and fresh specimen examination were identified as risk factors for local control in multivariate analysis. On the basis of these results, it seems possible to delineate “risk profiles” for different oncological outcomes.

Discussion

The prognostic significance of the margins is reduced, and other risk factors emerge, which require diversified treatment and follow-up.

Conclusions

Multidisciplinary treatment with adjuvant therapy, if indicated, reduces the prognostic importance of margins. Collaboration with a pathologist is an additional favourable prognostic factor and quality indicator.

An appendix with literature review is present in the online version.

NCCN Guidelines® Insights: Head and Neck Cancers, Version 1.2022

The NCCN Guidelines for Head and Neck Cancers address tumors arising in the oral cavity (including mucosal lip), pharynx, larynx, and paranasal sinuses. Occult primary cancer, salivary gland cancer, and mucosal melanoma (MM) are also addressed. The specific site of disease, stage, and pathologic findings guide treatment (eg, the appropriate surgical procedure, radiation targets, dose and fractionation of radiation, indications for systemic therapy). The NCCN Head and Neck Cancers Panel meets at least annually to review comments from reviewers within their institutions, examine relevant new data from publications and abstracts, and reevaluate and update their recommendations. These NCCN Guidelines Insights summarize the panel's most recent recommendations regarding management of HPV-positive oropharynx cancer and ongoing research in this area.

Phase II Randomized Trial of Transoral Surgery and Low-Dose Intensity Modulated Radiation Therapy in Resectable p16+ Locally Advanced Oropharynx Cancer: An ECOG-ACRIN Cancer Research Group Trial (E3311)

PURPOSE

Definitive or postoperative chemoradiation (CRT) is curative for human papillomavirus-associated (HPV+) oropharynx cancer (OPC) but induces significant toxicity. As a deintensification strategy, we studied primary transoral surgery (TOS) and reduced postoperative radiation therapy (RT) in intermediate-risk HPV+ OPC.

METHODS

E3311 is a phase II randomized trial of reduced- or standard-dose postoperative RT for resected stage III-IVa (American Joint Committee on Cancer-seventh edition) HPV+ OPC, determined by pathologic parameters. Primary goals were feasibility of prospective multi-institutional study of TOS for HPV+ OPC, and oncologic efficacy (2-year progression-free survival) of TOS and adjuvant therapy in intermediate-risk patients after resection. TOS plus 50 Gy was considered promising if the lower limit of the exact 90% binomial confidence intervals exceeded 85%. Quality of life and swallowing were measured by functional assessment of cancer therapy-head and neck and MD Anderson Dysphagia Index.

RESULTS

Credentialed surgeons performed TOS for 495 patients. Eligible and treated patients were assigned as follows: arm A (low risk, n = 38) enrolled 11%, intermediate risk arms B (50 Gy, n = 100) or C (60 Gy, n = 108) randomly allocated 58%, and arm D (high risk, n = 113) enrolled 31%. With a median 35.2-month follow-up for 359 evaluable (eligible and treated) patients, 2-year progression-free survival Kaplan-Meier estimate is 96.9% (90% CI, 91.9 to 100) for arm A (observation), 94.9% (90% CI, 91.3 to 98.6]) for arm B (50 Gy), 96.0% (90% CI, 92.8 to 99.3) for arm C (60 Gy), and 90.7% (90% CI, 86.2 to 95.4) for arm D (66 Gy plus weekly cisplatin). Treatment arm distribution and oncologic outcome for ineligible or step 2 untreated patients (n = 136) mirrored the 359 evaluable patients. Exploratory comparison of functional assessment of cancer therapy-head and neck total scores between arms B and C is presented.

CONCLUSION

Primary TOS and reduced postoperative RT result in outstanding oncologic outcome and favorable functional outcomes in intermediate-risk HPV+ OPC.

Therapeutic strategies for systemic therapies of human papillomavirus-related oropharyngeal cancer

Our understanding of human papillomavirus (HPV)-related oropharyngeal cancer (OPC) and its molecular basis continues to evolve and produce important insights into customized therapeutic strategies. Novel therapeutics exploiting HPV-related targets are being evaluated in the incurable setting, while the favorable prognosis of locoregionally advanced disease has stimulated investigation into de-escalation strategies. There is much opportunity for better personalization of standard therapy according to HPV status. This review discusses both current and investigational therapeutic strategies for HPV-related OPC.

Oropharyngeal Carcinoma Treated with Surgery Alone: Outcomes and Predictors of Failure

OBJECTIVE

To analyze the oncologic outcomes and risk factors for recurrence in patients who underwent surgery for oropharyngeal squamous cell carcinoma (OPSCC), and in whom adjuvant therapy was not recommended or was declined.

METHODS

Retrospective cohort study of patients with OPSCC who were treated with transoral surgery only at a tertiary care academic medical center from April 2010 to March 2019.

RESULTS

Seventy-four patients met inclusion criteria. In 16, adjuvant therapy was recommended but declined. There were 8 recurrences, of which 6 had been given recommendations for adjuvant therapy. Of the 8 recurrences, 2 died, 2 are alive with disease, and 4 were successfully salvaged. Five patients died of unrelated causes. Lymphovascular invasion (LVI, P = .016) had a significant impact on recurrence, while other pathologic features of the primary tumor such as size, location, human papillomavirus (HPV) status, and margin status did not. Margins were classified as "positive" in 4 patients, "close" in 54, and "negative" in 16. There were 3 local recurrences (4.1%), each of whom had declined adjuvant therapy. Lymph node features such as N-stage (P = .0004), number of positive nodes (P = .0005), and presence of extra-nodal extension (ENE, P = .0042) had a statistically significant impact on relapse. Smoking history and surgical approach showed no significant impact on recurrence.

CONCLUSION

Patients who undergo surgery for HPV-positive OPSCC with negative margins, no PNI, no LVI, and ≤1 positive lymph node without ENE have low risk for recurrence. These patients can likely be safely treated with surgery alone. Patients with these risk factors who decline adjuvant therapy are at risk for recurrence, and should be monitored.

Impact of surgical margins on local control in patients undergoing single-modality transoral robotic surgery for HPV-related oropharyngeal squamous cell carcinoma

BACKGROUND

The impact of close surgical margins on oncologic outcomes in HPV-related oropharyngeal squamous cell carcinoma (HPV + OPSCC) is unclear.

METHODS

Retrospective case series including patients undergoing single modality transoral robotic surgery (TORS) for HPV + OPSCC at three academic medical centers from 2010 to 2019. Outcomes were compared between patients with close surgical margins (<1 mm or requiring re-resection) and clear margins using the Kaplan-Meier method.

RESULTS

Ninety-nine patients were included (median follow-up 21 months, range 6-121). Final margins were close in 22 (22.2%) patients, clear in 75 (75.8%), and positive in two (2.0%). Eight patients (8.1%) recurred, including two local recurrences (2.0%). Four patients died during the study period (4.0%). Local control (p = 0.470), disease-free survival (p = 0.513), and overall survival (p = 0.064) did not differ between patients with close and clear margins.

CONCLUSIONS

Patients with close surgical margins after TORS for HPV + OPSCC without concurrent indications for adjuvant therapy may be considered for observation alone.

HPV/p16-positive oropharyngeal cancer treated with transoral robotic surgery: The roles of margins, extra-nodal extension and adjuvant treatment

PURPOSE

Human papilloma virus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) treatment outcomes are re-defining management. Traditional margins, the role of extranodal extension (ENE) and adjuvant treatment intensity continue to be debated. This study aimed to determine the impact of margins, ENE and adjuvant therapy on survival following transoral robotic surgery (TORS).

METHODS

Patients treated with TORS at an academic center were retrospectively identified (2013-2019). Survival outcomes were evaluated using Kaplan-Meier curves.

RESULTS

48 patients were included. 40 (83%) were male. Mean age was 61.2 years. 43 (90%) were stage I. 22 (45.8%) had ENE. 31 (65%) had margins >1 mm. 38 (79%) had indications for radiation therapy; 9 (24%) refused. Chemotherapy was recommended in 36 (75%) patients; 24 (67%) refused. Locoregional control was 98%, metastasis-free survival was 96%, and disease-specific survival was 100% at 5-years. Overall survival was 95%.

CONCLUSIONS

Given the high survival rate seen after TORS, it is likely that margins, ENE and adjuvant treatment may not significantly contribute to outcomes.

Prognostic Significance of Extranodal Extension in HPV-Mediated Oropharyngeal Carcinoma: A Systematic Review and Meta-analysis

OBJECTIVE

To determine the prognostic role of extranodal extension (ENE) among patients with human papilloma virus-positive (HPV+) oropharyngeal squamous cell carcinoma (OPSCC) through a systematic review and meta-analysis of institutional studies.

DATA SOURCES

MEDLINE, Embase, Scopus, and PubMed.

REVIEW METHODS

Two independent authors searched the databases on December 3, 2019, to identify studies of HPV+ OPSCC comparing prognostic outcomes stratified by ENE. The I² statistic was used to determine study heterogeneity. Fixed and random effects models were used to determine hazard ratios (HRs) with 95% CIs.

RESULTS

Eighteen observational studies met inclusion criteria, yielding 3603 patients with HPV+ OPSCC (1521 ENE+ and 2082 ENE-) with a median follow-up of 49 months. The presence of pathologic ENE (pENE) and radiologic ENE (rENE) was associated with decreased overall survival (pENE HR, 1.89 [95% CI, 1.15-3.13], I² = 35%; rENE HR, 2.64 [95% CI, 1.46-4.78], I² = 75%) and distant recurrence (pENE HR, 3.23 [95% CI, 1.25-8.33], I² = 0%; rENE HR, 3.83 [95% CI, 1.88-7.80], I² = 0%). Neither pENE nor rENE was associated with locoregional recurrence (pENE HR, 0.75 [95% CI, 0.20-2.84], I² = 0%; rENE HR, 2.03 [95% CI, 0.86-4.79], I² = 0%). pENE was not associated with disease-specific survival (pENE HR, 1.45 [95% CI, 0.84-2.49], I² = 0%).

CONCLUSION

pENE and rENE are moderately associated with an increased risk of all-cause mortality and recurrence with distant metastasis in a cohort of patients with HPV+ OPSCC. These findings may be used to inform exclusion criteria for deintensification trials and assist in refined risk stratification.

Significance of Extranodal Extension in Surgically Treated HPV-Positive Oropharyngeal Carcinomas

Squamous cell carcinomas of the head and neck are the subject of numerous current studies, especially in view of the increasing incidence of tumors induced by human papillomavirus (HPV) and the latest changes to the TNM classification of oropharyngeal squamous cell carcinoma (OPSCC). In addition to HPV status, the presence of extranodal extension of lymph node metastases represents an important risk and prognostic factor, which has now been integrated into the staging algorithm of the eighth edition of TNM classification for HPV-negative OPSCC. In the past numerous studies had shown a lack of prognostic significance of extranodal extension in HPV-associated tumors. However, extranodal extension–as a possible risk factor even in HPV-positive OPSCC–remains an important subject of current studies, which are now particularly characterized by high numbers of cases. In this paper, diagnostic methods and the prognostic significance of extranodal extension in surgically treated HPV-positive OPSCC are presented and discussed based on relevant literature, and the results of current publications are summarized. Further development of diagnostic criteria and procedures as well as international standardization of clinical diagnostics of extranodal extension should be encouraged. Several studies demonstrate that extranodal extension results in worse survival outcomes even in HPV-positive tumors, in contrast to results of previous studies. Consequently, whether the prognostic significance of extranodal extension is not actually relevant to outcome and the staging algorithm of HPV-positive OPSCC should be questioned and further analyzed.

Impact of Smoking on Survival Outcomes in HPV-Related Oropharyngeal Carcinoma: A Meta-analysis

Objective

Characterize the survival impact of smoking on HPV-related (human papillomavirus) oropharyngeal squamous cell carcinoma.

Data Sources

Articles from 2000 to 2019 in the PubMed, Embase, and Cochrane Library databases were systematically reviewed for content and inclusion/exclusion criteria.

Review Methods

Two reviewers independently analyzed the databases for eligibility and quality of the articles. Demographic data, smoking history, and survival outcomes were recorded. Hazard ratios and 95% CIs were collectively analyzed through a random effects meta-analysis model.

Results

Fifteen articles were included in the meta-analysis for overall survival, disease-specific survival, disease-free survival, progression-free survival, and locoregional recurrence outcomes. The overall survival hazard ratio was 2.4 for ever having smoked (95% CI, 1.4-4.0; P = .0006, I2 = .384) and 3.2 for current smoking (95% CI, 2.2-4.6; P < .0001, I2 = 0). The hazard ratio for disease-specific survival in current smokers was 6.3 (95% CI, 1.3-29.3; P = .0194, I2 = 0). Ever smoking had a larger impact on overall survival and disease-specific survival than the 10–pack year smoking threshold.

Conclusion

Smoking negatively affects survival in patients with HPV-related oropharyngeal carcinoma across all outcomes. Current smoking during treatment is associated with the greatest reduction in survival, possibly secondary to diminished radiation therapy efficacy.

A Phase 2 Trial of Alternative Volumes of Oropharyngeal Irradiation for De-intensification (AVOID): Omission of the Resected Primary Tumor Bed After Transoral Robotic Surgery for Human Papilloma Virus-Related Squamous Cell Carcinoma of the Oropharynx

PURPOSE

This trial tested the safety and efficacy of a novel, deintensified radiation therapy (RT) approach after initial surgical resection for patients with human papilloma virus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC).

METHODS AND MATERIALS

This single-arm phase 2 prospective clinical trial enrolled 60 patients with stage pT1-pT2 N1-3 HPV-associated OPSCC treated with transoral robotic surgery (TORS) and selective neck dissection at a single institution between May 2014 and September 2017. Patients had favorable features at the primary site (negative surgical margins ≥2 mm, no perineural invasion, and no lymphovascular invasion) but required adjuvant therapy based on lymph node involvement. Surgeries were all performed at a high-volume head and neck cancer center with expertise in TORS. Patients received postoperative RT to at-risk areas in the involved neck (60-66 Gy) and uninvolved neck (54 Gy). The resected primary site was treated as an active avoidance structure in the treatment planning of postoperative RT. Concurrent chemotherapy was administered for patients with extranodal extension.

RESULTS

Median follow-up of the 60 patients enrolled was 2.4 years (range, 8.5-53.8 months). A single patient recurred at the primary site, for 2-year local control of 98.3%. One patient (1.7%) developed a regional neck recurrence, and 2 patients (3.3%) developed distant metastases. Measured 2-year local recurrence-free survival was 97.9% (95% confidence interval, 86.1%-99.7%). Overall survival was 100% at the time of analysis. The mean radiation dose to the primary site was 36.9 Gy (standard deviation, 10.3 Gy). Two patients (3.3%) experienced late soft tissue necrosis in the primary site surgical bed that resolved within 2 months. Feeding tube dependence rates were 0% during RT, 3.3% temporarily during follow-up, and 0% at last follow-up.

CONCLUSIONS

Deintensified postoperative RT that avoids the resected primary tumor site and targets only the at-risk neck after TORS for selected patients with HPV-associated OPSCC may be safe and is worthy of further study.

Trans-oral robotic surgery for the management of oropharyngeal carcinomas: a 9-year institutional experience

Trans-oral robotic surgery (TORS) has changed surgical management of patients with oropharyngeal squamous cell carcinomas (OPSCC). In this study we present surgical and oncologic outcomes of patients with oropharyngeal squamous cell carcinomas, treated using TORS, with and without an adjuvant therapy. Sixty patients with oropharyngeal squamous cell carcinomas treated with TORS between January 2008 and December 2017 have been retrospectively evaluated considering clinicopathologic features, disease characteristics, adjuvant treatments and oncological outcomes. TORS was performed for OPSCC to the base of tongue in 41.7%, tonsils in 46.7%, soft palate and posterior pharyngeal wall in 3.3% and 5%, respectively. Neck dissection was performed in 43.3% of patients. Management strategies included surgery alone in 30%, TORS and adjuvant radiotherapy in 33.3%, and TORS plus adjuvant chemotherapy in 36.7%. The 5-year overall survival of the total group was 77.6%, the 5-year disease-free survival rate was 85.2%, and the 5-year local recurrence-free survival rate was 90.6%. Finally, in selected patients TORS appears to yield similar oncologic outcomes and functional outcomes to traditional techniques and non-operative treatment with a possible benefit on long-term quality of life. The future offers exciting opportunities to combine TORS and radiotherapy in unique ways. However, further research is urgently needed to clarify the indications for adjuvant therapy following TORS resections.

Tumour Cell Anaplasia and Multinucleation as Prognosticators in Oropharyngeal Squamous Cell Carcinoma

Human papilloma virus (HPV)-positive oropharyngeal squamous cell carcinomas (OPSCC) tend to have good outcomes, however a subset does not share this favourable prognosis. The aim of this paper is to investigate the utility of tumour cell anaplasia and multinucleation as prognostic markers in oropharyngeal squamous cell carcinoma. Retrospective review of 104 patients with OPSCC or squamous cell carcinoma of unknown primary site (SCCUP) who underwent primary resection and/or lymph node dissection. Slides of both primary and nodal metastatic disease were assessed for the presence of anaplasia and multinucleation. 53 patients were HPV-positive. Anaplasia was more frequent in males (p = 0.005), smokers (p = 0.003), and HPV-negative disease (p = 0.04). HPV status and > 10 pack-year smoking history were independent predictors of recurrence-free survival (RFS) and disease-specific survival (DSS). Neither anaplasia, nor multinucleation, at the primary site or in cervical metastases, had any significant impact on RFS or DSS. We did not find either anaplasia or multinucleation to have any significant prognostic impact in OPSCC. However, given the small number of adverse events in the HPV-positive cohort, we may have lacked sufficient power to detect significance in what was the subgroup of primary interest. Our study highlights the challenge of identifying markers of poor prognosis in HPV-positive OPSCC.

Does p16+ Predict a Favorable Prognosis for Oropharyngeal Cancer? Risk Factors for Treatment Failure for Patients Who Underwent Surgery-Based Therapy

BACKGROUND

This study aimed to identify prognostic clinicopathologic factors that could predict treatment failure and to analyze clinical data from p16+ oropharyngeal squamous cell carcinoma (OPSCC) patients who underwent surgery.

METHODS

Data from p16+ OPSCC patients who underwent surgery at Severance Hospital of Yonsei University were retrospectively reviewed.

RESULTS

The average smoking history was 14.6 pack-years (range 0-94 pack-years). Of the 188 patients, 73 (38.8%) underwent transoral robotic surgery (TORS) for surgical treatment of their primary lesions, and the remaining 115 patients (61.2%) underwent conventional surgery. Extracapsular nodal spread was detected in 87 patients (46.3%). At histologic examination, 67 patients (35.6%) showed positive surgical margins, and 121 patients (64.4%) had negative surgical margins. Postoperative adjuvant treatment was performed for 167 patients (88.8%). During the follow-up period, there were 18 recurrences including 2 local recurrences, 10 regional recurrences, and 6 distant metastases. During the study period, 17 deaths occurred. The univariate analysis showed that the American Joint Committee on Cancer (AJCC) 8th-edition staging system, lymphovascular invasion, more than four metastatic lymph nodes, and a smoking history of more than 10 pack-years were significantly associated with treatment failure. In the multivariate analysis, only the AJCC 8th-edition staging system was significantly associated with the patient's survival.

CONCLUSION

Surgical treatment methods including TORS for p16+ OPSCC patients showed excellent oncologic results, and many previously known clinicopathologic factors did not show a significant relationship with patient prognosis. Only the newly revised AJCC 8th-edition staging system showed a significant relationship with patient survival, and this should be considered in the setting of p16+ OPSCC treatment guidelines in the future.

The interplay of IMRT and transoral surgery in HPV-mediated oropharyngeal cancer: Getting the balance right

Transoral surgery (TOS) and IMRT represent two primary local ablative treatment modalities for oropharyngeal cancer (OPC). The choice of one over the other represents an interplay between the chance of cure vs risk of late sequelae. HPV-mediated (HPV+) OPC patients generally have excellent outcomes, especially in TNM-8 stage I disease. Controversies exist over which treatment has a more favorable toxicity profile and equal efficacy in the management of this population. Non-randomized retrospective data show comparable oncological and functional outcomes between TOS-based vs IMRT-based treatment for this disease. Several de-intensification concepts have been explored in this subset in both primary surgery-based vs primary radiotherapy-based trials. However, no robust mature trial data are available to convincingly guide treatment selection. TOS is often presented as one of the de-intensification options although the majority of series also describe the use of adjuvant treatments which inevitably result in non-negligible toxicities. Patient selection and surgeons' training are paramount. Understanding tumor biology and the prognostic value of traditional 'adverse' features will further guide trial design for refinement of risk tailored approach. In conclusion, comparative data suggests TOS and IMRT are both effective treatment for TNM-8 stage I HPV+ OPC with similar oncological and functional outcomes. TOS as a single modality has potential advantages in mitigating radiation included toxicities. TOS should be avoided in the presence of clinically overt extranodal extension or when negative margins are unlikely to be achieved. TOS is also less ideal for cases with radiological features predicting a high risk of distant metastasis.

Nomogram for preoperative prediction of nodal extracapsular extension or positive surgical margins in oropharyngeal squamous cell carcinoma

INTRODUCTION

Extracapsular extension (ECE) in regional lymph nodes and positive surgical margins (PSM) are considered high-risk adverse pathologic features in patients with oropharyngeal squamous cell carcinoma (OPSCC) that each constitute an indication for postoperative adjuvant chemoradiation. We identify pre-operative clinical factors that can predict post-operative ECE and/or PSM and create a nomogram to help clinical decision making.

METHODS

Adult patients with non-metastatic OPSCC with initial surgical treatment and confirmed HPV status diagnosed between 2010 and 2014 were selected from the National Cancer Database. Clinical staging was modified to American Joint Committee on Cancer 8th edition parameters. Logistic regression was used for multivariate analysis to identify predictors of pathologic ECE and/or PSM.

RESULTS

5065 patients were included. 47.5% of the 3336 HPV-positive (HPV+) patients had ECE/PSM. 40.4% of the 1729 HPV-negative (HPV-) patients with had ECE/PSM. A model was built that included age, clinical ECE, tumor grade, and clinical T and N staging for HPV+ patients. Increasing N-classification was highly predictive of pathologic ECE and/or PSM (N1 OR = 3.6, N2 OR = 7.0, N3 OR = 11.2, p < 0.01). Clinical ECE (OR = 4.1, p < 0.01), tumor grade (ORs 2.2-4.4 with p < 0.05), and increasing clinical T-classification (ORs 1.2-1.8, p < 0.05) were also associated with ECE and/or PSM. A similar model was built for HPV- with similar predictive capability. Two internally validated nomograms were designed that demonstrated good discrimination (HPV+ AUC = 0.66, 95% CI: 0.64-0.68, and HPV- AUC = 0.70, 95% CI: 0.67-0.72) and good calibration (goodness-of-fit statistic of HPV+ 6.32, p = 0.61 and HPV- 11.66, p = 0.17).

CONCLUSIONS

These are the first nomograms designed to help predict ECE or PSM for both HPV+ and HPV- OPSCC. The nomograms can facilitate shared decision-making between clinicians and patients as they consider upfront treatment selection for OPSCC.

Margin Analysis: Squamous Cell Carcinoma of the Oropharynx

Because of the common shared risk factors of smoking and heavy alcohol consumption, literature involving oropharyngeal squamous cell carcinoma (OPSCC) is often combined with oral squamous cell carcinoma. Human papilloma virus is now confirmed to be a major risk factor of OPSCC with its distinct epidemiology and favorable treatment outcome. The impact of adjuvant chemoradiation in the setting of positive surgical margins remains unclear but is likely influenced by tumor biology. This article reviews the tumor biology of OPSCC and summarizes recent findings on outcomes following surgical treatment of OPSCC.

[Robotic Surgery - Who is The Boss?]

In the head and neck region, great potential is seen in robot-assisted surgery (RAS). Mainly in cancer surgery, the use of robotic systems seems to be of interest. Until today, two robotic systems (DaVinci® und FLEX®) have gained approval for clinical use in the head and neck region, and multiple other systems are currently in pre-clinical testing. Although, certain groups of patients may benefit from RAS, no unbiased randomized clinical studies are available. Until today, it was not possible to satisfactorily prove any advantage of RAS as compared to standard procedures. The limited clinical benefit and the additional financial burden seem to be the main reasons, why the comprehensive application of RAS has not been realized so far.This review article describes the large variety of clinical applications for RAS in the head and neck region. In addition, the financial and technical challenges, as well as ongoing developments of RAS are highlighted. Special focus is put on risks associated with RAS and current clinical studies. We believe, that RAS will find its way into clinical routine during the next years. Therefore, medical staff will have to increasingly face the technical, scientific and ethical features of RAS.

Oncologic outcomes of extended neck dissections in human papillomavirus-related oropharyngeal squamous cell carcinoma

BACKGROUND

Oncologic outcomes of human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (SCC) requiring resection of major muscular or neurovascular tissue during neck dissection for invasive nodal disease remain uncertain.

METHODS

Patients with HPV-related oropharyngeal SCC requiring resection of major muscular or neurovascular tissue during their neck dissections were retrospectively identified.

RESULTS

Seventy-two patients were included. Regional and distant recurrences occurred in 6% and 17% of patients. Advanced T classification, pathological node number of 5 or more, and omission of adjuvant therapy were associated with decreased disease-free survival (DFS). The addition of adjuvant chemotherapy was not associated with improved survival.

CONCLUSION

Patients with invasive nodal disease from HPV-related oropharyngeal SCC can be managed with up-front surgery and adjuvant therapy, as indicated with good regional control. Although distant recurrence was the primary site of failure, adjuvant chemotherapy was not associated with improved outcomes. The T classification, node number, and adjuvant radiotherapy are independent prognostic factors in this patient population.

Transoral Resection of Human Papillomavirus (HPV)-Positive Squamous Cell Carcinoma of the Oropharynx: Outcomes with and Without Adjuvant Therapy

BACKGROUND

With the rise of oropharyngeal squamous cell carcinoma associated with human papillomavirus (HPV), appropriate treatment strategies continue to be tailored toward minimizing treatment while preserving oncologic outcomes. This study aimed to compare the outcomes for those undergoing transoral resection with or without adjuvant therapy for HPV-related oropharyngeal carcinoma.

METHODS

A case-match cohort analysis was performed at two institutions on patients with HPV-related oropharyngeal squamous cell carcinoma. All the subjects underwent transoral surgery and neck dissection. The patients treated with surgery alone were matched 1:1 to those treated with surgery and adjuvant therapy using two groups identified as confounders: T-stage (T1/2 or T3/4) and number of pathologically positive lymph nodes (≤4 or >4).

RESULTS

The study identified 105 matched pairs, with a median follow-up period of 42 months (range 3.1-102.3 months). The patients were staged as T1/T2 (86%) or T3/4 (14%). Each group had five patients with more than four positive lymph nodes. Adjuvant therapy significantly improved disease-free survival (hazard ratio [HR] 0.067; 95% confidence interval [CI] 0.01-0.62) and was associated with a lower risk of local and regional recurrence (risk ratio [RR] 0.096; 95% CI 0.02-0.47). No difference in disease-specific survival (HR 0.22; 95% CI 0.02-2.57) or overall survival (HR 0.18; 95% CI 0.01-2.4) was observed with the addition of adjuvant therapy. The risk of the gastrostomy tube was higher for those receiving adjuvant therapy (RR 7.3; 95% CI 2.6-20.6).

CONCLUSIONS

Transoral surgery is an effective approach for the treatment of HPV-related oropharyngeal carcinoma. The addition of adjuvant therapy appears to decrease the risk of recurrence and improve disease-free survival but may not significantly improve overall survival.

Avoidance of postoperative irradiation for cervical lymph node metastases of human papillomavirus-related tonsillar cancer

BACKGROUND

Several reports have suggested that selected patients with human papillomavirus-related oropharyngeal cancer can be managed with surgery alone. We retrospectively reviewed tonsillar cancer cases to analyze treatment de-intensification after transoral resection.

METHODS

Eighteen patients with tonsillar cancer who had undergone transoral resection were included. The patients' characteristics, p16 status, adverse features, clinical course, overall survival, and relapse-free survival according to p16 status were retrospectively examined.

RESULTS

Four lesions showed positive surgical margins and one lesion showed close surgical margin; these patients were treated with postoperative irradiation. Seven p16-positive patients had multiple node metastases and two had extracapsular spread. No p16-positive patients agreed to postoperative irradiation, and recurrence within the surgical field was not observed. The five-year overall and relapse-free survival rates were 89% and 74%, respectively. The five-year relapse-free survival rates of p16-positive and p16-negative patients were 81% and 50%, respectively (p = .075).

CONCLUSIONS

Postoperative irradiation for cervical lymph node metastases might be avoidable in selected patients with human papillomavirus-related tonsillar cancer.

LEVEL OF EVIDENCE

4.

Transoral robotic surgery with radial forearm free flap reconstruction: case control analysis

Background

The resection of large oropharyngeal tumors traditionally involves a lip-splitting mandibulotomy for adequate margin visualization and free flap reconstruction of the surgical defect. Transoral robotic surgery (TORS) has emerged as a technique that can resect large and complex oropharyngeal tumors, avoiding a lip-splitting approach. The aim of this study is to compare the lip-splitting mandibulotomy approach versus TORS for the management of advanced stage oropharyngeal carcinomas.

Methods

Prospectively collected data from 18 patients with advanced stage oropharyngeal squamous cell carcinoma (OPSCC) who received TORS with radial forearm free flap reconstruction (RFFF) was compared to a matched cohort of 39 patients who received a lip-splitting mandibulotomy and RFFF. Patients were matched for stage, p16 positivity, smoking, age and gender. Length of hospital stay (LOHS), tracheostomy decanulation time, operative time, surgical margin status, and post-operative complications were compared between groups.

Results

Patients who received TORS with RFFF had a significantly lower mean LOHS, compared to patients who were treated by lip-splitting mandibulotomy and RFFF (14.4 vs 19.7 days, p = 0.03). No significant differences were seen between groups in terms of operative time, tracheostomy decannulation time, margin positivity and post-operative complications.

Conclusion

TORS with radial forearm free flap reconstruction is a safe, effective and cost-saving alternative to the lip-splitting mandibulotomy approach for the treatment of advanced stage OPSCC.

Should We De-escalate the Treatment for HPV-Positive Tumors?

De-escalation or de-intensification of therapy is discussed since many retrospective analyses of former trials demonstrated significantly better outcome for patients suffering from p16/HPV16-positive oropharyngeal squamous cell carcinoma of head and neck (OHNSCC). These observations are comprehensively addressed, but the reader has to keep in mind that none of the currently discussed data result from prospective controlled trials addressing the HPV-discrimination in the primary endpoint design. Identification of the true HPV16-related tumors is still challenging and in addition with different clinical reports and lack of data of prospective trials not mature for routine clinical decision making in 2016. Independent of the currently lacking evidence for HPV-dependent treatment de-escalation, there are some relevant arguments to address this question in ongoing and future trials.

Adjuvant Radiation Therapy Alone for HPV Related Oropharyngeal Cancers with High Risk Features

Background

Current standard of care for oropharyngeal cancers with positive surgical margins and/or extracapsular extension is adjuvant chemoradiotherapy. It is unknown whether HPV+ oropharyngeal cancer benefits from this treatment intensification.

Objective

To investigate the outcomes of HPV+ patients treated with adjuvant radiotherapy alone when chemoradiotherapy was indicated based on high risk pathological features. They were compared with high risk HPV+ patients treated with adjuvant chemoradiotherapy.

Methods

All high risk HPV+ oropharyngeal cancer patients (9) who received radiotherapy alone were identified. We also identified 17 patients who received chemoradiotherapy as a comparison group. Median follow up time was 37.3 months.

Results

No local failures developed in adjuvant radiotherapy group. There was 1 distant recurrence in this cohort and 3 in CRT cohort. Regarding toxicity, 8 (47.1%) chemoradiotherapy patients had >10 lb. weight loss (p = 0.013), despite 75% of them having a percutaneous endoscopic gastrostomy tube placed. No individuals in radiotherapy group experienced a >10 lb. weight loss and none required a gastrostomy tube.

Conclusions

This series provides preliminary evidence suggesting that the omission of concurrent chemotherapy to adjuvant radiotherapy may offer comparative local control rates with a lower toxicity profile in the setting of HPV+ patients with traditional high risk features.

Pathology-based staging for HPV-positive squamous carcinoma of the oropharynx

OBJECTIVE

The rapid worldwide rise in incidence of human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) has generated studies confirming this disease as an entity distinct from traditional OPSCC. Based on pathology, surgical studies have revealed prognosticators specific to HPV-positive OPSCC. The current AJCC/UICC staging and pathologic nodal (pN)-classification do not differentiate for survival, demonstrating the need for new, HPV-specific OPSCC staging. The objective of this study was to define a pathologic staging system specific to HPV-positive OPSCC.

METHODS

Data were assembled from a surgically-managed, p16-positive OPSCC cohort (any T, any N, M0) of 704 patients from five cancer centers. Analysis was performed for (a) the AJCC/UICC pathologic staging, (b) newly published clinical staging for non-surgically managed HPV-positive OPSCC, and (c) a novel, pathology-based, "HPVpath" staging system that combines features of the primary tumor and nodal metastases.

RESULTS

A combination of AJCC/UICC pT-classification and pathology-confirmed metastatic node count (⩽4 versus ⩾5) yielded three groups: stages I (pT1-T2, ⩽4 nodes), II (pT1-T2, ⩾5 nodes; pT3-T4, ⩽4 nodes), and III (pT3-T4, ⩾5 nodes), with incrementally worse prognosis (Kaplan-Meier overall survival of 90%, 84% and 48% respectively). Existing AJCC/UICC pathologic staging lacked prognostic definition. Newly published HPV-specific clinical stagings from non-surgically managed patients, although prognostic, showed lower precision for this surgically managed cohort.

CONCLUSIONS

Three loco-regional "HPVpath" stages are identifiable for HPV-positive OPSCC, based on a combination of AJCC/UICC primary tumor pT-classification and metastatic node count. A workable, pathologic staging system is feasible to establish prognosis and guide adjuvant therapy decisions in surgically-managed HPV-positive OPSCC.

C3-Luc Cells Are an Excellent Model for Evaluation of Cellular Immunity following HPV16L1 Vaccination

C3 and TC-1 are the two model cell lines most commonly used in studies of vaccines and drugs against human papillomavirus (HPV) infection. Because C3 cells contain both the HPV16 E and L genes, but TC-1 cells contain only the HPV16 E genes, C3 cells are usually used as the model cell line in studies targeting the HPV16 L protein. However, expression of the L1 protein is difficult to detect in C3 cells using common methods. In our study, Short tandem repeat analysis (STR) was used to demonstrate that C3 cells are indeed derived from mice, PCR results show that HPV16 L1, E6 and E7 genes were detected in C3 genomic DNA, and RT-PCR results demonstrated that L1 transcription had occurred in C3 cells. However, the expression of C3 protein was not found in the results of western blot and immunohistochemistry (IHC). Growth and proliferation of C3 were inhibited by mice spleen lymphocytes that had been immunized with a vaccine against HPV16L1. The luciferase gene was integrated into C3 cells, and it was confirmed that addition of the exogenous gene had no effect on C3 cells by comparing cell growth and tumor formation with untransformed cells. Cells stably expressing luciferase (C3-luc) were screened and subcutaneously injected into the mice. Tumors became established and were observed using a Spectrum Pre-clinical in Vivo Imaging System. Tumor size of mice in the different groups at various time points was calculated by counting photons. The sensitivity of the animals to the vaccine was quantified by statistical comparison. Ten or 30 days following injection of the C3-luc cells, tumor size differed significantly between the PBS and vaccine groups, indicating that C3 cells were susceptible to vaccination even after tumors were formed in vivo.