Altered fractionation diminishes importance of tumor volume in oropharyngeal cancer: Subgroup analysis of ARTSCAN-trial

Importance of tumor volume, overall treatment time and fractionation sensitivity for p16-positive and p16-negative oropharyngeal tumors

BACKGROUND

Analyses of clinical outcomes following radiotherapy (RT) have advanced our understanding of fundamental radiobiological characteristics in head and neck squamous cell carcinoma (HNSCC). Low fractionation sensitivity appears to be a common feature, as well as susceptibility to changes in overall treatment time (OTT). Large tumors should be harder to cure if a successful RT requires the sterilization of all clonogenic cells. Congruently, primary tumor volume has proven to be an important parameter. However, most findings come from an era when p16-negative HNSCC was the dominant tumor type. HPV-associated, p16-positive, oropharyngeal tumors (OPSCC) are more radiosensitive and have better outcome. The current study aims to investigate the role of primary tumor volume, OTT and estimate α/ β -ratio for p16-positive OPSCC, and to quantify the differences in radiosensitivity depending on p16-status.

METHODS

A cohort of 523 patients treated with RT was studied using a tumor control probability (TCP)-model that incorporates primary tumor volume (V) raised to an exponent c, OTT and α/ β -estimation. The significance of V was also investigated in Cox-regression models.

RESULTS

In the p16-positive cohort (n = 433), the volume exponent c was 1.44 (95%CI 1.06-1.91), compared to 0.90 (0.54-1.32) for p16-negative tumors (n = 90). Hazard ratios per tumor volume doubling were 2.37 (1.72-3.28) and 1.83 (1.28-2.62) for p16-positive and p16-negative, respectively. The estimated α/ β -ratio was 9.7 Gy (-2.3-21.6), and a non-significant daily loss of 0.30 Gy (-0.17-0.92) was found. An additional dose of 6.8 Gy (interquartile range 4.8-9.1) may theoretically counteract the more radioresistant behavior of p16-negative tumors.

CONCLUSION

Primary tumor volume plays a crucial role in predicting local tumor response, particularly in p16-positive OPSCC. The estimated α/β-ratio for p16-positive oropharyngeal tumors aligns with previous HNSCC studies, whereas the impact of prolonged OTT was slightly less than previously reported. The differences in radiosensitivity depending on p16-status were quantified. The findings should be validated in independent cohorts.

Circulating tumour HPV16 DNA quantification - A prognostic tool for progression-free survival in patients with HPV-related oropharyngeal carcinoma receiving curative chemoradiotherapy

BACKGROUND AND PURPOSE

Circulating tumour (ct) human papillomavirus (HPV) DNA is detectable in HPV-related oropharyngeal carcinoma (OPSCC) patients and has the potential to become an important clinical tool. This study aimed to evaluate the prognostic significance of ctHPV16-DNA kinetics during treatment with chemoradiotherapy in HPV-related OPSCC. Patients with p16-positive OPSCC recruited to the ARTSCAN III trial, comparing radiotherapy plus cisplatin with radiotherapy plus cetuximab, constituted the study cohort.

MATERIALS AND METHODS

Blood samples before start and at the end of treatment of 136 patients were analysed. ctHPV16-DNA was quantified by real-time (q)PCR. The correlation between ctHPV16-DNA levels and tumour burden was investigated with Pearson regression analysis. The prognostic value of ctHPV16-DNA levels at baseline and decline during treatment was evaluated by area-under-the-curve (AUC) calculations and analysed with univariable and multivariable Cox proportional hazards models.

RESULTS

ctHPV16-DNA was detectable with qPCR in 108/136 patients before start of treatment and cleared in 74% of these patients at the end of treatment. Disease burden was significantly correlated with baseline ctHPV16-DNA levels (R = 0.39, p=<0.001). Both lower baseline levels and AUC-ctHPV16DNA were associated with improved progression-free survival (p = 0.01 and p < 0.001), overall survival (p = 0.013 and p = 0.002), but not local tumour control (p = 0.12 and p = 0.2, respectively), with a stronger association for AUC-ctHPV16DNA (likelihood ratio test 10.5 vs 6.5 in Cox regression analyses of progression-free survival). In multivariable analysis including tumour volume (GTV-T) and treatment allocation (cisplatin vs cetuximab), AUC-ctHPV16DNA remained a significant prognostic marker of progression-free survival.

CONCLUSION

ctHPV16-DNA is an independent prognostic factor in HPV-related OPSCC.

Early detection of mandible osteoradionecrosis risk in a high comorbidity veteran population

OBJECTIVE

Osteoradionecrosis (ORN) of the mandible is a devastating complication of external beam radiation therapy (EBRT) for head and neck squamous cell carcinoma (HNSCC). We sought to ascertain ORN risk in a Veteran HNSCC population treatment with definitive or adjuvant EBRT and followed prospectively.

STUDY DESIGN

Retrospective analysis of prospective cohort.

SETTING

Tertiary care Veterans Health Administration (VHA) medical center.

METHODS

Patients with HNSCC who initiated treatment at the Michael E. DeBakey Veterans Affairs Medical Center (MEDVAMC) are prospectively tracked for quality of care purposes through the end of the cancer surveillance period (5 years post treatment completion). We retrospectively analyzed this patient cohort and extracted clinical and pathologic data for 164 patients with SCC of the oral cavity, oropharynx, larynx, and hypopharynx who received definitive or adjuvant EBRT (2016-2020).

RESULTS

Most patients were dentate and 80 % underwent dental extractions prior to EBRT of which 16 (16 %) had complications. The rate of ORN was 3.7 % for oral cavity SCC patients and 8.1 % for oropharyngeal SCC patients. Median time to ORN development was 156 days and the earliest case was detected at 127 days post EBRT completion. All ORN patients were dentate and underwent extraction prior to EBRT start.

CONCLUSION

ORN development can occur early following EBRT in a Veteran population with significant comorbid conditions but overall rates are in line with the general population. Prospective tracking of HNSCC patients throughout the post-treatment surveillance period is critical to early detection of this devastating EBRT complication.

Response to primary chemoradiotherapy of locally advanced oropharyngeal carcinoma is determined by the degree of cytotoxic T cell infiltration within tumor cell aggregates

Background

Effective anti-tumor immune responses are mediated by T cells and require organized, spatially coordinated interactions within the tumor microenvironment (TME). Understanding coordinated T-cell-behavior and deciphering mechanisms of radiotherapy resistance mediated by tumor stem cells will advance risk stratification of oropharyngeal cancer (OPSCC) patients treated with primary chemoradiotherapy (RCTx).

Methods

To determine the role of CD8 T cells (CTL) and tumor stem cells for response to RCTx, we employed multiplex immunofluorescence stains on pre-treatment biopsy specimens from 86 advanced OPSCC patients and correlated these quantitative data with clinical parameters. Multiplex stains were analyzed at the single-cell level using QuPath and spatial coordination of immune cells within the TME was explored using the R-package Spatstat.

Results

Our observations demonstrate that a strong CTL-infiltration into the epithelial tumor compartment (HR for overall survival, OS: 0.35; p<0.001) and the expression of PD-L1 on CTL (HR: 0.36; p<0.001) were both associated with a significantly better response and survival upon RCTx. As expected, p16 expression was a strong predictor of improved OS (HR: 0.38; p=0.002) and correlated with overall CTL infiltration (r: 0.358, p<0.001). By contrast, tumor cell proliferative activity, expression of the tumor stem cell marker CD271 and overall CTL infiltration, regardless of the affected compartment, were not associated with response or survival.

Conclusion

In this study, we could demonstrate the clinical relevance of the spatial organization and the phenotype of CD8 T cells within the TME. In particular, we found that the infiltration of CD8 T cells specifically into the tumor cell compartment was an independent predictive marker for response to chemoradiotherapy, which was strongly associated with p16 expression. Meanwhile, tumor cell proliferation and the expression of stem cell markers showed no independent prognostic effect for patients with primary RCTx and thus requires further study.

Hypoxia in relationship to tumor volume using hypoxia PET-imaging in head & neck cancer - A scoping review

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Primary tumor volume and hypoxic volume has previously not been convincingly related.

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367 patients with head and neck squamous cell carcinoma from 21 different studies using hypoxia-PET

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The hypoxic volume increased significantly with primary tumor volume.

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In larger tumor the hypoxic fraction was significantly higher than in smaller tumors.

Background

Hypoxia and large tumor volumes are negative prognostic factors for patients with head and neck squamous cell carcinoma (HNSCC) treated with radiation therapy (RT). PET-scanning with specific hypoxia-tracers (hypoxia-PET) can be used to non-invasively assess hypoxic tumor volume. Primary tumor volume is readily available for patients undergoing RT. However, the relationship between hypoxic volume and primary tumor volume is yet an open question. The current study investigates the hypotheses that larger tumors contain both a larger hypoxic volume and a higher hypoxic fraction.

Methods

PubMed and Embase were systematically searched to identify articles fulfilling the predefined criteria. Individual tumor data (primary tumor volume and hypoxic volume/fraction) was extracted. Relationship between hypoxic volume and primary tumor volume was investigated by linear regression. The correlation between hypoxic fraction and log₂(primary tumor volume) was determined for each cohort and in a pooled analysis individual regression slopes and coefficients of determination (R²) were weighted according to cohort size.

Results

21 relevant articles were identified and individual data from 367 patients was extracted, out of which 323 patients from 17 studies had quantifiable volumes of interest. A correlation between primary tumor volume and PET-determined hypoxic volume was found (P <.001, R² = 0.46). Larger tumors had a significantly higher fraction of hypoxia compared with smaller tumors (P<.01). The weighted analysis of all studies revealed that for each doubling of the tumor volume, the hypoxic fraction increased by four percentage points.

Conclusion

This study shows correlations between primary tumor volume and hypoxic volume as well as primary tumor volume and the hypoxic fraction in patients with HNSCC. The findings suggest that not only do large tumors contain more cancer cells, they also have a higher proportion of potentially radioresistant hypoxic cells. This knowledge can be important when individualizing RT.

Primary tumor volume and prognosis for patients with p16-positive and p16-negative oropharyngeal squamous cell carcinoma treated with radiation therapy

BACKGROUND

The prescribed radiation dose to patients with oropharyngeal squamous cell carcinoma (OPSCC) is standardized, even if the prognosis for individual patients may differ. Easy-at-hand pre-treatment risk stratification methods are valuable to individualize therapy. In the current study we assessed the prognostic impact of primary tumor volume for p16-positive and p16-negative tumors and in relationship to other prognostic factors for outcome in patients with OPSCC treated with primary radiation therapy (RT).

METHODS

Five hundred twenty-three OPSCC patients with p16-status treated with primary RT (68.0 Gy to 73.1 Gy in 7 weeks, or 68.0 Gy in 4.5 weeks), with or without concurrent chemotherapy, within three prospective trials were included in the study. Local failure (LF), progression free survival (PFS) and overall survival (OS) in relationship to the size of the primary gross tumor volume (GTV-T) and other prognostic factors were investigated. Efficiency of intensified RT (RT with total dose 73.1 Gy or given within 4.5 weeks) was analyzed in relationship to tumor volume.

RESULTS

The volume of GTV-T and p16-status were found to be the strongest prognostic markers for LF, PFS and OS. For p16-positive tumors, an increase in tumor volume had a significantly higher negative prognostic impact compared with p16-negative tumors. Within a T-classification, patients with a smaller tumor, compared with a larger tumor, had a better prognosis. The importance of tumor volume remained after adjusting for nodal status, age, performance status, smoking status, sex, and hemoglobin-level. The adjusted hazard ratio for OS per cm³ increase in tumor volume was 2.3% (95% CI 0-4.9) for p16-positive and 1.3% (95% 0.3-2.2) for p16-negative. Exploratory analyses suggested that intensified RT could mitigate the negative impact of a large tumor volume.

CONCLUSIONS

Outcome for patients with OPSCC treated with RT is largely determined by tumor volume, even when adjusting for other established prognostic factors. Tumor volume is significantly more influential for patients with p16-positive tumors. Patients with large tumor volumes might benefit by intensified RT to improve survival.

Does Tumor Volume Have a Prognostic Role in Oropharyngeal Squamous Cell Carcinoma? A Systematic Review and Meta-Analysis

The aim of this study was to assess the prognostic value of tumor volume in oropharyngeal squamous cell carcinoma (OPSCC). The study was performed according to the PRISMA guidelines. A total of 1417 patients with a median age of 59.3 years (IQR 57.5−60) were included. The combined Hazard Ratios (HRs) for overall survival (OS) were 1.02 (95% CI, 0.99−1.05; p = 0.21) for primary tumor volume (pTV) and 1.01 (95% CI, 1.00−1.02; p = 0.15) for nodal tumor volume (nTV). Regarding locoregional control (LRC), the pooled HRs were 1.07 (95% CI, 0.99−1.17; p = 0.10) for pTV and 1.02 (95% CI, 1.01−1.03; p < 0.05) for nTV. Finally, the pooled HRs for disease-free survival (DFS) were 1.01 (95% CI, 1.00−1.03; p < 0.05) for pTV and 1.02 (95% CI, 1.01−1.03; p < 0.05) for nTV. In conclusion, pTV and nTV seem not to behave as reliable prognostic factors in OPSCC.