Randomized phase III trial of concurrent accelerated radiation plus cisplatin with or without cetuximab for stage III to IV head and neck carcinoma: RTOG 0522

Head and Neck Squamous Cell Carcinoma: Update on Epidemiology, Diagnosis, and Treatment

Squamous cell carcinoma arises from multiple anatomic subsites in the head and neck region. The risk factors for development of cancers of the oral cavity, oropharynx, hypopharynx, and larynx include tobacco exposure and alcohol dependence, and infection with oncogenic viruses is associated with cancers developing in the nasopharynx, palatine, and lingual tonsils of the oropharynx. The incidence of human papillomavirus-associated oropharyngeal cancer is increasing in developed countries, and by 2020, the annual incidence could surpass that of cervical cancer. The treatment for early-stage squamous cell cancers of the head and neck is generally single modality, either surgery or radiotherapy. The treatment for locally advanced head and neck cancers is multimodal, with either surgery followed by adjuvant radiation or chemoradiation as indicated by pathologic features or definitive chemoradiation. For recurrent disease that is not amenable to a salvage local or regional approach and for metastatic disease, chemotherapy with or without a biological agent is indicated. To date, molecular testing has not influenced treatment selection in head and neck cancer. This review will focus on the changing epidemiology, advances in diagnosis, and treatment options for squamous cell cancers of the head and neck, along with data on risk stratification specific to oropharyngeal cancer, and will highlight the direction of current trials.

Everything Old Is New Again: Using Nelfinavir to Radiosensitize Rectal Cancer

Repurposing agents approved for other indications to radiosensitize tumors may be advantageous. The study by Hill and colleagues utilizes nelfinavir, an HIV protease inhibitor (PI), in combination with radiotherapy in rectal cancer in a prospective study. This combination may improve tumor perfusion and regression compared with radiotherapy alone.

Advanced oropharyngeal squamous cell carcinoma: Pathogenesis, treatment, and novel therapeutic approaches

Oropharyngeal cancer accounts for approximately 2.8% of newly cancer cases. Although classically a tobacco related disease, most cases today are related to infection with human papilloma virus (HPV) and present with locally advanced tumors. HPV related tumors have been recognized as a molecularly distinct entity with higher response rates to therapy, lower rates of relapse, and improved overall survival. Treatment of oropharyngeal cancer entails a multi-disciplinary approach with concomitant chemoradiation. The role of induction chemotherapy in locally advanced tumors continues to be controversial however large studies have demonstrated no difference in survival or time to treatment failure. Surgical approaches may be employed with low volume oropharyngeal cancers and with development new endoscopic tools, more tumors are able to be resected via an endoscopic approach. Given advances in the understanding of HPV related oropharyngeal cancer, ongoing research is looking at ways to minimize toxicities via de-intensification of therapy. Unfortunately, some patients develop recurrent or metastatic disease. Novel therapeutics are currently being investigated for this patient population including immunotherapeutics. This review discusses the current understanding of the pathogenesis of oropharyngeal cancer and treatment. We also discuss emerging areas of research as it pertains to de-intensification as well novel therapeutics for the management of metastatic disease.

Systemic therapy for squamous cell carcinoma of the head and neck

The use of systemic therapy as part of curative treatment and palliation is an evolving paradigm for squamous cell cancer of the head and neck (SCCHN), which historically has been treated with local modalities. At present, the treatment armamentarium includes traditional cytotoxic therapy, targeted biological agents, and emerging immunotherapeutics. This article discusses the use of all of these systemic approaches for the curative and palliative treatment of SCCHN.

Palliative Radiation Therapy for Advanced Head and Neck Carcinomas: A Phase 2 Study

PURPOSE

Incurable head and neck cancer is hard to manage with usual palliative care. Radiation therapy (RT) in this setting is sometimes omitted because there is an apprehension that the side effects in the head and neck region might counterbalance the benefits. The objective of this phase 2 study was to evaluate whether highly conformal RT could improve the therapeutic ratio with this comprehensive Quality of Life (QOL) and toxicity evaluation.

METHODS AND MATERIALS

Patients from 2 academic centers, deemed unfit for radical treatment because of their poor medical condition or advanced cancer stage by an experienced tumor board, were offered 25 Gy in 5 daily intensity modulated RT fractions over 1 week to the symptomatic tumor volume. QOL was evaluated with the European Organization for Research and Treatment of Cancer QLQ-C15-PAL and QLQ-H&N35 questionnaires, and toxicities with the Common Terminology Criteria for Adverse Events version 4.0. Survival and time to tumor progression were calculated with the Kaplan-Meier method.

RESULTS

Thirty-two patients were recruited, of whom 66% had at least T4, N3, or M1 disease. The QOL questionnaires completion rate was 86%. Eighty-eight percent of patients received the planned dose. The median overall survival and progression-free survival times were, respectively, 6.5 and 3.2 months. No grade 4 or 5 toxicity was seen. Only 13% of patients had any grade 3 toxicities, and 17% of patients reported no toxicity at all. The QOL was equal or improved, and head and neck symptoms remained equal to or lower than the baseline values for most patients at up to 6 months. Eighty-five percent of patients would have chosen to receive this RT regimen again when asked.

CONCLUSIONS

This palliative RT regimen was highly tolerable and effective in preserving or improving self-reported QOL in most patients for up to 6 months, which corresponds to this population's median overall survival. Given the minimal side effects, intensification could be considered to achieve longer locoregional control.

Incorporation of Next-Generation Sequencing into Routine Clinical Care to Direct Treatment of Head and Neck Squamous Cell Carcinoma

PURPOSE

The clinical impact of next-generation sequencing (NGS) in patients with head and neck squamous cell carcinoma (HNSCC) has not been described. We aimed to evaluate the clinical impact of NGS in the routine care of patients with HNSCC and to correlate genomic alterations with clinical outcomes.

EXPERIMENTAL DESIGN

Single-center study examining targeted NGS platform used to sequence tumor DNA obtained from 213 HNSCC patients evaluated in outpatient head and neck oncology clinic between August 2011 and December 2014. We correlated tumor genomic profiling results with clinical outcomes.

RESULTS

PI3K/RTK pathway activation occurred frequently [activating PIK3CA mutation or amplification (13%), PTEN inactivation (3%), RAS activation (6%), EGFR or ERBB2 activation (9%)]. Alterations in pathways affecting cell-cycle regulation [CCND1 amplification (9%), CDKN2A inactivation (17%), BRCA2 inactivation (2%)] and squamous differentiation [NOTCH1 inactivation (8%) andEP300 inactivation (6%)] were identified. PIK3CA amplification (n = 43), not PIK3CA mutation, was associated with significantly poorer progression-free survival (P = 0.0006). Oncogenic RAS mutations (n = 13) were associated with significantly poorer progression-free survival (P = 0.0001) and lower overall survival (P = 0.003). Eight patients with advanced, treatment-refractory HNSCC enrolled on clinical trials matched to tumor profiling results, and 50% achieved a partial response.

CONCLUSIONS

Incorporation of NGS clinical assays into the routine care of patients with HNSCC is feasible and may readily facilitate enrollment into clinical trials of targeted therapy with a higher likelihood of success. Data can be utilized for discovery of genomic biomarkers of outcome. PIK3CA amplification and RAS mutations were frequently identified and associated with poorer prognosis in this cohort. Clin Cancer Res; 22(12); 2939-49. ©2016 AACR.

Gemcitabine-Based Chemoradiation in the Treatment of Locally Advanced Head and Neck Cancer: Systematic Review of Literature and Meta-Analysis

BACKGROUND

Platinum-based concurrent chemoradiation (CCRT) improves locoregional control and overall survival of locoregionally advanced (LA) squamous cell carcinoma of the head and neck (SCCHN) when compared to radiotherapy alone, but this approach is hampered by significant toxicity. Therefore, alternative ways to enhance the radiation effects are worth investigating. Gemcitabine (2',2'-difluorodeoxycytidine), in addition to its activity against a variety of solid tumors, including SCCHN, is one of the most potent radiosensitizers, and it has an overall favorable safety profile. In this paper, the clinical experience with gemcitabine-based chemoradiation in the treatment of patients with LA-SCCHN is reviewed.

METHODS

We conducted a review of the literature on the clinical experience with radiotherapy combined with either single-agent gemcitabine or gemcitabine/cisplatin-based polychemotherapy for the treatment of patients with LA-SCCHN. We also searched abstracts in databases of major international oncology meetings from the last 20 years. A meta-analysis was performed to calculate pooled proportions with 95% confidence intervals (CIs) for complete response rate and grade 3-4 acute mucositis rate.

RESULTS

A total of 13 papers were eligible for the literature review. For schedules using a gemcitabine dose intensity (DI) below 50 mg/m(2) per week, the complete response rate was 86% (95% CI, 74%-93%) with grade 3-4 acute mucositis rate of 38% (95% CI, 27%-50%) and acceptable late toxicity. In one of the studies employing such low DIs, survival data were provided showing a 3-year overall survival of 50%. Compared with DI ≥50 mg/m(2) per week, there was no difference in the complete response rate (71%; 95% CI, 55%-83%; p = .087) but a significantly higher (p < .001) grade 3-4 acute mucositis rate of 74% (95% CI, 62%-83%), often leading to treatment interruptions (survival data provided in 8 studies; 3-year overall survival, 27%-63%). Late toxicity comprising mainly dysphagia was generally underreported, whereas information about xerostomia and skin fibrosis was scarce.

CONCLUSION

This review highlights the radiosensitizing potential of gemcitabine and suggests that even very low dosages (less than 50 mg/m(2) per week) provide a sufficient therapeutic ratio and therefore should be further investigated. Refinements in radiation schemes, including intensity-modulated radiation therapy, in combination with low-dose gemcitabine and targeted agents, such as cetuximab, are currently being investigated.

IMPLICATIONS FOR PRACTICE

Cisplatin-based concurrent chemoradiation (CCRT) has become the standard treatment of locally advanced head and neck cancer (LAHNC). This approach is hampered by significant toxicity. This paper reviews the studies using gemcitabine as an alternative radio-sensitizer for CCRT in patients with LAHNC. In this capacity, despite its mild intrinsic toxicity, gemcitabine comes with high rates of severe mucositis when used in dosages exceeding 50 mg/m(2) per week. CCRT with low-dose gemcitabine provides a sufficient therapeutic ratio, combining clinical activity, similar to the higher-dose regimens, with lower toxicity. Further investigation is warranted.

EGFR monoclonal antibodies in locally advanced head and neck squamous cell carcinoma: What is their current role?

Treatment options for locally advanced squamous cell carcinoma of the head and neck (SCCHN) include either surgical resection followed by radiation or chemoradiation, or definitive chemoradiation for which single-agent cisplatin is the best studied and established. The increasing understanding of the molecular biology of SCCHN has led to an interest in the development of targeted therapies. The epidermal growth factor receptor (EGFR) is over-expressed in nearly 80-90% of cases of SCCHN and correlates with poor prognosis and resistance to radiation. Preclinical evidence showed that blocking EGFR restores radiation sensitivity and enhances cytotoxicity. This finding led to clinical trials evaluating this class of agents and the approval of cetuximab in combination with radiation for the treatment of locally advanced SCCHN. This review is focused on the anti-EGFR monoclonal antibodies and their role either with radiotherapy or chemoradiation in unresectable LA SCCHN.

HPV-Associated Head and Neck Cancer

Over the last two decades, it has been recognized that head and neck cancers, primarily in the oropharynx, can be a distinct entity that is causally related to human papilloma virus (HPV). Fakhry et al. established in 2008 that such tumors have a strikingly better prognosis with improved responsiveness to chemotherapy as well as chemoradiotherapy and favorable survival rates. Since then, new studies have contributed to our increased understanding of this new entity, ranging from a detailed understanding of the genetic fingerprint and risk modifiers such as smoking to successful early attempts to personalize therapy with de-escalation in the definitive intent treatment setting and specific evaluation of targeted therapies in this patient population. This Commentary seeks to summarize the state of the art of our understanding of HPV-associated head and neck cancers that has emerged since the publication of seminal findings by Fakhry et al.

Cetuximab and Radiotherapy Versus Cisplatin and Radiotherapy for Locally Advanced Head and Neck Cancer: A Randomized Phase II Trial

PURPOSE

No randomized trials have been conducted to directly compare radiotherapy (RT) with concomitant cisplatin (CDDP) versus concomitant cetuximab (CTX) as first-line treatment of locally advanced squamous cell carcinoma of the head and neck. In this randomized trial, we compared these two treatment regimens in terms of compliance, toxicity, and efficacy.

PATIENTS AND METHODS

Eligible patients were randomly assigned in a 1:1 ratio to receive either CDDP 40 mg/m(2) once per week or CTX 400 mg/m(2) as loading dose followed by CTX 250 mg/m(2) once per week concomitant to radical RT. For primary end points, compliance to treatment was defined as number of days of treatment discontinuation and drug dosage reduction. The acute toxicity rate was defined according to the National Cancer Institute Common Toxicity Criteria. Efficacy end points were local recurrence-free survival, metastasis-free survival, cancer-specific survival, and overall survival.

RESULTS

The study was discontinued early because of slow accrual after the enrollment of 70 patients. RT discontinuation for more than 10 days occurred in 13% of patients given CTX and 0% given CDDP (P = .05). Drug dosage reduction occurred in 34% given CTX and 53% given CDDP (difference not significant). Toxicity profiles differed between the two arms, with hematologic, renal, and GI toxicities more frequent in the CDDP arm, and cutaneous toxicity and the need for nutritional support more frequent in the CTX arm. Serious adverse events related to treatment, including four versus one toxic deaths, were higher in the CTX arm (19% v 3%, P = .044). Locoregional control, patterns of failure, and survivals were similar between the treatment arms.

CONCLUSION

CTX concomitant to RT lowered compliance and increased acute toxicity rates. Efficacy outcomes were similar in both arms. These results raise the issue of appropriately selecting patients with head and neck cancer who can benefit from CTX in combination with RT.

Interventions for the treatment of oral and oropharyngeal cancers: targeted therapy and immunotherapy

BACKGROUND

Oral cancers are the sixth most common cancer worldwide, yet the prognosis following a diagnosis of oral cavity or oropharyngeal cancers remains poor, with approximately 50% survival at five years. Despite a sharp increase in research into molecularly targeted therapies and a rapid expansion in the number of clinical trials assessing new targeted therapies, their value for treating oral cancers is unclear. Therefore, it is important to summarise the evidence to determine the efficacy and toxicity of targeted therapies and immunotherapies for the treatment of these cancers.

OBJECTIVES

To assess the effects of molecularly targeted therapies and immunotherapies, in addition to standard therapies, for the treatment of oral cavity or oropharyngeal cancers.

SEARCH METHODS

We searched the following electronic databases: Cochrane Oral Health Group Trials Register (to 3 February 2015), Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2015, Issue 1), MEDLINE via Ovid (1946 to 3 February 2015) and EMBASE via Ovid (1980 to 3 February 2015). We searched the US National Institutes of Health Trials Register (clinicaltrials.gov), the World Health Organization Clinical Trials Registry Platform, the American Society of Clinical Oncology conference abstracts and the Radiation Therapy Oncology Group clinical trials protocols for ongoing trials. We placed no restrictions on the language or date of publication.

SELECTION CRITERIA

We included randomised controlled trials where more than 50% of participants had primary tumours of the oral cavity or oropharynx, and which compared targeted therapy or immunotherapy, plus standard therapy, with standard therapy alone.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the results of the electronic searches, extracted data and assessed the risk of bias of the included studies. We attempted to contact study authors for missing data or clarification where necessary. We combined sufficiently similar studies in meta-analyses using random-effects models when there were at least four studies and fixed-effect models when fewer than four studies. We obtained or calculated a hazard ratio (HR) and 95% confidence interval (CI) for the primary outcomes where possible. For dichotomous outcomes, we reported risk ratios (RR) and 95% CIs.

MAIN RESULTS

Twelve trials (2488 participants) satisfied the inclusion criteria. In the included trials, 12% of participants (298 participants) had tumours of the oral cavity and 59% (1468 participants) had oropharyngeal tumours. The remaining 29% had tumours of the larynx or hypopharynx and less than 1% had tumours at other sites.No included trial was at low risk of bias; seven had an unclear risk of bias, and five had a high risk of bias. We grouped trials by intervention type into three main comparisons: standard therapy plus epidermal growth factor receptor monoclonal antibody (EGFR mAb) therapy (follow-up period 24 to 70 months); standard therapy plus tyrosine kinase inhibitors (TKIs) (follow-up period 40 to 60 months) and standard therapy plus immunotherapy (follow-up period 24 to 70 months), all versus standard therapy alone.Moderate quality evidence showed that EGFR mAb therapy may result in 18% fewer deaths when added to standard therapy (HR of mortality 0.82; 95% CI 0.69 to 0.97; 1421 participants, three studies, 67% oropharyngeal tumours, 2% oral cavity tumours).There was also moderate quality evidence that EGFR mAb may result in 32% fewer locoregional failures when added to radiotherapy (RT) (HR 0.68; 95% CI 0.52 to 0.89; 424 participants, one study, 60% oropharyngeal tumours).A subgroup analysis separating studies by type of standard therapy (radiotherapy (RT) or chemoradiotherapy (CRT)) showed some evidence that adding EGFR mAb therapy to RT may result in a 30% reduction in the number of people whose disease progresses (HR 0.70; 95% CI 0.54 to 0.91; 424 participants, one study, 60% oropharyngeal tumours, unclear risk of bias). For the subgroup comparing EGFR mAb plus CRT with CRT alone there was insufficient evidence to determine whether adding EGFR mAb therapy to CRT impacts on progression-free survival (HR 1.08; 95% CI 0.89 to 1.32; 891 participants, one study, 70% oropharyngeal tumours, high risk of bias). The high subgroup heterogeneity meant that we were unable to pool these subgroups.There was evidence that adding cetuximab to standard therapy may result in increased skin toxicity and rash (RR 6.56; 95% CI 5.35 to 8.03; 1311 participants, two studies), but insufficient evidence to determine any difference in skin toxicity and rash in the case of nimotuzumab (RR 1.06; 95% CI 0.85 to 1.31; 92 participants, one study).There was insufficient evidence to determine whether TKIs added to standard therapy impacts on overall survival (HR 0.99; 95% CI 0.62 to 1.57; 271 participants, two studies; very low quality evidence), locoregional control (HR 0.89; 95% CI 0.53 to 1.49; 271 participants, two studies; very low quality evidence), disease-free survival (HR 1.51; 95% CI 0.61 to 3.71; 60 participants, one study; very low quality evidence) or progression-free survival (HR 0.80; 95% CI 0.51 to 1.28; 271 participants, two studies; very low quality evidence). We did find evidence of an increase in skin rash (erlotinib: RR 6.57; 95% CI 3.60 to 12.00; 191 participants, one study; lapatinib: RR 2.02; 95% CI 1.23 to 3.32; 67 participants, one study) and gastrointestinal complaints (lapatinib: RR 15.53; 95% CI 2.18 to 110.55; 67 participants, one study).We found very low quality evidence from one small trial that adding recombinant interleukin (rIL-2) to surgery may increase overall survival (HR 0.52; 95% CI 0.31 to 0.87; 201 participants, 62% oral cavity tumours, 38% oropharyngeal tumours) and there was insufficient evidence to determine whether rIL-2 impacts on adverse effects.

AUTHORS' CONCLUSIONS

We found some evidence that adding EGFR mAb to standard therapy may increase overall survival, progression-free survival and locoregional control, while resulting in an increase in skin toxicity for some mAb (cetuximab).There is insufficient evidence to determine whether adding TKIs to standard therapies changes any of our primary outcomes.Very low quality evidence from a single study suggests that rIL-2 combined with surgery may increase overall survival compared with surgery alone.

Balancing Safety and Efficacy of Epidermal Growth Factor Receptor Inhibitors in Patients With Squamous Cell Carcinoma of the Head and Neck

The epidermal growth factor receptor (EGFR) is overexpressed in more than 80% of squamous cell cancers of the head and neck (SCCHN). An evolving understanding of the role of EGFR in tumorigenesis has made the receptor an important therapeutic target in SCCHN. Several EGFR inhibitors (EGFRIs) are active in SCCHN, and their use is associated with improvement in progression-free survival and overall survival in various treatment settings. Nevertheless, EGFR inhibition is associated with significant mucocutaneous toxicity that must be balanced against its anticipated efficacy. This review summarizes the relevant clinical trial experience with EGFRIs, with attention to efficacy, toxicity, and methods of selecting patients most likely to benefit from therapy.

Predictive factors of head and neck squamous cell carcinoma patient tolerance to high-dose cisplatin in concurrent chemoradiotherapy

Although high-dose cisplatin is the standard regimen of concurrent chemoradiotherapy (CCRT) for locally advanced head and neck squamous cell carcinoma (HNSCC), varying levels of patient tolerance towards cisplatin have been reported, and the predictive factors of cisplatin tolerance remain to be elucidated. The present study retrospectively reviewed newly diagnosed HNSCC patients who received CCRT. Cisplatin (80 mg/m²) was administered every 3 weeks. The proportion of high-dose cisplatin-tolerant patients (cumulative cisplatin dose, ≥200 mg/m²) was determined, and the predictive factors of cisplatin tolerance were analyzed in a logistic regression analysis. Between June 2006 and March 2013, a total of 159 patients were treated with CCRT. The median follow-up time was 36.7 months. A total of 73 patients (46%) tolerated a cumulative cisplatin dose ≥200 mg/m²; male gender [odds ratio (OR), 25.00; P=0.005] and high body surface area (BSA) (>1.80 m²; OR, 2.21; P=0.032) were significantly predictive of high-dose cisplatin tolerance. The high-dose cisplatin-tolerant patients had a significantly higher complete response (CR) rate (82 vs. 67%, P=0.045); however, there were no significant between-group differences in the 3-year OS (79.5 vs. 81.2%, P=0.59) or PFS (70.4 vs. 44.6%, P=0.076) by cisplatin tolerance. In clinical practice, approximately one-half of the patients tolerated high-dose cisplatin in CCRT. Male gender and high BSA could be predictive of cisplatin tolerance.

Taselisib (GDC-0032), a Potent β-Sparing Small Molecule Inhibitor of PI3K, Radiosensitizes Head and Neck Squamous Carcinomas Containing Activating PIK3CA Alterations

PURPOSE

ActivatingPIK3CAgenomic alterations are frequent in head and neck squamous cell carcinoma (HNSCC), and there is an association between phosphoinositide 3-kinase (PI3K) signaling and radioresistance. Hence, we investigated the therapeutic efficacy of inhibiting PI3K with GDC-0032, a PI3K inhibitor with potent activity against p110α, in combination with radiation in HNSCC.

EXPERIMENTAL DESIGN

The efficacy of GDC-0032 was assessedin vitroin 26 HNSCC cell lines with crystal violet proliferation assays, and changes in PI3K signaling were measured by Western blot analysis. Cytotoxicity and radiosensitization were assessed with Annexin V staining via flow cytometry and clonogenic survival assays, respectively. DNA damage repair was assessed with immunofluorescence for γH2AX foci, and cell cycle analysis was performed with flow cytometry.In vivoefficacy of GDC-0032 and radiation was assessed in xenografts implanted into nude mice.

RESULTS

GDC-0032 inhibited potently PI3K signaling and displayed greater antiproliferative activity in HNSCC cell lines withPIK3CAmutations or amplification, whereas cell lines withPTENalterations were relatively resistant to its effects. Pretreatment with GDC-0032 radiosensitizedPIK3CA-mutant HNSCC cells, enhanced radiation-induced apoptosis, impaired DNA damage repair, and prolonged G2-M arrest following irradiation. Furthermore, combined GDC-0032 and radiation was more effective than either treatment alonein vivoin subcutaneous xenograft models.

CONCLUSIONS

GDC-0032 has increased potency in HNSCC cell lines harboringPIK3CA-activating aberrations. Further, combined GDC-0032 and radiotherapy was more efficacious than either treatment alone inPIK3CA-altered HNSCCin vitroandin vivo This strategy warrants further clinical investigation.

Postoperative Adjuvant Lapatinib and Concurrent Chemoradiotherapy Followed by Maintenance Lapatinib Monotherapy in High-Risk Patients With Resected Squamous Cell Carcinoma of the Head and Neck: A Phase III, Randomized, Double-Blind, Placebo-Controlled Study

PURPOSE

This multicenter phase III study evaluated the efficacy and safety of lapatinib, an epidermal growth factor receptor/ErbB2 inhibitor, administered concomitantly with chemoradiotherapy and as maintenance monotherapy in patients with high-risk surgically treated squamous cell carcinoma of the head and neck (SCCHN).

PATIENTS AND METHODS

Patients with resected stage II to IVA SCCHN, with a surgical margin ≤ 5 mm and/or extracapsular extension, were randomly assigned to chemoradiotherapy (66 Gy total radiation dose and cisplatin 100 mg/m(2) per day administered on days 1, 22, and 43) plus placebo or lapatinib (1,500 mg per day) before and during chemoradiotherapy, followed by 12 months of maintenance monotherapy.

RESULTS

Six hundred eighty-eight patients were enrolled (lapatinib, n = 346; placebo, n = 342). With a median follow-up time of 35.3 months, the study ended early because of the apparent plateauing of disease-free survival (DFS) events. Median DFS assessed by an independent review committee was 53.6 months and not reached for lapatinib and placebo, respectively (hazard ratio, 1.10; 95% CI, 0.85 to 1.43). Investigator-assessed results confirmed the independent review committee assessment. No significant differences in DFS by human papillomavirus status or overall survival were observed between treatment arms. Similar numbers of patients in both treatment arms experienced adverse events (AEs), with more patients in the lapatinib arm than the placebo arm experiencing serious AEs (48% v 40%, respectively). The most commonly observed treatment-related AEs were diarrhea and rash, both predominantly in the lapatinib arm.

CONCLUSION

Addition of lapatinib to chemoradiotherapy and its use as long-term maintenance therapy does not offer any efficacy benefits and had additional toxicity compared with placebo in patients with surgically treated high-risk SCCHN.

Improving Quality of Life With Nabilone During Radiotherapy Treatments for Head and Neck Cancers

Objectives:

Patients treated for head and neck carcinomas experience a significant deterioration of their quality of life during treatments because of severe side effects. Nabilone has many properties that could alleviate symptoms caused by radiotherapy and improve patients’ quality of life. The aim of the present study was to compare the effects of nabilone versus placebo on the quality of life and side effects during radiotherapy for head and neck carcinomas.

Methods:

Fifty-six patients were randomized to nabilone or placebo. Patients filled the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 and the EORTC QLQ-H&N35; three independent questionnaires assessing appetite, nausea, and toxicity; and a visual analog scale for pain. These data were collected before radiotherapy, each week during radiotherapy, and 4 weeks after radiotherapy. Patients were weighed every week.

Results:

Nabilone did not lengthen the time necessary for a 15% deterioration of quality of life ( P = .4279), and it was not better than placebo for relieving symptoms like pain ( P = .6048), nausea ( P = .7105), loss of appetite ( P = .3295), weight ( P = .1454), mood ( P = .3214), and sleep ( P = .4438).

Conclusion:

At the dosage used, nabilone was not potent enough to improve the patients’ quality of life over placebo.

Sequential and Concurrent Chemoradiation: State of the Art

Most patients diagnosed with head and neck cancer have locally advanced disease. Sequential and concurrent chemoradiation are standard, nonsurgical, curative-intent treatment options. Controversy remains regarding the superiority of one approach to another. Definitive management strategies are evolving with increasing efforts to pursue deintensification of therapy for low-risk patients, and to pursue therapeutic intensification for high-risk patients. Both sequential therapy and concurrent chemoradiation play important roles in shaping treatment paradigms because both approaches may be used to investigate deintensification or intensification strategies. This article examines the latest evidence and state-of-the-art approaches, highlighting ongoing controversies and future directions.

Oral Mucositis Induced By Anticancer Therapies

Oral mucositis induced by conventional cytotoxic cancer therapies is a common and significant clinical problem in oncology. Mucositis symptoms, which include severe pain, may lead to dose reductions and unplanned interruptions of chemotherapy and/or radiotherapy, and often affect patients' quality of life. In addition, ulcerative mucositis represents a risk factor for local or systemic infectious complications that may be life-threatening in immunosuppressed patients. The development of biologically based targeted cancer therapies, which aim to block the growth, spread, and survival of tumors by interfering with specific molecular targets, may have reduced mucosal injury, but did not eliminate it. This article will review the epidemiology, pathobiology, and management of oral mucositis associated with conventional cytotoxic therapies for malignant diseases and will briefly summarize emerging information on oral mucosal injury associated with targeted therapies. Considerations for future research aimed at the development of more efficient and effective supportive care approaches will be presented, with emphasis on the contribution of dental researchers and clinicians in these efforts.

Molecular Aspects of Head and Neck Cancer Therapy

In spite of a rapidly expanding understanding of head and neck tumor biology and optimization of radiation, chemotherapy, and surgical treatment modalities, head and neck squamous cell carcinoma (HNSCC) remains a major cause of cancer-related morbidity and mortality. Although our biologic understanding of these tumors had largely been limited to pathways driving proliferation, survival, and differentiation, the identification of HPV as a major driver of HNSCC and genomic sequencing analyses has dramatically influenced our understanding of tumor biology and approach to therapy. Here, we summarize molecular aspects of HNSCC biology and identify promising areas for potential diagnostic and therapeutic agents.

Increased radiosensitivity of HPV-positive head and neck cancers: Molecular basis and therapeutic perspectives

Human papillomavirus driven head and neck squamous cell carcinoma (HNSCC), particularly oropharyngeal squamous cell carcinoma (OPSCC), are characterized by a significant survival advantage over their HPV-negative counterparts. Although the reasons behind this are still not fully elucidated, it is widely accepted that these tumors have a higher response to ionizing radiation that might explain their favorable outcomes. Potential underlying intrinsic mechanisms include impaired DNA repair abilities, differences in activated repopulation-signaling pathways and cell cycle control mechanisms. The role of the microenvironment is increasingly highlighted, particularly tumor oxygenation and the immune response. Recent studies have shown a distinct pattern of intratumoral immune cell infiltrates, according to HPV status, and have suggested that an increased cytotoxic T-cell based antitumor immune response is involved in improved prognosis of patients with HPV-positive OPSCC. These significant milestones, in the understanding of HPV-induced HNSCC, pave the way to new therapeutic opportunities. This article reviews the current evidence on the biological basis of increased radiosensitivity in HPV-positive HNSCC and discusses potential therapeutic implications.

Enhancement of Cetuximab-Induced Radiosensitization by JAK-1 Inhibition

BACKGROUND

It is known that cetuximab (an epidermal growth factor receptor [EGFr] inhibitor) is a radiosensitizer. Also, cetuximab is known to only partially inhibit the signal transducer and activator of transcription - 3 (STAT-3); a mediator of protection from apoptosis. Studies were performed to determine if the radiosensitizing effects of cetuximab could be enhanced with the addition of an inhibitor of STAT-3.

METHODS/RESULTS

The interaction of JAK-STAT-3 inhibition ([JAK1i]; Calbiochem, LaJolla, CA) and EGFr inhibition (cetuximab) was assessed with and without radiation. Four human head and neck cell lines were studied: UM-SCC-1 and UM-SCC-5, and two modified UM-SCC-5 lines; a STAT-3 knockdown line (STAT-3-2.4) and control (NEG-4.17). Exposure to either 0.5 μg/ml of cetuximab or 1 μM JAK1i for 8 or 24 h resulted in reduced activated STAT-3 (immunoblot), and the combination treatment showed greater reduction in activated STAT-3 compared to the individual treatments. The use of either post-radiation JAK1i (1 μM for 72 h) or post-radiation cetuximab (0.5 μg/ml) enhanced radiation-induced anti-proliferative and apoptotic effects but the greatest enhancement was seen when cells were exposed to both JAK1i and cetuximab post-radiation. Similar results were seen for radiosensitization as assessed by colony formation. Finally, the combination treatment of JAK1i (1 μM) and cetuximab (0.5 μg/ml), following radiation, resulted in an increase of unrepaired radiation-induced DNA double strand breaks at 6 and 24 h after radiation compared to the use of post-radiation JAK1i or cetuximab alone as delineated by neutral comet assay.

CONCLUSIONS

These findings suggest that dual inhibition of EGFr (cetuximab) and JAK-STAT-3 (JAK1i) leads to greater radiosensitization than with either cetuximab or JAK1i alone and suggests that this combination treatment may be clinically relevant even for tumors with a marked range of STAT-3 activity.

Human Papillomavirus-Negative Pharyngeal Cancer

Human papillomavirus-negative head and neck squamous cell carcinoma (HNSCC) carries a poor prognosis, and despite optimal treatment with chemoradiotherapy to the limit of tolerance, many patients will relapse. A number of methods for intensifying treatment of HNSCC have been investigated, leading to the current standards of care. Novel agents targeting tumor cell and stromal signaling, DNA damage response, and immune system are now reaching clinical trials in combination with chemoradiotherapy. In this review, we discuss the evidence for the current treatment of locally advanced human papillomavirus-negative HNSCC, as well as investigational therapies, such as hypoxia modification, molecular targeting of epidermal growth factor receptor family, vascular endothelial growth factor receptor or DNA damage response proteins in combination with radiation therapy.

EGFR targeted therapies and radiation: Optimizing efficacy by appropriate drug scheduling and patient selection

The epidermal growth factor receptor (EGFR) plays an important role in tumor progression and treatment resistance for many types of malignancies including head and neck, colorectal, and nonsmall cell lung cancer. Several EGFR targeted therapies are efficacious as single agents or in combination with chemotherapy. Given the toxicity associated with chemoradiation and poor outcomes seen in several types of cancers, combinations of EGFR targeted agents with or without chemotherapy have been tested in patients receiving radiation. To date, the only FDA approved use of an anti-EGFR therapy in combination with radiation therapy is for locally advanced head and neck cancer. Given the important role EGFR plays in lung and colorectal cancer and the benefit of EGFR inhibition combined with chemotherapy in these disease sites, it is perplexing why EGFR targeted therapies in combination with radiation or chemoradiation have not been more successful. In this review we summarize the clinical findings of EGFR targeted therapies combined with radiation and chemoradiation regimens. We then discuss the interaction between EGFR and radiation including radiation induced EGFR signaling, the effect of EGFR on DNA damage repair, and potential mechanisms of radiosensitization. Finally, we examine the potential pitfalls with scheduling EGFR targeted therapies with chemoradiation and the use of predictive biomarkers to improve patient selection.

Pan-HER Inhibitor Augments Radiation Response in Human Lung and Head and Neck Cancer Models

PURPOSE

Aberrant regulation of the EGF receptor family (EGFR, HER2, HER3, HER4) contributes to tumorigenesis and metastasis in epithelial cancers. Pan-HER represents a novel molecular targeted therapeutic composed of a mixture of six monoclonal antibodies against EGFR, HER2, and HER3.

EXPERIMENTAL DESIGN

In the current study, we examine the capacity of Pan-HER to augment radiation response across a series of human lung and head and neck cancers, including EGFR inhibitor-resistant cell lines and xenografts.

RESULTS

Pan-HER demonstrates superior antiproliferative and radiosensitizing impact when compared with cetuximab. The mechanisms underlying these effects appear to involve attenuation of DNA damage repair, enhancement of programmed cell death, cell-cycle redistribution, and induction of cellular senescence. Combined treatment of Pan-HER with single or fractionated radiation in human tumor xenografts reveals a potent antitumor and regrowth delay impact compared with Pan-HER or radiation treatment alone.

CONCLUSIONS

These data highlight the capacity of Pan-HER to augment radiation response in lung and head and neck cancer models and support investigation of Pan-HER combined with radiation as a promising clinical therapeutic strategy.

DNA double strand break repair defect and sensitivity to poly ADP-ribose polymerase (PARP) inhibition in human papillomavirus 16-positive head and neck squamous cell carcinoma

Patients with human papillomavirus-positive (HPV+) head and neck squamous cell carcinomas (HNSCCs) have increased response to radio- and chemotherapy and improved overall survival, possibly due to an impaired DNA damage response. Here, we investigated the correlation between HPV status and repair of DNA damage in HNSCC cell lines. We also assessed in vitro and in vivo sensitivity to the PARP inhibitor veliparib (ABT-888) in HNSCC cell lines and an HPV+ patient xenograft. Repair of DNA double strand breaks (DSBs) was significantly delayed in HPV+ compared to HPV- HNSCCs, resulting in persistence of γH2AX foci. Although DNA repair activators 53BP1 and BRCA1 were functional in all HNSCCs, HPV+ cells showed downstream defects in both non-homologous end joining and homologous recombination repair. Specifically, HPV+ cells were deficient in protein recruitment and protein expression of DNA-Pk and BRCA2, key factors for non-homologous end joining and homologous recombination respectively. Importantly, the apparent DNA repair defect in HPV+ HNSCCs was associated with increased sensitivity to the PARP inhibitor veliparib, resulting in decreased cell survival in vitro and a 10-14 day tumor growth delay in vivo. These results support the testing of PARP inhibition in combination with DNA damaging agents as a novel therapeutic strategy for HPV+ HNSCC.

Safety and efficacy of concurrent carboplatin plus radiotherapy for locally advanced head and neck cancer patients ineligible for treatment with cisplatin

OBJECTIVE

Cisplatin-based chemoradiotherapy is the standard treatment for patients with locally advanced squamous cell carcinoma of the head and neck. However, patients with advanced age, renal, cardiac or neurogenic dysfunction seem ineligible for cisplatin treatment. We evaluated the safety and efficacy of concurrent carboplatin plus radiotherapy in patients ineligible for cisplatin usage.

METHODS

We retrospectively analyzed the records of 25 consecutive locally advanced squamous cell carcinoma of the head and neck patients who received concurrent carboplatin plus radiotherapy at Shizuoka Cancer Center between August 2006 and March 2014. Carboplatin was administered tri-weekly or weekly.

RESULTS

Patient characteristics were analyzed. The median age was 75 years (range, 54-82), male:female ratio, 24:1; performance status, 0-1 (23) or 2 (2); primary tumor site, oropharynx (10), hypopharynx (12), larynx (1) or oral cavity (2); Stage III (3), IVa (19) or IVb (3); induction chemotherapy, with (2) or without (23); and a median creatinine clearance of 62 ml/min (range, 37-117). The main reasons for choosing carboplatin were age (40%), renal impairment (36%) and cardiac dysfunction (20%). All patients received a planned irradiation dose of 70 Gy. Median follow-up was 30.9 months. Complete response was observed 70% patients. Median progression-free survival duration was 42.7 months. Median overall survival could not be analyzed. The 2-year progression-free and overall survival rates were 68 and 74%, respectively. The main toxicity Grade 3 or 4 was oral mucositis (56%), thrombocytopenia (34%), neutropenia (28%) and infection (24%).

CONCLUSIONS

Concurrent carboplatin plus radiotherapy is tolerated and may be an option in treating locally advanced squamous cell carcinoma of the head and neck patients ineligible for treatment with cisplatin.

Human Papillomavirus-Associated Oropharyngeal Cancer: Defining Risk Groups and Clinical Trials

Human papillomavirus-associated oropharynx cancer (HPVA-OPC) is rapidly increasing in incidence and has unique epidemiologic, molecular, and biologic characteristics. Despite being recognized as having superior prognosis, current evidence does not support less intense therapy compared with HPV-negative OPC. Current combined modality therapies confer a significant risk of morbidity, and patients with HPVA-OPC have a younger median age. These patients, therefore, live longer with the adverse effects of treatment, and this spurs the development of treatment deintensification trials that attempt to decrease treatment-related morbidity without compromising efficacy. Many radiation and chemotherapy de-escalation trials are underway. Minimally invasive surgical techniques are also being evaluated. It is important to identify the ideal patient group for treatment deintensification and to define prognostic risk groups to avoid undertreating the poorer-risk subset in HPVA-OPC, and validated biomarkers are needed to identify patients with the best prognosis. Significant smoking exposure mitigates the favorable prognosis of HPVA-OPC. Currently, less intense treatment is an option only in the setting of clinical trials, and patients with HPVA-OPC should be offered clinical trial options whenever they are available. Finally, recognition of novel therapeutic targets and signaling pathways is critical to the development of new treatment strategies that are desperately needed for patients with poor risk and those with recurrent and metastatic disease.

Supportive Management of Mucositis and Metabolic Derangements in Head and Neck Cancer Patients

Oral mucositis (OM) is among the most undesirable, painful, and expensive toxicities of cytotoxic cancer therapy, and is disheartening for patients and frustrating for caregivers. Accurate assessment of the incidence of OM has been elusive, but accumulating data suggests that reported OM frequency is significantly less than its actual occurrence. It has been suggested that over 90% of head and neck cancer (HNC) patients receiving radiotherapy (RT) with concurrent cisplatin experience severe OM with symptoms of extreme pain, mucosal ulceration and consequent limitations in swallowing and achieving adequate nutritional intake. This panoply of symptoms inevitably impacts a patients' quality of life and their willingness to continue treatment. In spite of all the advances made in understanding the pathophysiology of OM, there is still no prophylactic therapy with proven efficacy. Strategies to limit the extent of OM and to manage its symptomatology include basic oral care, supportive medications, nutritional support and targeting aggressive treatments to high-risk patients. This review focuses on OM recognition, preventive measurements, and symptom-management strategies.

Heterogeneity of (18)F-FDG PET combined with expression of EGFR may improve the prognostic stratification of advanced oropharyngeal carcinoma

The Ang's risk profile (based on p16, smoking and cancer stage) is a well-known prognostic factor in oropharyngeal squamous cell carcinoma (OPSCC). Whether heterogeneity in (18)F-fluorodeoxyglucose (FDG) positron emission tomographic (PET) images and epidermal growth factor receptor (EGFR) expression could provide additional information on clinical outcomes in advanced-stage OPSCC was investigated. Patients with stage III-IV OPSCC who completed primary therapy were eligible. Zone-size nonuniformity (ZSNU) extracted from pretreatment FDG PET scans was used as an index of image heterogeneity. EGFR and p16 expression were examined by immunohistochemistry. Disease-specific survival (DSS) and overall survival (OS) served as outcome measures. Kaplan-Meier estimates and Cox proportional hazards regression models were used for survival analysis. A bootstrap resampling technique was applied to investigate the stability of outcomes. Finally, a recursive partitioning analysis (RPA)-based model was constructed. A total of 113 patients were included, of which 28 were p16-positive. Multivariate analysis identified the Ang's profile, EGFR and ZSNU as independent predictors of both DSS and OS. Using RPA, the three risk factors were used to devise a prognostic scoring system that successfully predicted DSS in both p16-positive and -negative cases. The c-statistic of the prognostic index for DSS was 0.81, a value which was significantly superior to both AJCC stage (0.60) and the Ang's risk profile (0.68). In patients showing an Ang's high-risk profile (N = 77), the use of our scoring system clearly identified three distinct prognostic subgroups. It was concluded that a novel index may improve the prognostic stratification of patients with advanced-stage OPSCC.

Phase II trial of bevacizumab + cetuximab + cisplatin with concurrent intensity-modulated radiation therapy for patients with stage III/IVB head and neck squamous cell carcinoma

BACKGROUND

The purpose of this study was to evaluate the efficacy and tolerability of the addition of 2 monoclonal antibodies, bevacizumab and cetuximab, to 2 cycles of high-dose cisplatin administered concurrently with intensity-modulated radiation therapy (IMRT) for head and neck squamous cell carcinoma (HNSCC).

METHODS

Patients with newly diagnosed stage III/IVB (M0) HNSCC received cetuximab (400 mg/m(2) loading dose, followed by 250 mg/m(2) weekly), bevacizumab (15 mg/kg, days 1 and 22), and cisplatin (50 mg/m(2) , days 1, 2, 22, and 23) concurrently with IMRT (70 Gy). The primary endpoint was progression-free survival (PFS). Secondary endpoints were overall survival (OS) and safety and tolerability.

RESULTS

Among 30 patients enrolled in this study, the primary tumor site was the oropharynx in 24 patients (p16 immunohistochemistry was positive in 17, negative in 1, and not done in 6 of the oropharyngeal tumors). Median age was 57 years (range, 38-77 years) and 27 patients had clinical stage IVA disease. All patients completed the full planned dose of radiation therapy. The most common ≥ grade 3 adverse events were lymphopenia, mucositis (functional), and dysphagia. With a median follow-up of 33.8 months, 2-year PFS was 88.5% (95% confidence interval [CI] = 68.1-96.1) and 2-year OS was 92.8% (95% CI = 74.2-98.1).

CONCLUSION

The addition of bevacizumab and cetuximab to 2 cycles of cisplatin, given concurrently with IMRT, was well-tolerated and was associated with favorable efficacy outcomes in this patient population. © 2015 Wiley Periodicals, Inc. Head Neck 38: E566-E570, 2016.

STAT1 Activation Is Enhanced by Cisplatin and Variably Affected by EGFR Inhibition in HNSCC Cells

Cisplatin is a cytotoxic chemotherapeutic drug frequently used to treat many solid tumors, including head and neck squamous cell carcinoma (HNSCC). EGF receptor (EGFR) inhibitors have also shown efficacy as alternatives to cisplatin in some situations. However, large clinical trials have shown no added survival benefit from the use of these two drugs in combination. Possible explanations for this include overlapping downstream signaling cascades. Using in vitro studies, we tested the hypothesis that cisplatin and EGFR inhibitors rely on the activation of the tumor suppressor STAT1, characterized by its phosphorylation at serine (S727) or tyrosine (Y701) residues. Cisplatin consistently increased the levels of p-S727-STAT1, and STAT1 siRNA knockdown attenuated cisplatin-induced cell death. EGFR stimulation also activated p-S727-STAT1 and p-Y701-STAT1 in a subset of cell lines, whereas EGFR inhibitors alone decreased levels of p-S727-STAT1 and p-Y701-STAT1 in these cells. Contrary to our hypothesis, EGFR inhibitors added to cisplatin treatment caused variable effects among cell lines, with attenuation of p-S727-STAT1 and enhancement of cisplatin-induced cell death in some cells and minimal effect in other cells. Using HNSCC tumor specimens from a clinical trial of adjuvant cisplatin plus the anti-EGFR antibody panitumumab, higher intratumoral p-S727-STAT1 appeared to correlate with worse survival. Together, these results suggest that cisplatin-induced cell death is associated with STAT1 phosphorylation, and the addition of anti-EGFR therapy to cisplatin has variable effects on STAT1 and cell death in HNSCC.

Molecular biology and immunology of head and neck cancer

In recent years, our knowledge and understanding of head and neck squamous cell carcinoma (HNSCC) has expanded dramatically. New high-throughput sequencing technologies have accelerated these discoveries since the first reports of whole-exome sequencing of HNSCC tumors in 2011. In addition, the discovery of human papillomavirus in relationship with oropharyngeal squamous cell carcinoma has shifted our molecular understanding of the disease. New investigation into the role of immune evasion in HNSCC has also led to potential novel therapies based on immune-specific systemic therapies.

Locally advanced head and neck cancer treated with accelerated radiotherapy, the hypoxic modifier nimorazole and weekly cisplatin. Results from the DAHANCA 18 phase II study

PURPOSE/OBJECTIVE

A phase II clinical trial evaluating the feasibility and outcome of treating locally advanced head and neck squamous cell carcinoma (HNSCC) with accelerated radiotherapy, the hypoxic modifier nimorazole and weekly cisplatin.

MATERIAL AND METHODS

A total of 227 patients with stage III or IV HNSCC of the larynx, oropharynx, hypopharynx, or oral cavity where included between January 2007 and December 2010. The prescribed radiotherapy (RT) dose was 66-68 Gy in 2 Gy fractions, 6 F/W. The hypoxic radiosensitiser nimorazole was given orally at a dose of 1200 mg/m(2) before each fraction. Concomitant cisplatin (40 mg/m(2)) i.v. was given once a week for a maximum of six cycles. Outcome data were evaluated in terms of loco-regional tumour control (LRC), event-free survival (EFS) and overall survival (OS). Morbidity data were evaluated based on the DAHANCA routine registration. Human papillomavirus (HPV)-status was estimated by immunohistochemical staining of p16.

RESULTS

Included were 178 (78%) men and 49 (22%) women with a median age of 57 years. All except five patients received RT as prescribed. At least five series of cisplatin was given to 164 (72%) of the patients, and 149 patients (66%) received the full dose of nimorazole. The five-year actuarial LRC, EFS and OS rates were 80%, 67% and 72%, respectively. The LRC rates according to site were: oropharynx: 88%, larynx: 77%, hypopharynx 72% and oral cavity 49%, respectively. HPV/p16 staining was obtained in 141 of the 150 oropharyngeal cancers. Of these, 112 (79%) were p16 pos and 29 (21%) were p16 neg. LRC for the p16 neg oropharyngeal cancers was poorer than for the p16 pos (74% vs. 91%; p = 0.02). Tube feeding during treatment was necessary for 146 (64%) patients. At 12 months this number was reduced to 6%.

CONCLUSION

The treatment was tolerable in this cohort of locally advanced HNSCC patients. Acute and late toxicity was comparable to similar studies of chemoradiotherapy, and the outcome superior to the data reported in the literature. This strongly indicates that RT of advanced head and neck cancer must include as well hypoxic modification, accelerated fractionation as chemoradiotherapy to yield optimal outcome.

Opportunities and challenges of radiotherapy for treating cancer

The past 20 years have seen dramatic changes in the delivery of radiation therapy, but the impact of radiobiology on the clinic has been far less substantial. A major consideration in the use of radiotherapy has been on how best to exploit differences between the tumour and host tissue characteristics, which in the past has been achieved empirically by radiation-dose fractionation. New advances are uncovering some of the mechanistic processes that underlie this success story. In this Review, we focus on how these processes might be targeted to improve the outcome of radiotherapy at the individual patient level. This approach would seem a more productive avenue of treatment than simply trying to increase the radiation dose delivered to the tumour.