Prevention of second primary tumors with isotretinoin in patients with squamous cell carcinoma of the head and neck: long-term follow-up

Treating Head and Neck Cancer in the Age of Immunotherapy: A 2023 Update

Most patients diagnosed with head and neck squamous cell carcinoma (HNSCC) will present with locally advanced disease, requiring multimodality therapy. While this approach has a curative intent, a significant subset of these patients will develop locoregional failure and/or distant metastases. The prognosis of these patients is poor, and therapeutic options other than palliative chemotherapy are urgently needed. Epidermal growth factor receptor (EGFR) overexpression is an important factor in the pathogenesis of HNSCC, and a decade ago, the EGFR targeting monoclonal antibody cetuximab was approved for the treatment of late-stage HNSCC in different settings. In 2016, the anti-programmed death-1 (PD-1) immune checkpoint inhibitors nivolumab and pembrolizumab were both approved for the treatment of patients with recurrent or metastatic HNSCC with disease progression on or after platinum-containing chemotherapy, and in 2019, pembrolizumab was approved for first-line treatment (either as monotherapy in PD-L1 expressing tumors, or in combination with chemotherapy). Currently, trials are ongoing to include immune checkpoint inhibition in the (neo)adjuvant treatment of HNSCC as well as in novel combinations with other drugs in the recurrent/metastatic setting to improve response rates and survival and help overcome resistance mechanisms to immune checkpoint blockade. This article provides a comprehensive review of the management of head and neck cancers in the current era of immunotherapy.

Toxicity, Genotoxicity, and Carcinogenicity of Isotretinoin

BACKGROUND

Acne is a chronic inflammatory disease mainly observed in adolescence, but it can also be seen during the neonatal, infantile, pre-pubertal, and adult periods. Isotretinoin (13-cis-retinoic acid) is a first-generation retinoid and is the most effective treatment for acne vulgaris.

OBJECTIVE

The present study has been systematically designed to figure out the toxic, genotoxic, and carcinogenic activities of isotretinoin.

METHODS

In this study, a systematic approach was followed by focusing on the possible links between these topics. The search of the databases was carried out author in accordance with the guidelines of the Centre for Reviews and Dissemination (2009) developed by York University National Institute of Health Research. The search was concentrated on the Web of Science, PubMed, Science Direct, Scopus, EBSCO Host, and Google Scholar databases.

RESULTS

Isotretinoin was found as a toxic agent in all studies. All researchers proposed that apoptosis is the only pathway of adverse effects of isotretinoin. However, genotoxicity, teratogenicity, and carcinogenicity information of isotretinoin is very limited and controversial.

CONCLUSION

More detailed studies need to clarify the genotoxic and carcinogenic potential of isotretinoin. Patients should be informed correctly, the risks of treatment should be explained, and awareness should be raised.

Complementary and Integrative Medicine in Head and Neck Cancer

Complementary/integrative medicine (CIM) is an evolving area of collaboration between oncology, patient and their beliefs, and practitioners of complementary medicine. Evidence-informed decision-making is necessary to advise patients on which treatments may be incorporated into standard of care treatments for cancer. Patients use CIM for a variety of reasons and often have unrealistic expectations of cure or disease modifications; on the other hand, there is increasing evidence that symptoms, side effects, and dysfunction related to cancer and its treatment can be ameliorated by CIM approaches to improve patient satisfaction and quality of life. Open communication between patients and providers is paramount.

Phase Ib Study of Chemoprevention with Green Tea Polyphenon E and Erlotinib in Patients with Advanced Premalignant Lesions (APL) of the Head and Neck

PURPOSE

On the basis of synergistic effects between green tea polyphenon E (PPE) and EGFR-tyrosine kinase inhibitor in preclinical studies, we conducted a phase Ib study of the PPE and erlotinib combination in patients with advanced premalignant lesions (APL) of the oral cavity and larynx.

PATIENTS AND METHODS

Patients were treated with a fixed dose of PPE (200 mg three times a day) and dose escalation of erlotinib (50, 75, 100 mg daily) for 6 months with tissue biopsy at baseline and 6 months. Primary endpoints were safety and toxicity; secondary endpoints were evaluation of pathologic response, cancer-free survival (CFS), overall survival (OS), and biomarker modulation.

RESULTS

Among 21 enrolled patients, 19 began treatment and 17 completed 6 months of treatment with PPE and erlotinib. Main characteristics of treated patients: 15 severe dysplasia or carcinoma in situ and 17 oral cavity. Only skin rash was associated with dose-limiting toxicity and MTD. Recommended doses for phase II studies are PPE 600 mg daily plus erlotinib 100 mg daily for 6 months. Pathologic responses in 17 evaluable patients: pathologic complete response (47%) and pathologic partial response (18%). The 5-year CFS and OS were 66.3% and 93%, respectively. Among tested biomarkers, only phosphorylated ERK was correlated with response to treatment.

CONCLUSIONS

Treatment with PPE and erlotinib combination was well tolerated in patients with APLs of the head and neck, and showed a high rate of pathologic response with excellent CFS. This combination deserves further investigation for the chemoprevention and/or prevention of second primary tumors in early-stage head and neck cancer.

Second primary malignancies in laryngeal carcinoma patients treated with definitive radiotherapy

INTRODUCTION

Second primary malignancy (SPM) is associated with decreased overall survival (OS) in laryngeal carcinomas (LC).

METHODS

One hundred eighty three LC patients were analyzed retrospectively. The primary and secondary endpoints were the incidence of SPM and the OS difference between patients with and without SPM.

RESULTS

SPM developed in 22 (12.0%) patients at median 52 months (range, 4-131 months), with a yearly 2.8% incidence, of which 19 (10.4%) and 3 (1.6%) were metachronous and synchronous, respectively. Lung was the commonest SPM (72.7%). Of 47 deaths, 12 (25.5%) were SPM related. Comparatively SPM patients had significantly shorter median OS (68.0 months vs. median not reached; P = 0.005), with lower 5-year (67.0% vs. 78.9%) and 8-year (32.6 vs. 69.8%) survival rates.

CONCLUSION

The present findings suggested the SPM as a competing risk factor for death in index LC patients with its annual incidence rate of 2.8% and for accounting one of every four deaths in this patients group. Emergence of lung carcinoma as the most frequent type of SPM and the ability to treat >50% of them with an estimated long-term outcomes emphasizes the importance of early diagnosis and curative treatment of SPMs.

The significance of gene mutations across eight major cancer types

Mutations occur spontaneously, which can be induced by either chemicals (e.g. benzene) or biological factors (e.g. virus). Not all mutations cause noticeable changes in cellular functions. However, mutation in key cellular genes leads to developmental disorders. It is one of the main ways in which proto-oncogenes can be changed into their oncogenic state. The progressive accumulation of multiple mutations throughout life leads to cancer. In the past few decades, extensive research on cancer biology has discovered many genes and pathways having role in cancer development. In this review, we tried to summarize the current knowledge of mutational effect on different cancer types and its consequences in brief for future reference and guidance of researchers in cancer biology.

Novel Molecular Targets for Chemoprevention in Malignancies of the Head and Neck

Cancers of the head and neck region are among the leading causes of cancer-related mortalities worldwide. Oral leukoplakia and erythroplakia are identified as precursor lesions to malignancy. Patients cured of an initial primary head and neck cancer are also susceptible to developing second primary tumors due to cancerization of their mucosal field. Multi-step acquisition of genetic mutations leading to tumorigenesis and development of invasive cancer has been previously described. Recently, whole exome sequencing of tumor specimens has helped to identify driver mutations in this disease. For these reasons, chemoprevention or the use of systemic or biologic agents to prevent carcinogenesis is an attractive concept in head and neck cancers. Nonetheless, despite extensive clinical research in this field over the past couple decades, no standard of care option has emerged. This review article reports on targeted interventions that have been attempted in clinical trials to date, and focuses on novel molecular pathways and drugs in development that are worthy of being tested for this indication as part of future endeavors.

Double-blind, randomized phase 3 trial of low-dose 13-cis retinoic acid in the prevention of second primaries in head and neck cancer: Long-term follow-up of a trial of the Eastern Cooperative Oncology Group-ACRIN Cancer Research Group (C0590)

BACKGROUND

13-Cis retinoic acid (13-CRA) is a synthetic vitamin A derivative. High-dose 13-CRA in patients with squamous cell cancers of the head and neck (SCCHNs) reduces the incidence of second primary tumors (SPTs). The authors report long-term results from a phase 3 randomized trial that compared treatment with low-dose 13-CRA versus placebo for patients who had early stage SCCHN, with a focus on the development of SPTs and overall survival (OS).

METHODS

In total, 176 patients who received treatment for stage I/II SCCHN were randomized to receive either low-dose 13-CRA (weight-based dose of 7.5 mg or 10 mg) or placebo for 2 years. A competing-risk approach and the log-rank test were used to compare the time to SPT and OS, respectively, between groups.

RESULTS

13-CRA neither significantly reduced the cumulative incidence of SPT (P = .61) nor improved the time to SPT (hazard ratio [HR] for 13-CRA/placebo; 0.86; P = .61). Despite limited power, there was a trend toward improved OS for the 13-CRA arm (HR, 0.75; P = .14), particularly among patients whose index tumor was surgically excised (N = 26; HR, 0.50; P = .057) and among women (N = 39; HR, 0.44; P = .065) and never/former smokers (N = 129; HR, 0.61; P = .055), with a median follow-up of 16 years. The main 13-CRA related toxicities were dry skin and cheilitis.

CONCLUSIONS

Treatment with low-dose 13-CRA for 2 years did not decrease the incidence of SPT; subset analysis indicates a potential survival advantage among patients who are women and never/former smokers. More targeted interventions based on clinical risk factors and molecular characterization of tumors may yield greater success in future prevention trials. Cancer 2017;123:4653-4662. © 2017 American Cancer Society.

Metastatic squamous cell carcinoma of colon from esophageal cancer

BACKGROUND

Esophageal cancer including squamous cell carcinoma (SCC) and adenocarcinoma represents 4% of all cancers in the United States. Patients with esophageal cancer frequently present with locally advanced disease, and about 40% of patients have evidence of metastatic disease on presentation. Common sites of metastasis include liver, lung and bone. Here, we present a rare case of colonic metastasis from primary esophageal SCC.

CASE PRESENTATION

A 60-year-old Caucasian male with a history of 20-pack-year cigarette smoking received surgery and adjuvant chemoradiotherapy for locally advanced SCC of larynx. Approximately 9 months later, he developed dysphagia, and found to have a esophageal SCC in the mid-esophagus with regional lymph node involvement. He underwent chemoradiation treatment with good response and improved symptoms but declined subsequent surgical resection for esophageal cancer. About 1 year after the diagnosis of esophageal cancer, he developed blood streaked bowel movement and severe anemia. Colonoscopy showed a 3-cm mass in the proximal ascending colon; biopsy showed metastatic SCC, consistent with metastasis from esophageal primary. He subsequently received palliative radiation to the ascending colon metastatic tumor with improvement of anemia, and remained transfusion independent for more than 3 months.

CONCLUSIONS

Colonic metastasis from esophageal SCC is rare, and associated with poor prognosis. There are no definite features in terms of location, histological differentiation etc. that contribute to colonic metastasis from primary esophageal SCC. The goal of treatment is palliative and data from our and other case reports support the use of chemotherapy and radiation for symptom improvement and disease control.

Potential strategies to ameliorate risk of radiotherapy-induced second malignant neoplasms

This review is aimed at the issue of radiation-induced second malignant neoplasms (SMN), which has become an important problem with the increasing success of modern cancer radiotherapy (RT). It is imperative to avoid compromising the therapeutic ratio while addressing the challenge of SMN. The dilemma is illustrated by the role of reactive oxygen species in both the mechanisms of tumor cell kill and of radiation-induced carcinogenesis. We explore the literature focusing on three potential routes of amelioration to address this challenge. An obvious approach to avoiding compromise of the tumor response is the use of radioprotectors or mitigators that are selective for normal tissues. We also explore the opportunities to avoid protection of the tumor by topical/regional radioprotection of normal tissues, although this strategy limits the scope of protection. Finally, we explore the role of the bystander/abscopal phenomenon in radiation carcinogenesis, in association with the inflammatory response. Targeted and non-targeted effects of radiation are both linked to SMN through induction of DNA damage, genome instability and mutagenesis, but differences in the mechanisms and kinetics between targeted and non-targeted effects may provide opportunities to lessen SMN. The agents that could be employed to pursue each of these strategies are briefly reviewed. In many cases, the same agent has potential utility for more than one strategy. Although the parallel problem of chemotherapy-induced SMN shares common features, this review focuses on RT associated SMN. Also, we avoid the burgeoning literature on the endeavor to suppress cancer incidence by use of antioxidants and vitamins either as dietary strategies or supplementation.

Cetuximab activity in dysplastic lesions of the upper aerodigestive tract

BACKGROUND

High risk head and neck mucosal premalignancy has a malignant conversion rate of up to 40%, despite adequate surgical therapy. Epidermal Growth Factor Receptor (EGFR) blocking agents, including cetuximab, have shown activity in head and neck squamous cell carcinoma (HNSCC) and have potential for therapy in high risk premalignancy.

METHODS

We conducted a randomized, prospective, phase II clinical trial to determine the effects of cetuximab on patients with high risk premalignancy. Patients were randomized to treatment with cetuximab 400mg/m(2) on week one followed by 250mg/m(2) on week 2-8 or observation, with the option for crossover to cetuximab therapy for patients originally randomized to the observation arm.

RESULTS

Two of 19 enrolled patients did not complete therapy due to treatment toxicity. Analysis of 17 patients who completed the trial regimen show a trend toward a larger mean decrease in grade of dysplasia in the cetuximab treated group (-1.0) vs. the observation group (-0.2) (P=0.082, one-sided exact Wilcoxon rank sum test). However, in the observation group, none of the 5 patients (0%) achieved complete resolution of dysplasia; while 4 of 12 (33.3%) cetuximab treated patients had no remaining dysplasia after therapy.

CONCLUSIONS

Treatment of high risk premalignancy of the upper aerodigestive tract with cetuximab alone may result in significant, durable, and complete clinical and histological resolution of moderate to severe dysplasia in at least a subset of high risk patients. These results warrant further investigation in larger studies with increased statistical power.

Impaired aldehyde dehydrogenase 1 subfamily member 2A-dependent retinoic acid signaling is related with a mesenchymal-like phenotype and an unfavorable prognosis of head and neck squamous cell carcinoma

Background

An inverse correlation between expression of the aldehyde dehydrogenase 1 subfamily A2 (ALDH1A2) and gene promoter methylation has been identified as a common feature of oropharyngeal squamous cell carcinoma (OPSCC). Moreover, low ALDH1A2 expression was associated with an unfavorable prognosis of OPSCC patients, however the causal link between reduced ALDH1A2 function and treatment failure has not been addressed so far.

Methods

Serial sections from tissue microarrays of patients with primary OPSCC (n = 101) were stained by immunohistochemistry for key regulators of retinoic acid (RA) signaling, including ALDH1A2. Survival with respect to these regulators was investigated by univariate Kaplan-Meier analysis and multivariate Cox regression proportional hazard models. The impact of ALDH1A2-RAR signaling on tumor-relevant processes was addressed in established tumor cell lines and in an orthotopic mouse xenograft model.

Results

Immunohistochemical analysis showed an improved prognosis of ALDH1A2^high OPSCC only in the presence of CRABP2, an intracellular RA transporter. Moreover, an ALDH1A2^highCRABP2^high staining pattern served as an independent predictor for progression-free (HR: 0.395, p = 0.007) and overall survival (HR: 0.303, p = 0.002), suggesting a critical impact of RA metabolism and signaling on clinical outcome. Functionally, ALDH1A2 expression and activity in tumor cell lines were related to RA levels. While administration of retinoids inhibited clonogenic growth and proliferation, the pharmacological inhibition of ALDH1A2-RAR signaling resulted in loss of cell-cell adhesion and a mesenchymal-like phenotype. Xenograft tumors derived from FaDu cells with stable silencing of ALDH1A2 and primary tumors from OPSCC patients with low ALDH1A2 expression exhibited a mesenchymal-like phenotype characterized by vimentin expression.

Conclusions

This study has unraveled a critical role of ALDH1A2-RAR signaling in the pathogenesis of head and neck cancer and our data implicate that patients with ALDH1A2^low tumors might benefit from adjuvant treatment with retinoids.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0476-0) contains supplementary material, which is available to authorized users.

Suppressive function of low-dose deguelin on the invasion of oral cancer cells by downregulating tumor necrosis factor alpha-induced nuclear factor-kappa B signaling

BACKGROUND

Deguelin has both antiproliferation and antimetastasis activities. However, high-dose deguelin elicits many undesired side effects. The purpose of this study was to investigate whether the low-dose deguelin can prevent the metastasis of oral cancer.

METHODS

The dose effects of deguelin on metastasis of oral cancer cells were analyzed by in vitro invasion assay and an orthotropic xenograft mouse model. The involvement of tumor necrosis factor alpha (TNF-α)-induced nuclear factor-kappa B (NF-κB) signaling was examined by Western blot and reporter assay.

RESULTS

Low-dose deguelin, which has minimal cytotoxicity, significantly inhibited the invasion and migration of oral cancer cells. These inhibitory effects of low-dose deguelin were mediated by suppressing TNF-α-induced activation of IκB kinase leading to the inhibition of IκB phosphorylation, NF-κB transcriptional activity, and matrix metalloproteinase-2 (MMP2) expression. The low-dose deguelin treatment significantly inhibited tumor growth and invasion without systemic toxicity.

CONCLUSION

The low-dose deguelin suppressed the invasion and migration of oral cancer by downregulating TNF-α-induced NF-κB signaling. © 2015 Wiley Periodicals, Inc. Head Neck 38: E524-E534, 2016.

Retinoid Chemoprevention: Who Can Benefit?

Acute promyelocytic leukemia (APL) is a treatment success story. From a highly deadly disease it was turned into a highly curable disease by the introduction of differentiation-induction therapy with all-trans retinoic acid (ATRA) in the 1990's. During the last quarter of century, ATRA and other retinoids were used for the treatment and prevention of other cancers and even other diseases. The results were less spectacular, but nevertheless important. Progress has been made toward understanding the mechanism of action of retinoids in different physiological and pathological contexts. For some diseases, specific genetic backgrounds were found to confer responsiveness to retinoid therapy. Therapies that include retinoids and other modalities are very diverse and used both for combined targeting of multiple pathways and for diminishing toxicity.

Combination of 13-Cis retinoic acid and lovastatin: marked antitumor potential in vivo in a pheochromocytoma allograft model in female athymic nude mice

Currently, there are no reliably effective therapeutic options for metastatic pheochromocytoma (PCC) and paraganglioma. Moreover, there are no therapies that may prevent the onset or progression of tumors in patients with succinate dehydrogenase type B mutations, which are associated with very aggressive tumors. Therefore, we tested the approved and well-tolerated drugs lovastatin and 13-cis-retinoic acid (13cRA) in vitro in an aggressive PCC mouse cell line, mouse tumor tissue-derived (MTT) cells, and in vivo in a PCC allograft nude mouse model, in therapeutically relevant doses. Treatment was started 24 hours before sc tumor cell injection and continued for 30 more days. Tumor sizes were measured from outside by caliper and sizes of viable tumor mass by bioluminescence imaging. Lovastatin showed antiproliferative effects in vitro and led to significantly smaller tumor sizes in vivo compared with vehicle treatment. 13cRA promoted tumor cell growth in vitro and led to significantly larger viable tumor mass and significantly faster increase of viable tumor mass in vivo over time compared with vehicle, lovastatin, and combination treatment. However, when combined with lovastatin, 13cRA enhanced the antiproliferative effect of lovastatin in vivo. The combination-treated mice showed slowest tumor growth of all groups with significantly slower tumor growth compared with the vehicle-treated mice and significantly smaller tumor sizes. Moreover, the combination-treated group displayed the smallest size of viable tumor mass and the slowest increase in viable tumor mass over time of all groups, with a significant difference compared with the vehicle- and 13cRA-treated group. The combination-treated tumors showed highest extent of necrosis, lowest median microvessel density and highest expression of α-smooth muscle actin. The combination of high microvessel density and low α-smooth muscle actin is a predictor of poor prognosis in other tumor entities. Therefore, this drug combination may be a well-tolerated novel therapeutic or preventive option for malignant PCC.

Genes and oral cancer

Oral cancers have been one of the leading causes of deaths particularly in the developing countries. Prime reason for this high mortality and morbidity is attributed to the delay in diagnosis and prompt treatment. Relentless research in the field of oncology has led to the advent of novel procedures for the early detection of oral cancers. Molecular biology is highly promising in this regard. It is a procedure that detects alterations at a molecular level much before they are seen under a microscope and much before clinical changes occur. Molecular studies serve as the basis by which we will eventually be able not only to augment clinical assessment and classification of oral lesions but also predict malignant potential of oral lesions, thus reducing the incidence and increasing the scope for early diagnosis and treatment of oral cancers. However, making such sophisticated tools available for the common man in developing countries is one of the most important challenges faced today.

Chemoprevention of lung cancer: concepts and strategies

Lung cancer develops in a stepwise fashion, with an accumulation of molecular alterations progressing through preinvasive steps to invasive disease. This progression could be arrested or reversed through pharmacologic treatments, which are known as cancer chemoprevention. Preclinical and clinical findings relating to different classes of candidate chemopreventive agents provide support for this strategy as an active and promising approach for controlling this disease.

Oral premalignancy: the roles of early detection and chemoprevention

Premalignancy and chemoprevention studies in head and neck cancer typically focus on the oral cavity. Avoiding or cessation of alcohol and smoking, early detection of potentially malignant disorders or cancer, and early detection of recurrent and/or second primary tumor form the basis of prevention of oral cancer. Analysis of tissue prospectively collected in evaluation of retinoids for chemoprevention trials allowed identification of molecular biomarkers of risk to develop oral cancer, loss of heterozygosity being the most validated one. Improving risk assessment and identification of new targets for chemoprevention represent the main challenges in this field.

Second malignant neoplasms: assessment and strategies for risk reduction

Improvements in early detection, supportive care, and treatment have resulted in an increasing number of cancer survivors, with a current 5-year relative survival rate for all cancers combined of approximately 66.1%. For some patients, these survival advances have been offset by the long-term late effects of cancer and its treatment, with second malignant neoplasms (SMNs) comprising one of the most potentially life-threatening sequelae. The number of patients with SMNs is growing, with new SMNs now representing about one in six of all cancers reported to the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program. SMNs reflect not only the late effects of therapy but also the influence of shared etiologic factors (in particular, tobacco and excessive alcohol intake), genetic susceptibility, environmental exposures, host effects, and combinations of factors, including gene-environment interactions. For selected SMNs, risk is also modified by age at exposure and attained age. SMNs can be categorized into three major groups according to the predominant etiologic factor(s): (1) treatment-related, (2) syndromic, and (3) those due to shared etiologic exposures, although the nonexclusivity of these groups should be underscored. Here we provide an overview of SMNs in survivors of adult-onset cancer, summarizing the current, albeit limited, clinical evidence with regard to screening and prevention, with a focus on the provision of guidance for health care providers. The growing number of patients with second (and higher-order) cancers mandates that we also further probe etiologic influences and genetic variants that heighten risk, and that we better define high-risk groups for targeted preventive and interventional clinical strategies.

Genetic variants in the PI3K/PTEN/AKT/mTOR pathway predict head and neck cancer patient second primary tumor/recurrence risk and response to retinoid chemoprevention

PURPOSE

The development of second primary tumors (SPT) or recurrence alters prognosis for curatively treated head and neck squamous cell carcinoma (HNSCC) patients. The 13-cis-Retinoic acid (13-cRA) has been tested as a chemoprevention agent in clinical trials with mixed results. Therefore, we investigated whether genetic variants in the PI3K/PTEN/AKT/mTOR pathway could serve as biomarkers to identify which patients are at high risk of an SPT/recurrence, while also predicting response to 13-cRA chemoprevention.

EXPERIMENTAL DESIGN

A total of 137 pathway single-nucleotide polymorphisms were genotyped in 440 patients from the Retinoid Head and Neck Second Primary Trial and assessed for SPT/recurrence risk and response to 13-cRA. Risk models were created based on epidemiology, clinical, and genetic data.

RESULTS

Twenty-two genetic loci were associated with increased SPT/recurrence risk, with six also being associated with a significant benefit following chemoprevention. Combined analysis of these high-risk/high-benefit loci identified a significant (P = 1.54 × 10(-4)) dose-response relationship for SPT/recurrence risk, with patients carrying four to five high-risk genotypes having a 3.76-fold [95% Confidence Interval (CI), 1.87-7.57] increase in risk in the placebo group (n = 215). Patients carrying four to five high-risk loci showed the most benefit from 13-cRA chemoprevention, with a 73% reduction in SPT/recurrence (95% CI, 0.13-0.58) compared with those with the same number of high-risk genotypes who were randomized to receive placebo. Incorporation of these loci into a risk model significantly improved the discriminatory ability over models with epidemiology, clinical, and previously identified genetic variables.

CONCLUSIONS

These results show that loci within this important pathway could identify individuals with a high-risk/high-benefit profile and are a step toward personalized chemoprevention for HNSCC patients.

Regulatory approval of cancer risk-reducing (chemopreventive) drugs: moving what we have learned into the clinic

This article endeavors to clarify the current requirements and status of regulatory approval for chemoprevention (risk reduction) drugs and discusses possible improvements to the regulatory pathway for chemoprevention. Covering a wide range of topics in as much depth as space allows, this report is written in a style to facilitate the understanding of nonscientists and to serve as a framework for informing the directions of experts engaged more deeply with this issue. Key topics we cover here are as follows: a history of definitive cancer chemoprevention trials and their influence on the evolution of regulatory assessments; a brief review of the long-standing success of pharmacologic risk reduction of cardiovascular diseases and its relevance to approval for cancer risk reduction drugs; the use and limitations of biomarkers for developing and the approval of cancer risk reduction drugs; the identification of individuals at a high(er) risk for cancer and who are appropriate candidates for risk reduction drugs; business models that should incentivize pharmaceutical industry investment in cancer risk reduction; a summary of scientific and institutional barriers to development of cancer risk reduction drugs; and a summary of major recommendations that should help facilitate the pathway to regulatory approval for pharmacologic cancer risk reduction drugs.

Global assessment of genetic variation influencing response to retinoid chemoprevention in head and neck cancer patients

Head and neck squamous cell carcinoma (HNSCC) patients are at an increased risk of developing a second primary tumor (SPT) or recurrence following curative treatment. 13-cis-retinoic acid (13-cRA) has been tested in chemoprevention clinical trials, but the results have been inconclusive. We genotyped 9,465 single nucleotide polymorphisms (SNP) in 450 patients from the Retinoid Head and Neck Second Primary Trial. SNPs were analyzed for associations with SPT/recurrence in patients receiving placebo to identify prognosis markers and further analyzed for effects of 13-cRA in patients with these prognostic loci. Thirteen loci identified a majority subgroup of patients at a high risk of SPT/recurrence and in whom 13-cRA was protective. Patients carrying the common genotype of rs3118570 in the retinoid X receptor (RXRA) were at a 3.33-fold increased risk (95% CI, 1.67-6.67) and represented more than 70% of the study population. This locus also identified individuals who received benefit from chemoprevention with a 38% reduced risk (95% CI, 0.43-0.90). Analyses of cumulative effect and potential gene-gene interactions also implicated CDC25C:rs6596428 and JAK2:rs1887427 as 2 other genetic loci with major roles in prognosis and 13-cRA response. Patients with all 3 common genotypes had a 76% reduction in SPT/recurrence (95% CI, 0.093-0.64) following 13-cRA chemoprevention. Carriers of these common genotypes constituted a substantial percentage of the study population, indicating that a pharmacogenetic approach could help select patients for 13-cRA chemoprevention. The lack of any alternatives for reducing risk in these patients highlights the need for future clinical trials to prospectively validate our findings.

The chemopreventive properties and therapeutic modulation of green tea polyphenols in oral squamous cell carcinoma

Chemoprevention is a relatively novel and promising approach for controlling cancer that uses specific natural products or synthetic agents to suppress, reverse, or prevent premalignancy before transformation into invasive cancer. Oral cavity squamous cell carcinoma (OCSCC) represents a large, worldwide health burden with approximately 274,000 cases diagnosed annually worldwide. Smoking and alcohol consumption are major inducers of OCSCC. Recently, the human papilloma virus was also shown to potentially be an etiologic factor. Due to its easily identifiable risk factors and the presence of premalignant regions, oral cancer makes a good candidate for chemoprevention. Green tea is the most widely consumed beverage in the world, and it has received considerable attention because of its abundant, scientifically proven, beneficial effects on human health. In this review, we discuss the role of green tea in oral cancer chemoprevention with regard to the multiple molecular mechanisms proposed in various in vitro, in vivo, and clinical trials.

Chemopreventive potential of natural compounds in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is one of the most fatal cancers worldwide. Despite advances in the management of HNSCC, the overall survival for patients has not improved significantly due to advanced stages at diagnosis, high recurrence rate after surgical removal, and second primary tumor development, which underscore the importance of novel strategies for cancer prevention. Cancer chemoprevention, the use of natural or synthetic compounds to prevent, arrest, or reverse the process of carcinogenesis at its earliest stages, aims to reverse premalignancies and prevent second primary tumors. Genomics and proteomics information including initial mutation, cancer promotion, progression, and susceptibility has brought molecularly targeted therapies for drug development. The development of preventive approaches using specific natural or synthetic compounds, or both, requires a depth of understanding of the cross-talk between cancer signaling pathways and networks to retain or enhance chemopreventive activity while reducing known toxic effects. Many natural dietary compounds have been identified with multiple molecular targets, effective in the prevention and treatment of cancer. This review describes recent advances in the understanding of the complex signaling networks driving cancer progression and of molecularly targeted natural compounds under preclinical and clinical investigation.

Cancer prevention with natural compounds

Botanical and nutritional compounds have been used for the treatment of cancer throughout history. These compounds also may be useful in the prevention of cancer. Population studies suggest that a reduced risk of cancer is associated with high consumption of vegetables and fruits. Thus, the cancer chemopreventive potential of naturally occurring phytochemicals is of great interest. There are numerous reports of cancer chemopreventive activity of dietary botanicals, including cruciferous vegetables such as cabbage and broccoli, Allium vegetables such as garlic and onion, green tea, Citrus fruits, soybeans, tomatoes, berries, and ginger, as well as medicinal plants. Several lead compounds, such as genistein (from soybeans), lycopene (from tomatoes), brassinin (from cruciferous vegetables), sulforaphane (from asparagus), indole-3-carbinol (from broccoli), and resveratrol (from grapes and peanuts) are in preclinical or clinical trials for cancer chemoprevention. Phytochemicals have great potential in cancer prevention because of their safety, low cost, and oral bioavailability. In this review, we discuss potential natural cancer preventive compounds and their mechanisms of action.

Effects of antioxidant supplements on cancer prevention: meta-analysis of randomized controlled trials

BACKGROUND

This meta-analysis aimed to investigate the effect of antioxidant supplements on the primary and secondary prevention of cancer as reported by randomized controlled trials.

METHODS

We searched Medline (PubMed), Excerpta Medica database, and the Cochrane Review in October 2007.

RESULTS

Among 3327 articles searched, 31 articles on 22 randomized controlled trials, which included 161 045 total subjects, 88 610 in antioxidant supplement groups and 72 435 in placebo or no-intervention groups, were included in the final analyses. In a fixed-effects meta-analysis of all 22 trials, antioxidant supplements were found to have no preventive effect on cancer [relative risk (RR) 0.99; 95% confidence interval (CI) 0.96-1.03). Similar findings were observed in 12 studies on primary prevention trials (RR 1.00; 95% CI 0.97-1.04) and in nine studies on secondary prevention trials (RR 0.97; 95% CI 0.83-1.13). Further, subgroup analyses revealed no preventive effect on cancer according to type of antioxidant, type of cancer, or the methodological quality of the studies. On the other hand, the use of antioxidant supplements significantly increased the risk of bladder cancer (RR 1.52; 95% CI 1.06-2.17) in a subgroup meta-analysis of four trials.

CONCLUSIONS

The meta-analysis of randomized controlled trials indicated that there is no clinical evidence to support an overall primary and secondary preventive effect of antioxidant supplements on cancer. The effects of antioxidant supplements on human health, particularly in relation to cancer, should not be overemphasized because the use of those might be harmful for some cancer.

Perspectives for cancer prevention with natural compounds

Cancer is the second leading cause of death in the United States. Despite the estimated 565,650 deaths in 2008 of Americans as a result of cancer, it is mostly a preventable disease. Simply by modification of diet, maintenance of optimum body weight, and regular physical activity, 30% to 40% of all instances of cancer could be prevented. Modification of diet alone by increasing vegetable and fruit intake could prevent 20% or more of all cases of cancer and may potentially prevent approximately 200,000 cancer-related deaths annually. Because of their safety, low toxicity, antioxidant properties, and general acceptance as dietary supplements, fruits, vegetables, and other dietary elements (phytochemicals and minerals) are being investigated for the prevention of cancer. Extensive research over the past several decades has identified numerous dietary and botanical natural compounds that have chemopreventive potential. In this review, we discuss promising natural chemopreventive compounds, their molecular targets, and their mechanisms, which may help the further design and conduct of preclinical and clinical trials.

Abstract B26: Analyzing health benefits beyond the treatment period

B26

When studying cancer treatments, the benefits and risks are usually reported following a specific duration of time. For example, the probability of recurrence might be reported with and without the treatment after five years. However, cancer treatments often provide benefits which last beyond the duration of the treatments themselves. Studies have demonstrated this clearly for calcium supplements in preventing recurrence of colorectal adenomas (1), and for isotretinoin in head and neck tumors (2).

The risks associated with such treatments, on the other hand, usually persist only as long as the treatments are being applied. It is therefore impractical to compare the reduction of one risk with the increase of others at any single point in time in these cases. This is especially true for treatments that carry multiple risks, such as tamoxifen (3). A preferred method would be to consider the patient's survival curves both with and without the treatment. Adjusting the patient's initial (cancer-free) survival curve according to a disease-specific survival curve and a risk-specific survival curve yields the patient's probability of survival over time, accounting for all factors relevant to the treatment decision. This is a much more effective method for weighing the risks of a treatment against its benefits. In this work, we describe the process of the analysis, and apply it to specific cases.

Citation Information: Cancer Prev Res 2008;1(7 Suppl):B26.

Autoantibody approach for serum-based detection of head and neck cancer

Currently, no effective tool exists for screening or early diagnosis of head and neck squamous cell carcinoma (HNSCC). Here, we describe an approach for cancer detection based on analysis of patterns of serum immunoreactivity against a panel of biomarkers selected using microarray-based serologic profiling and specialized bioinformatics. We biopanned phage display libraries derived from three different HNSCC tissues to generate 5,133 selectively cloned tumor antigens. Based on their differential immunoreactivity on protein microarrays against serum immunoglobulins from 39 cancer and 41 control patients, we reduced the number of clones to 1,021. The performance of a neural network model (Multilayer Perceptron) for cancer classification on a data set of 80 HNSCC and 78 control samples was assessed using 10-fold cross-validation repeated 100 times. A panel of 130 clones was found to be adequate for building a classifier with sufficient sensitivity and specificity. Using these 130 markers on a completely new and independent set of 80 samples, an accuracy of 84.9% with sensitivity of 79.8% and specificity of 90.1% was achieved. Similar performance was achieved by reshuffling of the data set and by using other classification models. The performance of this classification approach represents a significant improvement over current diagnostic accuracy (sensitivity of 37% to 46% and specificity of 24%) in the primary care setting. The results shown here are promising and show the potential use of this approach toward eventual development of diagnostic assay with sufficient sensitivity and specificity suitable for detection of early-stage HNSCC in high-risk populations.

Moving Toward Bioadjuvant Approaches to Head and Neck Cancer Prevention

Head and neck squamous cell carcinoma affects >45,000 Americans annually. Patients who are successfully treated for their primary tumor are at high risk of developing a second primary tumor, making effective preventive strategies highly desirable for this disease. Although a landmark study in 1990 suggested some benefit of high-dose retinoids in head and neck cancer prevention, subsequent trials using more tolerable doses have shown limited clinical success. Newer preventive strategies have included bioadjuvant therapy combining retinoids with interferon and alpha-tocopherol, combinations of molecularly targeted agents, and oncolytic viruses. Furthermore, considerable evidence has supported a cancer protective role for several nutrients, including green tea and curcumin analogs. Natural compounds such as these with favorable long-term safety profiles might be particularly suited to the cancer prevention setting, in which patients will usually tolerate only moderate risk and toxicity.

Utility of toluidine blue in oral premalignant lesions and squamous cell carcinoma: Continuing research and implications for clinical practice

Toluidine blue (TB) has been shown to aid in the detection and diagnosis of oropharyngeal squamous cell carcinoma (OSCC) and oral premalignant lesions (OPLs). TB has been shown to enhance visualization of oral lesions and assist in identifying sites of increased risk of dysplastic/malignant change and promote biopsy. TB has been shown to identify lesions with molecular changes associated with risk of progression of OPLs to OSCC. A recent prospective longitudinal study showed TB retention in histologic benign lesions and lesions with mild dysplasia that are at increased risk of progression to cancer. Clinical trials show that TB is useful in identifying asymptomatic OSCC and premalignant lesions at risk of progressing to SCC, which might otherwise be undetected until lesions become more advanced. The data supports TB use in oral examination of patients at risk of OSCC.

Combination of physical activity, nutrition, or other metabolic factors and vaccine response

A number of lifestyle factors that reduce cancer risk in the primary prevention setting may be potential new targets for use in combination with cancer vaccines. This review discusses the modulation of energy balance (physical activity, calorie restriction, and obesity prevention), and the supplementation with natural and synthetic analogs of vitamins A and E, as potential interventions for use in combination with cancer vaccines. Additionally, the pharmacologic manipulation of nutrient metabolism in the tumor microenvironment (e.g., arachidonic acid, arginine, tryptophan, and glucose metabolism) is discussed. This review includes a brief overview of the role of each agent in primary cancer prevention; outlines the effects of these agents on immune function, specifically adaptive and/or anti-tumor immune mechanisms, when known; and discusses the potential use of these interventions in combination with therapeutic cancer vaccines. Modulation of energy balance through exercise and strategies targeting nutrient metabolism in the tumor microenvironment represent the most promising interventions to partner with therapeutic cancer vaccines. Additionally, the use of vitamin E succinate and the retinoid X receptor-directed rexinoids in combination with cancer vaccines offer promise. In summary, a number of energy balance- and nutrition-related interventions are viable candidates for further study in combination with cancer vaccines.

Chemoprevention of squamous cell carcinoma of the head and neck

PURPOSE OF REVIEW

The aim of this article is to summarize progress in understanding of the biology of squamous cell carcinoma of the head and neck and of trials to prevent malignant conversion of oral premalignant lesions and the development of second primary tumors in those already treated for squamous cell carcinoma of the head and neck.

RECENT FINDINGS

The understanding of squamous cell carcinoma of the head and neck biology is rapidly evolving. Clinical trials for chemoprevention are involving more diverse regimens, following disappointing results of retinoid monotherapy. In-vitro and animal studies form the rationale for the next generation of studies, employing combination, synergistic treatments.

SUMMARY

Based on trial data to date, no recommendation for intervention with a chemopreventive agent can be made. It is clear, however, that smoking cessation is an effective intervention for preventing oral premalignant lesions and second primary tumors. Promising trials are being conducted and designed currently. The future of this area of study will involve rational choice of multidrug regimens based on current understanding of the biology of squamous cell carcinoma of the head and neck.

Reducing the "risk" of chemoprevention: defining and targeting high risk--2005 AACR Cancer Research and Prevention Foundation Award Lecture

Two large-scale, phase III cancer prevention trials, the Breast Cancer Prevention Trial (BCPT) of tamoxifen and Prostate Cancer Prevention Trial (PCPT) of finasteride, concluded with strikingly positive and simultaneously problematic results: reduced cancer risks but a major adverse finding with each agent that prevented its widespread use in the community. For most moderate-risk people, such as those studied in the BCPT and PCPT, the benefit of reduced breast or prostate cancer does not outweigh the major risk of tamoxifen (endometrial cancer in the BCPT) or apparent risk of finasteride (high-grade prostate cancer in the PCPT). Promising interventions with biologically active substances are likely to have adverse, perhaps unforeseen effects, especially with long-term preventive use. Acceptance of such agents will depend heavily on the level of cancer risk of the target population. This article outlines research in molecularly identified high-risk oral intraepithelial neoplasia that creates the clinical opportunity for optimizing the risk-benefit ratio of agents to prevent oral cancer. Two other major research efforts focused on improving preventive agent risk-benefit ratios are molecular-targeted research designed to target away from known adverse signaling pathways and multidisciplinary research based on the PCPT that will develop comprehensive models of prostate cancer risk (especially of aggressive prostate cancer) and pharmacoecogenetic models for identifying high-risk men most likely to benefit from (and not be harmed by) finasteride or similar (5alpha-reductase inhibiting) agents. Defining and targeting high-risk populations, developing molecular-targeted approaches, and developing accurate pharmacoecogenetic models promise to reduce the risk of chemoprevention and ultimately to reduce the risk and burden of major cancers.

Prevention of head and neck cancer

In the vast majority of cases, head and neck cancer is a preventable disease. The relationship between tobacco and alcohol and these cancers is well established. Despite efforts aimed at reduction of risk factor exposure and early detection methods, head and neck cancer remains one of the more common cancers worldwide. Recent advances in molecular techniques have provided a framework for future targets for early diagnosis and treatment of these malignancies. This review provides a summary of recent developments in primary and secondary prevention of head and neck cancer and innovative strategies aimed at a reduction in incidence and mortality from this disease. The future prevention of head and neck cancer will likely require solutions to the widespread use of tobacco products and innovative diagnostic techniques leading to improvements in overall survival.

Randomized phase III trial of low-dose isotretinoin for prevention of second primary tumors in stage I and II head and neck cancer patients

BACKGROUND

Isotretinoin (13-cis-retinoic acid) is a synthetic vitamin A derivative, or retinoid, widely used in the treatment of cystic acne. Preclinical and clinical studies of high-dose isotretinoin in patients with head and neck squamous cell cancer (HNSCC) have produced encouraging results. We conducted a phase III randomized trial of low-dose isotretinoin versus placebo in early-stage HNSCC patients to assess its effect on second primary tumor incidence and survival.

METHODS

We randomly assigned 1190 patients who had been treated for stage I or II HNSCC to receive either low-dose isotretinoin (30 mg/day) or placebo for 3 years. The patients were monitored for up to 4 more years. Survival was analyzed by the Kaplan-Meier method, and Cox proportional hazards models were used for multivariable survival analysis. All statistical tests were two-sided.

RESULTS

Isotretinoin did not statistically significantly reduce the rate of second primary tumors (hazard ratio [HR] = 1.06, 95% confidence interval [CI] = 0.83 to 1.35) or increase survival (HR = 1.03, 95% CI = 0.81 to 1.32) compared with placebo in patients with early-stage HNSCC. Current smokers had a higher rate of second primary tumors than that of never (HR = 1.64, 95% CI = 1.08 to 2.50) or former (HR = 1.32, 95% CI = 1.01 to 1.71) smokers. The hazard ratio of death from any cause for current smokers versus never smokers was 2.51 (95% CI = 1.54 to 4.10) and for current smokers versus former smokers was 1.60 (95% CI = 1.23 to 2.07). Major sites of second primary tumors (n = 261) included lung (31%), oral cavity (17%), larynx (8%), and pharynx (5%).

CONCLUSIONS

Low-dose isotretinoin was not effective in reducing the rate of second primary tumors or death or smoking-related disease. Smoking statistically significantly increased the rate of second primary tumors and death. Ongoing trials are testing higher doses of isotretinoin as part of combination bioadjuvant therapeutic methods for patients with locally advanced HNSCC.

Clinical significance of altered expression of retinoid receptors in oral precancerous and cancerous lesions: Relationship with cell cycle regulators

Alterations in expression of retinoid receptors are implicated in human cancers. We hypothesized that altered expression of retinoic acid receptors (RARalpha,beta,gamma) and retinoid X receptor RXRalpha and their relationship with cell cycle regulators (p53, p16, p21) is associated with development, progression and prognosis of oral cancer. Immunohistochemical analysis of RAR alpha, beta, gamma and RXRalpha proteins was carried out on serial sections from 244 oral squamous cell carcinomas (OSCCs), 102 potentially malignant lesions (65 hyperplasias, 37 dysplasias), 83 matched histologically normal oral tissues and 29 normal mucosa from non-exposed individuals without oral lesions and correlated with expression of cell cycle regulators p53, p16 and p21 as well as with clinicopathological parameters. Expression of retinoid receptors RARbeta, RARgamma, RXRalpha and cell cycle regulators p16 and p21 was decreased in majority of oral SCCs as well as in potentially malignant lesions. Multivariate stepwise logistic regression analysis carried out for comparison of non-exposed normal oral mucosa with histologically normal oral tissues from patients with oral lesions showed significant loss of RARbeta or p53 accumulation (RARbeta(-)/p53(+) Odd's ratio, OR = 266.6, p = 0.000); non-exposed normal mucosa from individuals without oral lesions with potentially malignant lesion was RARbeta(-)/p21(-)/p53(+) (OR = 215.7, p = 0.000); matched normal to potentially malignant stage was RARalpha(+)/p21(-) (OR = 4.414, p = 0.005); hyperplasia to dysplasia was RARalpha(+)/p53(+) (OR = 4.72, p = 0.005) and potentially malignant to malignant phenotype was RARalpha(+) (OR = 2.061, p = 0.004). The prognostic relevance of these factors was assessed in 115 of these SCC patients who were followed-up for a maximum period of 94 months (median 21 months). Multivariate analysis using Cox's proportional Hazard's model showed that RARalpha(+)/p21(-) phenotype was associated with shorter disease-free survival (Hazard's ratio, HR = 1.863, p = 0.0471). To our knowledge, this is the first large study showing alterations in expression of retinoid receptors at the protein level at different stages in development and progression of oral SCC. It also underscored the prognostic significance of retinoid receptors and their interactions with cell cycle regulators in multistep oral tumorigenesis.

Retinoids as chemoprevention for head and neck cancer: where do we go from here?

The retinoids, natural and synthetic derivatives of vitamin A, have a promising role in the chemoprevention of head and neck squamous cell carcinoma despite facing the limitations of toxicity as well as innate and acquired resistance. Adhering to the concept of field cancerization and following multi-step carcinogenesis, premalignant lesions of the head and neck have long been the focus of intervention with retinoids. Similarly, these agents have been applied towards preventing second primary malignancies from developing following curative therapy for upper aerodigestive cancers. Despite encouraging response rates, the need for overcoming innate and acquired retinoid resistance as well as minimizing retinoid-related toxicity will likely be relegated to the new generation of receptor-selective, synthetic retinoids. In the interim, retinoid-non-retinoid combinations as well as other classes of chemopreventive agents seem to provide promise in curtailing the incidence of aerodigestive malignancies.

Hyperacetylation enhances the growth-inhibitory effect of all-trans retinoic acid by the restoration of retinoic acid receptor beta expression in head and neck squamous carcinoma (HNSCC) cells

The chemotherapeutic effects of all-trans-retinoic acid (atRA) are mediated by the retinoic acid receptor beta (RARbeta), but RARbeta expression is reduced in a number of head and neck carcinoma (HNSCC) cells which causes resistance to RA treatment in half the patients with HNSCC. The possible mechanism for the reduced RARbeta expression has been suggested as the methylation of the CpG islands adjacent to the RA response elements (RARE) in the RARbeta promoter and the loss of histone acetylation. The suppressed RARbeta expression can be reactivated by a demethylating agent (5-aza-2'-deoxycytidine, 5-AzaC) or a histone deacetylase inhibitor (trichostatin A, TSA). Therefore, we sought to determine if the restoration of RARbeta activity, or a combination of these drugs, could restore the sensitivity to RA in RARbeta-negative HNSCC cells with an epigenetically methylated RARbeta promoter region. SqCC/Y1 cells resistant to atRA showed methylated and unmethylated forms in the RARbeta promoter region. RARbeta expression of these cells was restored by 5-AzaC or TSA treatment. Also, treatment with TSA and atRA combined synergistically increased the growth-inhibitory effect and highly induced the transcriptional activation of the RARbeta promoter compared to atRA treatment in HNSCC cells. Additionally, TSA alone and the combination 5-AzaC and TSA increased lysine-9 (Lys-9) acetylation and Lys-4 methylation of the first exon at the RARbeta gene, while decreasing the methylation of Lys-9 in the HNSCC cells.

Phase 2 Bioadjuvant Study of Interferon Alfa-2a, Isotretinoin, and Vitamin E in Locally Advanced Squamous Cell Carcinoma of the Head and Neck

OBJECTIVE

To evaluate the long-term effects of the combination of isotretinoin, interferon alfa-2a, and vitamin E in locally advanced squamous cell carcinoma of the head and neck.

DESIGN

Phase 2 prospective study.

SETTING

Tertiary care academic medical centers.

PATIENTS

Forty-five patients entered this study. All patients had stage III or IV squamous cell carcinoma of the head and neck and had been treated with surgical resection, radiation, or both. All patients were then treated with bioadjuvant chemopreventive treatment for 12 months. We previously reported a 24-month median follow-up of this phase 2 trial of the combination of isotretinoin, interferon alfa-2a, and vitamin E as bioadjuvant therapy after definitive local therapy. In that study, all 45 patients completed treatment, but 1 patient was excluded from analysis of recurrence and development of second primary tumors. Main Outcome Measure Longer-term (49.4-month median) follow-up.

RESULTS

Among the 45 patients treated under the protocol, only 7 patients (16%) had died. Nine (20%) of 45 patients experienced progressive disease. Only 1 second primary tumor (acute promyelocytic leukemia) occurred during follow-up, and no aerodigestive second primary tumors occurred among the 45 patients. The 5-year progression-free survival and overall survival percentages were 80% (95% confidence interval, 65.1%-89.1%) and 81.3% (95% confidence interval, 63.7%-90.9%), respectively. These results are significantly better than the historical 5-year overall survival for advanced squamous cell carcinoma of the head and neck (approximately 40%).

CONCLUSION

The bioadjuvant combination is highly effective in preventing recurrence and second primary tumors, and its role as standard therapy in advanced squamous cell carcinoma of the head and neck is being investigated in a randomized phase 3 study.

Chemoprevention of hepatocellular carcinoma: Use of tamoxifen in an animal model of hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is common worldwide and growing in importance in the West. HCC often occurs against a background of liver disease, tends to present at an advanced stage, and has a poor prognosis, suggesting that it is an ideal target for chemoprevention. We sought to identify in an animal model chemopreventive agents for HCC that might be tested in human subjects. To this end, we induced liver tumors by injecting ethyl-nitrosourea in 6-week-old male B6C3F1 mice. Two chemopreventive agents were administered over a period of 60 weeks: tamoxifen (420 mg/kg feed) and a retinoid, 13-cis-retinoic acid (200 mg/kg feed). Animals were killed at 60 weeks and their livers examined for HCC and premalignant lesions. All liver lesions (altered foci, adenomata, HCC) occurred significantly less frequently in the tamoxifen-treated group than the group given only ethylnitrosourea (HCC developed in 2 of 47 (4%) vs 11 of 44 (25%); P < .001). On the other hand, retinoic acid appeared to increase the number of liver tumors, and in 2 animals angiosarcoma developed. Tamoxifen significantly decreased the incidence of chemical hepatocarcinogenesis in this model, suggesting an important role for estrogens in the pathogenesis of HCC and suggesting that it should be tested in human beings as a chemopreventive agent against HCC.

Oral cancer: leukoplakia and squamous cell carcinoma

This article reviews the epidemiology, etiologic risk factors, clinical presentation, recognition, and diagnosis of oral precancer and cancer. The actual treatment and complications from treatment of oral cancer are discussed only briefly.

Oral cancer prevention and the evolution of molecular-targeted drug development

The multifaceted rationale for molecular-targeted prevention of oral cancer is strong. Oral cancer is a major global threat to public health, causing great morbidity and mortality rates that have not improved in decades. Oral cancer development is a tobacco-related multistep and multifocal process involving field carcinogenesis and intraepithelial clonal spread. Biomarkers of genomic instability, such as aneuploidy and allelic imbalance, can accurately measure the cancer risk of oral premalignant lesions, or intraepithelial neoplasia (IEN). Retinoid-oral IEN studies (eg, of retinoic acid receptor-beta, p53, genetic instability, loss of heterozygosity, and cyclin D1) have advanced the overall understanding of the biology of intraepithelial carcinogenesis and of preventive agent molecular mechanisms and targets-important advances for monitoring preventive interventions and assessing cancer risk and pharmacogenomics. Clinical management of oral IEN varies from watchful waiting to complete resection, although complete resection does not prevent oral cancer in high-risk patients. New approaches, such as interventions with molecular-targeted agents and agent combinations in molecularly defined high-risk oral IEN patients, are urgently needed to reduce the devastating worldwide consequences of oral cancer.