Impact of genomic instability in risk assessment and chemoprevention of oral premalignancies

Dysplasia/neoplasia surveillance in oral lichen planus patients: A description of clinical criteria adopted at a single centre and their impact on prognosis

The concept of dysplasia/neoplasia surveillance has been applied to long-standing conditions associated with an increased risk of cancer. Although still controversial, periodic direct clinical examination as well as endoscopic techniques are currently performed in patients with inflammatory bowel diseases, Barrett's esophagus, and melanocytic skin lesions in order to detect and treat dysplastic or early malignant changes and therefore improve the patients' prognosis. It is not known if patients with oral lichen planus (OLP), a chronic inflammatory condition associated with an increased risk of cancer development, might benefit from such surveillance as well, nor how this should be performed. Here we present the clinical criteria we have adopted over a 12-year period to detect early malignant transformation of OLP, and report on their impact on the management and prognosis of patients. Overall data from 45 patients affected by 117 neoplastic events arising from OLP have been evaluated. Our dysplasia/neoplasia surveillance has led us to diagnose most episodes (94.9%; n.: 111) of OLP malignant transformation in early intraepithelial and microinvasive phases, namely stage 0 and I oral cancers (T(is) N0M0 or T1N0M0). The 5-year survival rate, where applicable, has been 96.7%. Advanced stage oral cancers have been diagnosed in six patients, three of whom have died. We suggest that the application of strict and rigorous clinical criteria in dysplasia/neoplasia surveillance could help clinicians to detect and treat early OLP malignant transformation and therefore improve long-term survival rates. Nevertheless, a small subgroup of patients has been shown not to benefit from such surveillance and to be characterized by a rapid development of advanced-stage oral carcinomas, with consequent poor prognosis.

Randomized trial of fenretinide (4‐HPR) to prevent recurrences, new localizations and carcinomas in patients operated on for oral leukoplakia: Long‐term results

We assessed the efficacy of fenretinide at preventing relapses, new lesions and carcinomas after surgical excision of oral leukoplakia. In a controlled multicenter study, 170 patients operated on for oral leukoplakias with benign postoperative histology were randomized to 200 mg fenretinide daily for 1 year vs. no intervention. Preliminary analysis indicated that fenretinide had good tolerability and was effective at preventing relapses and new lesions during treatment. Analysis after 5-year follow-up suggested that fenretinide protected against relapses and new lesions up to 19 months after randomization, with both limits of the 95% hazard ratio CI for fenretinide vs. control below 1 for 7 months after randomization. There was also a protective effect against all first events, including cancer, for 25 months, with both limits of the 95% CI below 1 up to 11 months after randomization. Subsequently, risk ratio estimates were unstable. Fenretinide was well tolerated and effective at preventing relapses and new leukoplakias during treatment and after. The trial had to be stopped prematurely for very low recruitment and had insufficient power to reveal any protective effect against oral carcinoma; nevertheless, continuing studies on this promising chemopreventive are justified.

Chemoprevention of head and neck cancer

Cancer of the aerodigestive tract is associated with great morbidity and mortality in the United States and worldwide. Despite substantial improvements in the delivery of cytotoxic drugs and ionizing radiation therapies, which have resulted in better treatment outcomes, mortality from head and neck malignancies has changed minimally over the last fifty years. Furthermore, the long-term untoward consequences of treatment are significant. Based on this, prevention emerges as a very attractive strategy. Primary prevention through the avoidance of major risk factors, (eg, smoking and ethanol consumption) would result in substantial gains. Unfortunately, behavioral modification (eg, smoking cessation) is not easy to achieve and/or sustain, and even when attained, the carcinogenic risk does not seem to return to that of an individual who never smoked. Chemoprevention is a modality in which compounds are administered singly or in combination to individuals at increased carcinogenic risk in order to halt, prevent, or delay the onset of invasive cancer. This article will review the current status of chemoprevention of the upper aerodigestive tract (UADT), including its biologic basis, clinical models to test for chemopreventive efficacy, and some of the promising strategies that have completed clinical testing or are currently under investigation. Future prospects in the field will also be discussed.

Genomic instability in oral squamous cell carcinoma: relationship to betel-quid chewing

Genomic instability in repeated DNA sequences is exhibited by a variety of cancer types, including oral squamous cell carcinoma. Exposure to carcinogenic compounds may further increase the instability. We have used Inter-Simple Sequence Repeat (Inter-SSR) PCR methodology to detect genetic alterations in 37 oral cancer patients who had chewed betel-quid. Thirty-eight percent of DNA from tumors had genomic alterations in the sequences flanked by (CA)(8) and (GT)(8) repeats. Patients with tumor DNAs harboring genomic alterations had a two-fold higher consumption of betel-quid than patients without alterations in tumor DNA. Matched normal and tumor DNAs were also screened for microsatellite instability where four patients (10.8%) showed alterations in at least one microsatellite marker but there was no relationship between this phenotype and betel-quid chewing. These data indicate that exposure to carcinogens present in the betel-quid may contribute to genomic instability detected by inter-SSR PCR in a subset of oral tumors.