The impact of smoking status, disease stage, and index tumor site on second primary tumor incidence and tumor recurrence in the head and neck retinoid chemoprevention trial.

Second primary tumors (SPTs) develop at an annual rate of 3-7% in patients with head and neck squamous cell cancer (HNSCC). In a previous Phase III study, we observed that high doses of 13-cis-retinoic acid reduced the SPT rate in this disease. In 1991, we launched an intergroup, placebo-controlled, double-blind study to evaluate the efficacy of low-dose 13-cis-retinoic acid in the prevention of SPTs in patients with stage I or II squamous cell carcinoma of the larynx, oral cavity, or pharynx who had been previously successfully treated with surgery, radiotherapy, or both, and whose diagnoses had been established within 36 months of study entry. As of September 16, 1999, the Retinoid Head and Neck Second Primary (HNSP) Trial had completed accrual with 1384 registered patients and 1191 patients randomized and eligible. All of the patients were followed for survival, SPT development, and index cancer recurrence. Smoking status was assessed at study entry and during study. Smoking cessation was confirmed biochemically by measurement of serum cotinine levels. The annual rate of SPT development was analyzed in terms of smoking status and tumor stage. As of May 1, 2000, SPTs have developed in 172 patients. Of these, 121 (70.3%) were tobacco-related SPTs, including 113 in the aerodigestive tract (57 lung SPTs, 50 HNSCC SPTs, and 6 esophageal SPTs) and 8 bladder SPTs. The remaining 51 cases included 23 prostate adenocarcinomas, 8 gastrointestinal malignancies, 6 breast cancers, 3 melanomas, and 11 other cancers. The annual rate of SPT development observed in our study has been 5.1%. SPT development related to smoking status was marginally significant (active versus never, 5.7% versus 3.5%; P = 0.053). Significantly different smoking-related SPT development rates were observed in current, former, and never smokers (annual rate = 4.2%, 3.2%, and 1.9%, respectively, overall P = 0.034; current versus never smokers, P = 0.018). Stage II HNSCC had a higher overall annual rate of SPT development (6.4%) than did stage I disease (4.3%; P = 0.004). When evaluating the development of smoking-related SPTs, stage was also highly significant (4.8% for stage II versus 2.7% for stage I; P = 0.001). Smoking-related SPT incidence was significant for site as well (larynx versus oral cavity, P = 0.015; larynx versus pharynx, P = 0.011). Primary tumors recurred at an annual rate of 2.8% in a total of 97 patients. The rate of recurrence was higher in patients with stage II disease (4.1% versus 2.2%, P = 0.004) as well as oral cavity site when compared with larynx (P = 0.002). This is the first large-scale prospective chemoprevention study evaluating smoking status and its impact on SPT development and recurrence rate in HNSCC. The results indicate significantly higher SPT rates in active smokers versus never smokers and significantly higher smoking-related SPT rates in active smokers versus never smokers, with intermediate rates for former smokers.

Randomized phase III intergroup trial of isotretinoin to prevent second primary tumors in stage I non-small-cell lung cancer.

BACKGROUND: Promising data have suggested that retinoid chemoprevention may help to control second primary tumors (SPTs), recurrence, and mortality of stage I non-small-cell lung cancer (NSCLC) patients. METHODS: We carried out a National Cancer Institute (NCI) Intergroup phase III trial (NCI #I91-0001) with 1166 patients with pathologic stage I NSCLC (6 weeks to 3 years from definitive resection and no prior radiotherapy or chemotherapy). Patients were randomly assigned to receive a placebo or the retinoid isotretinoin (30 mg/day) for 3 years in a double-blind fashion. Patients were stratified at randomization by tumor stage, histology, and smoking status. The primary endpoint (time to SPT) and the secondary endpoints (times to recurrence and death) were analyzed by log-rank test and the Cox proportional hazards model. All statistical tests were two-sided. RESULTS: After a median follow-up of 3.5 years, there were no statistically significant differences between the placebo and isotretinoin arms with respect to the time to SPTs, recurrences, or mortality. The unadjusted hazard ratio (HR) of isotretinoin versus placebo was 1.08 (95% confidence interval [CI] = 0.78 to 1.49) for SPTs, 0.99 (95% CI = 0.76 to 1.29) for recurrence, and 1.07 (95% CI = 0.84 to 1.35) for mortality. Multivariate analyses showed that the rate of SPTs was not affected by any stratification factor. Rate of recurrence was affected by tumor stage (HR for T(2) versus T(1) = 1.77 [95% CI = 1.35 to 2.31]) and a treatment-by-smoking interaction (HR for treatment-by-current-versus-never-smoking status = 3.11 [95% CI = 1.00 to 9.71]). Mortality was affected by tumor stage (HR for T(2) versus T(1) = 1.39 [95% CI = 1.10 to 1.77]), histology (HR for squamous versus nonsquamous = 1.31 [95% CI = 1.03 to 1.68]), and a treatment-by-smoking interaction (HR for treatment-by-current-versus-never-smoking = 4.39 [95% CI = 1.11 to 17.29]). Mucocutaneous toxicity (P<.001) and noncompliance (40% versus 25% at 3 years) were higher in the isotretinoin arm than in the placebo arm. CONCLUSIONS: Isotretinoin treatment did not improve the overall rates of SPTs, recurrences, or mortality in stage I NSCLC. Secondary multivariate and subset analyses suggested that isotretinoin was harmful in current smokers and beneficial in never smokers.

Predicting cancer development in oral leukoplakia: ten years of translational research.

Our 10-year translational study of the oral premalignant lesion (OPL) model has advanced the basic understanding of carcinogenesis. Although retinoids have established activity in this model, a substantial percentage of our OPL patients progress to cancer, especially after treatment is stopped. On the basis of our 10-year OPL study, we have developed the first comprehensive tool for assessing cancer risk of OPL patients. This cancer risk assessment tool incorporates medical/demographic variables, epidemiological factors, and cellular and molecular biomarkers. Between 1988 and 1991, 70 advanced OPL patients were enrolled in a chemoprevention trial of induction with high dose isotretinoin (1.5 mg/kg/day for 3 months) followed by 9 months of maintenance treatment with either low dose isotretinoin (0.5 mg/kg/day) or beta-carotene (30 mg/d; total treatment duration, 1 year). We assessed the relationship between cancer risk factors and time to cancer development by means of exploratory data analysis, logrank test, Cox proportional hazard model, and recursive partitioning. With a median follow-up of 7 years, 22 of our 70 patients (31.4%) developed cancers in the upper aerodigestive tract following treatment. The overall cancer incidence was 5.7% per year. The most predictive factors of cancer risk are OPL histology, cancer history, and three of the five biomarkers we assessed (chromosomal polysomy, p53 protein expression, and loss of heterozygosity at chromosome 3p or 9p). In the multivariable Cox model, histology (P = 0.0003) and the combined biomarker score of chromosomal polysomy, p53, and loss of heterozygosity (P = 0.0008) are the strongest predictors for cancer development. Retinoic acid receptor beta and micronuclei were not associated with increased cancer risk. We have demonstrated a successful strategy of comprehensive cancer risk assessment in OPL patients. Combining conventional medical/demographic variables and a panel of three biomarkers can identify high risk patients in our sample. This result will need to be validated by future studies. With the identification of high risk individuals, more efficient chemoprevention trials and molecular targeting studies can be designed.

Uracil-ftorafur: an oral fluoropyrimidine active in colorectal cancer.

PURPOSE AND DESIGN: This review describes the early clinical development of uracil-ftorafur (UFT), an oral fluoropyrimidine, designed in 1978 by adding uracil to ftorafur. The review focuses on the treatment of colorectal cancer and summarizes the Japanese experience and the phase I and II trials performed in the United States and Europe. RESULTS: Clinical trials of UFT published in the Western world have included 581 patients with colorectal cancer. UFT has been administered in these trials as a single agent or biomodulated by leucovorin (LV). UFT was administered daily in split doses for periods that ranged from 14 to 28 days. The activity of oral UFT in large-bowel cancer when administered with oral LV (approximately 50 mg/dose) has resulted in objective response rates of approximately 40%. Response rates of approximately 25% (range, 17% to 39%) were reported when UFT was administered as a single agent or with lower doses of LV. The highest dose-intensities of UFT are achieved with 28-day schedules of administration. The maximum-tolerated dose (MTD) of UFT with this schedule, when administered concomitantly with oral LV 150 mg daily, is 300 mg/m2 daily. The dose-limiting toxicity (DLT) of UFT has generally been diarrhea. Other commonly described toxicities include nausea and vomiting, fatigue, and stomatitis. Myelosuppression occurs infrequently. Typically, hand-foot syndrome and neurologic toxicity are lacking. CONCLUSION: UFT is a fluoropyrimidine active in colorectal cancer. The oral route of administration and improved safety profile represent important advantages over both conventional and infusional fluorouracil (5-FU) regimens.

The effect of 13-cis-retinoic acid chemoprevention on human serum retinol levels.

This study of the effect of 13-cis-retinoic acid on serum levels of retinol was a laboratory correlate of a clinical chemoprevention trial in asymptomatic chronic smokers. All study participants had squamous metaplasia of the bronchial epithelium and received 6 months' treatment of either 13-cis-retinoic acid (1 mg/kg/day) or placebo. Baseline serum retinol levels were compared with levels taken immediately post-treatment. The placebo group (N = 38) had little change, whereas the 13-cis-retinoic acid group, (N = 35) experienced a decline in retinol levels (p = 0.06). Within the 13-cis-retinoic acid group, women's (N = 13) mean serum retinol levels dropped significantly, from 531 +/- 191 ng/ml (baseline) to 436 +/- 115 ng/ml (post-treatment) (p = 0.03); men's (N = 22) levels virtually did not change (p = 0.43). Therefore, the borderline-significant overall decline in the 13-cis-retinoic acid group was due entirely to the decline among women subjects. The etiology of this effect is unknown. Our results suggest that chronic 13-cis-retinoic acid administration may lead to a clinically significant reduction in serum retinol levels in females. This finding may have implications for currently ongoing chemoprevention trials that administer 13-cis-retinoic acid for 3 years.

Phase II trial of uracil/tegafur (UFT) plus leucovorin in patients with advanced hepatocellular carcinoma.

UNLABELLED: Although UFT 300 mg/m2/day and leucovorin 90 mg/day administered orally in divided doses administered every 8 hours for 28 days repeated every 35 days could be administered safely to patients with advanced hepatomas and good performance status, this combination and schedule has limited activity in treating advanced hepatoma. BACKGROUND/PURPOSE: Biochemical modulation of 5-fluorouracil has yielded higher response rates in hepatoma when compared to treatment with 5-fluorouracil as a single agent, although the impact on survival has been negligible. This study was conducted to determine the activity and evaluate the toxicity of uracil and tegafur in a 4:1 molar concentration ratio (UFT; Bristol-Myers Squibb, Wallingford, CT) plus oral calcium leucovorin in the treatment of patients with advanced hepatocellular carcinoma (hepatoma). PATIENTS AND METHODS: Sixteen patients with advanced measurable hepatocellular carcinoma were enrolled onto the trial. All patients had a Karnofski performance status > or = 60%, platelet count > or = 75,000/micro L, total bilirubin < or = 2.0 x institutional upper limit of normal but otherwise normal liver and kidney function profile and bidimensionally measurable disease by CT or ultrasound examination. None of these patients received prior cytotoxic chemotherapy or radiation therapy for advanced disease. Fourteen patients received 300 mg/m2/d UFT plus 90 mg/d leucovorin administered orally in divided daily doses every 8 hours for 28 days repeated every 35 days. Two patients registered for the trial but did not receive study medication. Objective tumor response, the primary purpose of this trial, was evaluated after two courses of therapy. Other end-points included toxicity, time to progression, and overall survival. RESULTS: Fourteen patients were evaluable for response and toxicity, respectively. No complete or partial responders were observed in this trial. Three patients had stable disease lasting 17 to 22 weeks. Toxicity was mild with severe (grade 3 or 4) liver pain, diarrhea, anorexia/nausea, fatigue, dyspnea, hyperbilirubinemia, anemia, and edema seen in 3 (21%), 2 (14%), 3 (21%), 2 (14%), 1 (7%), 1 (7%), 1 (7%) and 1 (7%) patients, respectively. The most frequent grade I and 2 toxic effects included fever of unknown origin, dyspnea, nausea, vomiting and diarrhea. CONCLUSION: UFT 300 mg/m2/d plus oral leucovorin 90 mg/d administered for 28 days did not demonstrate antitumor activity against advanced hepatomas. Further treatment using this regimen is not recommended for this disease.

UFT and leucovorin: a review of its clinical development and therapeutic potential in the oral treatment of cancer.

UFT is an oral antineoplastic drug combining uracil and tegafur in a 4:1 molar ratio. Tegafur acts as a prodrug of 5-fluorouracil (5-FU), being slowly metabolized by cytochrome P450 to 5-FU. Uracil competitively inhibits the metabolism of 5-FU, resulting in increased plasma and tumor 5-FU concentrations. At equimolar doses, higher peak plasma 5-FU concentrations are achieved with UFT plus oral leucovorin with similar systemic 5-FU exposure compared with low-dose continuous 5-FU infusions. The elimination half-life of 5-FU following UFT administration is approximately 7 h compared with 0.2 h with i.v. 5-FU. In phase II studies of UFT plus oral leucovorin for the treatment of advanced colorectal cancer, response rates ranged from 25 to 42%. UFT plus oral leucovorin is well tolerated, with manageable diarrhea being the only dose-limiting toxicity; the regimen is not associated with significant myelosuppression, mucositis, hand-foot syndrome or alopecia. UFT, with or without leucovorin, has also been evaluated alone or in combination with other cytotoxic agents for the treatment of advanced lung, breast and gastric cancers. UFT has also been evaluated as adjuvant therapy for colorectal, breast, gastric, head and neck, and superficial bladder cancers. UFT plus leucovorin offers patients an entirely oral cancer treatment, and appears to provide potential advantages over bolus 5-FU regimens with regard to toxicity and convenience of administration. These benefits should be advantageous in the adjuvant setting, as well as in advanced disease settings in which palliation is an important consideration. Ongoing clinical trials will further define the role of this promising oral treatment regimen.

A phase II study of ifosfamide in recurrent squamous cell carcinoma of the head and neck.

Chemotherapy has not significantly altered the overall survival of patients with recurrent squamous cell carcinoma of the head and neck; therefore, the development of new agents is essential. The purpose of the current phase II study was to define the efficacy of ifosfamide in the treatment of recurrent squamous cell carcinoma of the head and neck. All patients were required to have squamous cell carcinoma of the head and neck that had recurred following surgery or radiotherapy or both. Patients may have received prior chemotherapy. Patients were initially treated with ifosfamide 2 g/m2/day for 4 days (dose level 0). Dose level-1 was 2 g/m2/day for 3 days, and dose level-2 was 2 g/m2/day for 2 days. All patients received mesna 400 mg/m2/day prior to and 1,200 mg/m2/day as a continuous infusion after ifosfamide. Thirty-eight patients were enrolled in the study. Five patients were inevaluable for toxicity or response. Overall, the regimen was well tolerated, with grade 4 granulocytopenia the only significant toxicity occurring in 16 patients. Overall, eight of 31 evaluable patients (25.8%) had a major response. Only one of the 10 patients (10%) with prior chemotherapy responded, but seven of the 21 patients (33.3%) with no prior chemotherapy had major responses. Ifosfamide is an active agent in recurrent squamous cell carcinoma of the head and neck. Further studies of ifosfamide in combination with other agents, particularly as induction therapy in patients with locally advanced disease, are warranted.

Clinical studies in head and neck cancer chemoprevention.

Secondary neoplasms represent a major threat for patients with head and neck cancer. The prevention of secondary neoplasms has been a major goal of head and neck cancer chemoprevention efforts. In order to help develop effective strategies, reversal of oral premalignancy has been used as a model for chemoprevention. There is now sufficient data to show the chemopreventive effect in premalignant lesions of some natural compounds and their derivatives. Retinoids are the most studied chemopreventive agents for the treatment of oral leukoplakia. Other compounds with chemopreventive activity are carotenoids, Vitamin E derivatives and Selenium. There are two large prospective, randomized, chemoprevention clinical trials, one in Europe and the other in North America, using prevention of secondary malignancy as the primary study end-point. Until these trials are completed, the use of chemoprevention in head and neck cancer should be limited to clinical trials.

Phase I study of paclitaxel, cisplatin, and ifosfamide in patients with recurrent or metastatic squamous cell cancer of the head and neck.

The prognosis for patients with recurrent or metastatic squamous cell cancer of the head and neck is poor. Chemotherapy has not significantly improved survival. New agents and regimens are being developed in hopes of improving the outcome for these patients. A phase I/II trial using a combination of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ), cisplatin, and ifosfamide is being performed. The phase I portion is completed and reported here. Granulocytopenia was the dose-limiting toxicity. Overall, the regimen was well tolerated. Major responses were observed in four of 10 evaluable patients in the phase I study. The phase II trial is ongoing.

Chemoprevention of lung cancer.

Treatment of lung cancer remains frustrating. Most patients with lung cancer are not candidates for curative therapy, and new therapies have not made a substantial impact on survival. Consequently, some clinical investigators have focused their efforts on developing prevention strategies. Chemoprevention, the administration of agents to block or reverse carcinogenesis, is being investigated in ongoing trials. Studies of chemoprevention in lung cancer have included trials to reverse premalignant lesions such as sputum atypia or squamous metaplasia of the bronchial epithelium. Clinical trials of lung cancer prevention have often studied groups of participants with tobacco or asbestos exposure. Other clinical trials are being conducted among patients who have been treated for an early-stage lung cancer. As the result of diffuse epithelial injury, these patients are at very high risk for developing second primary tumors, predominantly in the lungs and upper aerodigestive tract. It is our hope that these studies may establish a new strategy for preventing lung cancer.

Current status of retinoid chemoprevention of lung cancer.

Clinical trials have suggested that retinoid chemoprevention prevents the development of second primary tumors following head and neck or non-small-cell lung cancer. The findings of these initial studies are now being evaluated in large multi-institution chemoprevention trials. If successful, these ongoing trials will establish the clinical role of retinoids in lung cancer prevention. The findings of these trials may also lead to strategies for primary lung cancer prevention. Until the results of these studies become available, however, lung cancer chemoprevention remains an experimental approach. The recent unexpected findings of increased lung cancer incidence in a beta-carotene study in Finnish smokers stresses the importance of establishing the efficacy of chemoprevention agents in carefully conducted clinical trials.

Retinoids and chemoprevention: clinical and basic studies.

Retinoids, which include natural vitamin A (retinol) and its esters and synthetic analogues, are the best-studied class of agents in chemoprevention. There are more than 4,000 different retinoids which have a wide spectrum of preclinical activities, structures, pharmacological profiles, tissue distributions, receptor specificities, and toxicities. A number of retinoids have significant activity in many in vivo experimental systems including skin, bladder, lung, breast and oral carcinogenesis. In clinical trials, several retinoids have achieved significant activity in the reversal of head and neck, skin, and cervical premalignancy, and in the prevention of second primary tumors associated with head and neck, skin, and non-small cell lung cancer. Since 1984, our group has conducted a series of clinical trials to explore the chemopreventive potential of 13-cis-retinoic acid (13cRA) in the aerodigestive tract. We have conducted two consecutive randomized studies in subjects with premalignant lesions of the oral cavity. These studies showed that high-dose 13cRA alone can achieve significant short-term reversal of oral premalignancy, and that high-dose followed by low-dose 13cRA can maintain suppression of oral carcinogenesis. Three other randomized trials have confirmed significant retinoid activity in this human carcinogenic system. We also developed a randomized, placebo-controlled trial of adjuvant high-dose 13cRA in patients with head and neck cancer. Second primary tumor development was significantly decreased in the 13cRA group, but 13cRA had no impact on primary disease recurrence or survival. This presentation will update the current status of clinical trials and correlative laboratory studies of potential intermediate endpoint biomarkers in retinoid chemoprevention of aerodigestive tract carcinogenesis.

Phase II study of carboplatin and continuous infusion bleomycin followed by cisplatin and 5-fluorouracil in recurrent head and neck cancer.

BACKGROUND: Recurrent squamous cell carcinoma of the head and neck is poorly responsive to most chemotherapy regimens. Carboplatin and bleomycin are effective single agents with non-overlapping toxicity; therefore, we sought to explore the efficacy of this regimen in a phase II study. In the second stage of the study, patients who did not respond to carboplatin and bleomycin were given treatment with cisplatin and 5-fluorouracil (5-FU). PATIENTS AND METHODS: Patients with recurrent squamous cell carcinoma of the head and neck were treated with carboplatin 400 mg/m2 followed by bleomycin 15 units intravenously as a continuous infusion for 4 days. Patients with no tumor response after 3 cycles of carboplatin and bleomycin were crossed-over to receive cisplatin 100 mg/m2 and 5-FU 1000 mg/m2/day continuous infusion for 5 days. RESULTS: Among the 20 carboplatin-bleomycin patients evaluable for toxicity, no cases of grade 4 granulocytopenia were reported and grade 3 or 4 thrombocytopenia developed in only three patients. Three partial responses occurred among the 19 patients (16%) [95% C.I. 0% to 32%] evaluable for response to carboplatin-bleomycin. None of the 11 patients crossed-over to cisplatin and 5-FU had a major response. CONCLUSION: The combination of carboplatin and bleomycin is well tolerated in patients with recurrent head and neck cancer, but the activity does not appear to be superior to the activity of either agent alone. Patients who did not respond to carboplatin and bleomycin were also resistant to the cisplatin and 5-FU regimen.

Micronuclei, a biomarker for chemoprevention trials: results of a randomized study in oral pre-malignancy.

Biomarkers are being sought that could serve as surrogate end points for chemoprevention trials. Micronuclei, cytoplasmic fragments of DNA, have been proposed as a biomarker and studied in oral pre-malignancy. This study evaluated micronuclei frequency in a randomized chemoprevention trial of oral pre-malignancy. A recent clinical trial evaluated the responses of pre-malignant oral lesions to 3 months of therapy with isotretinoin followed by 9 months of either low-dose isotretinoin or beta-carotene. For 57 study participants, micronuclei were counted in mucosal scrapings of the lesion and in normal-appearing mucosa at baseline and following 3 months and 12 months of therapy. Micronuclei counts were higher in scrapings from the lesion than in the normal-appearing mucosa. Following 3 months of isotretinoin, the micronuclei counts in scrapings of the lesion were significantly reduced. With treatment, the mean micronuclei count declined at 3 months. In a randomized comparison, both isotretinoin and beta-carotene maintained the suppression of micronuclei. The change in micronuclei count was not associated with the clinical or histological response to treatment. Chemoprevention treatment with isotretinoin led to a reduction in frequency of micronuclei, a marker of recent DNA injury, which was then maintained by both isotretinoin and beta-carotene.

Epidemiology, biology, and chemoprevention of aerodigestive cancer.

Cancers of the aerodigestive tract are a major cause of worldwide morbidity and mortality. Long term survival rates for these epithelial cancers have not improved substantially in the past 20 years despite intensive efforts to improve the prevention and therapy of these diseases. Therefore, new approaches are needed. One new investigative approach is chemoprevention, the chemical prevention of cancer. Chemoprevention studies in the upper aerodigestive tract have focused on the reversal of premalignant lesions and the prevention of second primary tumors. These chemoprevention efforts have resulted from an understanding of the multistep nature of epithelial carcinogenesis and the diffuse epithelial injury that results from carcinogen exposure. Ongoing research efforts are attempting to define these processes. The interaction between carcinogen exposure and host susceptibility in the development of cancers of the aerodigestive tract is being evaluated (e.g., with an assay of chromosomal sensitivity to the clastogen bleomycin). This review discusses several new aspects of the epidemiology, biology, and chemoprevention of aerodigestive tract carcinogenesis.

Retinoid chemoprevention of second primary tumors.

Retinoids, natural or synthetic derivatives of vitamin A, have been studied as cancer chemopreventive agents and as therapeutic agents in the treatment of solid tumors. Intensive clinical research has focused on the role of retinoids in preventing second primary tumors following head and neck or lung cancer. The frequent occurrence of second primary tumors in these areas provides clinical support for the hypothesis of field carcinogenesis. Based on evidence of its efficacy in reversing oral premalignancy, the synthetic retinoid 13-cis-retinoic acid (13cRA) was studied in a 1-year trial to prevent the incidence of new cancers in patients who had been treated for squamous cell carcinoma (SCC) of the head and neck. Second primary tumors developed in only 4% of 49 patients treated with 13cRA, as compared with 24% of 51 patients treated with placebo (P = .005). These findings have led to two ongoing large-scale trials of 13cRA in North America. One study, performed through the M.D. Anderson Cancer Center and its affiliated Community Clinical Oncology Program and the institutions of the Radiation Therapy Oncology Group (RTOG), will determine whether long-term administration of low-dose 13cRA will prevent second primary tumors following an initial head and neck cancer. Another intergroup study using a similar randomized double-blind design is being performed among patients who have undergone resection of a stage I non-small-cell lung cancer. In Europe, a large chemoprevention study called Euroscan is currently examining the efficacy of another retinoid, retinyl palmitate, in preventing second primary tumors following head and neck or lung cancer.(ABSTRACT TRUNCATED AT 250 WORDS)