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.

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.

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.

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

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.

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.

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.

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.

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.

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)

Randomized placebo-controlled trial of isotretinoin in chemoprevention of bronchial squamous metaplasia

PURPOSE

Retinoids have proven chemopreventive efficacy in both preclinical and clinical studies. This trial was designed to confirm the finding of an earlier uncontrolled trial that the synthetic retinoid etretinate had major activity in reversing squamous metaplasia found in the bronchial epithelium of chronic smokers.

PATIENTS AND METHODS

We prospectively evaluated 152 smokers with bronchoscopy and obtained biopsies from six sites. Subjects with dysplasia and/or a metaplasia index of greater than 15% were randomly assigned to receive either 1 mg/kg isotretinoin or placebo daily for 6 months. Of 86 subjects randomized (41 isotretinoin, 45 placebo), 69 were reevaluated at the completion of treatment.

RESULTS

In the group as a whole, the metaplasia index decreased over time from a mean +/- SE of 35.8% +/- 2.7% at baseline to 28.1% +/- 3.3% at the completion of treatment (P = .01) by repeated measures analysis of variance [ANOVA]); a reduction in the metaplasia index (> 8%) was noted in both isotretinoin and placebo groups (19 of 35 [54.3%] and 20 of 34 [58.8%], respectively). Complete reversal of squamous metaplasia was noted in nine subjects from each group. However, the magnitudes of the mean metaplasia index changes did not differ significantly in the two treatment groups. In both groups, smoking cessation resulted in significant declines in the extent of squamous metaplasia, whereas no significant change in metaplasia index was found among those who continued to smoke.

CONCLUSION

Squamous metaplasia was frequently observed in bronchial biopsy samples from chronic smokers. From this study, we conclude that isotretinoin has no effect on squamous metaplasia, a potential intermediate end point of bronchial carcinogenesis. Although determining the exact role of isotretinoin in lung cancer prevention requires further study, the finding that there was a significant decrease in squamous metaplasia in the placebo group emphasizes the critical importance of a placebo-controlled study design in chemoprevention trials using intermediate end points.

Cancer chemoprevention

PURPOSE

To review the most important recent advances in clinical trials and biologic studies within the growing field of chemoprevention.

METHODS

The most critical methods issue concerns the definitive end point of phase III trials, which is now cancer incidence. This end point usually needs thousands of subjects monitored for 5 to 10 or more years to determine efficacy. Biologic markers of potential intermediate end points are under intensive study and may one day replace cancer incidence. Validated intermediate end point biomarkers could greatly reduce phase III trial populations, durations, and costs.

RESULTS

Randomized clinical trials over the last 5 years have produced significant activity in reversing oral, skin, colon, and cervical premalignancy; in preventing primary skin and stomach cancer; and in preventing second primary tumors associated with head and neck and lung cancer. These clinical advances have been paralleled at the basic science level by elegant molecular studies of premalignant carcinogenesis and of chemopreventive agents' mechanisms of action. One major laboratory advance is the discovery of nuclear retinoic acid receptors and strong evidence of their roles both in carcinogenic progression and in its response to retinoids.

CONCLUSION

Chemoprevention has matured greatly in recent years with the significant reversal or suppression of premalignancy by chemopreventive agents in several sites. The future of chemoprevention will be determined largely by several ongoing phase III trials, including trials of retinoids, beta-carotene, and alpha-tocopherol in the aerodigestive tract, of tamoxifen and fenretinide in the breast, and of finasteride in the prostate.

Retinoid chemoprevention studies in upper aerodigestive tract and lung carcinogenesis

Chemoprevention is a clinical strategy to block or reverse carcinogenesis before the development of invasive cancer. Studies of chemoprevention in the lungs and upper aerodigestive tract have relied on the field carcinogenesis hypothesis, which predicts that diffuse epithelial injury will result from exposure of that epithelium to carcinogens. This hypothesis is supported by the frequent occurrence of multiple primary tumors within the exposed field. In addition, the understanding of carcinogenesis as a multistep process supports the use of interventions in damaged epithelium before the development of clinically invasive cancer. Current efforts are focused on applying to chemoprevention studies the increasing knowledge of the molecular events in carcinogenesis. In our program, clinical trials in lung and head and neck chemoprevention have focused on individuals with evidence of field carcinogenesis, i.e., a history of previous epithelial cancer or the presence of premalignant lesions. These trials include studies to develop clinically applicable intermediate markers of carcinogenesis and large Phase III trials to evaluate the efficacy of the retinoid isotretinoin in preventing second primary tumors following head and neck or lung cancers.

Phase II study of carboplatin and edatrexate (10-EdAM) with leucovorin rescue for patients with recurrent squamous cell carcinoma of the head and neck

Recurrent squamous cell carcinoma of the head and neck is poorly responsive to chemotherapy in most patients; therefore, the development of new approaches is essential. Edatrexate is a new antifolate with improved preclinical antitumor activity when compared to methotrexate. The purpose of this study was to define the feasibility and efficacy of combining edatrexate with another active single agent, carboplatin in chemotherapy-naive recurrent disease. Carboplatin was given as an outpatient on day 1 at a dosage based on the formula: Dose (mg/m2) = (0.091) (creatinine clearance) (body surface area) (desired percentage change in platelet count) + 86. Edatrexate (80 mg/m2) was given on days 1, 8, and 15 of a 21 day cycle. Calcium leucovorin 15 mg was given orally every 6 h for 4 doses after edatrexate. Of the 26 patients entered on the study, 1 was invaluable for toxicity or response and 3 patients were evaluable for toxicity only. Grade 3 or 4 neutropenia occurred in 2 patients each, and grade 3 or 4 thrombocytopenia occurred in 2 and 4 patients, respectively. Grade 3 stomatitis occurred in only two patients. Overall, major responses occurred in 2 of 22 evaluable patients (9%). The combination of carboplatin and edatrexate was not superior to the results expected with either agent alone.

A stopping rule for standard chemotherapy for metastatic breast cancer: lessons from a survey of Maryland medical oncologists

The sequential administration of standard chemotherapy regimens to treat metastatic breast cancer may keep patients and oncologists from considering other important, but more psychologically difficult, issues such as the patient's declining health or approaching death. This practice also utilizes health care resources for ever-decreasing individual patient benefit. If generally agreed-upon rules or guidelines were developed about stopping standard chemotherapy after a limited number of regimens, oncologists could recommend treatment discontinuation with greater confidence. Also, resources could be redirected. To inform the development of guidelines on when to stop chemotherapy for metastatic breast cancer, we surveyed fully trained Maryland medical oncologists about their knowledge and beliefs about chemotherapy for metastatic breast cancer. The survey instrument included open-ended questions and clinical vignettes. There was consensus about the value of first-line chemotherapy. Even though oncologists employed second-line chemotherapy, they were unenthusiastic about it. The frequent utilization of second-line regimens probably reflects an effort to offer marginal regimens to patients who want them. Based on these data, it is suggested that standard chemotherapy be stopped after breast cancer fails to stabilize or respond on a standard regimen. Patients who wish further treatment could be referred for investigational therapy if it is available and if they are eligible.

Reduction in oral mucosa micronuclei frequency following alpha-tocopherol treatment of oral leukoplakia

Micronuclei frequency, a marker of genotoxicity, was studied within a trial of alpha-tocopherol for chemoprevention of oral leukoplakia. Oral swabs were obtained from two sites, the leukoplakia lesion and normal-appearing mucosa, at baseline and following 24 weeks of therapy with 400 international units of alpha-tocopherol twice daily. These specimens were analyzed for micronuclei frequency. The major risk factors for oral carcinogenesis in the group studied were cigarette smoking and alcohol consumption. alpha-tocopherol therapy produced a significant reduction in micronuclei frequencies in specimens from both the visible lesions (P < 0.01) and the normal-appearing mucosa (P < 0.01). The micronuclei frequencies, both at baseline and following therapy, were greater in specimens taken from the lesion than in those from the normal-appearing mucosa. Although these results indicate that alpha-tocopherol has a beneficial effect in oral carcinogenesis, there was no significant clinical or histological response associated with the change in micronuclei frequency. Micronuclei frequency has not yet been validated as a biomarker for cancer incidence, and consequently, its utility as an intermediate end point for chemoprevention trials is not known. Determining clinical significance of micronuclei frequency patterns in oral carcinogenesis and chemoprevention will require further study.

Retinoids in chemoprevention of head and neck carcinogenesis

There is currently considerable excitement about the prospects of developing effective chemoprevention strategies for head and neck cancer. The field cancerization model provides the basic assumptions which guide current head and neck chemoprevention trials. The retinoid 13-cis-retinoic acid, as well as other agents, is currently being studied in clinical trials and will hopefully establish the role of chemoprevention in head and neck cancer.

Chemoprevention. Strategies for the control of cancer

High incidence and low survival rates of many epithelial cancers remain beyond the control of established preventive and therapeutic modalities. Chemoprevention is a new approach under study that involves the intervention within the premalignant process with specific chemical agents to reverse carcinogenesis and prevent the development of invasive cancer. The two biologic concepts that underlie this research are multistep carcinogenesis and field carcinogenesis. Major clinical issues include trial design and drug development in head and neck, lung, and breast cancer chemoprevention. Within the area of trial design, intermediate end point biomarkers will become very important for providing biologic insights in the short term and greater trial efficiencies in the long term. Drugs that are under the strongest investigation include retinoids and beta-carotene in the head and neck and lung, calcium in the colon, and tamoxifen in the breast. This new field has the potential to make an important contribution toward increasing our control over many deadly epithelial cancers Cancer 1993; 72:984-90.

Chemoprevention. Strategies for the control of cancer

High incidence and low survival rates of many epithelial cancers remain beyond the control of established preventive and therapeutic modalities. Chemoprevention is a new approach under study that involves the intervention within the premalignant process with specific chemical agents to reverse carcinogenesis and prevent the development of invasive cancer. The two biologic concepts that underlie this research are multistep carcinogenesis and field carcinogenesis. Major clinical issues include trial design and drug development in head and neck, lung, and breast cancer chemoprevention. Within the area of trial design, intermediate end point biomarkers will become very important for providing biologic insights in the short term and greater trial efficiencies in the long term. Drugs that are under the strongest investigation include retinoids and beta-carotene in the head and neck and lung, calcium in the colon, and tamoxifen in the breast. This new field has the potential to make an important contribution toward increasing our control over many deadly epithelial cancers Cancer 1993; 72:984-90.

Squamous metaplasia of the bronchial mucosa and its relationship to smoking

We performed flexible fiberoptic bronchoscopy (FFB) on 106 heavy cigarette smokers. Six bronchial biopsy specimens, obtained from the carina and five major bronchi, were screened for squamous metaplasia. Individual biopsy specimens were sectioned into 4-microns sections, and a metaplasia index (MI), or percentage of sections containing squamous metaplasia, was determined. Metaplasia was noted at one or more biopsy sites in 66 of 99 subjects (seven were excluded from the analysis). Twenty-five percent of the subjects showed metaplasia at three or more biopsy sites, and one subject had metaplasia on all six biopsy specimens. The presence of squamous metaplasia varied from 40.4 percent in the right lower lobe to 15.3 percent in the left upper lobe. The subjects were grouped into simple categories based on the number of packs smoked per day and the pack-year history of smoking. Subjects who smoked more than two packs per day (n = 11) had the highest MI (37.4 +/- 4.9 percent, mean +/- SEM). Fifty-seven subjects smoked more than one pack per day but fewer than or equal to two packs per day, and they had a mean MI of 22.3 +/- 2.9 percent. Subjects who smoked one pack per day or less (n = 31) had a mean MI of only 12.9 +/- 2.8 percent. The MI of those who smoked more than two packs per day was significantly greater than the MI of those who smoked one pack per day or less (p < or = 0.003). While the MI varied from 12.9 +/- 3.5 percent in subjects who had smoked less than 20 pack-years to a maximum of 29.1 +/- 4.5 percent in those who had smoked greater than 60 pack-years, no statistically significant difference was detected between these two groups. Thus, we conclude that heavy tobacco use is associated with important alterations of bronchial mucosa. Furthermore, the intensity of tobacco use (packs per day) rather than the number of pack-years appears to be the more important factor in promoting squamous metaplasia of the bronchial mucosa.

N-(4-hydroxyphenyl) retinamide is anticlastogenic in human lymphoblastoid cell lines

The in vitro anticlastogenic effects of a new synthetic retinoid derivative, N-(4-hydroxyphenyl)-retinamide (4-HPR), were studied in two human lymphoblastid cell lines (3640P and 4087P). Cell cultures were preincubated with 4-HPR in a range of concentrations from 10(-9) to 10(-6) M for 24 h. The number of chromatid breaks per cell (b/c) induced by a 2-hour treatment with 0.004 U/ml bleomycin was determined. The mean b/c values in cell cultures treated with bleomycin alone were 0.50 (3640P) and 0.73 (4087P). The presence of 10(-6) M 4-HPR significantly decreased this value in both cell lines to 0.27 in 3640P (p < 0.01) and 0.41 in 4087P (p < 0.05). Lower concentrations (10(-7) and 10(-8) M) of 4-HPR significantly decreased b/c only in cell line 3649 (p < 0.05). Incubation with the lowest concentration (10(-9) M) of 4-HPR did not decrease b/c values. These preliminary data demonstrate that 4-HPR has anticlastogenic effects in vitro and are similar to our results from previous studies on the in vitro antigenotoxic effects of 13-cis-retinoic acid (Trizna Z et al, Eur J Cancer, 1993, 29A: 137-140).

Regression of oral leukoplakia with alpha-tocopherol: a community clinical oncology program chemoprevention study

BACKGROUND

Oral leukoplakia is an important model for developing chemoprevention approaches for lesions in the upper aerodigestive tract. These lesions most often result from exposure to carcinogens such as tobacco and alcohol and may precede development of invasive cancer. The potent antioxidant alpha-tocopherol (vitamin E) has prevented the development of cancers of the oral cavities in animal models.

PURPOSE

The objectives of this study were to evaluate the toxicity and efficacy of alpha-tocopherol in patients with oral leukoplakia and to assess the feasibility of performing chemoprevention trials through the network of the Community Clinical Oncology Program (CCOP).

METHODS

A single-arm phase II study using the nontoxic agent alpha-tocopherol to treat oral premalignant leukoplakia was performed at seven institutions affiliated with the CCOP through The University of Texas M. D. Anderson Cancer Center. Patients with symptomatic leukoplakia or dysplasia were treated orally with alpha-tocopherol (400 IU) twice daily for 24 weeks. Follow-up was performed at 6, 12, and 24 weeks after the start of treatment to assess toxicity and response, and serum alpha-tocopherol levels were determined at baseline and at 6 and 24 weeks.

RESULTS

Of the 43 patients who have completed 24 weeks of treatment, 20 (46%) had clinical responses and nine (21%) had histologic responses. Mean serum alpha-tocopherol levels were 16.1 micrograms/mL at baseline and increased to 34.29 micrograms/mL after 24 weeks of treatment. Patient-recorded drug calendars, as well as serum drug levels, indicated excellent patient compliance; an average of 95% of the prescribed pills were taken. Treatment was extremely well tolerated; no grade 3 or 4 toxic effects were reported.

CONCLUSIONS

Administration of alpha-tocopherol resulted in both clinical and histologic responses in premalignant leukoplakia lesions. The study also demonstrated that chemoprevention trials can be performed through the CCOP. The major problems were that a high percentage of patients were not assessable for response, some patients withdrew because expenses were not reimbursable, and there was limited participation within the CCOP network. These problems may reflect difficulties inherent in the implementation of multi-institutional chemoprevention trials.

IMPLICATIONS

The efficacy of alpha-tocopherol alone and in combination with other chemopreventive agents for carcinogenesis in the upper aerodigestive tract should be explored in future trials.

Micronuclei: a potential intermediate marker for chemoprevention of aerodigestive tract cancer

Because they may be used as a quantifiable estimate of the extent of recent DNA injury, micronuclei, extrachromosomal fragments of DNA, are among the most studied potential intermediate markers of cancer chemoprevention. Serial measurements of micronuclei frequency may be easily performed on scrapings from the oral cavity or on bronchial brushings. Assessment of micronuclei frequency and its response to chemopreventive agents has been incorporated into studies of upper aerodigestive tract and lung cancer chemoprevention. These studies have helped define the characteristics of micronuclei and have suggested a role for this test in future chemoprevention studies. Micronuclei frequency has been shown to be increased in the oral and bronchial mucosa of individuals with known carcinogen exposure and is higher at the site of the greatest carcinogen exposure, such as the site where tobacco quids are held, than in grossly normal-appearing mucosa. Treatment with chemopreventive agents leads to a reduction in micronuclei frequency. In oral leukoplakia studies, this effect followed treatment with beta-carotene, retinol, alpha-tocopherol, and 13-cis-retinoic acid. The multistep process of epithelial carcinogenesis results from DNA damage and specific genetic events. That micronuclei reflect ongoing DNA injury suggests the hypothesis that long term suppression of cellular genotoxicity, as reflected by a reduction in micronuclei frequency, ultimately leads to a reduction in cancer incidence.

Chemoprevention strategies in lung carcinogenesis

Chemoprevention entails using specific agents to suppress carcinogenesis and thereby prevent the development of primary or second primary cancers. Because the concept of chemoprevention in patients with or at risk of lung cancer is new, ongoing clinical trials are based on data from epidemiologic and preclinical research, as well as on results of chemoprevention studies in head and neck cancer. The latter studies have provided a model for such studies in lung cancer, considering the two diseases have a similar etiology and biology of field carcinogenesis. Beta-carotene, natural vitamin A, and the retinoids may be effective chemopreventive agents. However, chronic administration of such agents may be required to prevent the development of cancer. Results of chemoprevention trials in head and neck cancer have demonstrated effective inhibition of the development of second primary tumors with the synthetic retinoid 13-cis-retinoic acid; investigators are hopeful this will be repeated in patients with lung cancer. Results of ongoing phase III trials and continued advances in the epidemiologic and biologic study of lung carcinogenesis should contribute to future research in this area.

Micronuclei in bronchial biopsy specimens from heavy smokers: characterization of an intermediate marker of lung carcinogenesis

Bronchial micronuclei, small fragments of extra-nuclear DNA formed during cell division, provide a non-specific but quantifiable marker of DNA damage. Micronuclei have been used to assess carcinogen exposure and as an intermediate endpoint in chemoprevention trials. As part of an ongoing chemoprevention trial, heavy smokers underwent screening bronchoscopy, with biopsies taken at 6 standardized sites. Micronuclei counts were obtained for each site in each of the 40 volunteers found to have squamous metaplasia. Unlike squamous metaplasia, the average micronuclei counts among these heavy smokers were not associated with smoking history. Micronuclei counts were also not associated with the presence or extent of metaplasia. A striking degree of intra-individual variability was observed by comparing the micronuclei counts from different biopsy sites within individuals. The findings suggest that use of micronuclei from single sites may be misleading as a marker of carcinogen exposure or as an estimate of cancer risk. Serial measurements in individuals may provide the most useful information concerning carcinogenic exposure and the impact of chemopreventive agents.

Current status of chemoprevention of head and neck cancer

Chemoprevention involves efforts to block or reverse carcinogenesis before the development of invasive cancer. Natural agents, such as retinol and beta carotene, as well as synthetic retinoids have been studied as potential chemopreventive agents. In the head and neck, chemoprevention studies have included efforts both to reverse premalignant lesions such as oral leukoplakia and to prevent the development of second primary tumors. In one recent trial, high-dose 13-cis-retinoic acid treatment resulted in a dramatic reduction in the incidence of second primary tumors. However, significant toxicities were associated with the high dosage. This trial, as well as previous studies of oral leukoplakia, have led to the development of a chemoprevention trial using a low dose of 13-cis-retinoic acid to prevent second primary tumors following head and neck cancer. The rationale and design of this study are discussed in detail.

Chemoprevention strategies for lung and upper aerodigestive tract cancer

The field cancerization hypothesis suggests that carcinogen exposure affects the entire epithelial lining of the lungs and upper aerodigestive tract. The concept that common exposures place the entire epithelium at risk for the development of invasive cancer is supported both by the occurrence of premalignant lesions such as leukoplakia and squamous metaplasia, and by the development of multiple primary tumors within the field. Chemoprevention trials in lung and upper aerodigestive tract cancer have included studies to reverse premalignant lesions and to prevent second primary tumors. Promising results have been reported in both settings using the retinoid 13-cis-retinoid acid. Several clinical trials are in progress which attempt both to reduce cancer incidence and to determine the mechanisms and biological markers of successful chemoprevention.

Intermediate biomarkers in upper aerodigestive tract and lung chemoprevention trials

Chemoprevention trials in lung and upper aerodigestive tract (UADT) cancer are guided by the field cancerization hypothesis. Inhaled carcinogens place the entire epithelial lining at risk for the development of cancer. The hypothesis is supported by the occurrence of premalignant lesions, such as leukoplakia or squamous metaplasia, and multiple primary tumors within the field. The concept of carcinogenesis as a multistep process suggests the possibility of blocking or reversing the progression to invasive cancer with systemic treatment. A series of ongoing clinical trials will determine the efficacy of retinoid chemoprevention and will attempt to develop intermediate biomarkers. Biomarkers which reliably reflect progression towards cancer could be used to dramatically improve the efficiency of chemoprevention trials and also would aid in screening potential chemoprevention agents. Genomic biomarkers include non-specific estimates of ongoing DNA injury, such as micronuclei, as well as development of aneuploidy and alterations in oncogenes. A class of biomarkers of increasing importance assess proliferation and growth regulation, and include proliferating cell nuclear antigen (PCNA), TGF-beta, EGFR and retinoid receptors. Other markers, such as the blood group antigens, reflect differentiation and may be associated with the development of premalignant lesions. Preliminary data from several of these markers has suggested an association with carcinogenic exposures and premalignant lesions, but none of these markers either alone or in panels have yet been validated as a reliable surrogate for the development of invasive cancer.

Double minute chromosomes and homogeneously staining regions in tumors taken directly from patients versus in human tumor cell lines

There is increasing evidence that copies of amplified oncogenes or drug-resistant genes located on extrachromosomal DNA (e.g. double minutes and/or episomes) can be eliminated from mammalian tumor cell lines by treatment of the cells with low concentrations of hydroxyurea. However, amplified oncogenes or drug-resistant genes located in an intrachromosomal site (such as in a homogeneously staining region (HSR)) cannot be eliminated from the cells. A question which arises is do primary human tumors have extrachromosomal DNA present often enough to make elimination of that extrachromosomal DNA a potentially important therapeutic strategy? To address that question we have reviewed published cytogenetic analyses of 200 tumors taken directly from patients to determine the percentage of primary human tumors which have amplified genes present on extrachromosomal DNA (present in the form of double minutes [DMs]) vs the percentage of tumors which have amplified genes located on an intrachromosomal site (in the form of HSRs). Of the 200 primary human tumors reviewed, 91% contained DMs only, 6.5% contained HSRs, and 2.5% contained both. Of interest, in a parallel review of 109 cell lines with cytogenetic and/or molecular evidence of gene amplification, 60.6% contained DMs, 26.6% contained HSRs, and 12.8% contained both. These data indicate that DMs are the predominant cytogenetic marker for gene amplification in patients, but are present less frequently in established cell lines. These findings indicate that ongoing efforts to eliminate amplified drug-resistant genes or oncogenes contained on DMs (or precursors of DMs) from tumor cells may be relevant for in vivo situations.

Steroid receptors, cellular kinetics, and lymph node status as prognostic factors in breast cancer

Steroid receptor status, cellular kinetics, abnormal proto-oncogene presence, and lymph node metastases all have been shown to provide prognostic information in breast cancer. The factors guide the choice of therapy and predict the course of the disease. Both disease-free survival and overall survival are predicted by these variables. Steroid receptors are the most reliable predictor of hormonal responsiveness. Lymph node involvement is crucial in determining the extent of the disease and the need for adjuvant therapy. Cellular kinetics and abnormal proto-oncogene presence predict tumor aggressiveness. Together these prognostic factors provide considerable information to the clinician.