Randomized trial of fenretinide to prevent second breast malignancy in women with early breast cancer.

BACKGROUND: Fenretinide, a vitamin A analogue, has been shown to inhibit breast carcinogenesis in preclinical studies. We determined the efficacy of fenretinide in preventing a second breast malignancy in women with breast cancer. METHODS: We randomly assigned 2972 women, aged 30-70 years, with surgically removed stage I breast cancer or ductal carcinoma in situ to receive for 5 years either fenretinide orally (200 mg/day) or no treatment. The primary end point was the incidence of contralateral breast cancer or ipsilateral breast cancer 7 years after randomization. Other end points considered post hoc were the same outcomes stratified by menopausal status, incidence of distant metastases, overall mortality, and tumors in other organs. The hazards of breast cancer occurrence were determined by Cox proportional hazards regression analysis. Statistical tests were two-sided. RESULTS: At a median observation time of 97 months, there were no statistically significant differences in the occurrence of contralateral breast cancer (P =.642) or ipsilateral breast cancer (P =.177) between the two arms. However, an interaction was detected between fenretinide treatment and menopausal status in both outcomes (P for interaction in both outcomes =.045), with a possible beneficial effect in premenopausal women (contralateral breast cancer: adjusted hazard ratio [HR] = 0.66, and 95% confidence interval [CI] = 0.41-1.07; ipsilateral breast cancer: adjusted HR = 0.65, and 95% CI = 0.46-0. 92) and an opposite effect in postmenopausal women (contralateral breast cancer: adjusted HR = 1.32, and 95% CI = 0.82-2.15; ipsilateral breast cancer: adjusted HR = 1.19, and 95% CI = 0.75-1. 89). There were no statistically significant differences between the two arms in tumors in other organs, incidence of distant metastasis, and all-cause mortality. CONCLUSIONS: Fenretinide treatment of women with breast cancer for 5 years appears to have no statistically significant effect on the incidence of second breast malignancies overall, although a possible benefit was detected in premenopausal women. These studies, particularly the post hoc analyses, are considered exploratory and need to be confirmed.

Studies evaluating antioxidants and beta-carotene as chemopreventives.

Cancer chemoprevention research takes leads from epidemiologic and laboratory research and develops them through in vitro and in vivo preclinical research and initial human studies into randomized controlled clinical trials. At present, the chemoprevention program is sponsoring 21 human efficacy studies. These trials are testing the potential of agents (beta-carotene, folic acid, 13-cis retinoic acid, 4-hydroxyphenyl retinamide, vitamins C and E, and minerals) as inhibitors of a variety of cancers in humans (colon, lung, esophagus, cervix, bladder, and skin). Endpoints in these studies include overall incidence of cancer, incidence of specific cancers, rate of regression or progression of preneoplastic changes, and changes in cellular or biochemical parameters. Study participants include volunteers from the general population; populations at high risk for cancer because of occupation, lifestyle, or place of residence; persons with previously treated cancers; and persons with preneoplastic lesions. Study designs include single agent randomization, combination of agents and complete factorial designs.

Randomized trial of fenretinide in superficial bladder cancer using DNA flow cytometry as an intermediate end point.

Retinoids have shown a potential activity in preventing tumor recurrence in superficial bladder cancer. We assessed the activity of the synthetic retinoid fenretinide in superficial bladder cancer using DNA flow cytometry and conventional cytology as surrogate biomarkers. A total of 99 subjects with resected superficial bladder cancer (pTa, pT1) were randomized to either fenretinide (200 mg day p.o. for 24 months) or no intervention. Cystoscopy and bladder washing for DNA flow cytometry end points (proportion of DNA aneuploid histograms, hyperdiploid fraction, and percentage of apoptotic cells) and proportion of abnormal cytological examinations were repeated every 4 months for up to 36 months. The primary study end point was the proportion of DNA aneuploid histograms after 12 months. This figure was 48.9% in the fenretinide arm and 41.9% in the control arm (odds ratio, 1.16; 95% confidence interval, 0.44-3.07). There was no difference in any other response biomarker between the two groups up to 36 months, nor was any biomarker able to predict recurrence risk. Recurrence-free survival was comparable between the arms (27 events in the fenretinide arm versus 21 in the control arm; P = 0.36). Twelve subjects in the fenretinide arm complained of diminished dark adaptability, and nine subjects in the fenretinide arm versus one control subject had mild dermatological alterations. We conclude that fenretinide showed a lack of effect on the DNA content distribution and the morphology of urothelial cells obtained in serial bladder washings. Recurrence-free survival was comparable between groups. Because our data are hampered by the lack of predictivity of the selected biomarkers, additional studies are necessary to assess the activity of fenretinide in preventing bladder cancer.

Study of postnatal effects of chemopreventive agents on offspring of ethylnitrosourea-induced transplacental carcinogenesis in rats. I. Influence of retinol acetate, alpha-tocopherol acetate, thiamine chloride, sodium selenite, and alpha-difluoromethylornithine.

We studied the influence of the vitamins retinol acetate, alpha-tocopherol acetate and thiamine chloride; the antioxidant sodium selenite and an inhibitor of polyamine biosynthesis, alpha-difluoromethylornithine, on the offspring of transplacental carcinogenesis by ethylnitrosourea in rats. Ethylnitrosourea was given to pregnant rats as a single i.v. injection, at a dose of 75 mg/kg body wt. or 5.5 mg/kg body wt., on the 21st day after conception. Retinol, tocopherol or thiamine was added to the diet, and selenite and alpha-difluoromethylornithine to drinking water of the offspring throughout their postnatal life at moderate doses. In control groups, ethylnitrosourea induced tumors of brain, spinal cord, peripheral nervous system and kidneys in the offspring. alpha-Difluoromethylornithine exerted a slight inhibitory effect; this agent decreased the total tumor multiplicity and the multiplicity of peripheral nervous system tumors and also prolonged survival time. Retinol, tocopherol, thiamine and selenite did not influence the development of the transplacentally-induced tumors.

Chemoprevention clinical trials.

As part of a program to develop drugs which will delay or prevent cancer in humans, the Chemoprevention Branch, National Cancer Institute, National Institutes of Health, is sponsoring 12 Phase I and 22 Phase II and III clinical trials. Three agent classes are significantly advanced in the trials. These are the retinoids, including 13-cis-retinoic acid, retinol, and 4-hydroxyphenylretinamide (nine studies), beta-carotene (seven studies), and calcium compounds (three studies). In addition, six promising new compounds are in Phase I or Phase II trials. These are: piroxicam, ibuprofen, oltipraz (a dithiolthione), difluoromethylornithine, glycyrrhetinic acid, and N-acetylcysteine. Key concepts related to the development of cancer chemopreventive agents are (1) the need for long-term administration, (2) the need for oral route of administration, (3) the matching of toxic side effects to degree of cancer risk.

Dental vacuum system with skirt technology.

A heat-sterilizable vacuum system (Legend) featuring a skirt technology that confines the user's hand to the sterile instruments during initial hose coupling and during patient treatment is described. Because the user does not grasp the non-sterile vacuum hose connector and hose, plastic barriers and mandatory disinfection of the hose connector, hose, and instrument holders after each patient are not necessary. The vacuum system described promotes asepsis by using sterile vacuum instruments, encourages sound asepsis practice, prevents cross-contamination, and is cost-effective.

Programmed tooth preparation for fixed partial dentures.

This article describes a method for efficient and precise tooth preparation for fixed partial dentures. Diagnostic procedures are also reviewed.

Designs for cast metal restorations.

This article reviewed clinical conditions that assist selection of specific design decisions for the tooth preparation for cast metal restorations. This decision should result in a conservative restoration for a given clinical situation. A paradigm is included to assist the dentist in the decision-making process.

Tissue management with dental impression materials.

The coordination of perceptive tissue management, diligent tooth preparation and prudent selection of the impression material for specific clinical conditions ensures the success of cast and ceramic restorations. The introduction of a knitted cord (Ultrapak with Astringedent) has alleviated the arduous aspects of tissue displacement and the new impression materials have displayed exceptional accuracy but healthy tissue is fundamental.