Lung cancer chemoprevention with retinol palmitate. Preliminary data from a randomized trial on stage Ia non small-cell lung cancer.

On the basis of epidemiologic and experimental evidence of an anticancer activity of vitamin A, a randomized clinical trial was activated in Milan with the aim of evaluating if retinol palmitate administration (per os, 300,000 I.U. daily) after complete resection of stage Ia non small-cell lung cancer could reduce the occurrence of cancer relapses (within 3 years) and/or the occurrence of new primary tumors (beyond 3 years). By September 1987, 181 patients had entered the trial: 87 in the treatment arm and 94 in the control arm. After a median follow-up of 14 months, the interim analysis was focused on the evaluation of toxicity, compliance, and early recurrences. Although the large majority of patients were affected by skin and mucous membrane desquamation and dryness during treatment, these symptoms were generally mild and well tolerated, and never induced the patient to stop the treatment. Other side effects like headache, hair loss, itching, or dyspepsia were detected at a much lower frequency. Only in 3 patients the treatment was interrupted, because of signs or symptoms potentially related to vitamin A administration. At the time of the analysis, a total of 42 (23%) patients had relapsed; 16 (18%) in the treated arm, and 26 (28%) in the control arm. The largest difference between treated patients and controls was observed for bone metastases (2 vs. 7) and brain metastases (3 vs. 6), and for squamous histology (6 vs. 11). Only 2 cases of new primary cancer were detected, both in the control arm. These results are promising both in terms of tolerance and efficacy of treatment, but given the short median follow-up they must be very cautiously interpreted. A longer follow-up is necessary to establish whether a significant proportion of early recurrences could be prevented, or only delayed, by vitamin A administration.