The quantity of beta-carotene (BC) accumulated in colonic polyps and colonic cancerous tissue in humans in situ was determined relative to the quantity accumulated in normal colon and rectal tissue. Serum concentration of BC, retinol, and alpha-tocopherol and tissue BC concentration were determined by high-performance liquid chromatography in samples obtained before and after oral supplementation with BC (30 mg/day). The serum BC and retinol concentrations significantly increased in response to supplementation in control, polyp, and cancer patients, but there was no change in serum alpha-tocopherol concentration. The BC concentration in tissue (colon, rectum, and tumor) of cancer patients was significantly less than that in tissue samples from control and polyp patients. Relative to baseline values, BC accumulated to a significant extent in tissues from all patients, including polyp and tumor tissue, during supplementation. The results indicate that BC does accumulate in colonic neoplastic tissue in humans and may potentially be utilized to augment cytotoxicity of chemotherapeutics or to prevent malignant transformation of cells.

The patients with colonic cancer seemed to undergo a significant reduction in their antioxidant reserves with respect to the normal subjects and or polyps. We can confirm that oral B-carotene supplementation induces also an increase in plasma alpha-carotene in all groups.

The isolated retroperitoneal malignant schwannoma unassociated with Von Recklinghausen's disease is an unusual neoplasm, representing 0.01% of all retroperitoneal malignant neoplasms, with a poor prognosis, and an average survival at 5 years of 50% in patients treated by radical exeresis. At present, it is impossible, without histologic and immunohistochemical examinations, to differentiate it from other isolated retroperitoneal sarcomatous neoplasms. The authors report a case of retroperitoneal malignant schwannoma 20 cm in diameter in a 62-year-old woman surgically treated by radical exeresis. Postoperative complications were absent, and the patient, discharged from the hospital on the 12th postoperative day, died 8 months later of diffuse metastases, without local relapse. Despite the patient's short survival, the authors believe radical surgery to be the best therapeutic choice. Only surgery can establish a final diagnosis and can offer the best chance of survival and a significant and sometimes prolonged relief of symptomatology.

In consideration of findings reported in the literature and of our study, we examined the correlation between antioxidants (beta-carotene, vitamin C, vitamin E) and colorectal carcinogenesis. Although diagnostic progress has been made in the last decades, no significant improvements in death rates have been achieved in the western world. Exogenous factors might be responsible for a complex alteration process of might be responsible for a complex alteration process of normal colonic mucosa into adenoma and carcinoma. Free radicals and reactive oxygen metabolites, due to increased production or to reduced inactivation, following a decrease in the antioxidant burden in the mucosa, might cause damage to DNA, thereby resulting in genetic alterations. This might represent the cause of the transformation process: normal mucosa --> adenoma --> carcinoma. In a prospective study, we observed a reduction of beta-carotene levels in normal colonic mucosa in patients with polyps and colorectal cancer. We also showed that beta-carotene supplementation raises levels of this micronutrient in the colonic mucosa of these patients. Findings from the literature and our trials show a significant decrease in the antioxidant capacity of colorectal mucosa in patients affected by colorectal cancer, although there is a significant interindividual variability. Such results suggest a possible chemopreventive role of antioxidant agents in colorectal cancer.

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