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Título

THE VITAMIN E LEVELS AND RELATIONSHIP ACUTE TOXICITY IN PROSTATE CANCER PATIENTS TREATED WITH RADICAL RADIOTHERAPY

Resumo

Introduction: Radiotherapy is an important curative treatment modality in the management of prostate cancer. Vitamin E is an important antioxidant, with great potential to protect the organism against damage caused by radiotherapy treatment. Knowledge of serum antioxidant levels during radiotherapy, such as vitamin E, can offer benefits such as reducing the amount and intensity of adverse effects and reducing the toxicity of the method as well. Objective: To analyze the possible correlation between vitamin E levels and the appearance of acute radiotherapy-induced toxicity. Methods: 54 consecutive patients with a diagnosis of carcinoma of the prostate treated by radiotherapy with a radical intent (70 Gy in 28 fractions). Vitamin E measurement was performed before radiotherapy. No patient received corrective treatment for Vitamin E levels. Acute gastrointestinal (GI) toxicity was analyzed weekly during radiotherapy and 7-10 days after therapy ended. To analyze acute GI toxicity, we used RTOG criteria. Results: 54 patients with an average age of 67.6 years (55-79 / CI95% 65,9-69,3 / SD ± 4,9) were evaluated. The serum vitamin E average was 1,17 mg/dL (0,5-5,0 / CI95% 0,8-1,5 / SD ± 0,6) and the average after radiotherapy was 0,57 mg/dL (0,06-1,35 / CI95% 0,45-0,69 / SD ± 0,35), with statistically significant difference (p < 0,0001). Dividing the patients into 2 groups, where Group 1 with Vitamin E < 1,0 mg/dL and group 2 with Vitamin E ≥ 1,0 mg/dL, we have 17 (31,5%) patients in Group 1 and 37 (68,5%) patients in group 2. No acute toxicity attributable to radiotherapy was seen in 13 patients (24%). Grade 1 toxicity was seen in 31 patients (57,4%), grade 2 in 9 (16.7%), and grade 3 in 1 (1,9%). The incidence of toxicity was analyzed in patients groups the vitamin E in table 1.
Vitamin E
Degree of toxicity Group 1 Group 2
G0 1 (7,7%) 12 (92,3%)
G1 8 (25,8%) 23 (74,2%)
G2 7 (77,8%) 2 (22,2%)
G3 1 (100%) 0 (0%)
p < 0,001
Conclusion: A vitamin E deficit after radiotherapy was observed. This highlights the need to monitor serum levels throughout radiotherapy treatment to minimize some of its deleterious side effects. Prostate cancer patients undergoing radiotherapy with low Vitamin E were more likely to experience Grade 2–3 acute gastrointestinal toxicity.