Objectives: Use of naturopathic and nutritional supplements (NNS) with antioxidant activity is controversial in patients receiving radiation therapy. The effects of concomitant use of NNS with antioxidant activity during radiation therapy for prostate cancer were investigated in terms of clinical tumor responsiveness, kinetics, and durability.
Materials and methods: A retrospective investigation was done of 134 patients treated with curative intent for limited-stage prostate cancer by radiation therapy. Patients self-selected to receive NNS as part of their treatment and maintenance during an extended post-treatment interval of at least 2 years. The outcome measures were the following: prostate-specific antigen (PSA) nadir; ≥24 months post-treatment PSA; time to reach nadir; and time to last follow-up were compared across +NNS and -NNS.
Results: Sixty-nine (69) patients elected to receive NNS while 65 did not. Seventy-seven (77) (+NNS 39, -NNS 38) patients received hormone therapy while 57 (+NNS 30, -NNS 27) did not. In the nonhormone cohort, median pretreatment PSA, nadir, post-treatment PSA, time to reach nadir, and time to follow-up were 5.5 ng/mL, 0.56 ng/mL, 0.61 ng/mL, 25 months, and 39.7 months for the -NNS group and 5.1 ng/mL, 0.32 ng/mL, 0.44 ng/mL, 27 months, and 50.1 months for the +NNS group, respectively (p>0.05 for all). Similarly, no significant differences were observed between +NNS and -NNS in the hormone-receiving cohort.
Conclusions: The clinical tumor response to radiation therapy in patients with limited-stage prostate cancer is not inhibited by concomitant NNS based on the magnitude of the PSA response, the velocity of the PSA nadir, and the duration of PSA normalization.