Permanent interstitial implantation using palladium-103: the New York Medical College preliminary experience

Palladium-103 is a low energy photon emitter available for permanent interstitial implantation. Pd-103 has energy and safety characteristics similar to Iodine-125, but its initial peripheral dose rate is approximately three times greater. This may provide improved control of rapidly proliferating tumors. At the Westchester Campus of New York Medical College, 15 patients with residual or recurrent unresectable lesions were implanted with Pd-103. There were five males and 10 females with an age range of 41 to 93 years (median 58). Implanted sites included the chest wall, nasopharynx, vagina, and zygomatic region. Peripheral doses ranged from 55 to 203 Gy (median 107 Gy). A complete response was achieved in eight patients and a partial response in seven patients, for an overall response rate of 100%. We noted improved control with smaller volumes and peripheral doses at or above 115 Gy. No unusual skin or mucosal reactions were recorded. Possible advantages of Pd-103 as a substitute for I-125 include improved control of rapidly proliferating tumors and a more rapid clinical response of lesions. Disadvantages include current higher cost and an impracticality in maintaining a running inventory because of the short half-life of the isotope. Our experience suggests that Pd-103 is an attractive alternative to I-125.