Can the cost of permanent prostate implants be reduced? An argument for peripheral loading with higher strength seeds

To evaluate the economic impact of higher vs. lower strength permanent radioactive seeds used for prostate brachytherapy in the treatment of localized adenocarcinoma of the prostate.

Treatment plans for 50 patients who received an iodine 125 implant as monotherapy for favorable risk prostate cancer were reviewed and specific activity (mCi/cc) was determined for prostate volumes that ranged from 12 to 87 cc. Current prices for individual model 6711 125I seeds were obtained from the manufacturer (Nycomed/Amersham). Total seed costs for three theoretical prostate implant volumes of 25, 40, and 55 cc were calculated using seed strengths of 0.25, 0.34, 0.50, and 0.75 mCi/seed.

Specific activities for prostate volumes of 25, 40, and 55 cc were 1.25, 1.15, and 1.00 mCi/cc, respectively. Total seed cost was inversely related to seed strength. For a 25-cc prostate the cost ranged from $1,890 (0.75 mCi/seed) to $5,625 (0.25 mCi/seed), for a 40-cc prostate $2,745 to $8,280, and for a 55-cc prostate $3,285 to $9,900. For a medium-sized gland (40 cc), the treatment plan using a seed strength of 0.75 mCi/seed resulted in a total seed cost of $2,745 vs. $6,075 for a plan using an activity of 0.34 mCi/seed. This savings of approximately 55% in total seed cost between seed strengths of 0.75 and 0.34 mCi/seed held true for small (25 cc) and large (55 cc) prostate volumes as well.

Given the current prices for 125I individual seeds, prostate implants using a peripheral loading technique with higher activity seeds may result in a significantly lower material cost than techniques using lower activity seeds. However, issues regarding morbidity as well as sensitivity to source placement error need to be addressed further before any final conclusions can be made.