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Purpose: To assess the efficacy of perioperative implantation of iridium-192 for stage I and II breast cancer., Materials and Methods: The authors retrospectively reviewed findings from 655 patients with stage I and II cancer treated with conservative surgery and Ir-192 implantation between 1982 and 1992. Hollow plastic tubes were placed in the tumor bed as a single- or double-plane implant at lumpectomy. Ribbons with Ir-192 seeds were inserted into the tubes 4-6 hours later. The Ir-192 was left in place for approximately 50 hours. External-beam irradiation was given to the whole breast 10-14 days later., Results: Follow-up ranged from 2 to 146 months. The local control at 10 years for stage I and II disease was 93% and 87%, respectively. The 10-year actuarial survival rate was 92% +/- 1 for stage I disease and 72% +/- 4 for stage II disease. The rate of survival with no evidence of disease for stage I and II disease combined was 82% +/- 1 at 5 years and 75% +/- 3 at 10 years., Conclusion: Perioperative implantation produced excellent local control equal to that with electron-beam therapy.

Two hundred forty-five women (250 breasts) with early-stage breast cancer were treated between June 1982 and June 1990 with lumpectomy, immediate (boost) interstitial iridium-192 to 15-20 Gy, and external-beam irradiation to the entire breast to 45-50 Gy. There were 123 stage I cancers (T1N0M0), 123 stage II cancers (36 T1N1, 50 T2N0, 33 T2N1, four T3N0), and four stage III cancers (two T2N2, two T3N1). At a median follow-up of 69 months (range, 26-122 months), there were 14 recurrences in the treated breasts. Four were at the site of primary disease, eight were in other quadrants, and two were in both. With immediate interstitial boost, the 11-year actuarial recurrence rate in the breast is 7.7% and the recurrence rate at the site of primary disease is 3.2%.

Several new electron-affinic compounds have been shown to possess radiosensitizing ability in hypoxic mammalian cells. The correlation between chemical structure and biological activity can aid in the design and synthesis of new agents with potentially greater hypoxic cell radiosensitizing ability.

Intraoperative interstitial implantation of iridium 192 during a lumpectomy for carcinoma of the breast has been well tolerated by the patient. This procedure has decreased the need for anesthesia and repeat hospitalization.

Preliminary results indicate that film dosimetry is a simple and precise method of determining volume dose distributions. Calculated dose distributions using computers or estimations of surface dose using TLD dosimeters are within 5% of the measured dose. Initial attempts to find suitable alternate techniques tailored to each clinical situation are encouraging.