High-dose rate intracavitary therapy for cervical cancer with a microSelectron: a preliminary report

Our early experience using microSelectron HDR to treat cervical cancer patients at Osaka University Hospital is presented. From June 1991 through December 1992, a total of 20 patients (stage Ib, 6; stage IIa, 2; stage IIb, 5; stage IIIb, 6 and stage IVa, 1) with previously untreated invasive uterine cervical cancer and intact uterus were treated with high-dose rate intracavitary therapy administered with a microSelectron. For the treatment, a standard rigid applicator made of stainless steel for a microSelectron was used. Twenty to 30 Gy of external irradiation was administered to the whole pelvic field and 30 to 20 Gy to the central shielded field (total 50 Gy/5-6 weeks) for patients in stage II-IVa. For stage Ib, 40 Gy was delivered to the central shielded field. The 192Ir source had an activity of 370 GBq as of the measuring time. Source loading corresponded to the Manchester System for cervical cancer. Thirty-two or 30 Gy was administered at point A in four fractions over four weeks of intracavitary irradiation. Early primary tumor responses for all patients were complete. There have been two local recurrences in stage IIb and IIIb patients. Three patients in stages Ib, IIb, and IIIb developed para-aortic lymph node metastases, and two of them died from generalized metastasis. No acute radiation injury has been observed. One patient in stage IIb developed subileus five months after irradiation. From our early experience, it is concluded that microSelectron HDR can be used for cervical cancer patients as safely and effectively as our previously used high-dose rate machine.