The impact of radiation dose in combined external beam and intraluminal Ir-192 brachytherapy for bile duct cancer.

PURPOSE

To examine the impact of radiation dose on both survival and morbidity in combined modality treatment of bile duct cancer.

METHODS AND MATERIALS

Forty-eight patients with cancer of the extrahepatic bile ducts were treated at Thomas Jefferson University Hospital from 1984-1990. Twenty-four patients received radiation as part of a combined modality approach using external beam radiation, brachytherapy implant and chemotherapy. Twenty-four patients received no radiation in the course of their treatment. Radiation was delivered via high energy photons at standard fractionation, 5 days/week, for an average of 46 Gy. The implant used Ir-192 ribbon sources (average activity was 29 mCi, active length was 6 cm) for a mean dose of 25 Gy at 1 cm. Chemotherapy consisted of 5-FU alone or combined with adriamycin or mitomycin-C.

RESULTS

Two-year survival for all 48 patients was 18% (median 9 months). Patients treated with radiation had a 2-year survival of 30% (median 12 months) vs. the no-radiation group, 17% (5.5 months, median), p = 0.01. Those treated to > 55 Gy experienced an extended 2-year survival of 48% (24 months, median), vs. those receiving < 55 Gy, 0% (6 months, median), p = 0.0003. This benefit was also seen when patients were stratified by T-stage. A dose response is further suggested by a lengthening of the median survival with increasing radiation dose (4.5 months, 9 months, 18 months and 25 months for < 45 Gy, 45-55, 55-65, 66-70 Gy, respectively). Neither surgical resection nor chemotherapy produced statistically significant benefits as independent variables. Complications due to radiation occurred in only one patient.

CONCLUSION

A dose response is shown with more than double the 2-year and median survival for doses > 55 Gy. A brachytherapy dose of 25 Gy, plus 44-46 Gy external beam is well tolerated. High dose combined brachytherapy and external beam radiation (60-75 Gy) appears to be the most effective modality for extrahepatic bile duct cancer.